Marine microwave radar signal processing device, marine microwave radar signal processing program, and marine microwave radar system

Abstract

To highly accurately detect an ocean current direction (specifically, offshore current direction) using a marine radar device.SOLUTION: A marine microwave radar signal processing device 2 comprises: a wavefront position detection unit 21 for detecting a position of an ocean wavefront based on the radar reflection power distribution of a single scan using a microwave radar device 1 for radiating a microwave onto an ocean surface; a Doppler velocity calculation unit 22 for calculating a Doppler velocity of a surface current before and after the position of the ocean wavefront based on the Doppler velocity distribution of the single scan using the microwave radar device 1; and a current direction detection unit 24 for detecting an ocean current direction based on an average velocity direction or the magnitude of an absolute value of velocity with reference to the Doppler velocity of the surface current before and after the position of the ocean wavefront.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to techniques for detecting ocean transport direction, particularly due to rip currents. [Background technology]

[0002] Patent Document 1 discloses a technique for calculating the Doppler velocity of surface currents using a short-wave radar device (resolution 1 km) that irradiates the ocean surface with short waves (wavelength 10 m to 100 m). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-241467 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, it is conceivable to detect the oceanic transport direction (particularly that caused by rip currents) using Patent Document 1. However, since it only irradiates short waves onto the ocean surface, it is not possible to detect the oceanic transport direction (width 10m to 30m, length 10m to 100m) with high accuracy.

[0005] Therefore, in order to solve the above problems, an object of the present disclosure is to detect the direction of ocean movement (especially that caused by rip currents) with high accuracy using a marine radar device. [Means for solving the problem]

[0006] In order to solve the above problem, we focused on the fact that in shallow water areas such as the coast, in addition to the movement of ocean waves due to swells, the front of the ocean wave front is pulled into the ocean wave and the rear of the ocean wave front is pushed out by the ocean wave. Therefore, using a microwave radar device that irradiates microwaves onto the ocean surface, the position of the ocean wave front is detected based on the radar reflection power distribution of a single scan, and the Doppler velocity of the surface current before and after the position of the ocean wave front is calculated based on the Doppler velocity distribution of the single scan. Then, the ocean transport direction (especially that due to a rip current) is detected based on the balance between the Doppler velocities of the surface currents before and after the position of the ocean wave front.

[0007] Specifically, the present disclosure relates to an ocean microwave radar signal processing device comprising: a wave front position detection unit that detects the position of the ocean wave front based on the radar reflected power distribution of a single scan using a microwave radar device that irradiates microwaves onto the ocean surface; a Doppler velocity calculation unit that calculates the Doppler velocity of surface currents before and after the position of the ocean wave front based on the Doppler velocity distribution of a single scan using the microwave radar device; and a transport direction detection unit that detects the ocean transport direction based on the average velocity direction or the magnitude of the absolute velocity value for the Doppler velocity of the surface currents before and after the position of the ocean wave front.

[0008] According to this configuration, the direction of ocean movement (particularly that caused by rip currents) can be detected with high accuracy using the Doppler velocity distribution of a single scan of the microwave radar.

[0009] And because microwave radar is used, ship radar can be repurposed to reduce costs, the antenna can be made smaller, and the system can be made more compact, allowing the system to be installed in more locations, further improving maritime safety.

[0010] The present disclosure also relates to an ocean microwave radar signal processing device, characterized in that the transport direction detection unit detects the ocean transport direction based on the direction of the average speed or the magnitude of the absolute value of the speed, and the direction from offshore to the coast.

[0011] With this configuration, the direction of ocean transport (particularly that caused by rip currents) can be detected with high accuracy with only a single scan, based on the offshore to shore direction as well.

[0012] The present disclosure also relates to an ocean microwave radar signal processing device, further comprising a wave front direction detection unit that detects the traveling direction of an ocean wave front based on the radar reflection power distribution of multiple scans using the microwave radar device, wherein the travel direction detection unit detects the ocean travel direction based on the direction of the average velocity or the magnitude of the absolute value of the velocity and the traveling direction of the ocean wave front.

[0013] According to this configuration, although multiple scans are required, the direction of ocean movement (particularly that caused by rip currents) can be detected with high accuracy based on the traveling direction of the ocean wave surface.

[0014] The present disclosure also relates to an ocean microwave radar signal processing device, characterized in that the travel direction detection unit uses a plurality of the microwave radar devices to detect the ocean travel direction at a target coastline based on the Doppler velocity distribution of each of the single scans.

[0015] With this configuration, even if the Doppler velocity distribution seen from one microwave radar is zero, the ocean movement direction (especially that caused by rip currents) can be detected with high accuracy even in a location where the Doppler velocity distribution seen from another microwave radar is not zero.

[0016] The present disclosure also relates to an ocean microwave radar signal processing device, wherein the travel direction detection unit detects the ocean travel direction caused by a rip current or an onshore current.

[0017] According to this configuration, the direction of ocean movement caused by a rip current or an onshore current can be detected with high accuracy using the Doppler velocity distribution of a single scan of the microwave radar.

[0018] The present disclosure also provides a marine microwave radar signal processing program for causing a computer to execute each processing step executed by each processing unit of the marine microwave radar signal processing device described above.

[0019] According to this configuration, it is possible to provide a program having the above-described effects.

[0020] The present disclosure also provides a marine microwave radar system comprising the marine microwave radar signal processing device described above and the microwave radar device.

[0021] According to this configuration, it is possible to provide a system having the effects described above.

[0022] The above disclosed inventions can be combined to the greatest extent possible. Effect of the Invention

[0023] In this manner, the present disclosure can use a marine radar device to detect the direction of ocean movement (especially that caused by rip currents) with high accuracy. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a diagram showing a configuration of an ocean microwave radar system according to the present disclosure. [Diagram 2] 11 is a diagram showing a procedure of a transport direction detection process according to the present disclosure. [Diagram 3] FIG. 2 is a diagram showing a specific example of a radar reflected power distribution according to the present disclosure. [Figure 4] FIG. 2 illustrates what is seen in the radar return power distribution of the present disclosure. [Diagram 5] FIG. 2 is a diagram showing a specific example of a Doppler velocity distribution according to the present disclosure. [Figure 6] FIG. 2 illustrates what is seen in the Doppler velocity distribution of the present disclosure. [Figure 7] 1 is a diagram showing the principle of the transport direction detection process of the present disclosure; [Figure 8]FIG. 2 illustrates a zoomed-in view of the Doppler velocity distribution of the present disclosure. [Figure 9] 11A to 11C are diagrams illustrating a specific example of a transport direction detection process according to the present disclosure. [Figure 10] 11A to 11C are diagrams illustrating a specific example of a transport direction detection process according to the present disclosure. [Figure 11] FIG. 1 is a diagram showing an example of using multiple microwave radar devices according to the present disclosure. [Figure 12] FIG. 13 is a diagram showing what is seen in a modified transport direction detection process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of the present disclosure, and the present disclosure is not limited to the following embodiments.

[0026] (Configuration of the marine microwave radar system of the present disclosure) The configuration of the marine microwave radar system of the present disclosure is shown in Fig. 1. The procedure of the travel direction detection process of the present disclosure is shown in Fig. 2. The marine microwave radar system M includes a microwave radar device 1 and a radar signal processing device 2. The radar signal processing device 2 includes a wave front position detection unit 21, a Doppler velocity calculation unit 22, a wave front direction detection unit 23, and a travel direction detection unit 24, and can be realized by installing the radar signal processing program shown in Fig. 2 in a computer.

[0027] The radar signal processing device 2 detects the ocean movement direction (for example, due to a rip current) using a microwave radar device 1 (resolution 1m to 10m) that irradiates microwaves (wavelength 1cm to 10cm) onto the ocean surface. Here, we focus on the fact that in shallow water areas such as the coast, in addition to the movement of ocean waves due to swells, the front of the ocean wave front is pulled into the ocean wave, and the rear of the ocean wave front is pushed out by the ocean wave.

[0028] Therefore, the radar signal processing device 2 detects the position of the ocean wave front based on the radar reflected power distribution of a single scan using the microwave radar device 1 (step S1), and calculates the Doppler velocities of the surface currents before and after the position of the ocean wave front based on the Doppler velocity distribution of the single scan (step S2).The radar signal processing device 2 then detects the ocean movement direction (particularly that due to a rip current) based on the balance between the Doppler velocities of the surface currents before and after the position of the ocean wave front (steps S3, S3-1 to S3-3).

[0029] (What is seen in the radar reflected power distribution disclosed herein) A specific example of the radar reflected power distribution of the present disclosure is shown in Fig. 3. What can be seen in the radar reflected power distribution of the present disclosure is shown in Fig. 4. In Fig. 3, it can be seen that the position of the ocean wave front is nearly parallel to the coast in the radar reflected power distribution of a single scan using the microwave radar device 1. And, it can be seen that the traveling direction of the ocean wave front approaches nearly perpendicular to the coast in the radar reflected power distribution of multiple scans (not shown in Fig. 3) using the microwave radar device 1.

[0030] 4, the microwave radar device 1 is installed on a coast or the like and irradiates microwaves onto the ocean surface. Then, in the radar reflected power distribution of a single scan using the microwave radar device 1, the irradiated power and the reflected power are high at the crest positions of the ocean wave surface close to the coast or the like, especially at the positions where the ripples are high, but the irradiated power and the reflected power are low at the trough positions of the ocean wave surface and at the crest positions opposite the coast or the like, even at the positions where the ripples are high.

[0031] However, since the radar signal processing device 2 executes radar signal processing so that it can see large targets such as land, it does not see small targets such as ripples one by one, but sees the spatial average of small targets such as ripples. Then, in the radar reflected power distribution of a single scan using the microwave radar device 1, the position of a mountain near the coast of the ocean wave surface is detected as the position of a linear pattern of the large-scale ocean wave surface.

[0032] (What is seen in the Doppler velocity distribution of this disclosure) A specific example of the Doppler velocity distribution of the present disclosure is shown in Fig. 5. What can be seen in the Doppler velocity distribution of the present disclosure is shown in Fig. 6. In Fig. 5, it can be seen that in the Doppler velocity distribution of a single scan using the microwave radar device 1, the Doppler velocity of the surface current does not match the traveling direction of the ocean wave front, compared to the radar reflected power distribution of multiple scans. In other words, the microwave radar device 1 is installed at a distance X = Y = 0, and at a distance X < 0, the balance between the Doppler velocities of the surface current before and after the position of the ocean wave front indicates an onshore current, and at a distance X > 0, the balance between the Doppler velocities of the surface current before and after the position of the ocean wave front indicates an offshore current.

[0033] In Fig. 6, the microwave radar device 1 is installed on a coast or the like and irradiates microwaves onto the ocean surface. Then, in the Doppler velocity distribution of a single scan using the microwave radar device 1, the Doppler velocity of the surface current is pushed out from the ocean wave at the crest position of the ocean wave surface opposite the coast or the like, the Doppler velocity of the surface current is pulled into the ocean wave at the trough position of the ocean wave surface, and the Doppler velocity is intermediate between these at the crest position of the ocean wave surface closer to the coast or the like. Note that the Doppler velocity of the surface current can be observed regardless of the magnitude of the irradiation power and the reflected power.

[0034] However, since the radar signal processing device 2 executes radar signal processing so that it can see large targets such as land, it does not see small targets such as ripples one by one, but sees the spatial average of small targets such as ripples. Then, in the Doppler velocity distribution of a single scan using the microwave radar device 1, the Doppler velocity distribution of small-scale surface currents (the rear side pushed out by the ocean wave and the front side pulled into the ocean wave) is detected with the position of the linear pattern of the large-scale ocean wave surface as the boundary.

[0035] (Principle of the transport direction detection process of the present disclosure) The principle of the transfer direction detection process of the present disclosure is shown in FIG. 7. The wave surface position detection unit 21 uses the microwave radar device 1 to detect the position of the ocean wave surface based on the radar reflection power distribution of a single scan (step S1). Here, the position of the ocean wave surface is the position of the mountains near the coast or the like on the ocean wave surface, and is the position of the linear pattern of the ocean wave surface on a large scale.

[0036] The Doppler velocity calculation unit 22 uses the microwave radar device 1 to calculate the Doppler velocities V f 、V b of the surface current before and after the position of the ocean wave surface based on the Doppler velocity distribution of a single scan (step S2). Here, the Doppler velocities V f 、V b of the surface current before and after the position of the ocean wave surface are the Doppler velocities of the surface current on a small scale (drawn into the ocean wave, pushed out from the ocean wave) with the position of the linear pattern of the ocean wave surface on a large scale as the boundary.

[0037] The transfer direction detection unit 24 detects the transfer direction of the ocean based on the direction of the average velocity or the magnitude of the absolute value of the velocity with respect to the Doppler velocities V f 、V b of the surface current before and after the position of the ocean wave surface (step S3). In FIG. 7, for the Doppler velocities V f 、V b of the surface current before and after the position of the ocean wave surface, the magnitude of the absolute value of the velocity is |V f | > |V b |, the direction of the average velocity is the direction of V f , and the transfer direction of the ocean is also the direction of V f . On the other hand, for the Doppler velocities V f 、V b of the surface current before and after the position of the ocean wave surface, if the magnitude of the absolute value of the velocity is |V f | < |V b |, the direction of the average velocity is the direction of V b , and the transfer direction of the ocean is also the direction of V b .

[0038] An enlarged view of the Doppler velocity distribution of the present disclosure is shown in FIG. 8. The microwave radar device 1 is installed at a distance X=Y=0, and at a distance X<0, each group of ocean wave surfaces is surrounded by a square. The Doppler velocity V of the surface current before and after the position of the ocean wave surface is f , V b The absolute value of the velocity is |V f |<|V b | and the direction of the average velocity is V b The Doppler velocity of the surface current around the position of the ocean wave front V f , V b A balance between indicates an onshore current.

[0039] In this way, the ocean movement direction (particularly that caused by a rip current) can be detected with high accuracy using the Doppler velocity distribution of a single scan of the microwave radar device 1. However, since it is desirable to detect which side is the front side or the rear side as viewed from the position of the ocean wave front, it is desirable to execute steps S3-1 to S3-3 shown in Figs. 9 and 10.

[0040] Furthermore, by using the microwave radar device 1, ship radar can be repurposed to reduce costs, the antenna can be made smaller, and the system can be made more compact, allowing the system to be installed in even more locations, further improving maritime safety.

[0041] (Specific example of the transport direction detection process of the present disclosure) A specific example of the transport direction detection process of the present disclosure is shown in Fig. 9. The transport direction detection unit 24 detects the ocean transport direction based on the direction of the average speed or the magnitude of the absolute value of the speed (step S3) and the direction from offshore to the coast (step S3-1).

[0042] In the left column of Figure 9, the Doppler velocity V of the surface current before and after the position of the ocean wave front is f , V b The absolute value of the velocity is |V f |>|V b | and the direction of the average velocity is V f The direction of ocean transport is also Vf , and from offshore to the coast is V b Since the direction is the same as the ocean current, the direction of ocean transport caused by the rip current is detected. In the right column of Figure 9, the Doppler velocity V f , V b The absolute value of the velocity is |V f |<|V b | and the direction of the average velocity is V b The direction of ocean transport is also V b , and from offshore to the coast is V b Since the direction is , the direction of ocean transport due to onshore currents is detected.

[0043] In this way, the direction of ocean transport (particularly that due to rip currents) can be detected with high accuracy with only a single scan, based also on the offshore to shore direction.

[0044] A specific example of the transport direction detection process of the present disclosure is also shown in Fig. 10. The wave front direction detection unit 23 detects the traveling direction of the ocean wave front based on the radar reflected power distribution of multiple scans using the microwave radar device 1 (step S3-2). In the left column of Fig. 10, the radar reflected power distributions of the first and second scans are compared, and the traveling direction of the ocean wave front is detected based on the shift direction of the power distribution.

[0045] The transport direction detection unit 24 detects the ocean transport direction (step S3-3) based on the direction of the average velocity or the magnitude of the absolute value of the velocity (step S3) and the direction of travel of the ocean wave front (step S3-2 needs to be performed with at least two scans during initial setup).

[0046] In the right column of Fig. 10, the Doppler velocity V of the surface current before and after the position of the ocean wave front is f , V b The absolute value of the velocity is |V f |>|V b | and the direction of the average velocity is V f The direction of ocean transport is also V f The direction of the ocean wave front is V bSince the direction of the ocean current due to the rip current is detected, the Doppler velocity V f , V b The absolute value of the velocity is |V f |<|V b |, then the direction of the average velocity is V b The direction of ocean transport is also V b The direction of the ocean wave front is V b Since the direction is , the direction of ocean transport due to onshore currents is detected.

[0047] In this way, although multiple scans are required, the direction of ocean transport (particularly that caused by rip currents) can be detected with high accuracy based on the traveling direction of the ocean wave surface.

[0048] (Example of using multiple microwave radar devices according to the present disclosure) A specific example of using multiple microwave radar devices according to the present disclosure is shown in Fig. 11. Using multiple microwave radar devices 1, the travel direction detection unit 24 detects the ocean travel direction on the target coastline based on the Doppler velocity distribution of each single scan (step S3).

[0049] In the left column of Figure 11, as viewed from one marine microwave radar system M1, (1) at a certain location within the target bay close to the system, the direction of travel of the ocean wave front is the approaching direction, and the direction of ocean transport due to the rip current is the receding direction, (2) at another location within the target bay far from the system, the direction of travel of the ocean wave front is the receding direction, and the direction of ocean transport due to the rip current is the approaching direction, and (3) at an intermediate location within the target bay, the direction of travel of the ocean wave front and the direction of ocean transport due to the rip current are neither the approaching direction nor the receding direction.

[0050] Here, in the left column of Fig. 11, it is possible to interpolate the traveling direction of the ocean wave surface and the transport direction of the ocean due to the rip current at a certain position in the target bay close to the system and another position in the target bay far from the system at an intermediate position in the target bay, but this may reduce the speed accuracy. Therefore, in the right column of Fig. 11, the traveling direction of the ocean wave surface is set to the approaching direction and the transport direction of the ocean due to the rip current is set to the receding direction at an intermediate position in the target bay as viewed from the other marine microwave radar system M2.

[0051] In this way, even if the Doppler velocity distribution seen from one microwave radar device 1 is zero, the ocean movement direction (especially that caused by rip currents) can be detected with high accuracy even in a location where the Doppler velocity distribution seen from another microwave radar device 1 is not zero.

[0052] (What is seen in the modified transport direction detection process) What is seen in the modified transfer direction detection process is shown in Fig. 12. In the left column of Fig. 12, the transfer direction detection unit 24 detects the transfer direction of the ocean caused by a rip current or an onshore current. In the right column of Fig. 12, the transfer direction detection unit 24 may detect the transfer direction of the ocean caused by a tidal current.

[0053] Here, in the right column of Figure 12, the transport direction detection unit 24 calculates the average of the transport directions of the ocean due to onshore currents at each position on the target coastline and integrates each of them to detect the overall transport direction of the ocean due to tidal currents including each position on the target coastline. [Industrial Applicability]

[0054] The marine microwave radar signal processing device, marine microwave radar signal processing program, and marine microwave radar system disclosed herein can use a microwave radar to detect the direction of ocean movement (especially that caused by rip currents) with high accuracy. [Explanation of symbols]

[0055] M, M1, M2: Ocean microwave radar system 1: Microwave radar device 2: Radar signal processing device 21: Wavefront position detector 22: Doppler velocity calculation section 23: Wavefront direction detector 24: Transport direction detection unit

Claims

1. a wavefront position detection unit that detects the position of an ocean wavefront based on a radar reflected power distribution of a single scan using a microwave radar device that irradiates microwaves onto an ocean surface layer; a Doppler velocity calculation unit that calculates the Doppler velocity of a surface current before and after the position of the ocean wave front based on a Doppler velocity distribution of a single scan using the microwave radar device; a flow direction detection unit that detects the flow direction of the ocean based on the direction of an average velocity or the magnitude of the absolute value of the velocity with respect to the Doppler velocity of the surface current before and after the position of the ocean wave front; A marine microwave radar signal processing device comprising:

2. The transport direction detection unit detects the ocean transport direction based on the direction of the average speed or the magnitude of the absolute value of the speed and the direction from offshore to coast.

2. A marine microwave radar signal processing device according to claim 1.

3. A wave front direction detection unit detects a traveling direction of an ocean wave front based on a radar reflected power distribution of a plurality of scans using the microwave radar device, The transport direction detection unit detects the transport direction of the ocean based on the direction of the average velocity or the magnitude of the absolute value of the velocity and the traveling direction of the ocean wave surface.

2. A marine microwave radar signal processing device according to claim 1.

4. The travel direction detection unit detects the travel direction of the ocean on the target coastline based on the Doppler velocity distribution of each of the single scans by using a plurality of the microwave radar devices.

2. A marine microwave radar signal processing device according to claim 1.

5. The transport direction detection unit detects the transport direction of the ocean caused by a rip current or an onshore current.

5. A marine microwave radar signal processing device according to claim 1, wherein the first and second signals are transmitted to the first and second terminals of the first and second terminals of the second ... first and second terminals of the second and second terminals of the first and second

6. 2. A marine microwave radar signal processing program for causing a computer to execute each processing step executed by each processing unit of the marine microwave radar signal processing device according to claim 1.

7. 2. A marine microwave radar system comprising: the marine microwave radar signal processing device according to claim 1; and the microwave radar device.

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