Related Research Areas
Atmospheric Composition, Water & Energy Cycles

Water vapor, particularly in the crucial regions of the uppermost troposphere and stratosphere, is controlled by small-scale processes. These phenomena govern critical science issues: changes in radiative forcing due to water vapor, and the transport of water vapor to the stratosphere, which in turn has enormous impact on future ozone loss rates. The isotopic composition of water vapor (the ratio HDO/H2O or H218O/H2O) is a key tracer for understanding the influence of convective processes on water vapor distributions. It also holds the key for diagnosing the response of the atmosphere to climate forcing by CO2. Because convective transport of water in the form of ice provides a source of isotopically enhanced water to the tropopause region, mapping these enhancements can provide a detailed understanding of the influence of tropical convection on water vapor transport to the upper troposphere and above. The measurement is made difficult by the scarcity of isotopically substituted water; the abundance of HDO is less than a ppbv in the dry stratosphere. The instrument uses the technique of integrated cavity output spectroscopy (ICOS) to obtain unprecedented measurement sensitivity. The instrument has demonstrated the capability to make rapid, highly sensitive measurements of water vapor and its major isotopomers: H2O, HDO, H218O, and H217O. Enhanced instrument sensitivity allows short integration times, as required for measurements in thin cirrus clouds and at sharp edges of convective features.

Project PI: James Anderson/Harvard University

Harvard University 12 Oxford Street, Link Bldg. Cambridge, MA 02138

Phone: (617) 495-5922

Fax: (617) 495-4902



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Started: Aug 09, 2010

Last Activity: Mar 16, 2011


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