JP2017150917A - Tsunami detector using ocean radar, tsunami detection program using ocean radar, and performance verification method for ocean radar - Google Patents
Tsunami detector using ocean radar, tsunami detection program using ocean radar, and performance verification method for ocean radar Download PDFInfo
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Abstract
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本願発明は、海洋レーダが受信した反射信号に基づいて津波を検知する技術に関し、より詳しくは異なる地点で算出される移動流の流速変動の相関によって津波の有無を判定しうる津波検知装置とこれに用いるプログラム、さらには海洋レーダの性能を検証する方法に関するものである。 The present invention relates to a technique for detecting a tsunami based on a reflected signal received by a marine radar, and more specifically, a tsunami detection apparatus capable of determining the presence or absence of a tsunami based on the correlation of flow velocity fluctuations of a moving flow calculated at different points. The present invention relates to a program used for the inspection, and a method for verifying the performance of the marine radar.
我が国は地震が頻発する国として知られ、近年では、東北地方太平洋沖地震をはじめ、兵庫県南部地震、新潟県中越地震など大きな地震が発生し、そのたびに甚大な被害を被っている。兵庫県南部地震や新潟県中越地震による被害が地震動による直接的なものであったのに対して、東日本大震災では津波によって計り知れない被害を受けた。極めて甚大な災害を受けたことによって、改めて津波の脅威を認識すると同時に、津波への備えに対する意識が高まっている。 Japan is known as an earthquake-prone country, and in recent years, major earthquakes such as the Tohoku-Pacific Ocean Earthquake, the Hyogoken-Nanbu Earthquake, and the Niigata-ken Chuetsu Earthquake have occurred. While the damage caused by the Hyogoken-Nanbu Earthquake and the Niigata Chuetsu Earthquake was directly caused by ground motion, the Great East Japan Earthquake suffered immeasurable damage from the tsunami. As a result of the enormous disaster, the tsunami threat has been recognized again, and at the same time, awareness of tsunami preparedness has increased.
津波から身を守るには、安全な場所への避難を一刻も早く開始することが極めて重要である。早期の避難開始は、より安全な場所への移動を可能とするからである。早期の避難を促すには、当然ながら津波の発生をできるだけ早く検知する必要があり、したがってこれまでも様々な手法によって津波を検知する試みがなされてきた。 To protect yourself from the tsunami, it is extremely important to start evacuation to a safe place as soon as possible. This is because early start of evacuation makes it possible to move to a safer place. In order to promote early evacuation, it is of course necessary to detect the occurrence of a tsunami as soon as possible, and so far, attempts have been made to detect tsunamis by various methods.
例えば、ＧＰＳ波浪計による津波検知が挙げられる。水深２００ｍ程度の海域にＧＰＳを取り付けたブイを設置し、ブイの上下変動の計測から波の高さを観測することで津波の発生を判定するわけである。現在、国により東北地方の日本海沿岸および東北地方から九州地方にかけての太平洋沿岸に１８基が設置されている。ただし、この手法によれば、検知する対象が特定の海域に限られ、しかも比較的高い設置・維持管理コストが掛かり、さらにはブイを繋ぐ係留索が切断する事故が発生するといった問題もある。 For example, the tsunami detection by a GPS wave meter is mentioned. A buoy with a GPS attached is installed in a sea area with a depth of about 200 m, and the occurrence of a tsunami is determined by observing the height of the wave from the measurement of vertical fluctuations of the buoy. Currently, 18 units are installed on the coast of the Sea of Japan in the Tohoku region and on the Pacific coast from Tohoku to Kyushu. However, according to this method, there is a problem that a target to be detected is limited to a specific sea area, and a relatively high installation / maintenance management cost is required, and further, an accident occurs in which a mooring line connecting buoys is cut.
その他、紀伊半島熊野灘沖で設置され、東北太平洋沖で整備が進められている海底設置式のネットワーク化された圧力計による津波検知が挙げられる。海底に設置した圧力計によって計測した水圧から海面の高さを観測することで津波の発生を判定するわけである。ただしこの手法によれば、広大な海域に網羅的に圧力計を設置することから、圧力計の計測信号を伝送するためのケーブルを張り巡らせる必要があり相当なコストがかかるうえ、漁業が盛んな沿岸域（岸から数十キロ）への設置が難しいといった問題がある。 Another example is tsunami detection using a networked pressure gauge installed off the coast of Kumino Peninsula and off the coast of the Tohoku Pacific Ocean. The occurrence of a tsunami is determined by observing the sea level from the water pressure measured by a pressure gauge installed on the seabed. However, according to this method, the pressure gauges are installed comprehensively in a vast sea area, so it is necessary to install a cable for transmitting the pressure gauge measurement signal, which costs considerable costs and the fishing industry is prosperous. There is a problem that it is difficult to install in the coastal area (tens of kilometers from the shore).
津波を検知するための海域計測としては、上記のほか海洋レーダが挙げられる。海洋レーダは陸域に設置する観測機器で、広く海面に電波を照射し、海面からの反射波を受信して解析することで海の表層の流況（流向・流速）を面的に取得することができる。すなわち海洋レーダは、ＧＰＳ波浪計と比較して対象とする海域がより広範囲であり、沖合から沿岸域まで津波の伝播をシームレスに連続的に観測できる。さらには、陸域設置の観測機器のため、ＧＰＳ波浪計や海底設置式の水圧計と比べ設置・維持管理コストを大幅に抑えることができる。 In addition to the above, marine radar can be used as the sea area measurement for detecting tsunamis. Ocean radar is an observation device installed on land, and it obtains the surface current (flow direction / velocity) of the surface of the sea by irradiating radio waves widely on the sea surface and receiving and analyzing reflected waves from the sea surface. be able to. In other words, the marine radar has a wider target sea area than the GPS wave meter, and can continuously and continuously observe the propagation of the tsunami from the offshore to the coastal area. Furthermore, since it is an observation device installed on land, installation and maintenance costs can be significantly reduced compared to GPS wave meters and seafloor type water pressure gauges.
ところで海洋レーダは、従来、海の表層の流況を把握することを目的として利用されてきたもので、津波を検出するために積極的に利用が検討されることは多くなかった。その中でも特許文献１では、津波のような表層流速変化の速い現象を検出することを目的としている。 By the way, the marine radar has been used for the purpose of grasping the flow condition of the surface layer of the sea, and it has not been actively studied to detect the tsunami. Among them, Patent Document 1 aims to detect a phenomenon such as a tsunami that causes a rapid change in the surface layer flow velocity.
特許文献１に開示された技術によれば、ドップラ周波数データの算出周期を十分に短縮する（例えば２分間隔）ことができることから、津波のように短時間に海の表層の流速が変化する現象を検出できる可能性が高まる。ところが特許文献１の技術は、既述した従来の海洋レーダの目的と同様に、あくまで海の表層の流況を把握するものである。津波発生時の流れには海流や潮流などの背景流が含まれるが、特許文献１ではこれらの現象を切り分けることなく、いわば合成したものとして海の表層の流況を把握する。本来であれば、得られた海の表層の流況から背景流の影響を取り除いた上で、津波か否かを判断し、あるいはその津波の速度や方向を算出することが望ましいが、特許文献１の技術ではこれを実現することはできない。 According to the technique disclosed in Patent Document 1, since the calculation period of Doppler frequency data can be sufficiently shortened (for example, every two minutes), a phenomenon in which the flow velocity of the sea surface layer changes in a short time like a tsunami. The possibility that can be detected increases. However, the technique of Patent Document 1 grasps the flow condition of the surface layer of the sea just like the purpose of the conventional marine radar described above. The flow at the time of tsunami generation includes background currents such as ocean currents and tidal currents. However, Patent Document 1 grasps the flow conditions of the surface layer of the ocean as if they were synthesized without separating these phenomena. Originally, it is desirable to determine the tsunami or calculate the speed and direction of the tsunami after removing the influence of the background current from the obtained surface current of the ocean. This is not possible with the first technology.
本願発明の課題は、従来が抱える問題を解決することであり、すなわち海洋レーダが直接観測する観測流から背景流を除去した流れ（以下、「移動流」という。）に基づいて、津波を検知することができる海洋レーダによる津波検知装置、海洋レーダによる津波検知プログラム、及び海洋レーダの性能検証方法を提供することである。 An object of the present invention is to solve the problems of the prior art, that is, to detect a tsunami based on a flow obtained by removing a background flow from an observation flow directly observed by an ocean radar (hereinafter referred to as a “moving flow”). A marine radar tsunami detection device, a marine radar tsunami detection program, and a marine radar performance verification method.
本願発明は、海洋レーダが直接観測する観測流から移動流を抽出するとともに、異なる地点の移動流の流速変動を比較してその相関に応じて津波検知の判断を行う、という点に着目したものであり、従来にはなかった発想に基づいてなされた発明である。 The invention of the present application focuses on the fact that the moving flow is extracted from the observation flow that is directly observed by the ocean radar, and the velocity fluctuation of the moving flow at different points is compared and the tsunami detection is judged according to the correlation. It is an invention made on the basis of an idea that has not existed before.
本願発明の海洋レーダによる津波検知装置は、観測流変動算出手段と、代表流速値算出手段、背景流変動算出手段、移動流変動算出手段、着目点変動抽出手段、対比点変動抽出手段、相関度算出手段、津波判定手段を備えたものである。このうち観測流変動算出手段は、海洋レーダの受信信号に基づいて観測流速値を求めるとともに、観測流速値の時刻変動を「観測流の流速変動」とする手段である。代表流速値算出手段は、所定間隔で設定された計算時刻を基準に平滑期間を定め、観測流の流速変動のうち平滑期間内にある観測流速値に基づいて求められる値を計算時刻の代表流速値とする手段である。背景流変動算出手段は、複数の代表流速値からなる代表値時刻変動と、代表値時刻変動に基づいて推定される推測時刻変動からなる流速値の時刻変動を「背景流の流速変動」とする手段である。移動流変動算出手段は、観測流の流速変動と背景流の流速変動に基づいて求められる流速値の時刻変動を「移動流の流速変動」とする手段である。着目点変動抽出手段は、着目観測点における移動流の流速変動から、あらかじめ定めた相関算出期間に相当する部分を「着目点変動」として抽出する手段である。対比点変動抽出手段は、対比観測点における移動流の流速変動から、相関算出期間に相当する部分を「対比点変動」として抽出する手段である。そして相関度算出手段は、着目点変動と対比点変動との相関の程度を求める手段であり、津波判定手段は、相関の程度があらかじめ定めた相関閾値を超えたときに津波の発生と判断する手段である。なお対比観測点は、着目観測点と同一の視線方向上にあって、着目観測点からあらかじめ定めた相関算出距離だけ離れた位置で設定される。 A tsunami detection device using a marine radar according to the present invention comprises an observation flow fluctuation calculation means, a representative flow velocity value calculation means, a background flow fluctuation calculation means, a moving flow fluctuation calculation means, a point of interest fluctuation extraction means, a contrast point fluctuation extraction means, a correlation degree. A calculation means and a tsunami determination means are provided. Among these, the observed flow fluctuation calculating means is a means for obtaining the observed flow velocity value based on the received signal of the marine radar and setting the time fluctuation of the observed flow velocity value as “observed flow velocity fluctuation”. The representative flow velocity value calculating means determines a smooth period based on the calculation time set at a predetermined interval, and calculates a value obtained based on the observed flow velocity value within the smooth period among the flow velocity fluctuations of the observed flow as the representative flow velocity at the calculation time. Means for value. The background flow fluctuation calculation means sets the time fluctuation of the flow velocity value consisting of a representative value time fluctuation consisting of a plurality of representative flow velocity values and an estimated time fluctuation estimated based on the representative value time fluctuation as a “background flow velocity fluctuation”. Means. The moving flow fluctuation calculation means is a means for setting the time fluctuation of the flow velocity value obtained based on the flow velocity fluctuation of the observation flow and the flow velocity fluctuation of the background flow as “moving flow velocity fluctuation”. The point-of-interest fluctuation extracting means is a means for extracting a portion corresponding to a predetermined correlation calculation period from the flow velocity fluctuation of the moving flow at the target observation point as “point-of-interest fluctuation”. The contrast point variation extracting means is a means for extracting a portion corresponding to the correlation calculation period from the flow velocity variation of the moving flow at the contrast observation point as “contrast point variation”. The correlation degree calculating means is a means for obtaining the degree of correlation between the focus point fluctuation and the contrast point fluctuation, and the tsunami determining means determines that a tsunami has occurred when the degree of correlation exceeds a predetermined correlation threshold. Means. The contrast observation point is set at a position that is on the same line-of-sight direction as the target observation point and is separated from the target observation point by a predetermined correlation calculation distance.
本願発明の海洋レーダによる津波検知装置は、観測流の流速変動から背景流の流速変動を差し引くことで、移動流の流速変動を求めるものとすることもできる。 The tsunami detection device using the marine radar according to the present invention can also obtain the flow velocity fluctuation of the moving flow by subtracting the flow velocity fluctuation of the background flow from the flow velocity fluctuation of the observation flow.
本願発明の海洋レーダによる津波検知装置は、平滑期間の終期が観測流速値を求めた最新時刻を超える直前の計算時刻まで、代表流速値を求め代表流速値算出手段を備えたものとすることもできる。この場合の背景流変動算出手段は、代表流速値算出手段が求めた最後の計算時刻より後であって海洋レーダの最新観測時刻までの期間を対象として、推測時刻変動を求める。また背景流変動算出手段は、複数の代表流速値を用いて自己回帰モデルに基づいて推測時刻変動を算出する。 The marine radar tsunami detection device of the present invention may include a representative flow velocity value calculating means for obtaining a representative flow velocity value until a calculation time immediately before the end of the smooth period exceeds the latest time at which the observed flow velocity value was obtained. it can. The background flow fluctuation calculation means in this case obtains the estimated time fluctuation for a period after the last calculation time obtained by the representative flow velocity value calculation means and until the latest observation time of the marine radar. Further, the background flow fluctuation calculating means calculates the estimated time fluctuation based on the autoregressive model using a plurality of representative flow velocity values.
本願発明の海洋レーダによる津波検知装置は、相関の程度が連続して相関閾値を超え、且つ連続する回数があらかじめ定めた繰り返し閾値を超えたときに津波の発生と判断することもできる。この場合相関度算出手段は、所定の時間間隔で継続的に相関の程度を求める。 The tsunami detection device using the marine radar according to the present invention can also determine that a tsunami has occurred when the degree of correlation continuously exceeds the correlation threshold and the number of consecutive times exceeds a predetermined repetition threshold. In this case, the correlation degree calculation means continuously obtains the degree of correlation at predetermined time intervals.
本願発明の海洋レーダによる津波検知装置は、津波が発生しない平常時の相関の程度に基づいて定められる相関閾値を用いることもできる。この場合相関度算出手段は、所定の時間間隔で継続的に相関の程度を求める。 The marine radar tsunami detection device of the present invention can also use a correlation threshold determined based on the degree of normal correlation where no tsunami occurs. In this case, the correlation degree calculation means continuously obtains the degree of correlation at predetermined time intervals.
本願発明の海洋レーダによる津波検知プログラムは、観測流変動算出処理と、代表流速値算出処理、背景流変動算出処理、移動流変動算出処理、着目点変動抽出処理、対比点変動抽出処理、相関度判定処理、津波判定処理をコンピュータに実行させる機能を備えたものである。このうち観測流変動算出処理は、海洋レーダの受信信号に基づいて観測流速値を求めるとともに、観測流速値の時刻変動を「観測流の流速変動」とする処理である。代表流速値算出処理は、所定間隔で設定された計算時刻を基準に平滑期間を定め、観測流の流速変動のうち平滑期間内にある観測流速値に基づいて求められる値を計算時刻の代表流速値とする処理である。背景流変動算出処理は、複数の代表流速値からなる代表値時刻変動と、代表値時刻変動に基づいて推定される推測時刻変動からなる流速値の時刻変動を「背景流の流速変動」とする処理である。移動流変動算出処理は、観測流の流速変動と背景流の流速変動に基づいて求められる流速値の時刻変動を「移動流の流速変動」とする処理である。着目点変動抽出処理は、着目観測点における移動流の流速変動から、あらかじめ定めた相関算出期間に相当する部分を「着目点変動」として抽出する処理である。対比点変動抽出処理は、対比観測点における移動流の流速変動から、相関算出期間に相当する部分を「対比点変動」として抽出する処理である。そして相関度判定処理は、着目点変動と対比点変動との相関の程度を求める処理であり、津波判定処理は、相関の程度があらかじめ定めた相関閾値を超えたときに津波の発生と判断する処理である。なお対比観測点は、着目観測点と同一の視線方向上にあって、着目観測点からあらかじめ定めた相関算出距離だけ離れた位置で設定される。 The tsunami detection program by the marine radar of the present invention includes an observation flow fluctuation calculation process, a representative flow velocity value calculation process, a background flow fluctuation calculation process, a moving flow fluctuation calculation process, a point of interest fluctuation extraction process, a contrast point fluctuation extraction process, and a correlation degree. It has a function for causing a computer to execute determination processing and tsunami determination processing. Among these, the observed flow fluctuation calculation process is a process for obtaining the observed flow velocity value based on the received signal of the marine radar and setting the time fluctuation of the observed flow velocity value as “observed flow velocity fluctuation”. In the representative flow velocity value calculation process, a smoothing period is determined based on the calculation time set at a predetermined interval, and the value obtained based on the observed flow velocity value within the smoothing period among the flow velocity fluctuations of the observed flow is determined as the representative flow velocity at the calculation time. It is processing to be a value. In the background flow fluctuation calculation process, the time fluctuation of the flow velocity value consisting of the representative value time fluctuation composed of a plurality of representative flow velocity values and the estimated time fluctuation estimated based on the representative value time fluctuation is referred to as “background flow velocity fluctuation”. It is processing. The moving flow fluctuation calculation process is a process in which the time fluctuation of the flow velocity value obtained based on the flow velocity fluctuation of the observed flow and the background flow velocity fluctuation is “moving flow velocity fluctuation”. The point-of-interest fluctuation extraction process is a process of extracting a portion corresponding to a predetermined correlation calculation period from the flow velocity fluctuation of the moving flow at the target observation point as the “point-of-interest fluctuation”. The contrast point variation extraction process is a process of extracting a portion corresponding to the correlation calculation period as a “contrast point variation” from the flow velocity variation of the moving flow at the contrast observation point. The correlation degree determination process is a process for obtaining the degree of correlation between the focus point fluctuation and the contrast point fluctuation. The tsunami determination process determines that a tsunami has occurred when the degree of correlation exceeds a predetermined correlation threshold. It is processing. The contrast observation point is set at a position that is on the same line-of-sight direction as the target observation point and is separated from the target observation point by a predetermined correlation calculation distance.
本願発明の海洋レーダの性能検証方法は、仮想津波観測流算出工程と、代表流速値算出工程、背景流変動算出工程、移動流変動算出工程、着目点変動抽出工程、対比点変動抽出工程、相関度判定工程を備えた方法である。このうち仮想津波観測流算出工程では、津波数値計算によって求められた複数地点の流速に基づいて理想津波受信信号を算出し、平常時に海洋レーダが取得した観測受信信号と理想津波受信信号とを複素積によって合成することで合成受信信号を算出し、合成受信信号に基づいて、流速値の時刻変動である仮想津波観測流を算出する。代表流速値算出工程では、所定間隔で設定された計算時刻を基準に平滑期間を定め、観測流の流速変動のうち平滑期間内にある観測流速値に基づいて求められる値を計算時刻の代表流速値とする。背景流変動算出工程では、複数の代表流速値からなる代表値時刻変動と、代表値時刻変動に基づいて推定される推測時刻変動からなる流速値の時刻変動を「背景流の流速変動」とする。移動流変動算出工程では、観測流の流速変動と背景流の流速変動に基づいて求められる流速値の時刻変動を「移動流の流速変動」とする。着目点変動抽出工程では、着目観測点における移動流の流速変動から、あらかじめ定めた相関算出期間に相当する部分を「着目点変動」として抽出する。対比点変動抽出工程では、対比観測点における移動流の流速変動から、相関算出期間に相当する部分を「対比点変動」として抽出する。相関度判定工程では、着目点変動と対比点変動との相関の程度を求める。そして、条件を変えて繰り返し仮想津波観測流算出工程を行うことで複数種類の仮想津波観測流を算出し、相関度判定工程で複数種類の仮想津波観測流から求めた着目点変動と対比点変動に対してそれぞれ相関の程度を求めることによって、海洋レーダの性能を検証する。なお対比観測点は、着目観測点と同一の視線方向上にあって、着目観測点からあらかじめ定めた相関算出距離だけ離れた位置で設定される。 The marine radar performance verification method of the present invention includes a virtual tsunami observation flow calculation step, a representative flow velocity value calculation step, a background flow fluctuation calculation step, a moving flow fluctuation calculation step, a point of interest fluctuation extraction step, a contrast point fluctuation extraction step, a correlation This method includes a degree determination step. Of these, in the virtual tsunami observation flow calculation process, the ideal tsunami reception signal is calculated based on the flow velocities at multiple points determined by the tsunami numerical calculation, and the observation reception signal acquired by the marine radar and the ideal tsunami reception signal are complex. A combined received signal is calculated by combining the products, and a virtual tsunami observation flow that is a time fluctuation of the flow velocity value is calculated based on the combined received signal. In the representative flow velocity value calculation step, a smoothing period is determined based on the calculation time set at a predetermined interval, and the value obtained based on the observed flow velocity value within the smoothing period among the flow velocity fluctuations of the observed flow is determined as the representative flow velocity at the calculation time. Value. In the background flow fluctuation calculation step, the time fluctuation of the flow velocity value consisting of the representative value time fluctuation composed of a plurality of representative flow velocity values and the estimated time fluctuation estimated based on the representative value time fluctuation is referred to as “background flow velocity fluctuation”. . In the moving flow fluctuation calculation step, the time fluctuation of the flow velocity value obtained based on the flow velocity fluctuation of the observed flow and the flow velocity fluctuation of the background flow is referred to as “moving flow velocity fluctuation”. In the point-of-interest variation extraction step, a portion corresponding to a predetermined correlation calculation period is extracted as “point-of-interest variation” from the flow velocity variation of the moving flow at the observation point of interest. In the contrast point variation extraction step, a portion corresponding to the correlation calculation period is extracted as “contrast point variation” from the flow velocity variation of the moving flow at the contrast observation point. In the correlation degree determination step, the degree of correlation between the target point variation and the contrast point variation is obtained. Then, by performing the virtual tsunami observation flow calculation process repeatedly under different conditions, multiple types of virtual tsunami observation flows are calculated, and the target point variation and contrast point variation obtained from the multiple types of virtual tsunami observation flows in the correlation determination step The performance of marine radar is verified by obtaining the degree of correlation for each. The contrast observation point is set at a position that is on the same line-of-sight direction as the target observation point and is separated from the target observation point by a predetermined correlation calculation distance.
本願発明の海洋レーダによる津波検知装置、海洋レーダによる津波検知プログラム、及び海洋レーダの性能検証方法には、次のような効果がある。
（１）海洋レーダが直接観測する観測流から移動流を抽出した上で、津波か否かの判定を行うことから、従来に比してより適切に津波を検知することができる。
（２）異なる地点での観測流の流速変動を照らし合わせ、その相関の程度に基づいて津波の判定を行うもので、この点からも従来に比してより適切に津波を検知することができる。
（３）２地点における観測流の流速変動の相関程度は、津波の発生直後、急激に変化することを発明者らは確認した。つまり本願発明によれば、津波の発生後速やかに津波を検知することが可能となる。
（４）実際の津波が発生する頻度は極めて小さく、したがって複数種類の津波の実測データを得ることは相当の年月を要する。一方、本願発明の海洋レーダの性能検証方法では、津波数値計算を利用して求められる仮想津波観測流を利用することから、比較的容易に複数種類の津波の模擬データを得ることができ、その結果、精度よく海洋レーダの性能を検証することができる。
The marine radar tsunami detection apparatus, marine radar tsunami detection program, and marine radar performance verification method of the present invention have the following effects.
(1) Since a moving flow is extracted from an observation flow directly observed by the ocean radar and a determination is made as to whether or not it is a tsunami, a tsunami can be detected more appropriately than in the past.
(2) Compared with fluctuations in the flow rate of observation streams at different points and makes tsunami determinations based on the degree of correlation. From this point, tsunamis can be detected more appropriately than in the past. .
(3) The inventors have confirmed that the degree of correlation between the fluctuations in the flow velocity of the observation stream at two points changes rapidly immediately after the occurrence of the tsunami. That is, according to the present invention, it is possible to detect a tsunami immediately after the occurrence of the tsunami.
(4) The frequency of actual tsunamis is extremely small, and therefore it takes a considerable amount of time to obtain measured data of multiple types of tsunamis. On the other hand, the marine radar performance verification method of the present invention uses a virtual tsunami observation flow obtained using tsunami numerical calculation, so that it is relatively easy to obtain simulated data of multiple types of tsunamis. As a result, the performance of the marine radar can be verified with high accuracy.
本願発明の海洋レーダによる津波検知装置、海洋レーダによる津波検知プログラム、及び海洋レーダの性能検証方法の実施形態の一例を、図に基づいて説明する。 One example of embodiments of a tsunami detection apparatus using a marine radar, a tsunami detection program using a marine radar, and a performance verification method for a marine radar according to the present invention will be described with reference to the drawings.
１．海洋レーダ
本願発明が海洋レーダを用いた津波検知に関するものであることから、まずは海洋レーダとその観測原理について簡単に説明する。図１は、海面に向けて電波を照射している海洋レーダＯＲを示す平面図である。この図に示すように海洋レーダＯＲは陸域に設置され、電波を海面に向けて放射状に照射する。例えば図１では、第１ビームＢ０１から第１２ビームＢ１２まで計１２のビーム上で流速が観測される。なお海洋レーダＯＲでは、３〜３０ＭＨｚの短波帯や３０〜３００ＭＨｚの超短波帯の電波が多用される。
1. Marine radar Since the present invention relates to tsunami detection using a marine radar, the marine radar and its observation principle will be briefly described first. FIG. 1 is a plan view showing a marine radar OR that emits radio waves toward the sea surface. As shown in this figure, the marine radar OR is installed in a land area and radiates radio waves radially toward the sea surface. For example, in FIG. 1, the flow velocity is observed on a total of 12 beams from the first beam B01 to the twelfth beam B12. In the ocean radar OR, radio waves in a 3-30 MHz short wave band and a 30-300 MHz ultra-short wave band are frequently used.
図２に示すように海面に向けて照射された電波は、波に当たるとあらゆる方向に散乱し、このうち後方散乱（照射方向と反対の方向に散乱）したものが海洋レーダＯＲで受信される。なお、海面に向けて照射された電波は、その半波長の表面波によって強く散乱されることが知られている（Ｂｒａｇｇ共鳴散乱）。したがって、海洋レーダＯＲで照射する電波の波長が例えば１２ｍ（送信周波数２４．５１５ＭＨｚ）のときは、波長が６ｍの表面波から強く散乱される。海洋レーダＯＲが受信した受信信号を、電波が反射した位置（海洋レーダＯＲからの距離）ごとに整理し、さらに周波数ごとに整理して、周波数と信号強度の関係として表したものが図３に示すドップラスペクトルである。 As shown in FIG. 2, the radio wave irradiated toward the sea surface is scattered in all directions when hit by the wave, and among these, the back scattered (scattered in the direction opposite to the irradiation direction) is received by the marine radar OR. It is known that radio waves irradiated toward the sea surface are strongly scattered by the half-wave surface waves (Bragg resonance scattering). Therefore, when the wavelength of the radio wave irradiated by the marine radar OR is, for example, 12 m (transmission frequency 24.515 MHz), it is strongly scattered from the surface wave having a wavelength of 6 m. The received signals received by the marine radar OR are arranged for each position where the radio wave is reflected (distance from the marine radar OR) and further arranged for each frequency, and the relationship between the frequency and the signal intensity is shown in FIG. It is a Doppler spectrum shown.
海に全く流れがないとした場合、表面波に後方散乱して得られた受信信号によるドップラスペクトルが図３に示す破線であり、特定の周波数（＋△ｆ１，−△ｆ１）で際立った受信信号を示している。このピークは一次散乱と呼ばれるもので、海面の表面波には風向きにより海洋レーダＯＲに向かう表面波と遠ざかる表面波があることから、正負それぞれで一次散乱が生じている。ところで海には、実際は海流や潮流などの流れ（以下、「背景流」という。）が生じており、さらに津波のように背景流とは異なる流れ（以下、「移動流」という。）が生じることもある。この背景流と移動流を合成した流れ（以下、「観測流」という。）があるため、実際には図３に示す実線のようなドップラスペクトルが得られる。 When there is no flow in the sea, the Doppler spectrum by the received signal obtained by backscattering into the surface wave is a broken line shown in FIG. 3, and the reception is conspicuous at a specific frequency (+ Δf1, −Δf1). The signal is shown. This peak is called primary scattering, and surface waves on the sea surface have surface waves that move away from the ocean radar OR depending on the wind direction, and surface waves that move away from the surface, so primary scattering occurs in both positive and negative directions. By the way, in the sea, currents such as ocean currents and tidal currents (hereinafter referred to as “background currents”) are actually generated, and further, a flow different from the background currents (hereinafter referred to as “moving currents”) such as tsunamis occurs. Sometimes. Since there is a flow (hereinafter referred to as “observation flow”) that combines the background flow and the moving flow, a Doppler spectrum as shown by a solid line in FIG. 3 is actually obtained.
実線のドップラスペクトルを見ると、その一次散乱が流れがない場合の破線のドップラスペクトルの一次散乱よりも正方向にシフトしていることが分かる。実線のドップラスペクトルが観測流を含み、破線のドップラスペクトルが観測流を含まないことを考えれば、一次散乱のシフトが観測流の影響であることが理解できる。そして一次散乱のシフト量（△ｆ２）が得られると、次式によって観測流の流速値Ｖｃ（以下、「観測流速値Ｖｃ」という。）を求めることができる。ただし、式中のＣｒは海洋レーダＯＲの電波の伝播速度、ｆは海洋レーダＯＲの電波の周波数である。
２．海洋レーダによる津波検知装置
次に、本願発明の海洋レーダによる津波検知装置に関し、構成する主な要素ごとに詳しく説明する。
2. Next, a tsunami detection device using a marine radar according to the present invention will be described in detail for each major component.
（観測流変動算出手段）
図４は、観測流の流速変動と背景流の流速変動を示すグラフ図であり、このうち上部に示す波形が「観測流の流速変動」である。観測流変動算出手段はこの観測流の流速変動を生成するものであり、具体的には、海洋レーダＯＲが受信した受信信号をもとに、既述した原理によって時刻ごとの観測流速値Ｖｃを求め、これを時間の順でつなぐことで観測流の流速変動を生成する。
(Observation flow fluctuation calculation means)
FIG. 4 is a graph showing the flow velocity fluctuation of the observed flow and the flow velocity fluctuation of the background flow, and the waveform shown in the upper part is “flow velocity fluctuation of the observation flow”. The observation flow fluctuation calculating means generates the flow fluctuation of the observation flow. Specifically, based on the received signal received by the ocean radar OR, the observation flow velocity value Vc for each time is calculated according to the principle described above. The flow velocity fluctuation of the observation flow is generated by obtaining and connecting them in order of time.
（背景流変動算出手段）
背景流変動算出手段は、観測流の流速変動に基づいて、図４の下部に示す「背景流の流速変動」を生成するものである。以下、背景流の流速変動を算出する手法について詳しく説明する。既述のとおり観測流は、背景流と移動流を合成したものであるから、観測流から移動流を剥ぎ取れば背景流を抽出することができる。換言すれば、観測流の流速変動から移動流の影響を取り除けば、背景流の流速変動を抽出することができる。ところで本願発明では移動流のうち津波に着目しており、そして津波は背景流に比して周期が短いことが知られている。つまり、津波の周期より長い期間で観測流の流速変動を平滑処理（スムージング）すれば、津波（移動流）の影響を取り除くことができる。
(Background flow fluctuation calculation means)
The background flow fluctuation calculation means generates “background flow velocity fluctuation” shown in the lower part of FIG. 4 based on the observation flow velocity fluctuation. Hereinafter, a method for calculating the flow velocity fluctuation of the background flow will be described in detail. As described above, since the observation flow is a combination of the background flow and the moving flow, the background flow can be extracted by stripping the moving flow from the observation flow. In other words, if the influence of the moving flow is removed from the flow velocity fluctuation of the observed flow, the flow velocity fluctuation of the background flow can be extracted. By the way, in this invention, it pays attention to tsunami among moving flows, and it is known that a tsunami has a short period compared with a background flow. That is, if the flow velocity fluctuation of the observed flow is smoothed (smoothed) in a period longer than the tsunami cycle, the influence of the tsunami (moving flow) can be removed.
具体的には代表流速値算出手段が、図４に示すように津波の周期と同程度またはそれよりも長い期間を「平滑期間」として定め、この平滑期間内にある観測流速値Ｖｃに対して統計処理を行って、その平滑期間における「代表流速値」を求める。このときの統計処理としては、単純に算術平均してもよいし、異常値を除いた上での平均値や、平滑期間の中央（あるいは始期や終期）に重みをつけた加重平均値、そのほか中央値などを採用してもよい。また代表流速値は、あらかじめ所定間隔で設定された「計算時刻」ごとに求められ、したがって平滑期間もこの計算時刻ごとに設定される。つまり計算時刻が進むたびに、平滑期間も移動していくわけである。この平滑期間の始期や（終期）は計算時刻を基準に設定され、例えば計算時刻を平滑期間の始期としたり、計算時刻を平滑期間の終期としたり、図４に示すように計算時刻を平滑期間の中央としてもよい。 Specifically, as shown in FIG. 4, the representative flow velocity value calculating means determines a period that is equal to or longer than the tsunami cycle as a “smooth period”, and for the observed flow velocity value Vc within the smooth period. Statistical processing is performed to obtain a “representative flow velocity value” during the smooth period. Statistical processing at this time may be simply arithmetic average, average value after excluding abnormal values, weighted average value with weighting in the middle (or beginning and end) of smoothing period, and others A median or the like may be adopted. Further, the representative flow velocity value is obtained for each “calculation time” set in advance at predetermined intervals, and accordingly, the smoothing period is also set for each calculation time. That is, as the calculation time advances, the smoothing period also moves. The start or end of the smoothing period is set based on the calculation time. For example, the calculation time is set as the start of the smoothing period, the calculation time is set as the end of the smoothing period, or the calculation time is set as the smoothing period as shown in FIG. It is good also as the center of.
既述のとおり観測流速値Ｖｃは、海洋レーダＯＲが受信した受信信号によるドップラスペクトルから求められる値であり、いわば実測値といえる。ところが、図４では計算時刻を平滑期間の中央とした結果、一定の期間で代表流速値を算出するための観測流速値Ｖｃが不足する。例えば、最新の観測流速値Ｖｃを求めた時点（図４のグラフ右端で、以下、「最新算出時刻」という。）で考えると、平滑期間のうち前半１／２期間では観測流速値Ｖｃが得られているものの、後半１／２期間では観測流速値Ｖｃがいまだ得られていない。このように代表流速値を算出するための観測流速値Ｖｃが不足する事態は、平滑期間の終期が最新算出時刻を超えた計算時刻から生じる。換言すれば、平滑期間の終期が最新算出時刻を超える直前の計算時刻まで、実測値に基づく代表流速値を算出することができる。 As described above, the observed flow velocity value Vc is a value obtained from the Doppler spectrum by the received signal received by the marine radar OR, and can be said to be an actually measured value. However, in FIG. 4, as a result of setting the calculation time to the center of the smoothing period, the observed flow velocity value Vc for calculating the representative flow velocity value in a certain period is insufficient. For example, when the latest observed flow velocity value Vc is calculated (at the right end of the graph in FIG. 4 and hereinafter referred to as “latest calculation time”), the observed flow velocity value Vc is obtained in the first half of the smooth period. However, the observed flow velocity value Vc has not been obtained yet in the latter half period. Thus, the situation where the observed flow velocity value Vc for calculating the representative flow velocity value is insufficient occurs from the calculation time when the end of the smoothing period exceeds the latest calculation time. In other words, the representative flow velocity value based on the actually measured value can be calculated until the calculation time immediately before the end of the smoothing period exceeds the latest calculation time.
計算時刻ごとに求めた代表流速値を時間の順でつないだ流速変動（以下、「代表値時刻変動」という。）が、背景流の流速変動を構成する。ただし図４に示すように、最新算出時刻まで背景流の流速変動を求めようとすると、代表値時刻変動だけでは不足する。そこで、その不足分を補うべく推測値時刻変動を求める。つまり、代表値時刻変動と推測値時刻変動によって背景流の流速変動を完成させるわけである。この推測値時刻変動は、代表流速値に相当する流速値（以下、「推定流速値」という。）を推定し、この推定流速値を時間の順でつなぐことで生成される。なお推定流速値は、平滑期間の終期が最新算出時刻を超えた後、最新算出時刻までの計算時刻ごとに求められる。 The flow velocity fluctuation obtained by connecting the representative flow velocity values obtained at each calculation time in the order of time (hereinafter referred to as “representative time fluctuation”) constitutes the flow velocity fluctuation of the background flow. However, as shown in FIG. 4, if the flow velocity fluctuation of the background flow is obtained until the latest calculation time, the representative value time fluctuation alone is insufficient. Therefore, the estimated time fluctuation is calculated to compensate for the shortage. That is, the flow velocity fluctuation of the background flow is completed by the representative value time fluctuation and the estimated value time fluctuation. This estimated time variation is generated by estimating a flow velocity value (hereinafter referred to as “estimated flow velocity value”) corresponding to the representative flow velocity value and connecting the estimated flow velocity values in order of time. Note that the estimated flow velocity value is obtained for each calculation time until the latest calculation time after the end of the smoothing period exceeds the latest calculation time.
推定流速値は、それまでの代表値時刻変動（代表流速値）に基づいて推定される。図５は、代表値時刻変動に基づく推定流速値の推定手法を説明するためのモデル図である。この図に示すように、あらかじめ定めた期間（推定元期間）内にある代表流速値によって第１の推定流速値を推定し、次に推定元期間内にある代表流速値と第１の推定流速値によって第２の推定流速値を推定する。このように最新算出時刻まで推定流速値を順次推定していき、推測値時刻変動を求める。 The estimated flow velocity value is estimated based on the representative value time variation (representative flow velocity value) up to that point. FIG. 5 is a model diagram for explaining an estimation method of the estimated flow velocity value based on the representative value time variation. As shown in this figure, the first estimated flow velocity value is estimated from the representative flow velocity value within a predetermined period (estimation source period), and then the representative flow velocity value and the first estimated flow velocity within the estimation source period are estimated. A second estimated flow velocity value is estimated from the value. In this way, the estimated flow velocity value is sequentially estimated until the latest calculation time, and the estimated value time variation is obtained.
推定流速値を推定する手法としては、過去の流速値（代表流速値や推定流速値）から得られる回帰曲線に基づいて推定するなど、従来から用いられている種々の手法を採用することができる。また、次式で示す自己回帰モデル（ＡＲモデル：Ａｕｔｏ−ｒｅｇｒｅｓｓｉｖｅ ｍｏｄｅｌ）に基づいて推定することもできる。
ｅ（ｓ）：代表流速値と推定流速値の誤差
ａ（ｓ）：時刻ｍ時点でのＡＲ係数
As a method for estimating the estimated flow velocity value, various conventionally used methods such as estimation based on a regression curve obtained from a past flow velocity value (representative flow velocity value or estimated flow velocity value) can be employed. . Moreover, it can also estimate based on the autoregressive model (AR model: Auto-regressive model) shown by following Formula.
（移動流変動算出手段）
移動流変動算出手段は、観測流の流速変動から背景流の影響を取り除いて「移動流の流速変動」を抽出するものである。具体的には、観測流速値Ｖｃと代表流速値（あるいは推定流速値）に基づいて、計算時刻ごとに移動流の流速値（以下、「移動流速値」という。）を求め、これを時間の順でつなぐことで移動流の流速変動を生成する。このとき、単に観測流速値Ｖｃと代表流速値（あるいは推定流速値）の差を移動流速値とすることもできるし、一方（あるいは双方）に係数を乗じた上で差を求めたものを移動流速値とすることもできる。
(Moving flow fluctuation calculation means)
The moving flow fluctuation calculating means extracts “moving flow velocity fluctuation” by removing the influence of the background flow from the observed flow velocity fluctuation. Specifically, based on the observed flow velocity value Vc and the representative flow velocity value (or estimated flow velocity value), the flow velocity value of the moving flow (hereinafter referred to as “moving flow velocity value”) is calculated at each calculation time, By connecting in order, the flow velocity fluctuation of the moving flow is generated. At this time, the difference between the observed flow velocity value Vc and the representative flow velocity value (or estimated flow velocity value) can be used as the moving flow velocity value, or the difference obtained by multiplying one (or both) by a coefficient is moved. It can also be a flow velocity value.
図６は、移動流の流速変動を示すグラフ図であり、（ａ）は津波が生じたときのもの、（ｂ）は津波が生じていない平常時のものである。この図が示すように、津波が生じたときは大きな流速の変化があることから比較的明瞭に移動流の流速変動を把握することができるが、一方の平常時は流速の変化が乏しく移動流の流速変動を把握し難いことがわかる。 6A and 6B are graphs showing fluctuations in the flow velocity of the moving flow, in which FIG. 6A shows a case where a tsunami occurs, and FIG. 6B shows a normal state where no tsunami occurs. As shown in this figure, when a tsunami occurs, there is a large change in the flow velocity, so it is possible to grasp the flow velocity fluctuation of the moving flow relatively clearly. It can be seen that it is difficult to grasp the flow velocity fluctuations.
（着目点変動抽出手段と対比点変動抽出手段）
ここまでで得られた移動流の流速変動に基づいて津波の発生を判断するわけであるが、本願発明は１地点のみの移動流の流速変動で判断するのではなく、２地点の移動流の流速変動を対比することによって判断することが一つの特徴となっている。ここでは便宜上、対比する一方の地点を「着目観測点」と、他方を「対比観測点」ということとする。なお着目観測点と対比観測点は、図７に示すように海洋レーダＯＲからのビーム（図では第５ビームＢ０５）上、すなわち同一の視線方向上で設定され、さらに対比観測点は、着目観測点からあらかじめ定めた相関算出距離（図では△Ｌ）だけ離れた位置で設定される。
(Point of interest fluctuation extraction means and contrast point fluctuation extraction means)
The generation of the tsunami is determined based on the flow velocity fluctuation of the mobile flow obtained so far. However, the present invention does not judge the flow velocity fluctuation of the mobile flow at only one point, but the movement flow at two points. One feature is to make a judgment by comparing flow velocity fluctuations. Here, for the sake of convenience, one point to be compared is referred to as a “observation point of interest” and the other is referred to as a “contrast observation point”. As shown in FIG. 7, the target observation point and the comparison observation point are set on the beam from the ocean radar OR (the fifth beam B05 in the figure), that is, on the same line-of-sight direction. It is set at a position away from the point by a predetermined correlation calculation distance (ΔL in the figure).
着目点変動抽出手段は、着目観測点における移動流の流速変動に基づいて「着目点変動」を抽出するものであり、対比点変動抽出手段は、対比観測点における移動流の流速変動に基づいて「対比点変動」を抽出するものである。図８は、着目点変動と対比点変動を示すグラフ図であり、（ａ）は現在時刻ｔ１におけるもの、（ｂ）はｔ１からさらに進んだ現在時刻ｔ２におけるものである。この図に示すように着目点変動（対比点変動）は、移動流の流速変動のうち現在時刻からあらかじめ定めた期間（以下、「相関算出期間」という。）だけ遡った部分（図の実線部分）を切り出したものである。なお相関算出期間は、確かな相関が把握できる程度の長さであって、しかも早期に津波を判定することができる程度の長さとするのがよく、例えば数十分から数時間（あるいは１時間程度）とすることができる。 The point-of-interest fluctuation extracting means extracts the “point-of-interest fluctuation” based on the flow velocity fluctuation of the moving flow at the observation point of interest. The contrast point fluctuation extracting means is based on the flow velocity fluctuation of the moving flow at the comparison observation point. "Contrast point fluctuation" is extracted. FIG. 8 is a graph showing the point-of-interest variation and the contrast point variation, where (a) is at the current time t1, and (b) is at the current time t2 further advanced from t1. As shown in this figure, the point-of-interest fluctuation (contrast point fluctuation) is a part of the flow velocity fluctuation of the moving flow that is back from the current time by a predetermined period (hereinafter referred to as “correlation calculation period”) (solid line part in the figure). ). It should be noted that the correlation calculation period is preferably long enough to grasp a certain correlation and long enough to determine a tsunami at an early stage. For example, the correlation calculation period is several tens of minutes to several hours (or one hour). Degree).
着目観測点の設定は、特定の視線方向（ビーム）のうち特定の地点を設定し、すなわち１観測点のみで着目点変動と対比点変動を算出してもよいし、複数（あるいはすべて）の視線方向（ビーム）でそれぞれ複数の地点を設定し、すなわち複数の観測点で着目点変動と対比点変動を算出してもよい。なお、同一の視線方向（ビーム）で複数の着目観測点を設定する場合は、海洋レーダＯＲの距離分解能（例えば２４．５１５ＭＨｚの海洋レーダであれば１．５ｋｍ）に依存することとなる。 The target observation point can be set by setting a specific point in a specific line-of-sight direction (beam), that is, the target point variation and contrast point variation can be calculated from only one observation point, or a plurality (or all) of the target observation point can be calculated. A plurality of points may be set in the line-of-sight direction (beam), that is, the target point variation and the contrast point variation may be calculated at a plurality of observation points. Note that setting a plurality of observation points of interest in the same line-of-sight direction (beam) depends on the distance resolution of the ocean radar OR (for example, 1.5 km for a marine radar of 24.515 MHz).
（相関度算出手段）
相関度算出手段は、着目点変動抽出手段で得られた着目点変動と、対比点変動抽出手段で得られた対比点変動とを照らし合わせ、両者の相関の程度（以下、「相関度」という。）を求めるものである。ここでいう相関度とは、着目点変動と対比点変動について相関分析を行った結果得られる値のことであり、例えば相関係数やコヒーレンスを挙げることができる。なお、着目点変動と対比点変動の組み合わせが複数求められたときは、その分だけ相関度は算出される。
(Correlation degree calculation means)
The correlation degree calculation means compares the attention point fluctuation obtained by the attention point fluctuation extraction means and the contrast point fluctuation obtained by the contrast point fluctuation extraction means, and determines the degree of correlation between them (hereinafter referred to as “correlation degree”). )). Here, the degree of correlation is a value obtained as a result of performing a correlation analysis on the point-of-interest variation and the contrast point variation, and examples thereof include a correlation coefficient and coherence. When a plurality of combinations of the target point variation and the contrast point variation are obtained, the degree of correlation is calculated accordingly.
（津波判定手段）
津波判定手段は、相関度算出手段によって得られた相関度（例えば相関係数）に基づいて津波の発生を判断するものである。既述のとおり、津波が発生したときは明瞭に移動流の流速変動の振れ幅が大きくなるが、平常時では振れ幅の変化は小さい。そこで本願発明者らは、異なる２地点で移動流の流速変動を対比すると、平常時に比べ津波発生時の方が、より相関度が高いと考えた。図９は、実線で示す着目点変動と、破線で示す対比点変動を重ねて示した示すグラフ図であり、（ａ）は津波が生じたときのもの、（ｂ）は津波が生じていない平常時のものである。この図からも分かるように、また本願発明者らが想定したとおり、平常時に比べ津波発生時の方が相関度は高い（相関係数が大きい）。したがって、あらかじめ相関度の閾値（以下、「相関閾値」という。）を設定しておけば、この相関閾値と相関度を照らし合わせることで津波発生の有無を判断することができる。具体的には、相関度が相関閾値を超えたときにその移動流が津波によるものと判断し、相関度が相関閾値を下回るときはその移動流は津波とは異なると判断するわけである。なお、図１０にも示すように相関度は、所定の時間間隔（例えば計算時刻）で継続して算出されることとするとよい。
(Tsunami judgment means)
The tsunami determining means determines the occurrence of a tsunami based on the degree of correlation (for example, correlation coefficient) obtained by the degree of correlation calculating means. As described above, when a tsunami occurs, the fluctuation width of the flow velocity fluctuation of the moving flow clearly increases, but the change of the fluctuation width is small in normal times. Therefore, the inventors of the present application considered that the correlation at the time of tsunami generation was higher than that at normal time when the flow velocity fluctuations of the moving flow were compared at two different points. FIG. 9 is a graph showing the focus point fluctuation indicated by the solid line and the contrast point fluctuation indicated by the broken line, with (a) when the tsunami occurs and (b) no tsunami. It is a normal thing. As can be seen from this figure, as the present inventors have assumed, the degree of correlation is higher when the tsunami occurs than when normal (the correlation coefficient is large). Therefore, if a correlation threshold (hereinafter referred to as “correlation threshold”) is set in advance, it is possible to determine whether or not a tsunami has occurred by comparing the correlation threshold with the correlation. Specifically, when the degree of correlation exceeds the correlation threshold, it is determined that the moving flow is due to a tsunami, and when the degree of correlation is less than the correlation threshold, it is determined that the moving flow is different from the tsunami. As shown in FIG. 10, the correlation degree may be calculated continuously at a predetermined time interval (for example, calculation time).
図１０は、平常時から津波発生後における、相関度の変化を示すグラフ図である。この図に示すように、津波発生（００：００）後の比較的早いタイミング（５〜１０分）で相関度は急激に上昇する。したがって、一度でも相関度が相関閾値を超えたとき、津波の発生と判断することもできる。あるいは、平常時でも稀に相関度が相関閾値を超えることも考えられるので、誤判断を避けるべく、相関度が連続して相関閾値を超え、しかもその連続する回数があらかじめ定めた回数（繰り返し閾値）を超えたときにはじめて津波の発生と判断することもできる。さらに、あらかじめ記憶された複数の平常時における相関度に基づいて、津波発生判断を行うこともできる。具体的には、求められた相関度が、平常時の相関度のうち上位（割合や順位）に該当するとき、もしくは平常時の相関度の最高値より高い場合に、津波発生判断を行う。 FIG. 10 is a graph showing a change in the degree of correlation after a tsunami occurs from normal times. As shown in this figure, the degree of correlation rapidly increases at a relatively early timing (5 to 10 minutes) after the tsunami occurrence (00:00). Therefore, when the degree of correlation exceeds the correlation threshold even once, it can be determined that a tsunami has occurred. Alternatively, since the correlation may rarely exceed the correlation threshold even in normal times, the correlation continuously exceeds the correlation threshold to avoid misjudgment. It is possible to determine that a tsunami has occurred for the first time. Furthermore, it is also possible to determine whether a tsunami has occurred based on the degree of correlation in a plurality of normal times stored in advance. Specifically, the tsunami occurrence determination is performed when the obtained correlation degree corresponds to a higher rank (ratio or rank) among the normal correlation degrees or higher than the highest correlation degree in normal times.
３．海洋レーダによる津波検知プログラム
次に、本願発明の海洋レーダによる津波検知プログラム（以下、便宜上単に「津波検知プログラム」という。）ついて詳しく説明する。なお津波検知プログラムは、ここまで説明した内容をコンピュータに実行させるものであり、したがって「２．海洋レーダによる津波検知装置」と重複する内容の説明はここでは避け、津波検知プログラムに特有の内容のみ説明することとする。すなわち、ここに記載されていない内容は「２．海洋レーダによる津波検知装置」で記載したものと同様である。
3. Next, a tsunami detection program by the marine radar according to the present invention (hereinafter simply referred to as “tsunami detection program” for convenience) will be described in detail. The tsunami detection program causes the computer to execute the contents described so far. Therefore, the description overlapping with “2. Tsunami detection device by ocean radar” is avoided here, and only the contents specific to the tsunami detection program are provided. I will explain. That is, the contents not described here are the same as those described in “2. Tsunami detection device by ocean radar”.
図１１と図１２は、津波検知プログラムに基づく主な処理の流れを示すフロー図であり、図１１は観測流速値の算出から移動流変動の算出までの処理を示し、図１２は着目点の設定から相関度の判定までの処理を示す。以下、これらの図にしたがって説明する。 11 and 12 are flowcharts showing the main processing flow based on the tsunami detection program. FIG. 11 shows the processing from the calculation of the observed flow velocity value to the calculation of the moving flow fluctuation, and FIG. The processing from the setting to the determination of the correlation degree is shown. Hereinafter, description will be made with reference to these drawings.
はじめに、海洋レーダＯＲが受信した受信信号を読み出すとともに、この受信信号を用いて観測流速値Ｖｃを算出し（Ｓｔｅｐ１０１）、さらに観測流速値Ｖｃに基づいて観測流の流速変動を算出する（Ｓｔｅｐ１０２）。次に、観測流の流速変動を用いて計算時刻ごとに代表流速値を算出し（Ｓｔｅｐ１０３）、この代表流速値に基づいて背景流の流速変動を算出する（Ｓｔｅｐ１０４）。観測流の流速変動と背景流の流速変動が得られると、これらを用いて移動流の流速変動を算出する（Ｓｔｅｐ１０５）。なお、ここまでの一連の処理は、相関度を判定しようとする着目観測点と対比観測点すべてに対して繰り返し行われる。 First, the received signal received by the marine radar OR is read out, the observed flow velocity value Vc is calculated using this received signal (Step 101), and the flow velocity fluctuation of the observed flow is calculated based on the observed flow velocity value Vc (Step 102). . Next, the representative flow velocity value is calculated for each calculation time using the flow velocity fluctuation of the observed flow (Step 103), and the flow velocity fluctuation of the background flow is calculated based on the representative flow velocity value (Step 104). When the flow velocity fluctuation of the observation flow and the flow velocity fluctuation of the background flow are obtained, the flow velocity fluctuation of the moving flow is calculated using these (Step 105). The series of processes so far are repeated for all the observation points of interest and the contrast observation points for which the degree of correlation is to be determined.
移動流の流速変動が算出できると、図１２に示すように着目観測点を設定する（Ｓｔｅｐ２０１）。例えば、ビーム番号が若い順であって、海洋レーダＯＲから近い順に着目観測点を順に設定することができる。着目観測点が設定されると、その地点における移動流の流速変動を読み出すとともに、事前に記憶された相関算出期間を読み出して、着目点変動を抽出する（Ｓｔｅｐ２０２）。次に、着目観測点と読み出した相関算出距離に基づいて対比観測点を設定し（Ｓｔｅｐ２０３）、この対比観測点における移動流の流速変動と相関算出期間を読み出して、対比点変動を抽出する（Ｓｔｅｐ２０４）。抽出された着目点変動と対比点変動を照らし合わせて相関度を算出し（Ｓｔｅｐ２０５）、読み出された相関閾値（あるいは繰り返し閾値）を比較することで津波発生の有無の判定結果を出力する（Ｓｔｅｐ２０６）。ここまでの処理が終わると、次の着目観測点を設定し（Ｓｔｅｐ２０７）、すべての着目観測点で一連の処理が完了するまで着目点変動の抽出（Ｓｔｅｐ２０２）〜津波発生の判定（Ｓｔｅｐ２０６）が繰り返し行われる。 When the flow velocity fluctuation of the moving flow can be calculated, the observation point of interest is set as shown in FIG. 12 (Step 201). For example, the observation points of interest can be set in order from the smallest beam number to the ocean radar OR. When the target observation point is set, the flow velocity fluctuation of the moving flow at that point is read out, and the correlation calculation period stored in advance is read out to extract the target point fluctuation (Step 202). Next, a comparison observation point is set based on the observation point of interest and the read correlation calculation distance (Step 203), the flow velocity fluctuation of the moving flow at this comparison observation point and the correlation calculation period are read out, and the comparison point fluctuation is extracted ( Step 204). The degree of correlation is calculated by comparing the extracted variation of the point of interest and the variation of the contrast point (Step 205), and the result of determining whether or not a tsunami has occurred is output by comparing the read correlation threshold (or repetition threshold) ( Step 206). When the processing up to here is completed, the next observation point of interest is set (Step 207), and extraction of the variation of the point of interest (Step 202) to determination of occurrence of tsunami (Step 206) are completed until a series of processing is completed at all the observation points of interest. Repeatedly.
４．海洋レーダの性能検証方法
次に、本願発明の海洋レーダの性能検証方法ついて詳しく説明する。なお本願発明の海洋レーダの性能検証方法は、ここまで説明した内容に基づいて行う方法であり、したがって「２．海洋レーダによる津波検知装置」や「３．海洋レーダによる津波検知プログラム」と重複する内容の説明はここでは避け、海洋レーダの性能検証方法に特有の内容のみ説明することとする。すなわち、ここに記載されていない内容は「２．海洋レーダによる津波検知装置」や「３．海洋レーダによる津波検知プログラム」で記載したものと同様である。
4). Marine Radar Performance Verification Method Next, the marine radar performance verification method of the present invention will be described in detail. The marine radar performance verification method of the present invention is a method performed based on the contents described so far, and therefore overlaps with “2. Tsunami detection device by ocean radar” and “3. Tsunami detection program by ocean radar”. The explanation of the contents is avoided here, and only the contents peculiar to the performance verification method of the marine radar will be explained. That is, the contents not described here are the same as those described in “2. Tsunami detection device by ocean radar” and “3. Tsunami detection program by ocean radar”.
本願発明の海洋レーダの性能検証方法は、津波が発生した際の相関度を算出し、その相関度によって対象となる海洋レーダＯＲの性能を検証する方法である。海洋レーダＯＲの性能を検証するにあたっては、１種類の津波のみを用いて検証するよりも、複数種類の津波を用いて検証するほうがその信頼度は向上する。しかしながら津波の発生頻度が極めて低いことを考えると、実際に生じた津波のみに限って複数種類のデータを収集することは現実的でない。そこで本願発明では、津波数値計算（シミュレーション）に基づく「仮想津波観測流」を利用することとした。 The marine radar performance verification method of the present invention is a method for calculating the degree of correlation when a tsunami occurs and verifying the performance of the target marine radar OR based on the degree of correlation. In verifying the performance of the ocean radar OR, the reliability is improved by verifying using a plurality of types of tsunami rather than verifying using only one type of tsunami. However, considering the extremely low frequency of tsunamis, it is not realistic to collect multiple types of data only for tsunamis that have actually occurred. Therefore, in the present invention, a “virtual tsunami observation flow” based on tsunami numerical calculation (simulation) is used.
図１３は、本願発明の海洋レーダの性能検証方法の主な工程の流れを示すフロー図である。以下、この図にしたがって説明する。はじめに津波数値計算を行うための諸条件を設定し（Ｓｔｅｐ３０１）、この諸条件に基づいて津波数値計算を行う（Ｓｔｅｐ３０２）。この数値計算の結果、位置ごと時刻ごとの津波（移動流）の流速が求められる。次に、算出された津波の流速に基づいて、その津波の流速に相当する海洋レーダＯＲの受信信号を算出する（Ｓｔｅｐ３０３）。つまり、この受信信号を海洋レーダＯＲが受信し、さらにこの受信信号に基づいて流速を算出したとすれば、その流速はＳｔｅｐ３０２で得られた流速となるわけである。なおＳｔｅｐ３０３で算出された受信信号は、津波数値計算の結果によるものであることから、ここでは便宜上、「理想津波受信信号」ということとする。
FIG. 13 is a flowchart showing the flow of main steps of the marine radar performance verification method of the present invention. Hereinafter, description will be made with reference to this figure. First, various conditions for performing tsunami numerical calculation are set (Step 301), and tsunami numerical calculation is performed based on these conditions (Step 302). As a result of this numerical calculation, the flow velocity of the tsunami (moving flow) at each position and time is obtained. Next, based on the calculated tsunami flow velocity, a received signal of the marine radar OR corresponding to the tsunami flow velocity is calculated (Step 303). That is, if the marine radar OR receives this reception signal and further calculates the flow velocity based on this reception signal, the flow velocity is the flow velocity obtained in
次に、評価対象となる海洋レーダＯＲが実際に受信した平常時の受信信号（以下、「実測受信信号」という。）と、Ｓｔｅｐ３０３で得た理想津波受信信号と合成し、これを「合成受信信号」として算出する（Ｓｔｅｐ３０４）。理想津波受信信号は津波のみの影響で得られる信号であるが、実際には海洋レーダＯＲは背景流の影響も含めて信号を受信することから、海洋レーダＯＲが現実に受信する受信信号として合成受信信号を求めるわけである。
Next, the normal received signal actually received by the marine radar OR to be evaluated (hereinafter referred to as “actually received signal”) and the ideal tsunami received signal obtained in
合成受信信号を作成するに当たっては、まず実測受信信号に対して１回目の高速フーリエ変換（ＦＦＴ：Ｆａｓｔ Ｆｏｕｒｉｅｒ Ｔｒａｎｓｆｏｒｍ）を行い、距離ごとの実測受信信号に変換する。そして、距離ごとの実測受信信号と理想津波受信信号を合成する。このとき、一般的に受信信号は複素数で表されることから、複素積によって合成するとよい。 In creating the combined received signal, first, a first fast Fourier transform (FFT) is performed on the actually received signal to convert it into an actually received signal for each distance. Then, the actual measurement reception signal and the ideal tsunami reception signal for each distance are combined. At this time, since the received signal is generally represented by a complex number, it may be synthesized by a complex product.
Ｓｔｅｐ３０４で合成受信信号が得られると、この合成受信信号に対して２回目の高速フーリエ変換を行い、合成受信信号のドップラスペクトルを算出し、さらにこのドップラスペクトルに基づいて仮想津波の観測流速値、及び仮想津波の観測流の流速変動（以下、「仮想津波観測流変動」という。）を算出する（Ｓｔｅｐ３０５）。なお、図６、図８、図９、図１０は、ここまで説明したＳｔｅｐ３０１〜Ｓｔｅｐ３０５の工程によって得られた仮想津波観測流変動に基づいて求められた波形である。
When a combined received signal is obtained in
次に、仮想津波観測流変動を用いて計算時刻ごとに代表流速値を算出し（Ｓｔｅｐ３０６）、この代表流速値に基づいて背景流の流速変動を算出する（Ｓｔｅｐ３０７）。そして仮想津波観測流変動と背景流の流速変動が得られると、これらを用いて移動流の流速変動を算出する（Ｓｔｅｐ３０８）。なお、ここまでの一連の処理は、相関度を判定しようとする着目観測点と対比観測点すべてに対して繰り返し行われる。ところで、ここまでの工程で得られた移動流の流速変動は、津波数値計算によって算出された津波の流速変動と概ね等しいはずである。そこで、図１４に示すように両者を重ねたところ、概ね一致することが検証された。 Next, the representative flow velocity value is calculated for each calculation time using the virtual tsunami observation flow fluctuation (Step 306), and the flow velocity fluctuation of the background flow is calculated based on the representative flow velocity value (Step 307). When the virtual tsunami observation flow fluctuation and the background flow velocity fluctuation are obtained, the flow velocity fluctuation of the moving flow is calculated using these (Step 308). The series of processes so far are repeated for all the observation points of interest and the contrast observation points for which the degree of correlation is to be determined. By the way, the flow velocity fluctuation of the moving flow obtained in the steps so far should be approximately equal to the fluctuation of the tsunami velocity calculated by the tsunami numerical calculation. Then, as shown in FIG. 14, when both were overlapped, it was verified that they were almost the same.
移動流の流速変動が算出できると、着目観測点を設定して着目点変動を抽出し（Ｓｔｅｐ３０９）、さらに対比観測点を設定して対比点変動を抽出する（Ｓｔｅｐ３１０）。そして抽出された着目点変動と対比点変動を照らし合わせて、相関度を算出する（Ｓｔｅｐ３１１）。 When the flow velocity fluctuation of the moving flow can be calculated, the target observation point is set and the target point fluctuation is extracted (Step 309), and the contrast observation point is set and the contrast point fluctuation is extracted (Step 310). Then, the degree of correlation is calculated by comparing the extracted point-of-interest fluctuation and contrast point fluctuation (Step 311).
ここまでの一連の工程を終えると、津波数値計算を行うための諸条件を変更して再設定し、再び津波数値計算（Ｓｔｅｐ３０２）〜相関度の算出（Ｓｔｅｐ３１１）の一連の工程を行う。所望の種類の津波数値計算による相関度が算定されると、換言すれば所望の種類の仮想津波による相関度が算出されると、その相関度によって当該海洋レーダＯＲの性能を評価する（Ｓｔｅｐ３１３）。すなわち、津波数値計算で条件を変えて複数想定した津波に対して、それぞれ当該海洋レーダＯＲの津波観測性能を評価することができるわけである。 When the series of steps so far is completed, various conditions for performing the tsunami numerical calculation are changed and reset, and the series of steps from the tsunami numerical calculation (Step 302) to the calculation of the correlation degree (Step 311) are performed again. When the degree of correlation by calculating the desired type of tsunami is calculated, in other words, when the degree of correlation by the desired type of virtual tsunami is calculated, the performance of the marine radar OR is evaluated based on the degree of correlation (Step 313). . That is, the tsunami observation performance of the marine radar OR can be evaluated with respect to a plurality of tsunamis assumed under different conditions in the tsunami numerical calculation.
本願発明の海洋レーダによる津波検知装置、海洋レーダによる津波検知プログラム、及び海洋レーダの性能検証方法は、津波が発生しうるあらゆる沿岸部で活用することができる。災害発生時に、早期の避難を促し、その結果数多くの人々の安全が確保できることを考えれば、産業上利用できるばかりでなく社会的にも大きな貢献が期待できる発明といえる。 The marine radar tsunami detection apparatus, marine radar tsunami detection program, and marine radar performance verification method of the present invention can be used in any coastal area where tsunamis can occur. Considering that early evacuation can be promoted in the event of a disaster and the safety of many people can be secured as a result, it can be said that the invention can be used not only industrially but can also make a great social contribution.
Ｂ 海洋レーダの視線方向（ビーム）
ＯＲ 海洋レーダ
B Gaze direction (beam) of ocean radar
OR Marine radar
Claims (7)
所定間隔で設定された計算時刻を基準に平滑期間を定め、前記観測流の流速変動のうち該平滑期間内にある前記観測流速値に基づいて求められる値を、当該計算時刻の代表流速値とする代表流速値算出手段と、
複数の前記代表流速値からなる代表値時刻変動と、該代表値時刻変動に基づいて推定される推測値時刻変動と、からなる流速値の時刻変動を「背景流の流速変動」とする背景流変動算出手段と、
前記観測流の流速変動と、前記背景流の流速変動と、に基づいて求められる流速値の時刻変動を「移動流の流速変動」とする移動流変動算出手段と、
着目観測点における前記移動流の流速変動から、あらかじめ定めた相関算出期間に相当する部分を「着目点変動」として抽出する着目点変動抽出手段と、
対比観測点における前記移動流の流速変動から、前記相関算出期間に相当する部分を「対比点変動」として抽出する対比点変動抽出手段と、
前記着目点変動と前記対比点変動との相関の程度を求める相関度算出手段と、
前記相関の程度が、あらかじめ定めた相関閾値を超えたときに津波の発生と判断する津波判定手段と、を備え、
前記対比観測点は、前記着目観測点と同一の視線方向上にあって、該着目観測点からあらかじめ定めた相関算出距離だけ離れた位置で設定される、ことを特徴とする海洋レーダによる津波検知装置。 An observation flow fluctuation calculation means for obtaining an observation flow velocity value based on the received signal of the marine radar and setting the time fluctuation of the observation flow velocity value as “flow fluctuation of the observation flow”;
A smoothing period is determined based on a calculation time set at a predetermined interval, and a value obtained based on the observed flow velocity value within the smoothing period among flow velocity fluctuations of the observed flow is defined as a representative flow velocity value at the calculation time. A representative flow velocity value calculating means,
A background flow in which the time variation of the flow velocity value composed of a representative value time variation composed of a plurality of the representative flow velocity values and an estimated value time variation estimated based on the representative value time variation is defined as “background flow velocity variation” Fluctuation calculation means;
A moving flow fluctuation calculating means that sets a time fluctuation of a flow velocity value obtained based on the flow velocity fluctuation of the observed flow and the flow velocity fluctuation of the background flow as "flow velocity fluctuation of the moving flow",
A point-of-interest variation extracting means for extracting a portion corresponding to a predetermined correlation calculation period as a “point-of-interest variation” from the flow velocity variation of the moving flow at the point of interest;
Contrast point fluctuation extraction means for extracting a portion corresponding to the correlation calculation period as “contrast point fluctuation” from the flow velocity fluctuation of the moving flow at the contrast observation point;
Correlation degree calculating means for obtaining a degree of correlation between the target point variation and the contrast point variation;
Tsunami determination means for determining the occurrence of a tsunami when the degree of correlation exceeds a predetermined correlation threshold,
Tsunami detection by an ocean radar, wherein the contrast observation point is set at a position on the same line-of-sight direction as the target observation point and separated from the target observation point by a predetermined correlation calculation distance apparatus.
前記背景流変動算出手段は、前記代表流速値算出手段が求めた最後の前記計算時刻より後であって、前記海洋レーダの最新観測時刻までの期間を対象として、前記推測値時刻変動を求め、
さらに前記背景流変動算出手段は、複数の前記代表流速値を用いて自己回帰モデルに基づいて前記推測値時刻変動を算出する、ことを特徴とする請求項１又は請求項２記載の海洋レーダによる津波検知装置。 The representative flow velocity value calculating means obtains the representative flow velocity value until the calculation time immediately before the end of the smoothing period is the latest time when the observed flow velocity value is obtained,
The background flow fluctuation calculation means obtains the estimated time fluctuation for a period after the last calculation time obtained by the representative flow velocity value calculation means and until the latest observation time of the marine radar,
3. The ocean radar according to claim 1, wherein the background flow fluctuation calculating unit calculates the estimated time fluctuation based on an autoregressive model using a plurality of the representative flow velocity values. 4. Tsunami detector.
前記津波判定手段は、前記相関の程度が連続して前記相関閾値を超え、且つ当該連続する回数があらかじめ定めた繰り返し閾値を超えたときに津波の発生と判断する、ことを特徴とする請求項１乃至請求項３のいずれかに記載の海洋レーダによる津波検知装置。 The correlation degree calculating means continuously obtains the degree of correlation at a predetermined time interval,
The tsunami determining means determines that a tsunami has occurred when the degree of correlation continuously exceeds the correlation threshold and the number of consecutive times exceeds a predetermined repetition threshold. The tsunami detection apparatus by the marine radar according to any one of claims 1 to 3.
前記相関閾値は、津波が発生しない平常時の前記相関の程度に基づいて定められる、ことを特徴とする請求項１乃至請求項４のいずれかに記載の海洋レーダによる津波検知装置。 The correlation degree calculating means continuously obtains the degree of correlation at a predetermined time interval,
5. The tsunami detection apparatus using a marine radar according to claim 1, wherein the correlation threshold is determined based on a degree of the correlation in a normal time when a tsunami does not occur.
所定間隔で設定された計算時刻を基準に平滑期間を定め、前記観測流の流速変動のうち該平滑期間内にある前記観測流速値に基づいて求められる値を、当該計算時刻の代表流速値とする代表流速値算出処理と、
複数の前記代表流速値からなる代表値時刻変動と、該代表値時刻変動に基づいて推測される推測値時刻変動と、からなる流速値の時刻変動を「背景流の流速変動」として算出する背景流変動算出処理と、
前記観測流の流速変動と、前記背景流の流速変動と、に基づいて求められる流速値の時刻変動を「移動流の流速変動」として算出する移動流変動算出処理と、
着目観測点における前記移動流の流速変動から、あらかじめ定めた相関算出期間に相当する部分を「着目点変動」として抽出する着目点変動抽出処理と、
対比観測点における前記移動流の流速変動から、前記相関算出期間に相当する部分を「対比点変動」として抽出する対比点変動抽出処理と、
前記着目点変動と前記対比点変動との相関の程度を求める相関度判定処理と、
前記相関の程度が、あらかじめ定めた相関閾値を超えたときに津波の発生と判断する津波判定処理と、をコンピュータに実行させる機能を備え、
前記対比観測点は、前記着目観測点と同一の視線方向上にあって、該着目観測点からあらかじめ定めた相関算出距離だけ離れた位置で設定される、ことを特徴とする海洋レーダによる津波検知プログラム。 An observation flow fluctuation calculation process for calculating an observation flow velocity value based on the received signal of the marine radar, and calculating a time fluctuation of the observation flow velocity value as “flow velocity fluctuation of the observation flow”;
A smoothing period is determined based on a calculation time set at a predetermined interval, and a value obtained based on the observed flow velocity value within the smoothing period among flow velocity fluctuations of the observed flow is defined as a representative flow velocity value at the calculation time. Representative flow velocity value calculation processing,
A background for calculating a time fluctuation of a flow velocity value composed of a representative value time fluctuation composed of a plurality of representative flow velocity values and an estimated value time fluctuation estimated based on the representative value time fluctuation as a “flow velocity fluctuation of a background flow” Flow fluctuation calculation processing,
A moving flow fluctuation calculation process for calculating a time fluctuation of a flow velocity value obtained based on the flow velocity fluctuation of the observed flow and the flow velocity fluctuation of the background flow as a “flow velocity fluctuation of the moving flow”;
A point of interest variation extraction process for extracting a portion corresponding to a predetermined correlation calculation period as a “point of interest variation” from the flow velocity variation of the mobile flow at the observation point of interest;
Contrast point fluctuation extraction processing for extracting a portion corresponding to the correlation calculation period as "contrast point fluctuation" from the flow velocity fluctuation of the moving flow at the contrast observation point;
Correlation degree determination processing for obtaining a degree of correlation between the target point variation and the contrast point variation;
A function of causing a computer to execute a tsunami determination process that determines that a tsunami occurs when the degree of correlation exceeds a predetermined correlation threshold,
Tsunami detection by an ocean radar, wherein the contrast observation point is set at a position on the same line-of-sight direction as the target observation point and separated from the target observation point by a predetermined correlation calculation distance program.
所定間隔で設定された計算時刻を基準に平滑期間を定め、前記仮想津波観測流のうち該平滑期間内にある前記流速値に基づいて求められる値を、当該計算時刻の代表流速値とする代表流速値算出工程と、
複数の前記代表流速値からなる代表値時刻変動と、該代表値時刻変動に基づいて推測される推測値時刻変動と、からなる流速値の時刻変動を「背景流の流速変動」として算出する背景流変動算出工程と、
前記仮想津波観測流と、前記背景流の流速変動と、に基づいて求められる流速値の時刻変動を「移動流の流速変動」として算出する移動流変動算出工程と、
着目観測点における前記移動流の流速変動から、あらかじめ定めた相関算出期間に相当する部分を「着目点変動」として抽出する着目点変動抽出工程と、
対比観測点における前記移動流の流速変動から、前記相関算出期間に相当する部分を「対比点変動」として抽出する対比点変動抽出工程と、
前記着目点変動と前記対比点変動との相関の程度を求める相関度判定工程と、を備え、
前記対比観測点は、前記着目観測点と同一の視線方向上にあって、該着目観測点からあらかじめ定めた相関算出距離だけ離れた位置で設定され、
条件を変えて繰り返し前記仮想津波観測流算出工程を行うことで複数種類の前記仮想津波観測流を算出し、前記相関度判定工程で複数種類の仮想津波観測流に対してそれぞれ前記相関の程度を求めることによって前記海洋レーダの性能を検証する、ことを特徴とする海洋レーダの性能検証方法。 Calculate the ideal tsunami reception signal based on the flow velocity at multiple points obtained by tsunami numerical calculation, and combine the observation reception signal acquired by the marine radar in normal time and the ideal tsunami reception signal by complex product to obtain the composite reception signal A virtual tsunami observation flow calculation step of calculating a virtual tsunami observation flow that is a time variation of the flow velocity value based on the combined received signal;
A smooth period is defined with reference to a calculation time set at a predetermined interval, and a value obtained based on the flow velocity value within the smooth period of the virtual tsunami observation flow is a representative flow velocity value at the calculation time. A flow rate calculation process;
A background for calculating a time fluctuation of a flow velocity value composed of a representative value time fluctuation composed of a plurality of representative flow velocity values and an estimated value time fluctuation estimated based on the representative value time fluctuation as a “flow velocity fluctuation of a background flow” Flow fluctuation calculation process;
A moving flow fluctuation calculation step for calculating a time fluctuation of a flow velocity value obtained based on the virtual tsunami observation flow and the flow velocity fluctuation of the background flow as a “flow velocity fluctuation of the moving flow”;
A point of interest fluctuation extraction step of extracting a portion corresponding to a predetermined correlation calculation period as a “point of interest fluctuation” from the flow velocity fluctuation of the moving flow at the target observation point;
A contrast point fluctuation extracting step of extracting a portion corresponding to the correlation calculation period as a “contrast point fluctuation” from the flow velocity fluctuation of the mobile flow at the contrast observation point;
A correlation degree determination step for obtaining a degree of correlation between the point-of-interest variation and the contrast-point variation,
The contrast observation point is on the same line-of-sight direction as the target observation point, and is set at a position away from the target observation point by a predetermined correlation calculation distance,
A plurality of types of virtual tsunami observation streams are calculated by repeatedly performing the virtual tsunami observation stream calculation step under different conditions, and the degree of correlation is calculated for each of the plurality of types of virtual tsunami observation streams in the correlation determination step. A method for verifying the performance of the marine radar, comprising: verifying the performance of the marine radar by obtaining it.
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