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10.5194/acpd-7-351-2007
http://www.atmos-chem-phys-discuss.net/7/351/2007/
http://www.atmos-chem-phys-discuss.net/7/351/2007/acpd-7-351-2007.html
http://www.atmos-chem-phys-discuss.net/7/351/2007/acpd-7-351-2007.pdf
351
381
2007-01-10
Diurnal variation of upper tropospheric humidity and its relations to convective activities over tropical Africa
E. S. Chung
B. J. Sohn
sohn@snu.ac.kr
J. Schmetz
M. Koenig
School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), Darmstadt, Germany
Diurnal variations of upper tropospheric humidity (UTH) as well as middle
tropospheric humidity (MTH) were examined in conjunction with the diurnal
cycle of convection over tropical Africa and the adjacent tropical Atlantic
Ocean using Meteosat-8 measurements. Cloud and humidity features were also
tracked to document the diurnal variations of humidity and clouds in the
Lagrangian framework.
<br><br>
A distinct diurnal variation of UTH (and MTH) is noted over regions where
tropical deep convective cloud systems are commonly observed. The amplitude
of the UTH diurnal variation is larger over land, while its variations over
convectively inactive subtropical regions are much smaller. The diurnal
variation of UTH tends to peak during nighttime over land, lagging deep
convection and high cloud whose maxima occurred in the late afternoon and
the evening, respectively. The time lag between the maximum UTH and deep
convection/high cloud maxima over the ocean appears to be longer in
comparison to that found over land. It was also indicated that both the UTH
(and MTH) and the cirrus anvil cloud show a variation which is in phase,
implying that moistening of the upper troposphere is closely linked to
process of development and dissipation of deep convective clouds.
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