New in-situ isotopic data from AVE_WIIF and implications for convective transport of water
Abstract
We report here on new in-situ data on the isotopic composition of atmospheric water vapor that allow an unprecedented view into processes affecting the water content of the troposphere and lower stratosphere. Isotopic data from the Harvard ICOS and Hoxotope instruments were obtained on three flights of the WB-57 during the AVE_WIIF campaign of July 2005, over altitudes from 5-19 km and in a variety of airmasses from near-tropical to pure midlatitudes in origin. Airmasses sampled ranged from undersaturated clear air to thin cirrus to thick anvil blowoff, with water concentrations from 10,000 ppm in the lower troposphere to 5 ppm in the stratosphere. As expected, in the middle troposphere we find a relatively compact relationship between water vapor and its isotopic composition, with significant variations associated with convective processes. In the troposphere, recent convective processes are associated with isotopic depletion. We observe no significant local isotopic enrichment from evaporating cloud ice, even near thick anvil blowoff. The upper troposphere shows near-constant isotopic composition. In the stratosphere, elevated water concentrations that may be the result of overshooting convection are associated with isotopic enhancement. We discuss the implications of these and other findings for the use of isotopic measurements in understanding the transport of water in the troposphere and stratosphere.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2005
- Bibcode:
- 2005AGUFM.A44C..06M
- Keywords:
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- 0320 Cloud physics and chemistry;
- 0322 Constituent sources and sinks;
- 0341 Middle atmosphere: constituent transport and chemistry (3334);
- 0368 Troposphere: constituent transport and chemistry;
- 0394 Instruments and techniques