Impact of Radiance Data Assimilation on Simulation of Tropical Cyclone Thane Using WRF-3DVAR Modelling System - Monitoring and Prediction of Tropical Cyclones in the Indian Ocean and Climate Change - page 385

Table 2: Vector displacement errors (VDEs) at different forecast time

Date (forecast hrs)(Day_hour) CNTL GTS RAD

26_00 (00 hrs) 140 72 64

27_00 (24 hrs) 135 127 122

28_00 (48 hrs) 131 116 77

29_00 (72 hrs) 318 201 26

30_00 (96 hrs) 525 339 179

experiment after assimilation of radiance along with GTS observation as
compared to the other two simulations.
The model initial time and day 2 (valid at 00 UTC 28 December 2011)
wind field at 850 hPa from the three experiments are shown in Fig. 3 (a-c) and
(d-f) respectively. It is clear that the close circulation around the storm is
simulated well in all experiments; however, the RAD simulations show stronger
wind as compared to the CNTL and GTS simulation at model initial time
as well as day 2 forecast. At model initial time the wind is stronger around
10 m/s in the RAD analysis as compared to CNTL and GTS simulations.
Similarly, in day 2 forecast the wind is stronger around 8-10 m/s surrounding
and neighbourhood of the storm after assimilation of radiance along with GTS
observations as compared to the other two simulations. The simulated position
of the system from RAD experiment is well correlated with observed one.
The time series of the minimum MSLP and maximum sustainable wind
(m/s) at 10 m height from surface obtained from three experiments and along
with observation from IMD are represented in Fig. 4(a) and (b) respectively. It

Fig. 3: Wind speed and magnitude (shaded m/s) at 850 hPa from (a) FNL; (b) GTS and
(c) RAD valid at 00 UTC 26 December 2011 (Int. time). Model simulated wind fields
(48 hrs) from (d) CNTL; (e) GTS and (f) RAD valid at 00 UTC 28 December 2011.