One of the primary goals of the Aqua satellite within the National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) program is improved understanding of the global water cycle, including the distribution and variation of atmospheric water vapor over a wide range of space and time scales.

Both the Atmospheric Infrared Sounder (AIRS) and the Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua make measurements of atmospheric water vapor. Here we use coincident observations of total column atmospheric water vapor to explore its variation at small spatial and temporal scales, as well as regional and seasonal variations. By making use of the full-resolution data products from both instruments (45 km for AIRS and 5 km for MODIS), it is possible to resolve extremely small-scale water vapor features. In additional, differences in the retrievals from the two instruments reveal characteristics about the different algorithmic approaches taken as well as fundamental differences about the assumed state of the atmosphere. Interseasonal comparisons show changes in water vapor distributions over the globe. Additional comparisons between retrievals from the two instruments reveal how well the individual algorithms perform on intermediate temporal and spatial scales. We also investigate how changes in the small-scale water vapor distribution manifest themselves on larger scales.