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Type: Journal article
Title: Investigating the mechanisms of diurnal rainfall variability using a regional climate model
Author: Evans, J.
Westra, S.
Citation: Journal of Climate, 2012; 25(20):7232-7247
Publisher: Amer Meteorological Soc
Issue Date: 2012
ISSN: 0894-8755
Statement of
Jason P. Evans, Seth Westra
Abstract: This study investigates the ability of a regional climate model (RCM) to simulate the diurnal cycle of precipitation over southeast Australia, to provide a basis for understanding the mechanisms that drive diurnal variability. When compared with 195 observation gauges, the RCM tends to simulate too many occurrences and too little intensity for precipitation events at the 3-hourly time scale. However, the overall precipitation amounts are well simulated and the diurnal variability in occurrences and intensities are generally well reproduced, particularly in spring and summer. In terms of precipitation amounts, the RCM overestimated the diurnal cycle during the warmer months but was reasonably accurate during winter. The timing of the maxima and minima was found to match the observed timings well. The spatial pattern of diurnal variability in the Weather Research and Forecasting model outputs was remarkably similar to the observed record, capturing many features of regional variability. The RCM diurnal cycle was dominated by the convective (subgrid scale) precipitation. In the RCM the diurnal cycle of convective precipitation over land corresponds well to atmospheric instability and thermally triggered convection over large areas, and also to the large-scale moisture convergence at 700 hPa along the east coast, with the strongest diurnal cycles present where these three mechanisms are in phase.
Keywords: Australia; Diurnal effects; Climate models; Model evaluation/performance; Regional models; Diurnal effects
Rights: © 2012 American Meteorological Society
RMID: 0020122571
DOI: 10.1175/JCLI-D-11-00616.1
Grant ID:
Appears in Collections:Civil and Environmental Engineering publications
Environment Institute publications

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