Cooperative Institute for Research in the Atmosphere

Multisatellite Water Vapor Products at the Weather/Climate Interface

Water vapor is the fuel for much of what we perceive as weather, including the formation of clouds and precipitation.  Since the primary source of water vapor is evaporation over the oceans, global satellite observations provide the key measurement of this key variable.  Weather forecasters use two CIRA-developed products, Blended Total Precipitable Water (BTPW) and Advected Layer Precipitable Water (ALPW), to track pipelines of moisture which support heavy precipitation.  Each product is driven primarily by passive microwave data, but infrared GOES and surface GPS data are important for BTPW.  ALPW is being transitioned to NOAA operations this year, and science upgrades to BTPW are also currently being transitioned.

ALPW allows forecasters to see the origins and transport of upper-level moisture.  When converging and aligned with low-level moisture this can be the difference between an ordinary weather event and an extraordinary one. Recent case studies and applications of ALPW for several different hazardous weather events and floods will be presented.

As satellite records begin to cover more decades, products to place the water vapor amounts into historical context become possible.  This is especially important to identify extreme events.  Results from a new percentile ranking of ALPW values which is being evaluated by forecasters this summer will be presented.

Experiences on the path from research at a cooperative institute to a product widely used by forecasters will be described.