 |
| Titel |
The vertical structure of cloud radiative heating over the Indian subcontinent during summer monsoon |
| VerfasserIn |
E. Johansson, A. Devasthale, T. L'Ecuyer, A. M. L. Ekman, M. Tjernström |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 20 ; Nr. 15, no. 20 (2015-10-21), S.11557-11570 |
| Datensatznummer |
250120105
|
| Publikation (Nr.) |
 copernicus.org/acp-15-11557-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
Clouds forming during the summer monsoon over the Indian subcontinent affect
its evolution through their radiative impact as well as the release of
latent heat. While the latter is previously studied to some extent,
comparatively little is known about the radiative impact of different
cloud types and the vertical structure of their radiative heating/cooling
effects. Therefore, the main aim of this study is to partly fill this
knowledge gap by investigating and documenting the vertical distributions of
the different cloud types associated with the Indian monsoon and their
radiative heating/cooling using the active radar and lidar sensors onboard
CloudSat and CALIPSO. The intraseasonal evolution of clouds from May to
October is also investigated to understand pre-to-post monsoon transitioning
of their radiative heating/cooling effects.
The vertical structure of cloud radiative heating (CRH) follows the northward
migration and retreat of the monsoon from May to October. Throughout this
time period, stratiform clouds radiatively warm the middle troposphere and
cool the upper troposphere by more than ±0.2 K day−1 (after
weighing by cloud fraction), with the largest impacts observed in June, July
and August. During these months, the fraction of high thin cloud remains high
in the tropical tropopause layer (TTL). Deep convective towers cause
considerable radiative warming in the middle and upper troposphere, but
strongly cool the base and inside of the TTL. This cooling is stronger during
active (−1.23 K day−1) monsoon periods compared to break periods
(−0.36 K day−1). The contrasting radiative warming effect of high
clouds in the TTL is twice as large during active periods than in break
periods. These results highlight the increasing importance of CRH with
altitude, especially in the TTL.
Stratiform (made up of alto- and nimbostratus clouds) and deep convection
clouds radiatively cool the surface by approximately −100 and
−400 W m−2 respectively while warming the atmosphere radiatively by
about 40 to 150 W m−2. While the cooling at the surface induced by
deep convection and stratiform clouds is largest during active periods of
monsoon, the importance of stratiform clouds further increases during break
periods. The contrasting CREs (cloud radiative effects) in the atmosphere and
at surface, and during active and break periods, should have direct
implications for the monsoonal circulation. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|