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Table 2:
Displace error (% of improvement with respect to control exp) in km
00 UTC of forecast day (date)
Track Error (km)
Control
Inserted SST grad
SSHA2SST
Initial (06.05.2002)
320
320
320
Day-1 (07.05.2002)
1025
610 (41%)
301 (71%)
Day-2 (08.05.2002)
826
686 (17%)
570 (31%)
Day-3 (09.05.2002)
781
560 (28%)
444 (43%)
Day-4 (10.05.2002)
717
474 (34%)
460 (36%)
Mean error
733.8
530
419
south of the vortex location (Fig. 1) in the NCEP skin temperature which drag
the cyclonic storm more southwards in the Control experiment. It is seen from
the table that the displacement error is higher in Control than Inserted SST
grad and SSHA2SST experiments during all the days. An improvement (with
minimum 17% and maximum 71%) in the track position is noticed in both
Inserted SST grad and SSHA2SST experiments with respect to control
experiments. It is also noticed that the improvement is more in SSHA2SST
than the Inserted SST grad experiments during all the days. The mean error
(considering all five days) is 733.8 km for Control, while it is 530 km and 419
km for Inserted SST grad and SSHA2SST experiments. This suggests that the
representation of SST is very much crucial in the prediction of cyclone track.
The results also indicate that the representation of converted SST from SSHA
is useful in the simulation of cyclone.
B. Sensitivity Study of Projected Warm SST on TC Intensity
It is demonstrated in the previous experiments that the representation of SST
converted from SSHA in the numerical model are able to bring out cyclone
track closer to the observations. Therefore, two experiments using two different
SST have been conducted. These two SST have been generated from SSHA by
linear interpolation keeping the gradient same. In the first experiment, the SST
has been kept in between 27 and 33 °C which is considered as current SST
pattern (hereafter referred to as CSST) whereas in the second experiment, SST
has been kept in between 29 and 33 °C for projected future pattern of SST
(hereafter referred to as PSST). It is seen from the IPCC 4th assessment reports
that the surface temperature may rise by about 1-2 °C over different regions of
the world and the future SST may exceed 28.25 °C (Henderson-Sellers et al.,
1998; Micheal et al., 2006). In this set of experiments, we assume that minimum
SST may reach 29 °C from the present minimum (27 °C) and we did not alter
the maximum SST value in the sensitivity experiments. The same cyclone is
considered and model configuration is same as described in Table 1. Other
geophysical parameters from USGS and initial and lateral boundary conditions
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