A Marine Boundary Layer Water Vapor Climatology Derived from Microwave and Near-Infrared Imagery

The synergy of the collocated Advanced Microwave Scanning Radiometer (AMSR) and the Moderate Resolution Imaging Spectroradiometer (MODIS) provides daily global estimates of marine planetary boundary layer water vapor. AMSR microwave radiometry provides the total column water vapor, while MODIS near-infrared imagery provides the water vapor above the cloud layers. The difference between the two gives the vapor between the surface and the cloud top, which may be interpreted as the boundary layer water vapor. Comparisons against radiosondes, and GPS-Radio occultation data demonstrate the robustness of these boundary layer water vapor estimates. We exploit the ~16 years of AMSR-MODIS synergy to study for the first time the spatial and seasonal variations of the boundary layer water vapor globally, in contrast to the sea surface temperature and the boundary layer cloud top height (equivalent to the inversion height) climatologies. The multi-sensor nature of the analysis demonstrates that there exists more information on boundary layer water vapor structure in the satellite observing system than is commonly assumed when considering the capabilities of single instruments.

© California Institute of Technology. U.S. Government sponsorship acknowledged.