Credibility of convection-permitting modeling to improve seasonal precipitation forecasting in the southwestern United States

Sujan Pal, Hsin I. Chang, Christopher L. Castro, Francina Dominguez

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Sub-seasonal to seasonal (S2S) forecasts are critical for planning and management decisions in multiple sectors. This study shows results from dynamical downscaling using a regional climate model at a convection-permitting scale driven by boundary conditions from the global reanalysis of the Climate Forecast System Model (CFSR). Convection-permitting modeling (CPM) enhances the representation of regional climate by better resolving the regional forcings and processes, associated with topography and land cover, in response to variability in the large-scale atmospheric circulation. We performed dynamically downscaled simulations with the Weather Research and Forecasting (WRF) model over the Upper and Lower Colorado basin at 12 km and 3 km grid spacing from 2000 to 2010 to investigate the potential of dynamical downscaling to improved the modeled representation of precipitation the Southwestern United States. Employing a convection-permitting nested domain of 3 km resolution significantly reduces the bias in mean (∼2 mm/day) and extreme (∼4 mm/day) summer precipitation when compared to coarser domain of 12 km resolution and coarse resolution CFSR products. The convection-permitting modeling product also better represents eastward propagation of organized convection due to mesoscale convective systems at a sub-daily scale, which largely account for extreme summer rainfall during the North American monsoon. In the cool season both coarse and high-resolution simulations perform well with limited bias of ∼1 mm/day for the mean and ∼2 mm/day for the extreme precipitation. Significant correlation was found (∼0.85 for summer and ∼0.65 for winter) for both coarse and high-resolution model with observed regionally and seasonally averaged precipitation. Our findings suggest that the use of CPM is necessary in a dynamical modeling system for S2S prediction in this region, especially during the warm season when precipitation is mostly convectively driven.
Original languageEnglish (US)
JournalFrontiers in Earth Science
Volume7
DOIs
StatePublished - Mar 5 2019
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2022-06-10
Acknowledged KAUST grant number(s): OSR-2018-CRG7-3706.2
Acknowledgements: This study was funded by the University of Arizona Transboundary Aquifer Assessment Program (TAAP), authorized by Public Law 109–448, along with the University of Arizona Technology and Research Initiative Fund (TRIF). Additional support for SP was provided by the Department of Atmospheric Sciences, University of Illinois. Support for H-IC, CC, and publication of this manuscript was provided by the King Abdullah University of Science and Technology, sub-award agreement OSR-2018-CRG7-3706.2.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.

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