Validation of Satellite-Based Measurements of Precipitable Water Vapor at Various Arctic Stations

Melting of Earth’s major ice sheets contributes significantly to global sea level rise. The observation of atmospheric and cloud properties are crucial to understanding the melting conditions of the Greenland Ice Sheet and Arctic sea ice, as well as other impacts of changing climate. Because of the difficulty in establishing observing stations in the Arctic, satellites are a particularly valuable source of observations. Polar atmospheric data are available from the AIRS (Atmospheric Infrared Sounder) and MODIS (Moderate Resolution Imaging Spectroradiometer) instruments onboard NASA’s Aqua and Terra polar-orbiting satellites. Satellite measurements have previously been used to examine trends in Arctic atmospheric water vapor content, but these instruments lack thorough validation in the polar regions. To further verify AIRS and MODIS in the Arctic, precipitable water vapor (PWV) measurements are compared with those derived from radiosoundings and microwave radiometer data from various Arctic observatories, including Barrow, Eureka, Summit and field campaigns over sea ice. Preliminary results from Summit Station show a higher correlation with AIRS measurements than with MODIS. AIRS reports low PWV values when PWV is greater than about 0.1 cm and over reports when the values are less than 0.1 cm. The biases in PWV are examined using data from the other Arctic observatories.