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Vaughan Phillips

Universitetslektor

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The influence of time-dependent melting on the dynamics and precipitation production in maritime and continental storm clouds

Författare

  • Vaughan Phillips
  • Andrei Pokrovsky
  • Alexander Khain

Summary, in English

Simulations of one maritime and four continental observed cases of deep convection are performed with the Hebrew University Cloud Model that has spectral bin microphysics. The maritime case is from observations made on 18 September 1974 during the Global Atmospheric Research Program's Atlantic Tropical Experiment ( GATE). The continental storm cases are those of summertime Texas clouds observed on 13 August 1999, and green-ocean, smoky, and pyro-clouds observed during the Large-Scale Biosphere Atmosphere Experiment in Amazonia-Smoke, Aerosols, Clouds, Rainfall, and Climate ( LBA-SMOCC) campaign on 1-4 October 2002. Simulations have been performed for these cases with a detailed melting scheme. This scheme allows calculation of liquid water fraction within each mass bin for the melting of graupel, hail, snowflakes, and crystals, as well as alteration of the sedimentation velocity of ice particles in the course of their melting. The results obtained with the detailed melting scheme are compared with corresponding results from simulations involving instantaneous melting at the freezing ( 0 degrees C) level. The detailed melting scheme allows penetration of ice from the freezing level down into the boundary layer by distances ranging from a few hundred meters for the numerous, smaller particles to similar to 1.5 km for the largest particles, which are much scarcer. In these simulations, most of the mass of ice falling out melts over this short distance of a few hundred meters. The deepening and intensification of the layer of latent cooling enhances the convective destabilization of the troposphere. This effect is especially pronounced under continental conditions, causing significant changes in the accumulated rain amount.

Publiceringsår

2007

Språk

Engelska

Sidor

338-359

Publikation/Tidskrift/Serie

Journal of Atmospheric Sciences

Volym

64

Issue

2

Dokumenttyp

Artikel i tidskrift

Förlag

Amer Meteorological Soc

Ämne

  • Physical Geography

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 1520-0469