Comparison of AIRS version 5 and microwave radiometer total precipitable water

Integrated precipitable water (IPW) derived from the Atmospheric Infrared Sounder (AIRS) aboard NASA's Earth Observing System's Aqua satellite are compared to ground-based microwave radiometer line of site (MWR-LOS) IPW retrievals at Atmospheric Radiation Measurement (ARM) sites located in the tropical western Pacific, northern Alaska, and central Oklahoma. Comparisons reveal biases in the ratio of AIRS-to-MWR-LOS IPW that are site and seasonally dependent. The AIRS-to-MWR-LOS IPW ratio is analyzed for temporal changes throughout the life of AIRS, as well as ratio differences as a function of time of day of the retrieval (daytime vs. nighttime), AIRS surface type classification, and the distance of the AIRS retrieval from the MWR-LOS location.