CN115753602A - Sea fog detection method and system - Google Patents
Sea fog detection method and system Download PDFInfo
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Abstract
The invention discloses a sea fog detection method and system, and relates to the field of sea fog detection.
Description
Technical Field
The invention relates to the field of sea fog detection, in particular to a sea fog detection method and system.
Background
Sea fog is a weather phenomenon that in the lower atmosphere of the sea or coastal areas, a large number of water drops or ice crystals are generated due to water vapor condensation, so that the horizontal visibility of the atmosphere is less than 1km, and the sea fog can seriously affect the traffic, operation, production, military activities and the like at sea. Therefore, the method for monitoring and forecasting the generation development and the influence range of the sea fog provides basis for scientific regulation and management of relevant departments, and has important practical significance for disaster prevention and reduction. Because only a few or even no sites exist on the ocean, an effective observation means is lacked, and the business application of sea fog monitoring is difficult to meet. The spectrum imager of the geostationary satellite has wide visual field, can realize continuous detection in a marine area, and provides powerful observation data for quantitatively researching the characteristics and the influence range of the sea fog elimination. However, the satellite imager can only passively receive solar short-wave radiation reflected by a target object and long-wave radiation emitted by the earth, and has great limitation on the detection capability of an atmospheric vertical structure, for example, when high clouds exist on sea fog, signals can interfere with each other, and the accuracy of sea fog detection is affected, so that the existing sea fog detection method based on the satellite imager is only suitable for single-layer cloud fog, and if a cloud layer covers a fog area, the detection result is judged as the cloud area, and the sea fog shielded by the cloud layer cannot be identified. Therefore, the existing sea fog detection technology based on satellite remote sensing has the following defects: and when the high-rise layer has clouds, the sea fog detection cannot be carried out. However, in all cloud systems of real atmosphere, the proportion of high clouds (ice clouds) exceeds 40%, and the judgment of whether water clouds or sea fog exist below the ice clouds is always a difficult point in the field of satellite remote sensing.
Disclosure of Invention
In order to solve the problem that the sea fog detection accuracy is influenced when high clouds exist on the sea fog, the invention provides a sea fog detection method, which comprises the following steps:
s1: acquiring satellite data under a real cloud and fog environment through a satellite imager, wherein the satellite data comprises longitude and latitude data, and acquiring primary data and cloud detection data corresponding to a target ocean area in the satellite data through the longitude and latitude data, wherein the primary data comprises the reflectivity of a first channel, a second channel and a third channel, and the brightness temperature of the fourth channel and a fifth channel; the first channel is a visible light channel with the central wavelength of 0.64 micrometer, the second channel is a near-infrared channel with the central wavelength of 1.6 micrometer, the third channel is a near-infrared channel with the central wavelength of 2.25 micrometer, the fourth channel is a long-wave infrared channel with the central wavelength of 8.5 micrometer, and the fifth channel is a long-wave infrared channel with the central wavelength of 11 micrometer;
s2: establishing a cloud simulation model corresponding to each set cloud type based on radiation transmission simulation, and simulating a real cloud environment detected by a satellite imager under each set cloud type to obtain a cloud simulation environment corresponding to each set cloud type; each set cloud type includes: the system comprises a single-layer water cloud, a single-layer sea fog, a single-layer ice cloud, an upper-layer ice cloud, a lower-layer water cloud and an upper-layer ice cloud, lower-layer sea fog; the cloud and fog simulation model comprises all spectrum channels in the primary data;
s3: obtaining the reflectivity and brightness temperature of each spectral channel in each cloud and fog simulation environment through each cloud and fog simulation model;
s4: designing criterion conditions corresponding to the types of the set clouds through the reflectivity and the brightness temperature of each spectrum channel in each cloud fog simulation environment, wherein the criterion conditions comprise: the method comprises the following steps of (1) judging conditions of a water phase state, a single-layer water cloud, a single-layer sea fog, an ice phase state, a single-layer ice cloud, an upper layer ice cloud, a lower layer water cloud and an upper layer ice cloud, lower layer sea fog;
s5: the method comprises the following steps of acquiring a set cloud type corresponding to a target ocean area by using criterion conditions through primary data and cloud detection data corresponding to the target ocean area in a real cloud environment, wherein the acquisition method comprises the following steps:
s51: acquiring a cloud top phase state corresponding to a target ocean area by using a water phase state criterion condition and an ice phase state criterion condition according to the brightness and the temperature of a fourth channel and a fifth channel in the primary data, wherein the cloud top phase state is a water phase state or an ice phase state;
s52: when the cloud top phase state is the water phase state, acquiring a set cloud type corresponding to the target ocean area by utilizing the single-layer water cloud criterion condition and the single-layer sea fog criterion condition according to the reflectivity of the first channel and the second channel in the primary data;
s53: and when the cloud top phase state is the ice phase state, acquiring a set cloud and mist type corresponding to the target ocean area by using the single-layer ice cloud criterion condition, the upper-layer ice cloud lower-layer water cloud criterion condition and the upper-layer ice cloud lower-layer sea mist criterion condition according to the reflectivity of the first channel, the second channel and the third channel in the primary data.
Further, in step S4, designing criterion conditions corresponding to each set cloud type according to the reflectivity and the brightness temperature of each spectral channel in each cloud simulation environment includes:
the method comprises the following steps of obtaining difference characteristics of the reflectivity of each spectral channel among cloud and mist simulation environments by carrying out sensitivity analysis on the reflectivity of a first channel, a second channel and a third channel under the cloud and mist simulation environments, wherein the difference characteristics are obtained by the following steps:
based on the particle characteristics of the water cloud with effective particle radius of 10-20 microns and the sea fog with effective particle radius of 3-5 microns, and in the simulation process, the reflectivity of each spectral channel in each cloud and fog simulation environment is obtained:
when the optical thickness and the effective particle radius are both smaller than the corresponding set lower limit value, the reflectivity difference value of the first channel and the second channel is smaller than 0, and when the optical thickness and the effective particle radius are both larger than the corresponding set upper limit value, the reflectivity difference value is larger than or equal to 0, so that the characteristics of:
the difference between the reflectivities of the water cloud particles corresponding to the first channel and the second channel is greater than or equal to a threshold value, the difference between the reflectivities of the sea fog particles corresponding to the first channel and the second channel is less than the difference characteristic of the threshold value, and the threshold value is equal to 0;
the difference features obtained during the simulation further include: the difference characteristics of the reflectivity of each spectral channel among the cloud simulation environments corresponding to the single-layer ice cloud, the upper-layer ice cloud lower-layer water cloud and the upper-layer ice cloud lower-layer sea fog;
setting a single-layer water cloud criterion condition and a single-layer sea fog criterion condition according to the difference characteristics corresponding to the water cloud particles and the sea fog particles;
adjusting a threshold value in the corresponding difference characteristics of the water cloud particles and the sea fog particles, and setting a single-layer ice cloud criterion condition, an upper-layer ice cloud lower-layer water cloud criterion condition and an upper-layer ice cloud lower-layer sea fog criterion condition according to the difference characteristics of the reflectivity of each spectral channel between the single-layer ice cloud, the upper-layer ice cloud lower-layer water cloud and the corresponding cloud and fog simulation environment of the upper-layer ice cloud lower-layer sea fog.
Further, the data types of the cloud detection data include: cloud, possibly cloud, clear sky and possibly clear sky.
Further, in step S5, before step S51, the method further includes:
s50: and judging whether the data type of the cloud detection data is 'cloud' or 'possible cloud', if so, entering the step S51.
Further, the water phase criterion condition is as follows: the brightness temperature corresponding to the fifth channel is greater than a first preset value, and the difference value of the brightness temperatures corresponding to the fourth channel and the fifth channel is less than or equal to a second preset value;
the ice phase state criterion condition is as follows: the brightness temperature corresponding to the fifth channel is less than or equal to a first preset value, or the difference value of the brightness temperatures corresponding to the fourth channel and the fifth channel is greater than or equal to a third preset value; the third preset value is greater than the second preset value.
Further, the single-layer water cloud criterion condition is as follows: the difference value of the corresponding reflectivity of the first channel and the second channel is more than or equal to zero;
the single-layer sea fog criterion condition is as follows: the difference value of the corresponding reflectivity of the first channel and the second channel is less than zero;
the single-layer ice cloud criterion condition is as follows: and the reflectivity difference value corresponding to the second channel and the third channel is greater than a fourth preset value.
Further, the air conditioner is characterized in that,
the criterion conditions of the upper ice cloud layer and the lower water cloud layer are as follows: the reflectivity difference value corresponding to the second channel and the third channel is less than or equal to a fourth preset value; the reflectivity difference value corresponding to the first channel and the second channel is greater than or equal to a fifth preset value;
the criterion conditions of the upper ice cloud layer and the lower sea fog layer are as follows: the reflectivity difference value corresponding to the second channel and the third channel is less than or equal to a fourth preset value; and the reflectivity difference value corresponding to the first channel and the second channel is smaller than a fifth preset value.
Further, the first preset value, the second preset value, the third preset value, the fourth preset value and the fifth preset value are sequentially as follows: 238K, -1K, 0.5K, 0.04, 0.08.
The invention also provides a sea fog detection system, comprising:
the real data acquisition module is used for acquiring satellite data under a real cloud and mist environment through a satellite imager, wherein the satellite data comprises longitude and latitude data, primary data and cloud detection data corresponding to a target ocean area in the satellite data are acquired through the longitude and latitude data, and the primary data comprises the reflectivity of a first channel, a second channel and a third channel and the brightness and temperature of a fourth channel and a fifth channel; the first channel is a visible light channel with the central wavelength of 0.64 micrometer, the second channel is a near-infrared channel with the central wavelength of 1.6 micrometer, the third channel is a near-infrared channel with the central wavelength of 2.25 micrometer, the fourth channel is a long-wave infrared channel with the central wavelength of 8.5 micrometer, and the fifth channel is a long-wave infrared channel with the central wavelength of 11 micrometer;
the model establishing module is used for establishing a cloud and mist simulation model corresponding to each set cloud and mist type based on radiation transmission simulation, and is used for simulating a real cloud and mist environment detected by a satellite imager under each set cloud and mist type to obtain a cloud and mist simulation environment corresponding to each set cloud and mist type; each set cloud type includes: the device comprises a single-layer water cloud, a single-layer sea fog, a single-layer ice cloud, an upper-layer ice cloud, a lower-layer water cloud and an upper-layer ice cloud, lower-layer sea fog; the cloud and fog simulation model comprises all spectrum channels in the primary data;
the simulation data acquisition module is used for acquiring the reflectivity and the brightness temperature of each spectral channel in each cloud and mist simulation environment through each cloud and mist simulation model;
the criterion condition setting module is used for designing criterion conditions corresponding to the set cloud and mist types through the reflectivity and the brightness temperature of each spectral channel in each cloud and mist simulation environment, and the criterion conditions comprise: the method comprises the following steps of (1) judging conditions of a water phase state, a single-layer water cloud, a single-layer sea fog, an ice phase state, a single-layer ice cloud, an upper layer ice cloud, a lower layer water cloud and an upper layer ice cloud, lower layer sea fog;
the detection module is used for acquiring the set cloud and mist type corresponding to the target ocean area by using the criterion condition through the primary data and the cloud detection data corresponding to the target ocean area under the real cloud and mist environment, and specifically comprises the following steps:
the cloud top phase state detection unit is used for acquiring a cloud top phase state corresponding to the target ocean area according to the brightness temperature of a fourth channel and a fifth channel in the primary data by using a water phase state criterion condition and an ice phase state criterion condition, wherein the cloud top phase state is a water phase state or an ice phase state;
the first detection unit is used for acquiring a set cloud and mist type corresponding to a target ocean area by using a single-layer water cloud criterion condition and a single-layer sea mist criterion condition according to the reflectivity of a first channel and a second channel in primary data when the cloud top phase state is a water phase state;
and the second detection unit is used for acquiring a set cloud type corresponding to the target ocean area by utilizing the single-layer ice cloud criterion condition, the upper-layer ice cloud lower-layer water cloud criterion condition and the upper-layer ice cloud lower-layer sea fog criterion condition according to the reflectivity of the first channel, the second channel and the third channel in the primary data when the cloud top phase state is the ice phase state.
Compared with the prior art, the invention at least has the following beneficial effects:
(1) According to the invention, through each cloud and mist simulation model, the reflectivity and brightness temperature of each spectral channel in each cloud and mist simulation environment are obtained, the criterion condition corresponding to each set cloud and mist type is designed, and after the cloud top phase state corresponding to the target ocean area is judged, the set cloud and mist type corresponding to the target ocean area is obtained according to the reflectivity of the first channel, the second channel and the third channel in the primary data by utilizing the single-layer water cloud criterion condition, the single-layer sea mist criterion condition, the single-layer ice cloud criterion condition, the upper-layer ice cloud lower-layer water cloud criterion condition and the upper-layer ice cloud lower-layer sea mist criterion condition, so that the limitation that low-layer sea mist or water cloud cannot be effectively detected when the ice cloud is shielded is broken through, the detection of the low-layer water cloud and the sea mist under the ice cloud is realized, the technical level of a satellite imager on the sea mist monitoring is improved, and a more accurate and efficient sea mist detection result is provided for future service application;
(2) The method comprises the steps of sensitively analyzing the reflectivity of a first channel, a second channel and a third channel in each cloud and mist simulation environment to obtain the difference characteristics of the reflectivity of each spectral channel among the cloud and mist simulation environments, and setting a single-layer water cloud criterion condition and a single-layer sea mist criterion condition according to the difference characteristics corresponding to water cloud particles and sea mist particles; the method comprises the steps of adjusting a threshold value in the corresponding difference characteristics of water cloud particles and sea fog particles, setting single-layer ice cloud criterion conditions, upper-layer ice cloud lower-layer water cloud criterion conditions and upper-layer ice cloud lower-layer sea fog criterion conditions according to the difference characteristics of the reflectivity of each spectral channel among single-layer ice clouds, upper-layer ice cloud lower-layer water clouds and cloud simulation environments corresponding to upper-layer ice cloud lower-layer sea fog, simulating real cloud environments corresponding to each set cloud fog type, and carrying out data analysis on the reflectivity of each spectral channel obtained in the simulation process to design the criterion conditions corresponding to each set cloud fog type.
Drawings
FIG. 1 is a flow chart of a sea fog detection method;
fig. 2 is a block diagram of a sea fog detection system.
Detailed Description
The following are specific embodiments of the present invention and are further described with reference to the accompanying drawings, but the present invention is not limited to these embodiments.
Example one
In order to realize the detection of low-layer water cloud and sea fog below ice cloud and improve the technical level of a satellite imager on sea fog monitoring, as shown in fig. 1, the invention provides a sea fog detection method, which comprises the following steps:
s1: acquiring satellite data in a real cloud and fog environment through a satellite imager, wherein the satellite data comprises longitude and latitude data, acquiring primary data and cloud detection data corresponding to a target ocean area in the satellite data through the longitude and latitude data (namely, matching the corresponding primary data and the cloud detection data according to the geographic position of the target ocean area), and the primary data comprises the reflectivity of a first channel, a second channel and a third channel and the brightness temperature of the fourth channel and a fifth channel; the first channel is a visible light channel with the central wavelength of 0.64 micrometer, the second channel is a near-infrared channel with the central wavelength of 1.6 micrometer, the third channel is a near-infrared channel with the central wavelength of 2.25 micrometer, the fourth channel is a long-wave infrared channel with the central wavelength of 8.5 micrometer, and the fifth channel is a long-wave infrared channel with the central wavelength of 11 micrometer;
it should be noted that, the primary data and the cloud detection data further include invalid values before being used in the following steps.
S2: establishing a cloud and mist simulation model corresponding to each set cloud and mist type by using an accurate forward radiation transmission mode based on radiation transmission simulation, wherein the cloud and mist simulation model is used for simulating a real cloud and mist environment detected by a satellite imager under each set cloud and mist type so as to obtain a cloud and mist simulation environment corresponding to each set cloud and mist type; each set cloud type includes: the device comprises a single-layer water cloud, a single-layer sea fog, a single-layer ice cloud, an upper-layer ice cloud, a lower-layer water cloud and an upper-layer ice cloud, lower-layer sea fog; the cloud and fog simulation model comprises various spectral channels (a first channel, a second channel, a third channel, a fourth channel and a fifth channel) in primary data;
specifically, in the cloud and fog simulation environment, ice cloud particles adopt polymers which are composed of solid cylinders and have rough surfaces, and water cloud and sea fog particles adopt spheres with regular shapes; the parameters of ice cloud, water cloud and sea fog are set in sequence as follows: the thickness of the ice cloud and the water cloud is 1 kilometer, the sea fog is 0.5 kilometer, and the heights are 10 kilometers, 2 kilometers and 0.5 kilometer respectively; the effective particle radii of the ice cloud, water cloud and sea fog are set to 0-70 microns, 0-10 microns, respectively, and the optical thickness ranges from 0-40.
S3: obtaining the reflectivity and brightness temperature of each spectral channel in each cloud and mist simulation environment through each cloud and mist simulation model;
s4: designing criterion conditions corresponding to the types of the set clouds through the reflectivity and the brightness temperature of each spectrum channel in each cloud fog simulation environment, wherein the criterion conditions comprise: the method comprises the following steps of (1) judging conditions of a water phase state, a single-layer water cloud, a single-layer sea fog, an ice phase state, a single-layer ice cloud, an upper layer of ice cloud and a lower layer of water cloud and an upper layer of ice cloud and a lower layer of sea fog;
specifically, the difference characteristics of the reflectivity of each spectral channel between the cloud and fog simulation environments are obtained according to the reflectivity under each cloud and fog simulation environment, and the criterion conditions corresponding to the cloud and fog types are designed according to the difference characteristics.
It should be noted that the purpose of simulating five cloud and mist environments of the set cloud and mist types, namely, the single-layer water cloud, the single-layer sea mist, the single-layer ice cloud, the upper-layer ice cloud, the lower-layer water cloud, and the upper-layer ice cloud, the lower-layer sea mist, is to perform sensitivity analysis on the reflectivities of the first channel, the second channel, and the third channel in each cloud and mist simulation environment so as to obtain the difference characteristic of the reflectivities of each spectral channel among the set cloud and mist types. Specifically, both the water cloud and the sea fog are composed of liquid water, the main difference being the particle size, the water cloud effective particle radius being mainly between 10 and 20 microns, and the sea fog effective particle radius being mostly 3 to 5 microns. The simulation results show that the difference of the channel reflectivity is characterized by: when the optical thickness and the effective particle radius are small (both are smaller than the corresponding set lower limit value), the reflectivity difference between the first channel and the second channel is smaller than 0, and when the optical thickness and the effective particle radius are large (both are larger than the corresponding set upper limit value), the reflectivity difference is larger than 0, so that the reflectivity difference between the first channel and the second channel corresponding to most water cloud particles is larger than 0, and the reflectivity difference between the first channel and the second channel corresponding to sea fog particles is smaller than 0, and based on the difference characteristics of the channel reflectivity, the identification of water clouds and sea fog can be realized. For ice cloud, the reflectivity of most ice cloud particles in the first channel is greater than that of the second channel (if the cloud top phase state is judged to be an ice phase state and the reflectivity difference value between the second channel and the third channel is greater than 0.04, the ice cloud is represented as a single-layer ice cloud). When the upper layer of ice cloud is shielded and the lower layer of ice cloud or sea fog exists, the characteristics of the lower layer of water cloud or sea fog can be interfered, when the upper layer of ice cloud is thicker (exceeds a set value), signals received by the satellite imager mainly come from the ice cloud, and the reflectivity of each channel is represented as the characteristics of the ice cloud; however, when the optical thickness of the upper layer of ice cloud is relatively thin (the optical thickness is less than 7.5), the signal received by the satellite imager shows that the signal has both a part of ice cloud characteristics and a part of water cloud or sea fog characteristics, and the water cloud and the sea fog can be distinguished by adjusting the threshold values (the fifth preset value in this embodiment) corresponding to the first channel and the second channel in combination with the channel reflectivity difference characteristics of the water cloud and the sea fog.
In step S4, designing the criterion conditions corresponding to each set cloud type according to the reflectivity and brightness temperature of each spectral channel in each cloud simulation environment, including:
through sensitivity analysis of the reflectivity of the first channel, the second channel and the third channel in each cloud and mist simulation environment, the difference characteristic of the reflectivity of each spectral channel among the cloud and mist simulation environments is obtained, and the difference characteristic obtaining method comprises the following steps:
based on the particle characteristics of the water cloud with the effective particle radius of 10-20 microns and the sea fog with the effective particle radius of 3-5 microns, and in the simulation process, the particle characteristics are obtained through the reflectivity of each spectral channel in each cloud and fog simulation environment:
when the optical thickness and the effective particle radius are both smaller than the corresponding set lower limit values, the reflectivity difference value of the first channel and the second channel is smaller than 0, and when the optical thickness and the effective particle radius are both larger than the corresponding set upper limit values, the reflectivity difference value is larger than or equal to 0, so that the characteristics that:
the difference between the reflectivities of the water cloud particles corresponding to the first channel and the second channel is greater than or equal to a threshold value, the difference between the reflectivities of the sea fog particles corresponding to the first channel and the second channel is less than the difference characteristic of the threshold value, and the threshold value is equal to 0;
the difference features obtained during the simulation further include: the difference characteristics of the reflectivity of each spectral channel among the cloud simulation environments corresponding to the single-layer ice cloud, the upper-layer ice cloud and the lower-layer water cloud and the upper-layer ice cloud and the lower-layer sea fog;
setting a single-layer water cloud criterion condition and a single-layer sea fog criterion condition according to the difference characteristics corresponding to the water cloud particles and the sea fog particles;
adjusting a threshold value in the corresponding difference characteristics of the water cloud particles and the sea fog particles, and setting a single-layer ice cloud criterion condition, an upper-layer ice cloud lower-layer water cloud criterion condition and an upper-layer ice cloud lower-layer sea fog criterion condition according to the difference characteristics of the reflectivity of each spectral channel between the single-layer ice cloud, the upper-layer ice cloud lower-layer water cloud and the corresponding cloud and fog simulation environment of the upper-layer ice cloud lower-layer sea fog.
The water phase state criterion conditions are as follows: the luminance temperature corresponding to the fifth channel is larger than a first preset value (238K), and the difference value of the luminance temperatures corresponding to the fourth channel and the fifth channel is smaller than or equal to a second preset value (-1K);
the ice phase state criterion condition is as follows: the brightness temperature corresponding to the fifth channel is less than or equal to a first preset value (238K), or the difference value of the brightness temperatures corresponding to the fourth channel and the fifth channel is greater than or equal to a third preset value (0.5K); the third preset value (0.5K) is greater than the second preset value (-1K).
The single-layer water cloud criterion condition is as follows: the difference value of the corresponding reflectivity of the first channel and the second channel is more than or equal to zero;
the single-layer sea fog criterion condition is as follows: the difference value of the corresponding reflectivity of the first channel and the second channel is less than zero;
the single-layer ice cloud criterion condition is as follows: the difference of the reflectivity of the second channel and the third channel is larger than a fourth preset value (0.04).
The criterion conditions of the upper ice cloud layer and the lower water cloud layer are as follows: the difference value of the reflectivity of the second channel and the third channel is less than or equal to a fourth preset value (0.04); moreover, the reflectivity difference value corresponding to the first channel and the second channel is greater than or equal to a fifth preset value (0.08);
the criterion conditions of the upper layer ice cloud and the lower layer sea fog are as follows: the difference value of the reflectivity of the second channel and the third channel is less than or equal to a fourth preset value (0.04); and the reflectivity difference value corresponding to the first channel and the second channel is smaller than a fifth preset value (0.08).
The first preset value, the second preset value, the third preset value, the fourth preset value and the fifth preset value are as follows in sequence: 238K, -1K, 0.5K, 0.04, 0.08.
S5: acquiring a set cloud type corresponding to a target ocean area by using a criterion condition through primary data and cloud detection data corresponding to the target ocean area in a real cloud environment; the data types of the cloud detection data include: cloud, possibly cloud, clear sky and possibly clear sky.
The method for acquiring the set cloud type corresponding to the target ocean area by using the criterion condition comprises the following steps of S50: and judging whether the data type of the cloud detection data is 'cloud' or 'possible cloud', if so, entering the step S51.
The cloud top phase state refers to the topmost phase state of the cloud, and if the cloud top phase state is an "aqueous phase state", the cloud top phase state may be a single-layer water cloud or a single-layer sea fog; if the ice phase is "ice cloud", the uppermost part is ice cloud, and water cloud or sea fog may exist below the uppermost part.
S51: acquiring a cloud top phase state corresponding to a target ocean area by using a water phase state criterion condition and an ice phase state criterion condition according to the brightness and temperature of a fourth channel and a fifth channel in the primary data, wherein the cloud top phase state is a water phase state or an ice phase state;
s52: when the cloud top phase state is a water phase state, acquiring a set cloud fog type corresponding to a target ocean area by using a single-layer water cloud criterion condition and a single-layer sea fog criterion condition according to the reflectivity of a first channel and a second channel in primary data;
s53: and when the cloud top phase state is the ice phase state, acquiring a set cloud type corresponding to the target ocean area by using the single-layer ice cloud criterion condition, the upper-layer ice cloud lower-layer water cloud criterion condition and the upper-layer ice cloud lower-layer sea fog criterion condition according to the reflectivity of the first channel, the second channel and the third channel in the primary data.
After the sea fog detection method is used for obtaining the set cloud fog type corresponding to the target sea area, the method also comprises the steps of obtaining satellite-borne laser radar detection data aiming at the target sea area, and verifying the accuracy of the detection result of the method so as to demonstrate the applicability of the method under different sea areas and cloud conditions.
The method comprises the steps of sensitively analyzing the reflectivity of a first channel, a second channel and a third channel in each cloud and mist simulation environment to obtain the difference characteristics of the reflectivity of each spectral channel among the cloud and mist simulation environments, and setting a single-layer water cloud criterion condition and a single-layer sea mist criterion condition according to the difference characteristics corresponding to water cloud particles and sea mist particles; the method comprises the steps of adjusting threshold values in corresponding difference characteristics of water cloud particles and sea fog particles, setting single-layer ice cloud criterion conditions, upper-layer ice cloud lower-layer water cloud criterion conditions and upper-layer ice cloud lower-layer sea fog criterion conditions according to difference characteristics of reflectivity of each spectral channel among single-layer ice cloud, upper-layer ice cloud lower-layer water cloud and cloud fog simulation environments corresponding to upper-layer ice cloud lower-layer sea fog, simulating real cloud fog environments corresponding to set cloud fog types, and carrying out data analysis on the reflectivity of each spectral channel obtained in the simulation process to design the criterion conditions corresponding to the set cloud fog types.
Example two
As shown in fig. 2, the present invention further provides a sea fog detection system, comprising:
the real data acquisition module is used for acquiring satellite data in a real cloud and fog environment through a satellite imager, wherein the satellite data comprises longitude and latitude data, primary data and cloud detection data corresponding to a target ocean area in the satellite data are acquired through the longitude and latitude data, and the primary data comprises the reflectivity of a first channel, a second channel and a third channel and the brightness temperature of a fourth channel and a fifth channel; the first channel is a visible light channel with the central wavelength of 0.64 micrometer, the second channel is a near-infrared channel with the central wavelength of 1.6 micrometer, the third channel is a near-infrared channel with the central wavelength of 2.25 micrometer, the fourth channel is a long-wave infrared channel with the central wavelength of 8.5 micrometer, and the fifth channel is a long-wave infrared channel with the central wavelength of 11 micrometer;
the model establishing module is used for establishing a cloud and mist simulation model corresponding to each set cloud and mist type based on radiation transmission simulation, and is used for simulating a real cloud and mist environment detected by a satellite imager under each set cloud and mist type to obtain a cloud and mist simulation environment corresponding to each set cloud and mist type; each set cloud type includes: the system comprises a single-layer water cloud, a single-layer sea fog, a single-layer ice cloud, an upper-layer ice cloud, a lower-layer water cloud and an upper-layer ice cloud, lower-layer sea fog; the cloud and fog simulation model comprises all spectrum channels in the primary data;
the simulation data acquisition module is used for acquiring the reflectivity and the brightness temperature of each spectral channel in each cloud and mist simulation environment through each cloud and mist simulation model;
a criterion condition setting module, configured to design a criterion condition corresponding to each set cloud type according to a reflectivity and a luminance temperature of each spectrum channel in each cloud simulation environment, where the criterion condition includes: the method comprises the following steps of (1) judging conditions of a water phase state, a single-layer water cloud, a single-layer sea fog, an ice phase state, a single-layer ice cloud, an upper layer of ice cloud and a lower layer of water cloud and an upper layer of ice cloud and a lower layer of sea fog;
the detection module is used for acquiring the set cloud and mist type corresponding to the target ocean area by using the criterion condition through the primary data and the cloud detection data corresponding to the target ocean area under the real cloud and mist environment, and specifically comprises the following steps:
the cloud top phase detection unit is used for acquiring a cloud top phase corresponding to the target ocean area according to the brightness and the temperature of a fourth channel and a fifth channel in the primary data by using a water phase criterion condition and an ice phase criterion condition, wherein the cloud top phase is a water phase or an ice phase;
the first detection unit is used for acquiring a set cloud and mist type corresponding to a target ocean area by utilizing a single-layer water cloud criterion condition and a single-layer sea mist criterion condition according to the reflectivity of a first channel and a second channel in primary data when the cloud top phase state is a water phase state;
and the second detection unit is used for acquiring the set cloud fog type corresponding to the target ocean area by using the single-layer ice cloud criterion condition, the upper-layer ice cloud lower-layer water cloud criterion condition and the upper-layer ice cloud lower-layer sea fog criterion condition according to the reflectivity of the first channel, the second channel and the third channel in the primary data when the cloud top phase state is the ice phase state.
According to the invention, through each cloud and mist simulation model, the reflectivity and the brightness temperature of each spectral channel under each cloud and mist simulation environment are obtained, the criterion condition corresponding to each set cloud and mist type is designed, and after the cloud top phase state corresponding to the target ocean area is judged, the set cloud and mist type corresponding to the target ocean area is obtained according to the reflectivity of the first channel, the second channel and the third channel in the primary data by utilizing the single-layer water cloud criterion condition, the single-layer sea mist criterion condition, the single-layer ice cloud criterion condition, the upper-layer ice cloud lower-layer water cloud criterion condition and the upper-layer ice cloud lower-layer sea mist criterion condition.
It should be noted that all directional indicators (such as up, down, left, right, front, back \8230;) in the embodiments of the present invention are only used to explain the relative positional relationship between the components, the motion situation, etc. in a specific posture (as shown in the attached drawings), and if the specific posture is changed, the directional indicator is changed accordingly.
Moreover, descriptions of the present invention as relating to "first," "second," "a," etc. are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit ly indicating a number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise explicitly stated or limited, the terms "connected", "fixed", and the like are to be understood broadly, for example, "fixed" may be fixedly connected, may be detachably connected, or may be integrated; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.
In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of the technical solutions by those skilled in the art, and when the technical solutions are contradictory to each other or cannot be realized, such a combination of the technical solutions should not be considered to exist, and is not within the protection scope of the present invention.
Claims (9)
1. A sea fog detection method is characterized by comprising the following steps:
s1: acquiring satellite data in a real cloud and fog environment through a satellite imager, wherein the satellite data comprises longitude and latitude data, and acquiring primary data and cloud detection data corresponding to a target ocean area in the satellite data through the longitude and latitude data, wherein the primary data comprises the reflectivity of a first channel, a second channel and a third channel and the brightness temperature of a fourth channel and a fifth channel; the first channel is a visible light channel with the central wavelength of 0.64 micrometer, the second channel is a near-infrared channel with the central wavelength of 1.6 micrometer, the third channel is a near-infrared channel with the central wavelength of 2.25 micrometer, the fourth channel is a long-wave infrared channel with the central wavelength of 8.5 micrometer, and the fifth channel is a long-wave infrared channel with the central wavelength of 11 micrometer;
s2: establishing a cloud simulation model corresponding to each set cloud type based on radiation transmission simulation, and simulating a real cloud environment detected by a satellite imager under each set cloud type to obtain a cloud simulation environment corresponding to each set cloud type; each set cloud type includes: the system comprises a single-layer water cloud, a single-layer sea fog, a single-layer ice cloud, an upper-layer ice cloud, a lower-layer water cloud and an upper-layer ice cloud, lower-layer sea fog; the cloud and fog simulation model comprises all spectrum channels in the primary data;
s3: obtaining the reflectivity and brightness temperature of each spectral channel in each cloud and mist simulation environment through each cloud and mist simulation model;
s4: designing criterion conditions corresponding to the types of the set clouds through the reflectivity and the brightness temperature of each spectrum channel in each cloud fog simulation environment, wherein the criterion conditions comprise: the method comprises the following steps of (1) judging conditions of a water phase state, a single-layer water cloud, a single-layer sea fog, an ice phase state, a single-layer ice cloud, an upper layer of ice cloud and a lower layer of water cloud and an upper layer of ice cloud and a lower layer of sea fog;
s5: the method comprises the following steps of acquiring a set cloud type corresponding to a target ocean area by using criterion conditions through primary data and cloud detection data corresponding to the target ocean area in a real cloud environment, wherein the acquisition method comprises the following steps:
s51: acquiring a cloud top phase state corresponding to a target ocean area by using a water phase state criterion condition and an ice phase state criterion condition according to the brightness and temperature of a fourth channel and a fifth channel in the primary data, wherein the cloud top phase state is a water phase state or an ice phase state;
s52: when the cloud top phase state is the water phase state, acquiring a set cloud type corresponding to the target ocean area by utilizing the single-layer water cloud criterion condition and the single-layer sea fog criterion condition according to the reflectivity of the first channel and the second channel in the primary data;
s53: and when the cloud top phase state is the ice phase state, acquiring a set cloud type corresponding to the target ocean area by using the single-layer ice cloud criterion condition, the upper-layer ice cloud lower-layer water cloud criterion condition and the upper-layer ice cloud lower-layer sea fog criterion condition according to the reflectivity of the first channel, the second channel and the third channel in the primary data.
2. The method of claim 1, wherein in step S4, designing the criterion condition corresponding to each set cloud type according to the reflectivity and brightness temperature of each spectral channel in each cloud simulation environment includes:
through sensitivity analysis of the reflectivity of the first channel, the second channel and the third channel in each cloud and mist simulation environment, the difference characteristic of the reflectivity of each spectral channel among the cloud and mist simulation environments is obtained, and the difference characteristic obtaining method comprises the following steps:
based on the particle characteristics of the water cloud with effective particle radius of 10-20 microns and the sea fog with effective particle radius of 3-5 microns, and in the simulation process, the reflectivity of each spectral channel in each cloud and fog simulation environment is obtained:
when the optical thickness and the effective particle radius are both smaller than the corresponding set lower limit values, the reflectivity difference value of the first channel and the second channel is smaller than 0, and when the optical thickness and the effective particle radius are both larger than the corresponding set upper limit values, the reflectivity difference value is larger than or equal to 0, so that the characteristics that:
the difference between the reflectivities of the water cloud particles corresponding to the first channel and the second channel is greater than or equal to a threshold value, the difference between the reflectivities of the sea fog particles corresponding to the first channel and the second channel is less than the difference characteristic of the threshold value, and the threshold value is equal to 0;
the difference features obtained during the simulation further include: the difference characteristics of the reflectivity of each spectral channel among the cloud simulation environments corresponding to the single-layer ice cloud, the upper-layer ice cloud and the lower-layer water cloud and the upper-layer ice cloud and the lower-layer sea fog;
setting a single-layer water cloud criterion condition and a single-layer sea fog criterion condition according to the difference characteristics corresponding to the water cloud particles and the sea fog particles;
and adjusting a threshold value in the corresponding difference characteristics of the water cloud particles and the sea fog particles, and setting a single-layer ice cloud criterion condition, an upper-layer ice cloud lower-layer water cloud criterion condition and an upper-layer ice cloud lower-layer sea fog criterion condition according to the difference characteristics of the reflectivity of each spectral channel among cloud simulation environments corresponding to the single-layer ice cloud, the upper-layer ice cloud lower-layer water cloud and the upper-layer ice cloud lower-layer sea fog.
3. The sea fog detection method of claim 2, wherein the data types of the cloud detection data comprise: cloud, possibly cloud, clear sky and possibly clear sky.
4. The sea fog detection method of claim 3, wherein in the step S5, before the step S51, the method further comprises:
s50: and judging whether the data type of the cloud detection data is 'cloud' or 'possible cloud', if so, entering the step S51.
5. The sea fog detection method of claim 2,
the water phase state criterion conditions are as follows: the brightness temperature corresponding to the fifth channel is greater than a first preset value, and the difference value of the brightness temperatures corresponding to the fourth channel and the fifth channel is less than or equal to a second preset value;
the ice phase state criterion condition is as follows: the brightness temperature corresponding to the fifth channel is less than or equal to a first preset value, or the difference value of the brightness temperatures corresponding to the fourth channel and the fifth channel is greater than or equal to a third preset value; the third preset value is greater than the second preset value.
6. The sea fog detection method of claim 5,
the single-layer water cloud criterion condition is as follows: the difference value of the corresponding reflectivity of the first channel and the second channel is more than or equal to zero;
the single-layer sea fog criterion condition is as follows: the difference value of the corresponding reflectivity of the first channel and the second channel is less than zero;
the single-layer ice cloud criterion condition is as follows: and the reflectivity difference value corresponding to the second channel and the third channel is greater than a fourth preset value.
7. The sea fog detection method of claim 6,
the criterion conditions of the upper ice cloud layer and the lower water cloud layer are as follows: the difference value of the reflectivity of the second channel and the third channel is less than or equal to a fourth preset value; the reflectivity difference value corresponding to the first channel and the second channel is greater than or equal to a fifth preset value;
the criterion conditions of the upper ice cloud layer and the lower sea fog layer are as follows: the reflectivity difference value corresponding to the second channel and the third channel is less than or equal to a fourth preset value; and the reflectivity difference value corresponding to the first channel and the second channel is smaller than a fifth preset value.
8. The sea fog detection method of claim 7, wherein the first preset value, the second preset value, the third preset value, the fourth preset value and the fifth preset value are sequentially as follows:
238K、-1K、0.5K、0.04、0.08。
9. a sea fog detection system, comprising:
the real data acquisition module is used for acquiring satellite data in a real cloud and fog environment through a satellite imager, wherein the satellite data comprises longitude and latitude data, primary data and cloud detection data corresponding to a target ocean area in the satellite data are acquired through the longitude and latitude data, and the primary data comprises the reflectivity of a first channel, a second channel and a third channel and the brightness temperature of a fourth channel and a fifth channel; the first channel is a visible light channel with the central wavelength of 0.64 micrometer, the second channel is a near-infrared channel with the central wavelength of 1.6 micrometer, the third channel is a near-infrared channel with the central wavelength of 2.25 micrometer, the fourth channel is a long-wave infrared channel with the central wavelength of 8.5 micrometer, and the fifth channel is a long-wave infrared channel with the central wavelength of 11 micrometer;
the model establishing module is used for establishing a cloud and mist simulation model corresponding to each set cloud and mist type based on radiation transmission simulation, and is used for simulating a real cloud and mist environment detected by a satellite imager under each set cloud and mist type to obtain a cloud and mist simulation environment corresponding to each set cloud and mist type; each set cloud type includes: the system comprises a single-layer water cloud, a single-layer sea fog, a single-layer ice cloud, an upper-layer ice cloud, a lower-layer water cloud and an upper-layer ice cloud, lower-layer sea fog; the cloud and fog simulation model comprises all spectrum channels in the primary data;
the simulation data acquisition module is used for acquiring the reflectivity and the brightness temperature of each spectral channel in each cloud and mist simulation environment through each cloud and mist simulation model;
the criterion condition setting module is used for designing criterion conditions corresponding to the set cloud and mist types through the reflectivity and the brightness temperature of each spectral channel in each cloud and mist simulation environment, and the criterion conditions comprise: the method comprises the following steps of (1) judging conditions of a water phase state, a single-layer water cloud, a single-layer sea fog, an ice phase state, a single-layer ice cloud, an upper layer ice cloud, a lower layer water cloud and an upper layer ice cloud, lower layer sea fog;
the detection module is used for acquiring the set cloud and mist type corresponding to the target ocean area by using the criterion condition through the primary data and the cloud detection data corresponding to the target ocean area under the real cloud and mist environment, and specifically comprises the following steps:
the cloud top phase state detection unit is used for acquiring a cloud top phase state corresponding to the target ocean area according to the brightness temperature of a fourth channel and a fifth channel in the primary data by using a water phase state criterion condition and an ice phase state criterion condition, wherein the cloud top phase state is a water phase state or an ice phase state;
the first detection unit is used for acquiring a set cloud and mist type corresponding to a target ocean area by utilizing a single-layer water cloud criterion condition and a single-layer sea mist criterion condition according to the reflectivity of a first channel and a second channel in primary data when the cloud top phase state is a water phase state;
and the second detection unit is used for acquiring the set cloud fog type corresponding to the target ocean area by using the single-layer ice cloud criterion condition, the upper-layer ice cloud lower-layer water cloud criterion condition and the upper-layer ice cloud lower-layer sea fog criterion condition according to the reflectivity of the first channel, the second channel and the third channel in the primary data when the cloud top phase state is the ice phase state.
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| CN116400320B (en) * | 2023-06-09 | 2023-08-15 | 成都远望探测技术有限公司 | Sea fog effective particle radius estimation method based on laser and W-band radar |
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