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Fig. 6:
Average difference (km) in location of centre of CDs as estimated by SSD,
NOAA and Navy, NRL based on different satellites.
Inter-comparison has also been done between the centre estimated by SSD,
NOAA and Navy, NRL and the results are shown in Fig. 6. Total 79 observations
are used in the study (Table 3) and the average difference in location of centres
is found to be 72 km. It is comparatively higher than the difference in location
of centres by Satellite Division of IMD and Navy, NRL.
4. Conclusions
Following broad conclusions are drawn from the results and discussion.
There is difference in estimation of location and intensity of CDs by various
operational centres due to the subjectivity involved in the estimation. However,
the difference in estimation decreases with increase in intensity of CDs.
The difference in intensity based on visible and infrared imageries of
Kalpana-1 and INSAT 3A satellites and the microwave imageries based on
polar orbiting satellites is higher in case of lower intensity of the system such
as depressions and cyclonic storms. It then decreases in case of severe cyclonic
storms and very severe cyclonic storms. The intensity estimated by NRL based
on microwave imagery is higher in 55% cases than that estimated by infrared/
visible imagery. The difference is positive in only 13% cases and equal in 32%
cases. The average difference in intensity is T0.5. In 71% of cases of T5.0 or
more, the intensity estimated by NRL is higher than that of IMD
The average difference in location of centres based on estimates of Navy,
NRL using microwave imageries and estimates of satellite division of IMD
based on visible/infrared imageries of geostationary satellites is about 82 km.
It gradually decreases with increase in intensity of the CD. The difference is
higher (more than 100 km) when intensity is T1.0 or T1.5. Considering the
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