Ocean microwave radar signal processing device, ocean microwave radar signal processing program, and ocean microwave radar system

Abstract

To highly accurately calculating a transport speed (especially, by a tidal current) in a two-dimensional direction of the ocean with the use of an ocean radar device.SOLUTION: An ocean microwave radar signal processing device 2 includes: a wave surface speed calculation section 21 for calculating an advance speed of an ocean wave surface based on a radar reflection power distribution of a plurality of times of scanning with the use of a microwave radar device 1 for radiating a microwave to an ocean surface layer; and a transport speed calculation section 23 for calculating an ocean transport speed by subtracting an intrinsic speed (not affected by the ocean transport speed) of the ocean wave from the advance speed of the ocean wave surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to techniques for calculating ocean transport velocities, particularly those due to tidal 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 calculate ocean transport velocities (particularly those caused by tidal currents) using Patent Document 1. However, since it only calculates the Doppler velocity of the surface current in a one-dimensional direction, it is not possible to calculate the ocean transport velocities in two-dimensional directions with high accuracy.

[0005] In order to solve the above problem, an object of the present disclosure is to use a marine radar device to calculate two-dimensional ocean transport velocities (particularly those due to tidal currents) with high accuracy. [Means for solving the problem]

[0006] To solve the above problem, we focused on the fact that in deep water areas, unlike on the coast, the movement of water particles due to tidal currents is independent of the movement of ocean waves due to swells. Therefore, using a microwave radar device that irradiates microwaves onto the ocean surface, we calculate the traveling speed of the ocean wave front based on the radar reflected power distribution of multiple scans. Then, we calculate the ocean transport speed (especially that due to tidal currents) by subtracting the intrinsic speed of the ocean wave from the traveling speed of the ocean wave front.

[0007] Specifically, the present disclosure relates to an ocean microwave radar signal processing device comprising: a wave front velocity calculation unit that calculates the traveling speed of an ocean wave front based on the radar reflected power distribution of multiple scans using a microwave radar device that irradiates microwaves onto the ocean surface; and a transport speed calculation unit that calculates the ocean transport speed by subtracting the intrinsic speed of the ocean wave (which is not affected by the ocean transport speed) from the traveling speed of the ocean wave front.

[0008] According to this configuration, it is possible to calculate the two-dimensional transport speed of the ocean (particularly that due to tidal currents) with high accuracy using the reflected power distribution of multiple scans 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 provides a marine microwave radar signal processing device further comprising a natural velocity calculation unit that calculates the natural velocity of the ocean wave based on a water depth distribution.

[0011] According to this configuration, the characteristic speed of ocean waves can be calculated based on the water depth distribution, and then the transport speed in two dimensions of the ocean (particularly that due to tidal currents) can be calculated with high accuracy.

[0012] The present disclosure also relates to a marine microwave radar signal processing device, wherein the intrinsic velocity calculation unit corrects the water depth distribution based on tidal levels.

[0013] According to this configuration, the water depth distribution can be corrected based on the tidal levels, and then the transport speed in two dimensions in the ocean (particularly that due to tidal currents) can be calculated with high accuracy.

[0014] The present disclosure also relates to a marine microwave radar signal processing device, further comprising an intrinsic velocity calculation unit that uses the microwave radar device to calculate the intrinsic velocity of the ocean wave based on the radar reflection power distribution of the multiple scans.

[0015] With this configuration, the inherent speed of ocean waves can be calculated based on the reflected power distribution of multiple scans of a microwave radar, instead of the water depth distribution and tidal levels, and the two-dimensional transport speed of the ocean (especially that due to tidal currents) can be calculated with high accuracy.

[0016] The present disclosure also relates to a marine microwave radar signal processing device, wherein the travel speed calculation unit calculates a travel speed of the ocean due to tidal currents.

[0017] According to this configuration, the two-dimensional transport speed of the ocean caused by tidal currents can be calculated with high accuracy using the reflected power distribution of multiple scans 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 makes it possible to use the marine radar device to calculate the two-dimensional transport speed of the ocean (particularly that caused by tidal 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] FIG. 11 is a diagram showing a procedure of a transport speed calculation 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 the principle of the transport speed calculation process of the present disclosure. [Figure 6] FIG. 11 is a diagram showing a specific example of a transport speed calculation process according to the present disclosure. [Figure 7] FIG. 11 is a diagram showing a specific example of a transport speed calculation process according to the present disclosure. [Figure 8] FIG. 13 is a diagram showing what is seen in a modified transport speed calculation 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 velocity calculation 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 velocity calculation unit 21, an intrinsic velocity calculation unit 22, and a travel velocity calculation unit 23, 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 calculates ocean transport speed (for example, due to tidal currents) 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 deep water areas, unlike the coast, the movement of water particles due to tidal currents is independent of the movement of ocean waves due to swells.

[0028] Therefore, the radar signal processing device 2 calculates the traveling speed of the ocean wave front based on the radar reflected power distribution of multiple scans (step S1) using the microwave radar device 1. Then, the radar signal processing device 2 calculates the ocean transport speed (e.g., due to tidal currents) by subtracting the intrinsic speed of the ocean wave from the traveling speed of the ocean wave front (step S4).

[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] (Principle of the transport speed calculation process of the present disclosure) The principle of the transport velocity calculation process of the present disclosure is shown in Fig. 5. The wave front velocity calculation unit 21 calculates the traveling velocity V of the ocean wave front based on the radar reflected power distribution of multiple scans using the microwave radar device 1. a (Step S1). Here, the traveling speed of the ocean wave surface V a is the characteristic velocity of ocean waves V w is not necessarily equal to the ocean transport velocity V t In the left column of FIG. 5, the wave front velocity calculation unit 21 calculates the traveling velocity V of the ocean wave front based on the deviation a between the radar reflected power distributions of the first and second scans and the time t between the first and second scans. a Calculate =a / t.

[0033] The intrinsic velocity calculation unit 22 calculates the intrinsic velocity V of the ocean wave based on the distribution of the water depth h. w (Step S2) Here, the natural velocity of ocean waves V w is the ocean transport velocity V tIn the right column of FIG. 5, the intrinsic velocity calculation unit 22 refers to a nautical chart or the like and calculates the intrinsic velocity V of ocean waves based on the distribution of water depth h and the acceleration of gravity g. w =√(gh) (shallow water waves).

[0034] The transport velocity calculation unit 23 calculates the traveling velocity V a from the characteristic velocity of ocean waves V w By subtracting t =V a -V w (Step S4). That is, the traveling speed V a is the characteristic velocity of ocean waves V w The ocean transport speed V t is added.

[0035] In this way, the reflected power distribution of multiple scans of the microwave radar device 1 is used to calculate the two-dimensional transport velocity V t (e.g., due to tidal currents) can be calculated with high accuracy. Then, based on the distribution of water depth h, the characteristic velocity of ocean waves V w After calculating the two-dimensional transport velocity V t (e.g., due to tidal currents) can be calculated with high accuracy.

[0036] 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.

[0037] In addition, in the conventional technology, by simply installing a single shortwave radar device, it is only possible to calculate the Doppler velocity of the swell in one dimension, but by installing multiple shortwave radar devices, it is possible to calculate the Doppler velocity of the swell in two dimensions.

[0038] On the other hand, in the present disclosure, even if only a single microwave radar device 1 is installed, the two-dimensional transport velocity V tBy installing multiple microwave radar devices 1, the two-dimensional ocean transport velocity V t (e.g., due to tidal currents) can be calculated with greater accuracy.

[0039] (Specific example of the transport speed calculation process of the present disclosure) A specific example of the transport velocity calculation process of the present disclosure is shown in FIG. 6. The intrinsic velocity calculation unit 22 calculates the intrinsic velocity V w The first calculation method is to calculate the characteristic velocity of ocean waves V based on the distribution of water depth h. w In calculating h, the distribution of water depth h is corrected based on the tidal levels (step S2).

[0040] In the left column of FIG. 6, the intrinsic velocity calculation unit 22 refers to a nautical chart and the tide level at high tide, and calculates the intrinsic velocity V of an ocean wave based on the distribution of water depth h (deeper than water depth h′ described later) and the acceleration of gravity g. w In the right column of FIG. 6, the intrinsic velocity calculation unit 22 calculates the intrinsic velocity V of ocean waves based on the distribution of water depth h' (shallower than the above-mentioned water depth h) and the acceleration of gravity g, with reference to a nautical chart and the tide level at low tide. w Calculate '=√(gh') (shallow water waves).

[0041] In this way, the distribution of water depth h is corrected based on the tidal level, and the two-dimensional transport velocity V t (e.g., due to tidal currents) can be calculated with greater accuracy.

[0042] A specific example of the transport velocity calculation process of the present disclosure is also shown in FIG. w As a second calculation method, the microwave radar device 1 is used to calculate the intrinsic velocity V of the ocean wave based on the radar reflected power distribution of multiple scans. w is calculated (step S3).

[0043] In the left and right columns of FIG. 7 , the intrinsic velocity calculation unit 22 calculates the intrinsic velocity V of the ocean wave based on the wavelength λ of the radar reflected power distribution in the first scan and the period p in which the radar reflected power distribution in the first scan is repeated as the radar reflected power distribution in the nth scan. w Calculate = λ / p.

[0044] In this way, instead of the distribution of water depth h and the tidal level, the characteristic velocity V of the ocean wave is calculated based on the reflected power distribution of multiple scans of the microwave radar device 1. w After calculating the two-dimensional transport velocity V t (e.g., due to tidal currents) can be calculated with high accuracy.

[0045] (What is seen in the modified transport speed calculation process) FIG. 8 shows what is seen in the modified transport velocity calculation process. In the left column of FIG. 8, the transport velocity calculation unit 23 calculates the ocean transport velocity V due to the tidal current. t In the right column of FIG. 8, the transport velocity calculation unit 23 calculates the ocean transport velocity V t2 , V t1 may be calculated.

[0046] However, in the right column of FIG. 8, the wave front velocity calculation unit 21 calculates the traveling velocity V of the ocean wave front based on the overall position shift of the radar reflected power distribution of multiple scans. a 8, the intrinsic velocity calculation unit 22 corrects the distribution of water depth h based on the tidal level (tide observation stations are installed sparsely), so the transport velocity calculation unit 23 may particularly reduce the detection accuracy of the rip current. [Industrial Applicability]

[0047] 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 calculate two-dimensional ocean transport speeds (especially those due to tidal currents) with high accuracy. [Explanation of symbols]

[0048] M: Ocean Microwave Radar System 1: Microwave radar device 2: Radar signal processing device 21: Wave surface velocity calculation section 22: Specific velocity calculation part 23: Transfer speed calculation section

Claims

1. a wave front velocity calculation unit that calculates the traveling velocity of an ocean wave front based on a radar reflected power distribution of multiple scans using a microwave radar device that irradiates microwaves onto an ocean surface layer; a transport velocity calculation unit that calculates the transport velocity of the ocean by subtracting an intrinsic velocity of the ocean wave (not affected by the transport velocity of the ocean) from the traveling velocity of the ocean wave surface; A marine microwave radar signal processing device comprising:

2. The apparatus further includes a specific velocity calculation unit that calculates the specific velocity of the ocean wave based on the water depth distribution.

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

3. The intrinsic velocity calculation unit corrects the water depth distribution based on tidal levels.

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

4. The microwave radar device further includes a specific velocity calculation unit that calculates the specific velocity of the ocean wave based on the radar reflected power distribution of the multiple scans.

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

5. The transport speed calculation unit calculates the transport speed of the ocean due to a tidal 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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