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| Titel |
A daytime climatological distribution of high opaque ice cloud classes over the Indian summer monsoon region observed from 25-year AVHRR data |
| VerfasserIn |
A. Devasthale, H. Grassl |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 12 ; Nr. 9, no. 12 (2009-06-24), S.4185-4196 |
| Datensatznummer |
250007444
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| Publikation (Nr.) |
 copernicus.org/acp-9-4185-2009.pdf |
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| Zusammenfassung |
| A daytime climatological spatio-temporal distribution of high opaque ice
cloud (HOIC) classes over the Indian subcontinent (0–40° N, 60° E–100° E) is
presented using 25-year data from the Advanced Very High Resolution
Radiometers (AVHRRs) for the summer monsoon months. The HOICs are important
for regional radiative balance, precipitation and troposphere-stratosphere
exchange. In this study, HOICs are sub-divided into three classes based on
their cloud top brightness temperatures (BT). Class I represents very deep
convection (BT<220 K). Class II represents deep convection
(220 K<=BT<233 K) and Class III background convection (233 K<=BT<253 K).
Apart from presenting finest spatial resolution (0.1×0.1 degrees) and
long-term climatology of such cloud classes from AVHRRs to date, this study
for the first time illustrates on (1) how these three cloud classes are
climatologically distributed during monsoon months, and (2) how their
distribution changes during active and break monsoon conditions. It is also
investigated that how many deep convective clouds reach the tropopause layer
during individual monsoon months. It is seen that Class I and Class II clouds
dominate the Indian subcontinent during monsoon. The movement of monsoon over
continent is very well reflected in these cloud classes. During monsoon
breaks strong suppression of convective activity is observed over the Arabian
Sea and the western coast of India. On the other hand, the presence of such
convective activity is crucial for active monsoon conditions and all-India
rainfall. It is found that a significant fraction of HOICs (3–5%) reach the
tropopause layer over the Bay of Bengal during June and over the north and
northeast India during July and August. Many cases are observed when clouds
penetrate the tropopause layer and reach the lower stratosphere. Such cases
mostly occur during June compared to the other months. |
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