Effects of moist convection on mesoscale predictability

AMS Citation:
Zhang, F., C. Snyder, and R. Rotunno, 2003: Effects of moist convection on mesoscale predictability. Journal of the Atmospheric Sciences, 60, 1173-1185, doi:10.1175/1520-0469(2003)060<1173:EOMCOM>2.0.CO;2.
Date:2003-05-01
Resource Type:article
Title:Effects of moist convection on mesoscale predictability
Abstract: In a previous study by the authors, it was shown that the problematic numerical prediction of the 24-25 January 2000 snowstorm along the east coast of the United States was in some measure due to rapid error growth at scales below 500 km. In particular they found that moist processes were responsible for this strong initial-condition sensitivity of the 1 - 2-day prediction of mesoscale forecast aspects. In the present study they take a more systematic look at the processes by which small initial differences ("errors") grow in those numerical forecasts. For initial errors restricted to scales below 100 km, results show that errors first grow as small-scale differences associated with moist convection, then spread upscale as their growth begins to slow. In the context of mesoscale numerical predictions with 30-km resolution, the initial growth is associated with nonlinearities in the convective parameterization (or in the explicit microphysical parameterizations, if no convective parameterization is used) and proceeds at a rate that increases as the initial error amplitude decreases. In higher-resolution (3.3 km) simulations, errors first grow as differences in the timing and position of individual convective cells. Amplification at that stage occurs on a timescale on the order of 1 h, comparable to that of moist convection. The errors in the convective-scale motions subsequently influence the development of meso- and larger-scale forecast aspects such as the position of the surface low and the distribution of precipitation, thus providing evidence that growth of initial errors from convective scales places an intrinsic limit on the predictability of larger scales.
Peer Review:Refereed
Copyright Information:Copyright 2003 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 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statement, requires written permission or a license form the AMS. Additional details are provided in the AMS Copyright Policy, available on the AMS Web site located at (http://www.ametsoc.org/AMS) or from the AMS at 617-227-2425 or copyright@ametsoc.org.
OpenSky citable URL: ark:/85065/d7db82c3
Publisher's Version: 10.1175/1520-0469(2003)060<1173:EOMCOM>2.0.CO;2
Author(s):
  • Fuqing Zhang
  • Chris Snyder - NCAR/UCAR
  • Richard Rotunno - NCAR/UCAR
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