Prepared by
David R. Maidment
Jerome Patoux
Christine Cotton
The quicktime movie shows the atmospheric moisture from June 1991 to July 1993. It is interesting to observe the motion of the circulating air above the ocean and the continent: the winds (Easterlies) take up water from the ocean (high humidity areas) at low latitudes. They blow toward the continent and penetrate above Central America and the central part of the United States.
DOS/Windows/Windows NT: Atmospheric Moisture Flow over North America (4.0M)
The data shown here were obtained from the US National Weather Service's National Meteorological Center (now called the Environmental Modeling Center of the National Centers for Environmental Prediction) which determines such values at regular intervals during each day as a part of its mission of numerical weather prediction to support weather forecasting. The data are determined by a General Circulation Model of the atmosphere whose equations are solved over the whole earth. Each 12 hours the condition of the atmosphere is sensed through radiosonde balloons released from weather stations, from satellite and from ground data sources, and the computed values in the GCM are adjusted to account for the measurements in a procedure called the Global Data Accumulation System. The computed values are archived at the National Center for Atmospheric Research in Boulder, Colorado, and the results shown here are time averages for monthly intervals of the archived data. A more refined mesoscale atmospheric model for North America, called the Eta model is presently under development at the Environmental Modeling Center's, Mesoscale Modeling Branch.
Because GCM's evolve over time in complexity and method, the computed values for comparable weather conditions in later years may not be quite the same as those in earlier years when the models were simpler than they are now. These differences have inspired reanalysis projects at the US Environmental Modeling Center in which the observed global weather data have been reassimilated for historical periods and the condition of the atmosphere recomputed with a consistent GCM. CD-ROMs of some data are available from NCAR. Comparable numerical weather prediction tasks and reanalysis projects have been carried out by the European Centre for Medium-Range Weather Forecasts located in Reading, England.
These materials may be used for study, research, and education, but please credit the authors and the Center for Research in Water Resources, The University of Texas at Austin. All commercial rights reserved. Copyright 1998 Center for Research in Water Resources.
