Over the Asian monsoon region, stable water isotopic composition in precipitation is observed to be more enriched during winter than during summer as well as along summer transects from the coast to inland regions, counter to the expectation of Rayleigh distillation. Here we use climate model simulations with the Laboratoire de Météorologie Dynamique-Zoom (LMDZ) General Circulation Model nudged with reanalysis wind to understand the isotopic trends. Over Southeast Asia, the seasonal range is caused by the recycling via evapotranspiration in the winter and by the convergence of isotopically depleted vapor in the summer as a result of the flow around the Tibetan Plateau. Over Central Asia, recycling via evapotranspiration in the summer contributes to a higher isotopic composition inland. Isotope vapor data from the Tropospheric Emission Spectrometer (TES) confirms that summer vapor over Southeast Asia is more depleted, even at similar water vapor content, than winter vapor there or vapor over Central Asia, implying a higher contribution from convergence of isotopically depleted vapor than from local recycling of enriched vapor.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- 1041 GEOCHEMISTRY / Stable isotope geochemistry;
- 3337 ATMOSPHERIC PROCESSES / Global climate models;
- 3354 ATMOSPHERIC PROCESSES / Precipitation;
- 3360 ATMOSPHERIC PROCESSES / Remote sensing