Geoscience Reference
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Table 2 (b):
Products available from Indian satellites
Period
Available data
1984-1987
3 hourly visible (VIS) and infrared (IR) radiance data
without base map
1987-1993
3 hourly VIS and IR with base map
1993-2002
3 hourly regular VIS and IR, sea surface temperature
(SST), outgoing longwave radiation (OLR), quantitative
precipitation estimate (QPE), cloud motion vector (CMV)
2002 onwards
Water vapour (WV) imagery including above all
Table 2 (c):
Resolution of satellites used for TC monitoring
Satellites
Met payload
Channels
Spectral
Resolution
range (m)
Spatial
Temporal
(km)
(hrs)
KALPANA-1
VHRR
VIS
0.55-0.75
2
1
(Sep'02)
WV
5.7-7.1
8
1
IR
10.5-12.5
8
1
INSAT-3A
VHRR
VIS
0.55-0.75
2
3
(Apr'03)
WV
5.7-7.1
8
3
IR
10.5-12.5
8
3
CCD
VIS
0.62-0.68
1
3
NIR
0.77-0.86
1
3
SWIR
1.55-1.69
1
3
2.3
Methods Used to Interpret Genesis, Location and
Intensity of CDs
During satellite era (1961 to present), genesis and intensity of CDs over NIO
are mainly monitored by Infrared (IR) and visible cloud imageries from
geostationary satellites as surface observations over ocean are scanty (IMD,
2003; Mohapatra et al., 2012). The intensity of CDs is mainly estimated based
on associated maximum MSW. During 1961-1973, the intensity estimation in
mid-sea region took into consideration the once/twice daily available polar
satellite imageries along with available ship observations. Initially, the MSW
was calculated based on the cloud characteristics as observed in satellite imagery
(Fritz et al., 1966). Timechalk et al. (1967) developed empirical technique to
estimate MSW from the diameter of the dense overcast cloud mass and the
cloud pattern. It was replaced by T number classification system given by
Dvorak (1972). Dvorak's technique has also undergone several changes
(Dvorak, 1973, 1975, 1984).
Dvorak's technique (Dvorak, 1975, 1984) is used to determine intensity
of CDs using IR and visible cloud pattern taken by Kalpana and INSAT-3A
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