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The impact of vertical resolution on regional model simulation of the west African summer monsoon
Author(s) -
Druyan Leonard M.,
Fulakeza Matthew,
Lonergan Patrick
Publication year - 2008
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.1636
Subject(s) - climatology , monsoon , precipitation , horizontal resolution , environmental science , african easterly jet , forcing (mathematics) , wind shear , convection , tropical wave , geology , zonal and meridional , atmospheric sciences , meteorology , wind speed , geography , tropical cyclone
The RM3 regional climate model is used to simulate the west African summer monsoon for six June–September seasons using NCEP reanalysis data for lateral boundary forcing. The study compares the performance of the previously published 16‐level version with a newly tested 28‐level version, both running on a horizontal grid with 0.5° spacing, in order to determine what improvements in simulations are achieved by increased vertical resolution. Comparisons between the performances include diagnostics of seasonal mean precipitation rates and circulation, vertical profiles of cumulus heating rates, frequencies of shallow and deep convection and diagnostics related to transient African easterly waves (AEWs). The characteristics of a composite AEW simulated at both vertical resolutions are presented. Results show that the most significant impact of increasing the vertical resolution is stronger circulation, stronger vertical wind shear and higher amplitude AEWs. The simulations with higher vertical resolution also achieve higher peaks of cumulus latent heating rates. Spatial–temporal correlations between simulated daily 700 mb meridional winds versus corresponding NCEP reanalysis data and simulated daily precipitation versus estimates from the Tropical Rainfall Measurement Mission (TRMM) archive were equally high at both vertical resolutions. Copyright © 2007 Royal Meteorological Society