Relationship between precipitation rates at the ground and aloft-a modeling study

Two cloud-resolving mesoscale models, the Karlsruhe Atmospheric Mesoscale Model (KAMM) and the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model (MM5), were used to study reflectivity factor-rain-rate (Z-R) relationships and instantaneous and hor...

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Bibliographic Details
Published in:Journal of applied meteorology and climatology 2003-09, Vol.42 (9), p.1285
Main Authors: Dotzek, Nikolai, Fehr, Thorsten
Format: Article
Language:English
Subjects:
Algorithms
Atmosphere
Atmospheric research
Clouds
Precipitation rate
Rain
Online Access:Get full text
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Summary:Two cloud-resolving mesoscale models, the Karlsruhe Atmospheric Mesoscale Model (KAMM) and the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model (MM5), were used to study reflectivity factor-rain-rate (Z-R) relationships and instantaneous and horizontally averaged profiles of precipitation rate for convective storms of varying intensity. Simulations were conducted for idealized terrain. KAMM modeled a single shower cloud; MM5 was used to study split-storm supercell development. Both models consistently confirm analytical results from earlier studies: convective drafts and stratification of air density significantly alter the local rain rate and, therefore, also any Z-R relation relying on conditions of stagnant air and sea level air density. Air density effects can be almost completely corrected for by a recently proposed algorithm, but effects of convective drafts remain. They can lead to upward precipitation mass fluxes of significant magnitude and subsequent horizontal displacement of precipitation. Applicability of simple Z-R relations over complex terrain with distinct watershed boundaries will be strongly degraded by such convection effects on precipitation mass fluxes. [PUBLICATION ABSTRACT]
ISSN:1558-8424
1558-8432