Stratospheric Water Vapor Processes and Trends from In Situ Observations
In-situ observations of water vapor in the stratosphere and in the tropopause region are an important tool to study trends and processes of stratospheric water vapor.
Balloon-borne in-situ observations of stratospheric and tropospheric water vapor, ozone, and temperature are currently launched at a number of operational and campaign-based sites. At Lindenberg, Germany, these soundings are launched twice per month, with one sounding during daytime and one during nighttime. The nighttime soundings carry an additional backscatter instrument to provide cloud and aerosol information at two wavelengths. These observations allow studies of cloud microphysics and provide an in-situ consistency check of the water vapor observations.
At Boulder, CO (which has by far the longest record of stratospheric water vapor), at Hilo, HI, and at Costa Rica, water vapor soundings are launched at a roughly monthly schedule. The data set at Costa Rica is currently the most extensive data set of in-situ water vapor in the tropical upper troposphere and lower stratosphere. These soundings provide relative humidity over ice at the cold point tropopause and constitute the only long term data set for water vapor entering the stratosphere. Costa Rica has a pronounced rainy season with widespread deep convection, as well as a distinct dry season with nearly complete absence of deep convection. On average, high relative-humidity values, which are observed at the tropopause, are a strong indication that dehydration may occur throughout the year.
Studying data from different sites provides indications about the consistency of the observations and emphasizes that routine in-situ observations are needed at multiple locations to understand the details of water vapor processes and trends in the stratosphere.
Thursday, 6 November 2014, 10:30AM
3450 Mitchell Lane
Bldg. 2 Large Auditorium (Rm 1022)