US 12,204,015 B1Granted

Estimation method and system for quasi-real-time monitoring of moving velocity vector of typhoon based on synthetic aperture radar

AssigneeNuist

InventorsGuosheng Zhang, Yuanben Li

Life of this patent

Estimating the term…

Loading patent…

Abstract

An estimation method and system for quasi-real-time monitoring of a moving velocity vector of a typhoon based on a synthetic aperture radar includes: (1) determining, using a threshold method, a position of a typhoon eye wall of a synthetic aperture radar (SAR) sea surface wind field of a typhoon; (2) extracting a final typhoon eye region using a maximum gradient method according to the position of the typhoon eye wall, and estimating an approximate ellipse of the typhoon eye wall and determining a center of the approximate ellipse as a typhoon center; (3) estimating large-scale background wind vector information using the estimated typhoon center and approximate ellipse; and (4) determining a moving velocity vector of the typhoon using the estimated background wind vector information and typhoon center.

Claims2

Dependent claims

An estimation method for quasi-real-time monitoring of a moving velocity vector of a typhoon based on a synthetic aperture radar, comprising the following steps:

(1) determining, using a threshold method, a position of a typhoon eye wall of a synthetic aperture radar (SAR) sea surface wind field of a typhoon, wherein step (1) specifically comprises:
determining the position of the typhoon eye wall with a suitable threshold in the SAR wind field as an initial threshold, extracting a region within the typhoon eye wall as an initial typhoon eye region, and estimating an initial typhoon center, wherein the suitable threshold is 90% of a maximum wind speed in the wind field;
and the initial typhoon center is mean values of longitudes and latitudes of all points within the initial typhoon eye region;
(2) extracting a final typhoon eye region using a maximum gradient method according to the position of the typhoon eye wall, and estimating an approximate ellipse of the typhoon eye wall and determining a center of the approximate ellipse as a typhoon center, wherein step (2) specifically comprises:
emanating rays from the estimated typhoon center in 360 degrees at intervals of 1 degree and calculating a gradient maximum;
and with a mean value of pixel wind speed values at 360 gradient maximums as a new threshold, extracting the final typhoon eye region and a position of the typhoon center;
(3) estimating large-scale background wind vector information using the estimated typhoon center and approximate ellipse according to the following formula:
{right arrow over (U)}(r,θ)=Umax·f(R)+A·;
wherein {right arrow over (U)} represents a wind speed at an elevation of 10 m over a sea surface, in unit of m/s;
Umax represents a maximum sea surface wind speed of the typhoon, namely a typhoon intensity, in unit of m/s;
R represents a distance of a certain point to the typhoon center, in unit of km;
represents the moving velocity vector of the typhoon, which is an idealized parameter and related to sea surface friction, with a value of 0.5;
and f(R) represents a parameterized model function of a distance to the typhoon center, which is Holland or Rankine model;
and
(4) determining a moving velocity vector of the typhoon using the estimated background wind vector information and typhoon center according to the following formula:
V
m
→
=
U
→
(
r
,
θ
)
-
U
max
·
f
⁡
(
R
)
A
;
wherein {right arrow over (U)}(r,θ) represents a sea surface wind field obtained by SAR inversion;
and f(R) and Umax represent typhoon wind fields simulated by the parameterized model function.

36 more elements

An estimation system for quasi-real-time monitoring of a moving velocity vector of a typhoon based on a synthetic aperture radar, comprising:

a typhoon eye wall module configured to determine, using a threshold method, a position of a typhoon eye wall of a synthetic aperture radar (SAR) sea surface wind field of a typhoon, wherein the typhoon eye wall module is further configured to determine the position of the typhoon eye wall with a suitable threshold in the SAR wind field as an initial threshold, extract a region within the typhoon eye wall as an initial typhoon eye region, and estimate an initial typhoon center, wherein the suitable threshold is 90% of a maximum wind speed in the wind field;
and the initial typhoon center is mean values of longitudes and latitudes of all points within the initial typhoon eye region;
a typhoon center module configured to extract a final typhoon eye region using a maximum gradient method according to the position of the typhoon eye wall, and estimate an approximate ellipse of the typhoon eye wall and determine a center of the approximate ellipse as a typhoon center, wherein the typhoon center module is configured to emanate rays from the estimated typhoon center in 360 degrees at intervals of 1 degree and calculate a gradient maximum, and with a mean value of pixel wind speed values at 360 gradient maximums as a new threshold, extract the final typhoon eye region and a position of the typhoon center;
a wind vector information module configured to estimate large-scale background wind vector information using the estimated typhoon center and approximate ellipse according to the following formula:
{right arrow over (U)}(r,θ)=Umax·f(R)+A·;
wherein {right arrow over (U)} represents a wind speed at an elevation of 10 m over a sea surface, in unit of m/s;
Umax represents a maximum sea surface wind speed of the typhoon, namely a typhoon intensity, in unit of m/s;
R represents a distance of a certain point to the typhoon center, in unit of km;
represents the moving velocity vector of the typhoon, which is an idealized parameter and related to sea surface friction, with a value of 0.5;
and f(R) represents a parameterized model function of a distance to the typhoon center, which is Holland or Rankine model;
and
a moving velocity vector module configured to determine a moving velocity vector of the typhoon using the estimated background wind vector information and typhoon center according to the following formula:
V
m
→
=
U
→
(
r
,
θ
)
-
U
max
·
f
⁡
(
R
)
A
;
wherein {right arrow over (U)}(r,θ) represents a sea surface wind field obtained by SAR inversion;
and f(R) and Umax represent typhoon wind fields simulated by the parameterized model function.

33 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/819,778Filed 29 Aug 2024
Priority: CN 202410406479.27 Apr 2024
Granted: 21 Jan 2025
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G01S 13/589
Velocity or trajectory determination systems; Sense-of-movement determination systems: measuring the velocity vector
G01S 13/62
Velocity or trajectory determination systems; Sense-of-movement determination systems: sense-of-movement determination
G01S 13/90
For mapping or imaging: using synthetic aperture techniques , e.g. synthetic aperture radar [SAR] techniques
G01S 13/9029
SAR image post-processing techniques: specially adapted for moving target detection within a single SAR image or within multiple SAR images taken…