The NASA NVAP-MEaSUREs project: a reanalyzed and extended record of global water vapor from 1987-2010

The NASA Water Vapor Project (NVAP) dataset is an existing earth system data record consisting of global blended total column and layered water vapor from a variety of sensors. The present dataset provides gridded daily water vapor fields from 1988-2001 over both ocean and land, and has been used in a diverse assortment of over 70 climate, modeling, and hydrometeorological studies. A current project under the NASA MEaSUREs program (NVAP-MEaSURES) aims to reanalyze this dataset and extend it through 2010.

The existing NVAP dataset contains several time-dependent biases due to changes in data processing and retrieval algorithms over time. To remediate these issues, NVAP-MEaSURES will emphasize a) consistent retrieval algorithms through time, b) intercalibrated satellite radiance inputs, and c) NASA AIRS water vapor retrievals beginning in 2002. The result will be a highly stable, 24-year water vapor record for use in studies of both weather and climate. The final dataset will be available to the community in 2012, with releases to science investigators before then.

Three approaches will be used in the creation of NVAP-MEaSURES to best serve the user community: 1) A data set which emphasizes stability and consistency through time for climate research (“NVAP-Climate”), 2) A data set which emphasizes spatial and temporal coverage for synoptic weather applications (“NVAP-Weather”), and 3) an ocean-only dataset for comparison to other ocean-oriented datasets (“NVAP-Ocean”). The algorithms and data sources in each component of NVAP-MEaSURES will be described.

Initial results from the 24 years of NVAP-MEaSURES are being compared to independent sources of water vapor for validation. These comparisons will be presented along with initial examples of the dataset.