应环境变化与地表过程重点实验室姚檀栋院士的邀请,法国Laboratoire de Météorologie Dynamique (LMD)实验室Camille Risi博士前来青藏高原研究所交流并作学术报告。

题　  目：The added value of tropospheric water vapor isotopic measurements for evaluation cloud and precipitation processes in climate models

报 告 人：Camille Risi 博士

主 持 人：姚檀栋 院士

时　  间：2013年4月25日(星期四) 9:30-11:30

地　  点：青藏高原研究所912会议室

简 　 介:

Dr. Camille Risi did her PhD thesis at LMD/IPSL under the supervision of Sandrine Bony and Jean Jouzel. Then she did a 1 year and a half post-doc at University of Colorado in Boulder under the supervision of David Noone. Then she eventually came back to LMD/IPSL as a permanent scientist. Since her PhD thesis, she has worked on water isotopes (both observations and modelling) with the goal of using them to evaluate the representation of physical processes in atmospheric and land surface models.

Despite continuous improvements in climate models, uncertainties persist regarding the amplitude of the projected global warming and the associated precipitation changes. Better evaluating the representation of physical processes such as clouds, water vapor transport, atmospheric convection and land surface-atmosphere interactions is necessary to assess the credibility in climate change projections. Because of fractionation during phase changes, the water vapor isotopic composition reflects the history of phase changes during the water cycle. A growing number of water isotopic observations are becoming available, both in situ and by remote sensing. To what extent could these water isotopic measurements, combined with meteorological measurements, provide process-oriented diagnostics to evaluate the representation of cloud and precipitation processes in models? We explore this question using the LMDZ atmospheric general circulation model in which we have implemented water isotopes. First, we present how remote-sensing atmospheric water vapor measurements in the tropics and subtropics can be used to better evaluate the representation of vertical transport and of the convective processes, and the interplay between the different parameterizations producing clouds and rain. Second, we discuss the use of atmospheric water vapor measurements to evaluate the role of continental recycling in atmospheric moisture variability. Finally, the availability of new water isotopic observations and our improved understanding of the processes controlling the isotopic distribution allow us to revisit the interpretation of tropical water isotopic records (ice cores, speleothems). We show that both tropical mean temperature and convection upstream air mass trajectories affect the isotopic records. We discuss how such records could be used to better evaluate the capacity of climate models to simulate the precipitation response to climate changes.

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