Can a Regional Climate Model Improve the Ability to Forecast the North American Monsoon?

Abstract

Global climate models are challenged to represent the North American monsoon, in terms of its climatology and interannual variability. To investigate whether a regional atmospheric model can improve warm season forecasts in North America, a retrospective Climate Forecast System (CFS) model reforecast (1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000) and the corresponding NCEP-NCAR reanalysis are dynamically downscaled with the Weather Research and Forecasting model (WRF), with similar parameterization options as used for highresolution numerical weather prediction and a new spectral nudging capability. The regional model improves the climatological representation of monsoon precipitation because of its more realistic representation of the diurnal cycle of convection. However, it is challenged to capture organized, propagating convection at a distance from terrain, regardless of the boundary forcing data used. Dynamical downscaling of CFS generally yields modest improvement in surface temperature and precipitation anomaly correlations in those regions where it is already positive in the global model. For the North American monsoon region, WRF adds value to the seasonally forecast temperature only in early summer and does not add value to the seasonally forecast precipitation. CFS has a greater ability to represent the large-scale atmospheric circulation in early summer because of the influence of Pacific SST forcing. The temperature and precipitation anomaly correlations in both the global and regional model are thus relatively higher in early summer than late summer. As the dominant modes of early warm season precipitation are better represented in the regional model, given reasonable large-scale atmospheric forcing, dynamical downscaling will add value to warm season seasonal forecasts. CFS performance appears to be inconsistent in this regard.

Influence of initial soil moisture and vegetation conditions on monsoon precipitation events in northwest México

“…3). For the storm periods, WRF-Hydro precipitation amounts are within the range of values reported in the reanalysis products (Table III) and consistent with prior studies reproducing organized convection in mountain areas of the NAM region (e.g., Carbone et al, 2002;Vivoni et al, 2009;Castro et al, 2012).…”

“…The Weather Research and Forecasting (WRF) modeling system (ARW version 3.8) is a nonhydrostatic, terrain-following, eta-coordinate mesoscale model used widely for operational weather and climate forecasting in the NAM region (e.g., Vivoni et al, 2009;Mearns et al, 2012;Sharma and Huang, 2012;Castro et al, 2012;Tripathi and Dominguez, 2013). Multiple modeling options exist in WRF for atmospheric physics and dynamics, including turbulence, radiation, planetary boundary layer, cumulus, and microphysics parameterizations, with Table I indicating the selected schemes in this study.…”

Sensitivity of a regional climate model to land surface parameterization schemes for East Asian summer monsoon simulation

“…RCMs have also been increasingly used to meet the demand of forecast (e.g. Castro et al 2012;Ratnam et al 2013;Shukla and Lettenmaier 2013), to conduct sensitivity experiments (e.g. Xue et al 2012;Barlage et al 2015;Oaida et al 2015), to project future climate change scenarios (e.g.…”

A climate change projection for summer hydrologic conditions in a semiarid watershed of central Arizona

“…Furthermore, the WRF downscaling of the HadCM3 model underestimated precipitation substantially during the historical period as compared to the NLDAS product, consistent with Castro et al (2012) and Robles-Morua et al (2015). Applying a bias correction derived in the historical period (i.e., based on comparisons to regional data)…”

“…3). This demonstrates the advantages of using a mesoscale model in that orographic effects on precipitation can be captured more realistically (e.g., Castro et al 2012;Tripathi and Dominguez 2013). Relative soil moisture differences exhibit a small increase in the future period (+0.001 to 0.03, Fig.…”