Geoscience Reference
In-Depth Information
Fig. 22.11
Forecast 3-h accumulated rainfall ending at 0830 UTC using radar retrieval winds and
CNTL; Actual 3-h accumulated rainfall over Hong Kong based on analysis of raingauge data is
given in lower panel. The numbers in the color bar denote the amount of raingauge over Hong
Kong with 3-h rainfall exceeding the respective thresholds
.i;j/
.
u
B
;
v
B
/
The summation is made over the grid points
.
is the background
.
;
/
W
velocity to be described later, and
u
v
is the velocity to be retrieved.
's are
the weighting coefficients.
The second term in (
22.8
) is a measure of the difference between the observed
.
v
ob
r
/
.
v
r
/
and the retrieved
radial velocities as given by:
J
2
D
X
i;j
v
r
v
ob
r
/
2
:
W
2
.
(22.10)
The third, fourth and fifth terms in (
22.8
) are the smoothing terms involving the
divergence, vorticity and Laplacian of the retrieved velocity field respectively. They
are given by:
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