Abstracts for the 6th International GAME Conf.
3-5 December 2004
Kyoto Japan
Features of Cloud Types over the Bay of Bengal Using Split Window Measurements and TRMM Satellite Data
Tomotsugu INOUE (1), Hiroaki UEDA (1), Toshiro INOUE (3)
(1) University of Tsukuba
(3) Meteorological Research Institute
The Asian monsoon is characterized the enhanced convection which is
composed of diurnal cycle as well as intraseasonal variation, besides
the basic seasonal evolution. Although several studies have used
Outgoing Logwave Radiation (OLR) and Black Body Temperature (TBB),
these data sets are not necessarily represented deep convection area
attended latent heating. Therefore, the main objective of the present
study is to reveal spatiotemporal structures of cloud properties over
the Bay of Bengal in summer derived from split window measurements. In
this study, split window data from Advanced Very High Resolution
Radiometer (AVHRR) on board NOAA-9 is utilized during the period 1986
to 1993. Optically thin clouds (cirrus type clouds) can be identified
by inspection of the image constructed from the brightness temperature
difference (BTD) between 11ƒÊm and 12ƒÊm (split window) data. Cloud
type classification based on a threshold technique in the TBB-BTD
diagram. In boreal summer, optically thick clouds (cumulonimbus type
clouds) associated with deep convection appear principally over the
eastern Bay of Bengal, while cirrus type clouds including anvil clouds
are found over the whole Bay of Bengal. With respect to seasonal
evolution, cirrus type clouds observed nearby the tropic abrupt
northward expand in the monsoon onset. Its expanded cirrus type clouds
reduce gradually after the monsoon season. Although this annual cycle
is similar to that of OLR, cumulonimbus type clouds exhibit different
variability from OLR. Finally, comparison of cloud type derive from
split window measurements and Tropical Rain fall Measuring Mission
(TRMM) Precipitation Radar (PR) data is conducted for convective
activity area. Very good agreement is obtained for the distribution of
cumulonimbus type clouds and large precipitation area over the Bay of
Bengal.
Submittal Information
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Tsukuba, Ibaraki 305-8572 | |
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s0430629@ipe.tsukuba.ac.jp | |