The impact of positive-definite moisture transport on NWP precipitation forecasts

A positive-definite transport scheme for moisture is tested in a nonhydrostatic forecast model using convection-permitting resolutions. Use of the positive-definite scheme is found to significantly reduce the large positive bias in surface precipitation forecasts found in the non-positive-definite model forecasts, in particular at high precipitation thresholds. The positive-definite scheme eliminates spurious sources of water arising from the clipping of negative moisture values in the non-positive-definite model formulation, leading to the bias reduction.

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Copyright 2009 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work.


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Author Skamarock, William
Weisman, Morris
Publisher UCAR/NCAR - Library
Publication Date 2009-01-01T00:00:00
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Topic Category geoscientificInformation
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Metadata Date 2023-08-18T18:56:31.045728
Metadata Record Identifier edu.ucar.opensky::articles:15423
Metadata Language eng; USA
Suggested Citation Skamarock, William, Weisman, Morris. (2009). The impact of positive-definite moisture transport on NWP precipitation forecasts. UCAR/NCAR - Library. http://n2t.net/ark:/85065/d7rf5w3f. Accessed 20 June 2025.

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