Tsunami monitoring radar system including transmitting antenna for radiating transmission signal for detecting tsunami as radio wave toward sea

Patent metadata

Field	Value
Publication number	US-9544748-B2
Application number	US-201414890323-A
Country	US
Kind code	B2
Filing date	Jan 23, 2014
Priority date	May 31, 2013
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

A tsunami monitoring system includes a transmitting antenna configured to radiate a transmission signal to detect a tsunami as a radio wave toward a sea, and a receiving antenna configured to receive reflected waves reflected by the tsunami as a receiving signal. The tsunami monitoring system includes a signal generator circuit configured to generate the transmission signal having a predetermined frequency, a signal processor portion configured to generate a beat signal of a frequency difference between the transmission signal and the receiving signal, and a wave height estimator portion configured to divide a radio wave radiation region into a plurality of regions, calculate a flow velocity of a sea surface of the tsunami for each region on the basis of the beat signal, and estimate a wave height of the tsunami from a calculated flow velocity.

First claim

The invention claimed is:

1. A tsunami monitoring radar system comprising:
a transmitting antenna that radiates a transmission signal to detect a tsunami as a radio wave toward a sea;
a receiving antenna that receives reflected waves reflected by the tsunami as a receiving signal;
a signal generator circuit that generates the transmission signal having a predetermined frequency;
a signal processor portion that generates a beat signal of a frequency difference between the transmission signal and the receiving signal; and
a wave height estimator portion that divides a radio wave radiation region into a plurality of regions, calculates a flow velocity of a sea surface of the tsunami for each region on the basis of the beat signal, and estimates a wave height of the tsunami from the calculated flow velocity.

2. The tsunami monitoring radar system as claimed in claim 1 , further comprising:
an arrival predictor portion that predicts an arrival time and an arrival wave height with respect to the tsunami on the basis of the wave height of the tsunami.

3. The tsunami monitoring radar system as claimed in claim 2 ,
wherein the arrival predictor portion calculates the arrival wave height by the following equation:
η 0 h 0 1/4 =cons tan t

where η 0 is the arrival wave height of the tsunami, and h 0 is a static water depth at a predetermined distance from an installation position of the transmitting and receiving antennas.

4. The tsunami monitoring radar system as claimed in claim 1 , further comprising:
a tsunami simulator portion that executes a tsunami simulation of a behavior of the tsunami on the basis of the estimated wave height of the tsunami.

5. The tsunami monitoring radar system as claimed in claim 1 ,
wherein the wave height estimator portion calculates the wave height of the tsunami by the following equation:

∂
η

∂
r

=

-

1
g

⁢

∂

U
r

∂
t

where r is a radius centered on the transmitting antenna, η is the wave height of the tsunami, t is a time, and U r is a flow velocity in a direction of the radius r.

6. The tsunami monitoring radar system as claimed in claim 1 ,
wherein the wave height estimator portion calculates the wave height of the tsunami by the following equation:

∂
η

∂
r

=

1

g
⁢

⁢
h

⁢

{

-

∂

∂
r

⁢

(

M
r
2

h

)

-

g
⁢

⁢

n
2

h

7
3

⁢

M
r
2

-

∂

M
r

∂
t

}

where r is a radius centered on the transmitting antenna, η is the wave height of the tsunami, h is a static water depth of the sea, g is a gravitational acceleration, M r is a linear flow amount in a direction of the radius r, and n is a sea bottom friction coefficient.

7. The tsunami monitoring radar system as claimed in claim 1 ,
wherein the wave height estimator portion calculates the wave height of the tsunami by the following equation:

η
=

U
r

⁢

h
g

where η is the wave height of the tsunami, h is a static water depth of the sea, g is a gravitational acceleration, and U r is a flow velocity in a direction of the radius r.

8. The tsunami monitoring radar system as claimed in claim 1 ,
wherein the wave height estimator portion calculates the wave height of the tsunami by the following equation:

∂
2

⁢
η

∂

r
2

+

1

r
2

⁢

∂
2

⁢
η

∂

θ
2

+

Assignees

• Mitsubishi Electric Corp

Inventors

• Ishikawa Hiroaki
• Kawai Takashi
• Nagano Takafumi
• Isono Taizo

Classifications

• G01S13/50

  Systems of measurement based on relative movement of target · CPC title

• G01S13/95

  for meteorological use · CPC title

• H04W4/027

  using movement velocity, acceleration information · CPC title

• G01C13/00

  Surveying specially adapted to open water, e.g. sea, lake, river or canal (liquid level metering G01F) · CPC title

• H04W4/90 Primary

  Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS] · CPC title