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Seasonal variations in the isotopic composition of near-surface water vapour in the eastern Mediterranean Cover

Seasonal variations in the isotopic composition of near-surface water vapour in the eastern Mediterranean

By: ,   and    
Open Access
|Jan 2008

Abstract

Although the isotopic composition of precipitation is widely used in global climate change studies, use of water vapour isotopes is considerably more limited. Here we present the results from 9 yr of atmospheric vapour measurements in the Eastern Mediterranean, at a site in Israel. The measurements show a strong mean seasonal cycle of about 4‰ in 18O (peaking around July). This seasonality could not be adequately explained by changes in surface interactions or in air mass trajectories, as usually invoked for variations in local precipitation. We could explain this cycle only as a combination of three components: (1) rainout effects; (2) temperature and relative humidity control of the initial vapour and (3) seasonal variations in the vertical mixing across the top of the planetary boundary layer. This last component is emphasized in the current study, and it was shown to be a significant factor in the seasonal cycle features. The measurements were also compared with an isotope-enabled GCM (CAM2) run, which exhibited a markedly different seasonal cycle. Such comparisons with vapour isotopes data could help in constraining models better.

Language: English
Page range: 674 - 684
Submitted on: Nov 28, 2006
Accepted on: Mar 18, 2008
Published on: Jan 1, 2008
Published by: Stockholm University Press
In partnership with: Paradigm Publishing Services

© 2008 Alon Angert, Jung-Eun Lee, Dan Yakir, published by Stockholm University Press
This work is licensed under the Creative Commons Attribution 4.0 License.