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| Titel |
Long-term trend analysis and climatology of tropical cirrus clouds using 16 years of lidar data set over Southern India |
| VerfasserIn |
A. K. Pandit, H. S. Gadhavi, M. Venkat Ratnam, K. Raghunath, S. V. B. Rao, A. Jayaraman |
| 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 ; 15, no. 24 ; Nr. 15, no. 24 (2015-12-16), S.13833-13848 |
| Datensatznummer |
250120228
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| Publikation (Nr.) |
 copernicus.org/acp-15-13833-2015.pdf |
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| Zusammenfassung |
| Sixteen-year (1998–2013) climatology of cirrus clouds and their macrophysical
(base height, top height and geometrical thickness) and optical properties
(cloud optical thickness) observed using a ground-based lidar over Gadanki
(13.5° N, 79.2° E), India, is presented. The climatology obtained
from the ground-based lidar is compared with the climatology obtained from
7 and a half years (June 2006–December 2013) of Cloud-Aerosol Lidar
with Orthogonal Polarization (CALIOP) observations. A very good agreement is
found between the two climatologies in spite of their opposite viewing
geometries and the differences in sampling frequencies. Nearly 50–55 % of
cirrus clouds were found to possess geometrical thickness less than 2 km.
Ground-based lidar is found to detect a higher number of sub-visible clouds than
CALIOP which has implications for global warming studies as sub-visible
cirrus clouds have significant positive radiative forcing. Cirrus clouds
with mid-cloud temperatures between −50 to −70 °C
have a mean geometrical thickness greater than 2 km in contrast to the
earlier reported value of 1.7 km. Trend analyses reveal a statistically
significant increase in the altitude of sub-visible cirrus clouds which is
consistent with the recent climate model simulations. The mid-cloud altitude
of sub-visible cirrus clouds is found to be increasing at the rate of
41 ± 21 m year−1. Statistically significant decrease in optical thickness
of sub-visible and thick cirrus clouds is observed. Also, the fraction of sub-visible cirrus cloud is found to have increased by 9 % in the last
16 years (1998 to 2013). This increase is mainly compensated by a 7 % decrease in thin cirrus cloud fraction. This has implications for the temperature and
water vapour budget in the tropical tropopause layer. |
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