Variability of Water Vapor in the Middle and Upper Troposphere

Water vapor in the middle and upper troposphere has a significant impact on clouds and climate. Satellite footprints average over kilometers of air both horizontally and vertically, yet in situ data indicate that water vapor is highly variable on finer scales. Extensive in situ measurements of atmospheric water have been made by the Jet Propulsion Laboratory (JPL) Laser Hygrometer (JLH) on the NASA WB-57 high-altitude research aircraft. JLH is a precise, near-infrared diode laser spectrometer with a 1.3-s integration time, yielding data with high spatial resolution along the aircraft flight path. Water vapor measurements from a number of different WB-57 aircraft missions will be examined, including the Aura Validation Experiment (AVE), the Middle Latitude Cirrus Experiment (MidCiX), Pre-AVE, and the CRYSTAL-FACE mission. From these data sources, the mean and statistical distribution of water vapor will be characterized as functions of pressure, latitude, and season in the middle and upper troposphere. To place these in situ data in a larger context, and to evaluate their utility for satellite validation, water vapor retrievals from the Tropospheric Emission Spectrometer (TES) on EOS Aura will also be shown.