WO2019101247A2 - Laser maritime-visibility monitoring instrument, and method of detecting sea fog - Google Patents

Abstract

A multi-angle scanning method and a monitoring instrument are provided. In the invention, multi-angle backscattered optical signals are analyzed and processed, so as to solve for an atmospheric extinction coefficient and thereby obtain accurate measurements in respect of the spatial distribution of atmospheric visibility. A numerical basis is thus provided to better understand the physical processes of the formation, development, and dissipation of sea fog, thus effectively improving sea fog detection and forecasting capabilities. Further, multiple laser maritime-visibility monitoring instruments may be arranged around critical maritime areas, and data may be transmitted to terminal servers for integrated analysis, thus forming an observation network. The invention allows for precision sea fog detection capabilities across a large range.

Description

Laser sea surface visibility monitor and method for detecting sea fog

This application claims the priority of the PCT International Application filed on July 20, 2018 in the China Patent Office Receiving Office, application number PCT/CN2018/096463, and the invention name "Laser Sea Surface Visibility Monitor and Method for Detecting Sea Fog". The entire contents of this application are incorporated herein by reference.

Technical field

The invention relates to a laser sea surface visibility monitor and a method for detecting sea fog.

Background technique

Sea fog is one of the most important disastrous weather on the sea, and it is also the enemy of ship navigation safety. At present, the understanding of sea fog distribution is mostly based on coastal observation stations, marine vessels and buoy observations. However, these data are rare, and there are representative and data quality problems. Therefore, there is a lack of comprehensive and clear distribution of sea fog. To understanding. The existing instrumental visibility instruments are mainly transmissive and forward-scattering. The measurement is based on the uniformity of the meteorological environment around the installation site. The non-scanning mode of operation can only give meteorological parameters of isolated points. Reflecting the distribution of meteorological environmental parameters, in the case of local rain or snow, the reading is highly prone to errors; in addition, in order to measure a wide range of meteorological environments, multiple point visibility measuring instruments need to be set at multiple points. This kind of setting not only leads to a sharp increase in operating and management costs, but also provides discrete, isolated point environmental parameters, which does not give a continuous distribution of environmental parameters in the measurement area, and cannot weather the weather that seriously affects the safety of the ship. Make precise feedback.

Summary of the invention

The invention provides a sea fog detection system and method based on laser radar. Through the detection and analysis of the backscattered light generated by the interaction between the atmosphere and the laser, accurate measurement of the spatial distribution of atmospheric visibility is achieved, providing a numerical basis for a better understanding of the physical processes of sea fog formation, development and dissipation, thereby effectively Improve the ability to monitor and forecast sea fog. A laser sea surface visibility monitor is set up in key ports and surrounding areas, and a sea fog three-dimensional integrated monitoring network based on a new type of laser radar based on shore, island and buoy platform is established, which can effectively obtain high-resolution, wide-area real-time visibility distribution of the sea surface. It plays a significant role in shipping safety and port operation efficiency and channel utilization.

In order to achieve the above object, the present invention provides the following technical solutions:

A method for detecting sea fog using a laser visibility monitor to measure atmospheric visibility distribution, including:

By combining the echo signals of the laser scanning at multiple angles, the extinction coefficients of the sampling points on the scanning path at each specific angle are determined, thereby obtaining the visibility distribution in each specific angular direction, wherein each sampling point The echo signal is a function of the backscatter coefficient and the extinction coefficient;

Optionally, the relationship between the near-field backscattering coefficient and the backscattering coefficient of the far field from the sea fog region, β _i (z _m )=δ·β _i (z _n ), where δ is a constant;

Further, the backscattering coefficient of the near field of the sea fog region is equal to the backscattering coefficient of the far field.

Optionally, the backward reflection coefficients at adjacent sampling points are equal at the same angle.

Optionally, the method further includes:

The initial angular direction is selected, and the measurement of the sampling points of the plurality of sampling distances at each subsequent angle is projected in the initial angular direction;

Select a starting sampling point at a specific angle, and select a difference between two sets of measurement data of adjacent sampling points for the near field point or the far field point, and the backscattering coefficient at the two points has a functional relationship;

The data of different angles and the same projection distance are connected, and the optical thickness in the resolution distance can be simplified by processing and difference, thereby obtaining the extinction coefficient and the visibility value.

The above process is iteratively performed to obtain a visibility distribution within the scan range of the multi-angle scan measurement.

Optionally, the laser sea surface visibility monitor is installed at a suitable location on the coast, port or island with reference to the area and height of the advection fog in the monitored sea area, and the area within the depth of several thousand meters of the sea surface is leveled and/or Scan vertically, or at an elevation angle to obtain visibility information at different locations on the surface.

Optionally, the echo signal of each sampling point is transformed into a function of the backscattering coefficient and the optical thickness, and the optical thickness of each sampling point at each specific angle is determined by combining the echo signals of the plurality of angles. And then calculate the corresponding extinction coefficient to obtain the visibility distribution in each specific angular direction.

In addition, a laser sea surface visibility monitor using one of the above methods is provided, comprising:

Laser transmitting module, echo signal receiving module, signal acquisition module, scanning module. The laser emitting module is configured to emit a pulsed laser beam, the echo signal receiving module is configured to receive a backscattered signal of the atmosphere to the laser and convert the optical signal into an electrical signal, and the signal collecting module is configured to receive the electrical a signal for controlling the elevation and azimuth of the laser detection and scanning at any angle. When operating, the laser sea surface visibility monitor performs the method of one of claims 1 to 7.

Optionally, the laser emitting module comprises a laser for emitting micro-focus high repetition frequency laser pulses and a beam expander collimator. The beam expander collimator collimates the single-pulse energy micro-focus laser beam, and the power density of the expanded laser beam in any vertical propagation direction conforms to the laser human eye safety standard, which prevents the laser beam from facing the sea surface. In the past, the ship personnel caused injuries and ensured the safety of the eyes. With high repetition frequency, the signal-to-noise ratio can be improved and sea fog information can be detected at a longer distance.

Optionally, the laser emitting module comprises a Nd:YAG solid state laser or a semiconductor laser or a fiber laser.

Optionally, the echo signal receiving module comprises an optical telescope, a filter, and a detector.

Optionally, the signal acquisition module comprises a data acquisition card and an embedded board.

Optionally, the scanning module is connected to the embedded board and the laser sea surface visibility monitor housing, and is configured to control the housing to be horizontally and/or vertically according to a control instruction of the embedded board. Scanning motion. The laser sea surface visibility monitor can scan the visibility distribution in different directions of the sea surface to obtain the sea fog generation, development and dissipation process.

Optionally, the scanning module is connected to the laser sea surface visibility monitor housing to drive the laser sea surface visibility monitor to rotate integrally, or the scanning module is disposed on the laser sea surface visibility monitor optical component non-light path The side drives the optical member to rotate integrally, or the scanning rotating device is disposed on one side of the beam expander and the optical path of the telescope to rotate the light beam after the light beam enters the scanning head of the scanning rotating device.

Optionally, the device has an IP65 degree of protection, and the casing is protected against salt spray to meet the high salt and high humidity environment in the sea.

Optionally, the communication system is a wireless data transmission system or a wired data transmission system, where the wireless data transmission system includes a GPRS communication module and/or a WiFi network module, and the wired data transmission system is a network cable or a serial port. Line or fiber.

Optionally, the power supply system is further included, and the power supply system is a utility power grid, or a wind energy, solar energy or wind and solar hybrid system is adopted.

By implementing the above technical solution, the following technical effects are provided: the laser sea surface visibility monitor provided by the present invention can accurately measure the spatial distribution of atmospheric visibility by detecting and analyzing the backscattered light generated by the interaction between the atmosphere and the laser, and The measurement results are not affected by weather conditions such as fog and smoke. It can effectively obtain the piece-by-section information of the visibility distribution in the whole detection path, accurately monitor the atmospheric environment characteristics such as cloud, fog, smoke and dust from the installation location to a certain distance. By changing the scanning direction, it can also obtain the visibility and fog in all directions in real time. And information such as aerosol distribution.

DRAWINGS

1 is a schematic structural diagram of a sea fog detecting system based on a laser radar according to an embodiment of the present invention;

2 is a schematic diagram of a multi-angle scanning algorithm of a sea fog detecting system based on a laser radar according to an embodiment of the present invention;

3 is a schematic structural diagram of a laser sea surface visibility monitor according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of application of a laser radar-based sea fog detecting system and method according to an embodiment of the present invention.

Figure 5 shows the measurement results of the current front-dissipation visibility meter;

Figure 6 is a view showing the installation of the laser sea surface visibility monitor of the present invention in the example;

7 is a scanning view of a 00:36 to 00:48 laser sea surface visibility monitor in the example of the present invention, a) a detection distance of 4 km, and b) a detection distance of 6 km;

8 is a scanning view of a 01:38 to 01:50 laser sea surface visibility monitor in the example of the present invention, a) a detection distance of 4 km, and b) a detection distance of 6 km;

9 is a scanning view of a 02:03 to 02:14 laser sea surface visibility monitor in the example of the present invention, a) a detection distance of 4 km, and b) a detection distance of 6 km;

10 is a scanning view of a 02:07 to 04:53 laser sea surface visibility monitor in the example of the present invention;

Figure 11 is a comparison diagram of the laser sea surface visibility monitor and the B ground front visibility meter in the example of the present invention;

12 is a comparison diagram of a laser sea surface visibility monitor and a B ground front visibility meter in the example of the present invention;

Figure 13 is a comparison diagram of the laser sea surface visibility monitor and the B ground front visibility meter in the example of the present invention;

14 is a correlation coefficient diagram of a rainy day laser sea surface visibility monitor and a B ground front visibility meter in the example of the present invention;

Figure 15 is a comparison diagram of the laser sea surface visibility monitor and the B ground front visibility meter in the example of the present invention;

Figure 16 is a comparison diagram of the foggy laser sea surface visibility monitor and the B ground front visibility meter in the example of the present invention;

Figure 17 is a comparison diagram of the foggy laser sea surface visibility monitor and the B ground front visibility meter in the example of the present invention;

Figure 18 is a comparison diagram of a cloudy laser sea surface visibility monitor and a B ground front visibility meter in the example of the present invention;

Figure 19 is a graph showing the correlation coefficient between the cloudy laser sea surface visibility monitor and the B ground front visibility meter in the example of the present invention.

Detailed ways

In order to better understand the technical solutions of the present invention, the embodiments provided by the present invention are described in detail below with reference to the accompanying drawings.

1 is a schematic diagram of a laser visibility measuring instrument 1 according to an embodiment of the present invention, including a laser emitting module 11, an echo signal receiving module 12, a signal collecting module 13, and a scanning module 14.

According to an embodiment of the present invention, a laser radar based sea fog detecting method is provided. By scanning the target atmosphere in a certain direction, for example, the horizontal direction, and using the detection of backscattered light, the data of the visibility of the laser sea surface can be obtained in real time, and the laser sea surface visibility monitor can be remotely monitored and debugged. management.

As shown in FIG. 2, the sea fog scanning detecting method will be specifically described below.

For the area to be measured, the laser sea surface visibility monitor 1 is used to scan in the first direction, for example, the horizontal direction from the emission end point A, and the plane of the paper surface of Fig. 2 is the scanning plane. The echo signals P ₁ , ... P _i , ... P _L , 0 <= i <= L of different angles α ₁ , ... α _i , ... α _L are measured. By combining these multiple sets of signals, the backscattering coefficient and the extinction coefficient of the atmosphere are solved.

Processing the echo signal to obtain a distance correction signal

RCS _i (r)=C·β _i (r)·exp(-2τ _i (r)) (1)

Where C is the system constant of the lidar, β _i (r) is the backscattering coefficient of the atmosphere, and τ _i (r) is the optical thickness from point A to point r.

Take the logarithm on both sides,

Ln(RCS _i (r))=ln(C·β _i (r))-2τ _i (r) (2)

Using z as a variable, it is expressed as

Ln(RCS _i (z))=ln(C·β _i (z))-2τ _i (z) (3)

Where z is the distance from the sampling point of the echo signal to the transmitting end face in the specified initial direction, and the distance r from the sampling point of the echo signal to the transmitting end face after the rotation angle α _i of the specified initial direction satisfies the relationship:

r=z/cosα _i

The atmosphere has a function in the specified initial direction from the backscattering coefficients β _i (z _m ) and β _i (z _n ) of the near and far fields of the sea fog region, ie β _i (z _m )=δ·β _i (z _n ), where the value of δ is related to the external environment, the type of particulate matter, and the temperature and humidity. And τ _i (z)=τ ₀ (z)/cosα _i , then

Ln(RCS _i (z))=ln(C·β _i (z))-2τ ₀ (z)·x _i (4)

Where x _i =1/cosα _i .

Substituting the data of the near field z _m , the far field z _n and z _n+1 in a certain detection direction into the formula (4)

Ln(RCS _i (z _m ))=ln(C·β _i (z _m ))-2τ ₀ (z _m )·x _i (5)

Ln(RCS _i (z _n ))=ln(C·β _i (z _n ))-2τ _O (z _n )·x _i (6)

Ln(RCS _i (x _n+1 ))=ln(C·β _i (z _n+1 ))-2τ ₀ (z _n+1 )·x _i (7)

Subtract (5) from equation (6), subtract (5) from equation (7)

Ln(RCS _i (z _n ))-ln(RCS _i (z _m ))=ln(C·β _i (z _n ))-ln(C·β _i (z _m ))-2(τ ₀ (z _n )-τ ₀ (z _m ))·x _i (8)

Ln(RCS _i (z _n+1 ))-ln(RCS _i (z _m ))=ln(C·β _i (z _n+1 ))-ln(C·β _i (z _m ))-2( τ ₀ (z _n+1 )-τ ₀ (z _m ))·x _i (9)

Substituting β _i (z _m )=δ ₁ ·β _i (z _n ), β _i (z _m )=δ ₂ ·β _i (z _n+1 ) and simplifying the formula

Ln(RCS _i (z _n )/RCS _i (z _m ))=ln(δ ₁ )-2(τ ₀ (z _n )-τ ₀ (z _m ))·x _i (10)

Ln(RCS _i (z _n+1 )/RCS _i (z _m ))=ln(δ ₂ )-2(τ ₀ (z _n+1 )-τ ₀ (z _m ))·x _i (11)

Equation (11) minus (10) is available

Ln(RCS _i (z _n+1 )/RCS _i (z _n ))=ln(δ ₂ /δ ₁ )+2(τ ₀ (z _n )-τ ₀ (z _n+1 ))·x _i ( 12)

Equation 12 is a straight line equation that passes the line of signals for different angles α ₁ ,...α _i

Sex fit, we can get the slope of the line, thus getting

Δτ _n =τ ₀ (z _n )-τ ₀ (z _n+1 ), atmospheric extinction coefficient

α(z _n )=Δ'τ _n (13)

By repeating the above process, the extinction coefficient of each sampling point on the detection path at an angle can be obtained, thereby obtaining the extinction coefficient of each sampling point, and then the visibility distribution on the detection path at an angle can be obtained.

If the average visibility of the direction is obtained, σ _{w is} obtained by averaging the extinction coefficients, according to the visibility formula

The horizontal visibility at that particular angle can be ascertained.

One specific embodiment of the present invention for solving visibility has been set forth above. Those skilled in the art will appreciate that many variations can be made on the basis of this specific algorithm.

The existing visibility inversion often uses the slope method to find the extinction coefficient, which requires the assumption of the same visibility in the horizontal direction of the atmosphere, which will cause the inversion deviation of the true value of the visibility. However, although the atmospheric extinction coefficient based on the Fernald inversion method is more accurate, the maximum extinction distance and the extinction value at the end of the measurement distance are both unknown. The improper selection of the initial value will have a greater impact on the result, and the ratio of the laser to radar Need to be assumed. Therefore, a reasonable algorithm is needed to invert a wide range of correct extinction distribution values. The multi-angle algorithm used in the data processing of the laser sea fog visibility monitor overcomes the instability of the initial value of the atmospheric extinction coefficient in the previous method, and the influence of the laser radar is assumed, and the detection path can be obtained during the scanning measurement process. Visibility distribution at each point above, effectively identifying sea fog.

The algorithm is based on multi-angle measurement, and obtains atmospheric echo signals at sampling points of multiple sampling distances at each angle.

The initial angular direction is selected, and then the measurement of the sampling points of the plurality of sampling distances at each angle is projected in the initial angular direction;

The initial sampling point to be calculated is selected, and the difference between the two sets of measurement data of adjacent sampling points is selected for the near field or far field point, and the backscattering coefficient at the two points has a functional relationship. The data of different angles and the same projection distance are connected, and the optical thickness in the resolution distance can be simplified by mathematical processing and difference, thereby obtaining the extinction coefficient and the visibility value.

The above process is iteratively performed to obtain the visibility distribution within the scanning range during the multi-angle scanning measurement process.

Thus, in accordance with the above-described embodiments of the present invention, there is provided a method of detecting sea fog by measuring the visibility of the atmosphere using a laser radar, comprising:

By combining the echo signals of multiple angles, the extinction coefficients of each sampling point at each specific angle are determined, thereby obtaining the visibility distribution in each specific angular direction;

Preferably, an approximation is taken that the backscatter coefficients at adjacent sampling points are equal at the same angle.

Preferably, the scanning plane of the laser scan of the atmospheric target at the plurality of angles is substantially a horizontal plane.

Preferably, the ratio of the near-field backscattering coefficient to the far-field backscattering coefficient from the sea fog region is a constant.

In one embodiment, preferably, the ratio of the near-field backscatter coefficient of the distance sea fog region to the backscatter coefficient of the far field on the detection path of each angle is approximately 1, that is, the near-field backscatter coefficient The backscattering coefficients of the far field are taken as equals as the criterion for the deviation of the iterative end point to ensure the measurement accuracy.

In addition, the present invention also provides a laser sea surface visibility monitor based on the above method, which uses the above algorithm to measure the sea fog visibility distribution, as shown in FIG.

The laser sea surface visibility monitor comprises: a laser transmitting module 11, an echo signal receiving module 12, a signal collecting module 13, and a scanning module 14. The laser emitting module 11 is configured to emit a pulsed laser beam, and the echo signal receiving module 12 is configured to receive a backscattered signal of the atmosphere to the laser and convert the optical signal into an electrical signal, and the signal collecting module 13 is configured to receive the electrical signal, and the scanning module 14 is used to control the elevation and azimuth of laser detection and scan at any angle.

As shown in FIG. 3, the laser emitting module 11 includes a laser 21 and a beam expanding collimator 22 for emitting microfocus high repetition frequency laser pulses. The beam expander collimator 22 collimates the single-pulse energy micro-focus laser beam, and the power density of the expanded laser beam in any vertical propagation direction conforms to the laser human eye safety standard, and prevents the laser beam from facing the sea surface. In the past, the ship personnel caused injuries and ensured the safety of the eyes. With high repetition frequency, the signal-to-noise ratio can be improved and sea fog information can be detected at a longer distance. The laser 21 is an Nd:YAG solid-state laser or a semiconductor laser or a fiber laser. The types of lasers are characterized by miniaturization, long service life and low maintenance. They are suitable for the remote installation of sea fog detection equipment and long-term unattended placement conditions. The single-pulse energy micro-focus laser can prevent the laser beam from causing damage to the ship personnel passing by the sea and ensure the safety of the human eye. With high repetition frequency, the signal-to-noise ratio can be improved and sea fog information can be detected at a longer distance. The laser 21 has a wavelength in the near infrared band. For example, at 1064 nm, the band has a high atmospheric transmittance and a long laser transmission distance. The near-infrared laser sea surface visibility monitor can overcome the influence of strong background light on the sea surface and the sky during daytime detection, and realize the measurement of the all-weather sea fog distribution. The echo signal receiving module 12 includes an optical telescope 25, a filter 24, and a detector 23. The signal acquisition module 13 includes a data acquisition card 26 and an embedded board 27. The scanning module 14 is connected to the embedded board 27 and the laser sea surface visibility monitor 1 housing for controlling the housing to be horizontally and/or vertically according to the control instruction of the embedded board 27. Scanning motion. The laser sea surface visibility monitor 1 can realize the measurement of the visibility distribution in different directions of the sea surface by scanning, and obtain the sea fog generation, development and dissipation process.

The scanning module 14 is connected to the outer casing of the laser sea surface visibility monitor 1 to drive the laser sea surface visibility monitor 1 to rotate integrally, or the scanning module 14 is disposed on the laser sea surface visibility monitor 1 optical component non-light path One side drives the optical member to rotate integrally, or the scanning rotating device is disposed on one side of the beam expander and the optical path of the telescope to rotate the light beam after the light beam enters the scanning head of the scanning rotating device.

The laser sea surface visibility monitor has IP65 protection grade, and the outer casing is treated with salt spray prevention to meet the high salt and alkali environment and high humidity environment.

The communication system is a wireless data transmission system or a wired data transmission system, and the wireless data transmission system includes a GPRS communication module and a WiFi network module. The wired data transmission system is a network cable or a serial cable or an optical fiber.

The power supply system is a utility power grid, or a wind energy, solar energy or wind and solar hybrid system.

According to the laser sea fog detecting method provided by the present invention, the laser sea surface visibility monitor is installed at a suitable location on the coast, the port or the island with reference to the area and height of the advection fog in the monitored sea area, and the sea surface is several kilometers. The areas in the depth range are scanned horizontally and/or vertically to obtain visibility information at different locations on the sea surface.

Through the communication system to transmit data to the client terminal server, the data collected by the laser sea surface visibility monitor can be collected in real time, and the laser sea surface visibility monitor can be remotely monitored, debugged and managed.

The invention provides a sea fog detecting system and method based on a laser radar, wherein the laser sea surface visibility monitor adopts a fully solidified and modular structure, and can regularly collect and acquire visibility distribution data in an unattended environment. And automatically store the record. According to the actual environmental conditions, the appropriate location can be selected and scanned and monitored in the direction that needs to be monitored. As shown in FIG. 4, the communication system provided by the embodiment of the present invention transmits the measurement data of the laser sea surface visibility monitor 1 to the communication base station 4 and the central control room 5 through the GSM communication module 3, and the communication base station transmits the measurement data to the mobile terminal. To obtain the information of the mobile phone alert 6, the laser sea surface visibility monitor 1 can be sent to the terminal computer 7 or the terminal display 8 via the wireless communication network 2 to display the data collected by the signal acquisition module 13. The collected signals may also be sent to the terminal computer 7 or the terminal display 8 in a wired manner to display the data collected by the signal acquisition module 13. When the collected signal is sent to the terminal computer 7, the collected signal may be a signal that has not been subjected to the inversion processing by the signal acquisition module 13, and the inversion process is completed on the terminal computer 7; When the signal is transmitted to the terminal display 8, the acquired signal is a signal that has been subjected to the inversion processing by the signal acquisition module 13. In another embodiment, the signal collected by the signal acquisition module 13 is uploaded to a network server, inverted in the network server, and the inverted signal is sent to the terminal computer. The laser sea surface visibility monitor 1 is installed in an open field of view, and the scanning angle range can be set by itself. The equipment can be connected to the existing power grid (220V, 50Hz AC), or it can be powered by solar, wind or wind. The embedded wireless communication module is configured as an optional component inside the control box of the laser sea surface visibility monitor. The data is transmitted to the terminal information platform through GPRS/CDMA wireless technology, which can collect data collected by the remote monitoring device in real time and remotely operate the device. Monitoring, debugging and management. It adopts GPRS/CDMA wireless communication and has the advantages of wide network coverage, reliable transmission, flexible networking and fast construction period. The software system combines measurement data with GIS for analysis, providing real-time accurate and accurate detection of fogging in the scanning area.

Test case

The occurrence of sea fog is characterized by contingency, mobility, locality, and uneven spatial distribution. The existing point-type visibility meter is limited by its measurement principle, and only the data at the installation point can be obtained, and the visibility value is given by the point-to-face. If the visibility of the installation site is good, the sea fog occurs in the channel area. According to the measurement results of the existing point-type visibility meter, if the ship is traveling normally, it is prone to accidents and threaten the safety of life and property. The laser radar has the advantages of long detection range and high temporal and spatial resolution. The laser sea surface visibility monitor effectively obtains the visibility distribution information on the entire detection path by detecting the backscattering of the interaction between the laser and various media in the atmosphere. Through scanning observation, the visibility of sea surface visibility can be effectively obtained, the sea fog can be accurately identified, and the process of its generation and dissipation can be observed.

The following example shows the port area where the laser sea surface visibility monitor is installed. Many existing point-type visibility meters measure high visibility values, but there is a real case of sea fog actually present on the sea surface. The laser sea surface visibility monitor effectively solves the measurement misjudgment problem of the point visibility meter, accurately measures the sea fog distribution, and gives the process of sea fog motion diffusion, the time of generation and dissipation, not only provides the sea fog warning forecast for the traffic department. It also provides data support for the meteorological department to study the formation mechanism of sea fog.

As shown in Figure 5, the installation locations of the three existing point-type visibility meters in the port area are respectively 122.035473 east longitude, 29.914883 north latitude, 122.04442 east longitude, 29.91093 north latitude, 122.046675 east longitude, and 29.937772 north latitude. The upper limit of visibility of the visibility device of C and C is 20km, and the upper limit of visibility of the visibility device of A is 30km. It can be seen from the figure that from 0 o'clock to 1 o'clock, the visibility values measured by the three visibility meters are high. After 1 o'clock in the morning, the visibility value of C is decreased, while the visibility values of the other two locations are kept above 20 km.

As shown in Figure 6, a laser sea surface visibility monitor installation diagram is shown. The scanning range covers A, B, and C, and can give visibility information of the entire sea area. The laser sea surface visibility monitor is placed in the A ground. The B ground is located at a radar scanning angle of about 105° and a linear distance of about 0.95 km. The C ground is located at a radar scanning angle of about 20° and a linear distance of about 3.2 km. The laser sea surface visibility monitor is 11 minutes from a single scan of 120° to 20°.

Figure 7 to Figure 9 show the scanning views of the laser sea surface visibility monitor at 00:36, 01:38, and 02:03, respectively. The detection distance of the left image is 4km, and the detection distance of the right image is 6km. The rightmost side of the figure is the color bar, which uses different colors from gray to dark blue to represent different visibility values, where the upper limit of visibility is set to 40km, expressed in dark blue, if the visibility value is greater than 40km, it is indicated in white. It can be clearly seen from the following three figures that before 1 am, the visibility in the entire scanning area is relatively high, ranging from 20 km to 30 km. At 1:30, sea fog appeared at a distance of 2.5 km from the C direction, and the visibility value of C began to decrease. When the wind direction is southerly, at 2 o'clock in the morning, it can be observed that the sea fog is spreading toward the southeast. Since the main area where sea fog occurs is between B and C, the existing point-type visibility meters placed in Areas A and B always give high-visibility measurements.

Figure 10 shows the sea surface visibility distribution and sea fog change measured by the laser sea surface visibility monitor.

In order to verify the accuracy of the measurement results of the laser sea surface visibility monitor, the measurement data deviations of the laser sea surface visibility monitor and the front scattered visibility meter were analyzed under different weather conditions, and rain, fog, sunny, cloudy days were selected respectively. ) Several typical weather phenomena. The results of the laser sea surface visibility monitor and the forward scatter visibility meter were linearly fitted to obtain the correlation coefficient. The laser sea surface visibility monitor takes measurements in the 105° scan direction and compares it to the existing forward scatter visibility.

Figure 11 is a comparison of the laser sea surface visibility monitor and the B ground front visibility meter. Weather: shower to moderate rain, southeast wind 1 to 2.

Figure 12 is a comparison of the laser sea surface visibility monitor and the B ground front visibility meter. The weather is: light rain ~ yin, northwest wind 4 to 5 level.

Figure 13 is a comparison of the laser sea surface visibility monitor and the B ground front visibility meter. Weather: from heavy rain to heavy rain, east wind 3 to 4.

The data of the laser sea surface visibility monitor was compared with the previous observation results, and the linear fitting was used. The correlation coefficient was 0.9585, as shown in Fig. 14.

Figure 15 and Figure 16 are comparisons of the laser sea surface visibility monitor and the front-dissipation visibility meter in foggy weather.

The data of the laser sea surface visibility monitor was compared with the previous observation results, and the linear fitting was used. The correlation coefficient was 0.7397, as shown in Fig. 17.

Figure 18 is a comparison of the laser sea surface visibility monitor and the front scattered visibility meter on a cloudy day (sunny day).

The data of the laser sea surface visibility monitor was compared with the previous observation results, and the linear fitting was used. The correlation coefficient was 0.9116, as shown in Fig. 19.

Statistics on the above data, the correlation coefficient and relative error of the forward scattering visibility meter and the laser sea surface visibility monitor are as follows under different visibility conditions. Both show good agreement.

Visibility range	Correlation coefficient	Average absolute error	Average relative error	Mean square error
0 to 5km	0.9335	514.5327	0.159413	417.013
5 to 10km	0.8254	805.0602	0.113177	575.3866
>10km	0.829	2369.94	0.130509	2682.795

The measurement results of this example show that the laser sea surface visibility monitor can effectively solve the problem that the point visibility meter can only obtain the visibility at the isolated point and is prone to misjudgment. In the above-mentioned sea fog example, the monitor that the laser sea surface can see exhibits excellent measurement performance, obtains the visibility distribution in the entire scanning area, and gives the process of sea fog motion diffusion, generation and dissipation time. In addition, the visibility of the laser sea surface visibility monitor in the direction of the position of the forward scattering visibility meter is compared with the result of the point forward scattering visibility meter. Under different visibility ranges, the correlation is greater than 0.8, especially at low visibility, the correlation is higher, greater than 0.9, verifying the accuracy of the laser sea surface visibility monitor.

By implementing the above technical solution, the following technical effects are provided: the laser sea surface visibility monitor provided by the present invention can accurately measure the spatial distribution of atmospheric visibility by detecting and analyzing the backscattered light generated by the interaction between the atmosphere and the laser, and The measurement results are not affected by weather conditions such as fog and smoke. It can effectively obtain the piece-by-section information of the visibility distribution in the whole detection path, accurately monitor the atmospheric environment characteristics such as cloud, fog, smoke and dust from the installation location to a certain distance. By changing the scanning direction, it can also obtain the visibility and fog in all directions in real time. And information such as aerosol distribution.

It will be apparent that the method and apparatus of the present invention are not limited to measuring sea fog and may be suitable for measuring other meteorological targets.

Clause 1 A method of detecting a meteorological target by measuring the visibility of the atmosphere by laser visibility, comprising:

By combining the echo signals of multiple angles, the extinction coefficient of each sampling point at each specific angle is determined, thereby obtaining the visibility distribution in each specific angular direction, thereby obtaining the visibility of the meteorological target in the multi-angle scanning range. Distribution, where the echo signal for each sample point is a function of the backscatter coefficient and the extinction coefficient.

Clause 2: The method of clause 1, wherein the near-field backscatter coefficient from the meteorological target region is a function of the backscatter coefficient of the far field, β _i (z _m ) = δ · β _i (z _n ).

Clause 3: The method of clause 1, wherein the backscattering coefficient of the near field from the meteorological target region and the backscattering coefficient of the far field are approximately equal.

Clause 4: The method of clause 1, wherein the retroreflection coefficients at adjacent sampling points are approximately equal at the same angle.

Clause 5: The method of clause 1, wherein the method further comprises:

The initial angular direction is selected, and the measurement of the sampling points of the plurality of sampling distances at each subsequent angle is projected in the initial angular direction;

Select a starting sampling point at a specific angle, and select a difference between two sets of measurement data of adjacent sampling points for the near field point or the far field point, and the backscattering coefficient at the two points has a functional relationship;

The data of different angles and the same projection distance are connected, and the optical thickness in the resolution distance can be simplified by processing and difference, thereby obtaining the extinction coefficient and the visibility value.

The above process is iteratively performed to obtain a visibility distribution within the scan range of the multi-angle scan measurement.

Clause 6: If the method of Clause 1 refers to the area and height of the advection fog in the monitored sea area, the laser sea surface visibility monitor is installed at a suitable location on the coast, port or island, and the area within a few thousand meters of the sea surface Perform horizontal and / or vertical scanning to obtain visibility information at different locations on the surface of the sea.

Clause 7: A laser visibility monitor comprising: a laser transmitting module, an echo signal receiving module, a signal collecting module, and a scanning module. The laser emitting module is configured to emit a pulsed laser beam, the echo signal receiving module is configured to receive a backscattered signal of the atmosphere to the laser and convert the optical signal into an electrical signal, and the signal collecting module is configured to receive the electrical The scanning module is configured to control the elevation and azimuth angles of the laser detection and perform scanning at any angle. When operating, the laser visibility monitor performs the method of one of claims 1 to 6.

Clause 8: The laser visibility monitor of clause 7, wherein the laser emitting module comprises a laser for emitting microfocus high repetition frequency laser pulses and a beam expanding collimator. The beam expander collimator collimates the single-pulse energy micro-focus laser beam, and the power density of the expanded laser beam in any vertical propagation direction conforms to the laser human eye safety standard, which prevents the laser beam from facing the sea surface. In the past, the ship personnel caused injuries and ensured the safety of the eyes. With high repetition frequency, the signal-to-noise ratio can be improved and sea fog information can be detected at a longer distance.

Clause 9: The laser visibility monitor of clause 7, wherein the laser emitting module comprises a Nd:YAG solid state laser or a semiconductor laser or a fiber laser.

Clause 10: The laser visibility monitor of clause 7, wherein the echo signal receiving module comprises an optical telescope, a filter, and a detector.

Clause 11: The laser visibility monitor of clause 7, wherein the signal acquisition module comprises a data acquisition card and an embedded board.

Clause 12: The laser visibility monitor of clause 7, wherein the scanning module is coupled to the embedded board and the laser sea surface visibility monitor housing for use according to the embedded board Control commands control the housing to perform scanning motion in a horizontal and/or vertical direction. The laser sea surface visibility monitor can scan the visibility distribution in different directions of the sea surface to obtain the sea fog generation, development and dissipation process.

Clause 13: The laser visibility monitor according to Item 7, wherein the scanning module is connected to the laser sea surface visibility monitor housing to drive the laser sea surface visibility monitor to rotate integrally, or the scanning module Provided on the non-light path side of the optical component of the laser sea surface visibility monitor to drive the optical component to rotate integrally, or the scanning rotating device is disposed on one side of the beam expander and the optical path of the telescope, and is incident on the light beam The scan head of the scanning rotary device rotates the light beam.

Item 14: The laser sea surface visibility monitor according to Item 7, characterized in that the device has an IP65 protection level, and the outer casing is subjected to salt spray protection to adapt to the high salinity and high humidity environment conditions of the sea.

Clause 15: The laser sea surface visibility monitor of clause 7, further comprising a communication system, the communication system being a wireless data transmission system or a wired data transmission system, the wireless data transmission system comprising a GPRS communication module and/or Or a WiFi network module, the wired data transmission system is a network cable or a serial cable or an optical fiber.

Clause 16: The laser sea surface visibility monitor of clause 7, further comprising a power supply system, the power supply system being a utility power grid, or a wind energy, solar energy or wind and solar hybrid system.

Clause 17: The method of clause 1, wherein the echo signal of each sample point is transformed into a function of a backscatter coefficient and an optical thickness, and each specific one is determined by combining echo signals of a plurality of angles The optical thickness of each sampling point under the angle, and then the corresponding extinction coefficient is calculated, thereby obtaining the visibility distribution in each specific angular direction.

For the foregoing method embodiments, for the sake of simple description, it is possible to express them as a series of action combinations, but those skilled in the art should understand that the present invention is not limited by the described action sequence, because according to the present invention, Some steps can be performed in other orders or at the same time. In addition, those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present invention.

The above description is only a preferred embodiment of the invention and is not intended to limit the invention in any way. While the invention has been described above in the preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above, or modify the equivalents of equivalent changes without departing from the scope of the technical solutions of the present invention. Example. Therefore, any simple modifications, equivalent changes, and modifications of the above embodiments may be made without departing from the spirit and scope of the invention.

Claims (20)

1. A method for detecting sea fog using a laser visibility monitor to measure atmospheric visibility distribution, including:

   By combining the echo signals of the laser scanning at multiple angles, the extinction coefficients of the sampling points on the scanning path at each specific angle are determined, thereby obtaining the visibility distribution in each specific angular direction, wherein each sampling point The echo signal is a function of the backscatter coefficient and the extinction coefficient.
2. The method of claim 1 wherein the near-field backscatter coefficient from the sea fog region is a function of the backscatter coefficient of the far field, β _i (z _m ) = δ · β _i (z _n ).
3. The method of claim 1 wherein the backscattering coefficient of the near field from the sea fog region and the backscattering coefficient of the far field are taken to be equal.
4. The method of claim 1 wherein the retroreflection coefficients at adjacent sampling points are taken equal at the same angle.
5. The method of claim 1 wherein said method further comprises:

   The initial angular direction is selected, and the measurement of the sampling points of the plurality of sampling distances at each subsequent angle is projected in the initial angular direction;

   Select a starting sampling point at a specific angle, and select a difference between two sets of measurement data of adjacent sampling points for the near field point or the far field point, and the backscattering coefficient at the two points has a functional relationship;

   The data of different angles and the same projection distance are connected, and the optical thickness in the resolution distance can be simplified by processing and difference, thereby obtaining the extinction coefficient and the visibility value.

   The above process is iteratively performed to obtain a visibility distribution within the scan range of the multi-angle scan measurement.
6. The method of claim 1, wherein the laser sea surface visibility monitor is installed at a suitable location on the coast, port or island with reference to the area and height of the advection fog in the monitored sea area, and the area within a depth of several kilometers of the sea surface is leveled. And/or vertical scanning, or scanning at an elevation angle to obtain visibility information at different locations on the sea surface.
7. The method of claim 1 wherein the echo signals of each sample point are transformed into a function of backscatter coefficient and optical thickness to determine the angle of each particular angle by echoing the echo signals of the plurality of angles The optical thickness of each sampling point is used to calculate the corresponding extinction coefficient, thereby obtaining the visibility distribution in each specific angular direction.
8. A laser sea surface visibility monitor comprises: a laser emitting module, an echo signal receiving module, a signal collecting module, a scanning module, the laser emitting module is configured to emit a pulsed laser beam, and the echo signal receiving module is configured to receive an atmosphere a backscattering signal for the laser and converting the optical signal into an electrical signal, the signal acquisition module for receiving the electrical signal, the scanning module for controlling the elevation and azimuth of the laser detection and scanning at any angle, The laser sea surface visibility monitor performs the method of one of claims 1 to 7 when in operation.
9. The laser sea surface visibility monitor of claim 8 wherein said laser emitting module comprises a laser for emitting microfocus high repetition frequency laser pulses and a beam expanding collimator. The beam expander collimator collimates the single-pulse energy micro-focus laser beam, and the power density of the expanded laser beam in any vertical propagation direction conforms to the laser human eye safety standard, which prevents the laser beam from facing the sea surface. In the past, the ship personnel caused damage and ensured the safety of the human eye. The high repetition frequency was adopted to improve the signal-to-noise ratio and detect sea fog information at a longer distance.
10. A laser sea surface visibility monitor according to claim 8, wherein the laser emitting module comprises a Nd:YAG solid laser or a semiconductor laser or a fiber laser.
11. A laser sea surface visibility monitor according to claim 8 wherein said echo signal receiving module comprises an optical telescope/filter and a detector.
12. The laser sea surface visibility monitor according to claim 8, wherein the signal acquisition module comprises a data acquisition card and an embedded board.
13. The laser sea surface visibility monitor according to claim 8, wherein said scanning module is coupled to said embedded board and said laser sea surface visibility monitor housing for controlling according to said embedded board The command controls the outer casing to perform scanning movement in a horizontal and/or vertical direction, or a certain elevation angle direction, and the laser sea surface visibility monitor can realize the visibility distribution measurement of the sea surface in different directions by scanning, and obtain the sea fog generation, development and dissipation process.
14. The laser sea surface visibility monitor according to claim 8, wherein the scanning module is connected to the laser sea surface visibility monitor housing to drive the laser sea surface visibility monitor to rotate integrally, or the scanning module is set. On the non-light path side of the optical component of the laser sea surface visibility monitor to drive the optical component to rotate integrally, or the scanning rotating device is disposed on one side of the beam expander and the optical path of the telescope, at the beam entrance station The scanning head of the scanning rotating device rotates the light beam.
15. The laser sea surface visibility monitor according to claim 8, wherein the device has an IP65 protection level, and the outer casing is subjected to anti-salt mist treatment to adapt to the environment of high salinity and high humidity in the sea.
16. A laser sea surface visibility monitor according to claim 8, further comprising a communication system, the communication system being a wireless data transmission system or a wired data transmission system, the wireless data transmission system comprising a GPRS communication module and/or WiFi The network module, the wired data transmission system is a network cable or a serial cable or an optical fiber.
17. A laser sea surface visibility monitor according to claim 8, further comprising a power supply system, the power supply system being a utility power grid, or a wind energy, solar energy or wind and solar hybrid system.
18. The laser sea surface visibility monitor of claim 8 wherein said performing the method of one of claims 1 to 7 to invert the acquired signal is performed by said signal acquisition module.
19. A laser sea surface visibility monitor according to claim 8 further comprising a terminal computer for receiving the acquired signals, wherein said method of performing one of claims 1 to 7 for inverting the acquired signals is by the terminal The computer is done.
20. A laser sea surface visibility monitor according to claim 8 further comprising a network server, said signal collected by said signal acquisition module being uploaded to a network server, wherein said method of one of claims 1 to 7 is performed to perform the acquired signal The inversion is done by the web server.

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