Sensitivity of temperature to physical parameterization schemes of RegCM4 over the CORDEX‐Southeast Asia region

Abstract

This study examines the simulated temperature over Southeast Asia (SEA) using the Regional Climate Model version 4.3 (RegCM4.3), and its sensitivity to selected cumulus and ocean surface flux schemes. Model simulations were conducted for the SEA domain at 36 km spatial resolution for the period of 1989-2008, as part of the Southeast Asia Regional Climate Downscaling/Coordinated Regional Climate Downscaling Experiment-Southeast Asia (SEACLID/CORDEX-Southeast Asia) project. A total of 18 sensitivity experiments were conducted with a combination of six cumulus parameterization schemes and three ocean surface flux schemes. The model's skill in representing mean, maximum and minimum temperatures is evaluated against observed gridded data sets. Results indicate a predominant cold bias in all simulations, particularly over mainland SEA (Indochina) during the season of December to February. Nevertheless, the seasonal correlation is highest over this region. The cold bias of the model is also evident in the temperature distributions, such that there are more cold months than observed, which may be associated with the underestimation of the daily maximum temperature. A few simulations also reveal a warm bias over some areas in the Maritime Continent. Further examination shows that both radiative and surface fluxes influence the simulated temperature, which may also have effects that partially offset each other in some areas. Comparison of the sensitivity experiments reveals differences in model performance, and underlines the importance in choosing the appropriate configuration for RegCM4.3 before it is used to downscale climate projections, particularly for the SEA region. This study also shows a strong influence of the choice of cumulus scheme on temperature. Based on performance metrics for temperature among the schemes tested, the Massachusetts Institute of Technology (MIT) Emanuel cumulus scheme and the Biosphere-Atmosphere Transfer Scheme version 1e (BATS1e) ocean surface flux scheme can be used in future simulations for the region.

Thirty Years of Regional Climate Modeling: Where Are We and Where Are We Going next?

“…An enlightening example is the community from South East Asia (SEA) which, despite relatively modest computing resources, has been able to design and complete locally most of the experiments for the CORDEX‐SEA phase I activities (Cruz et al, ; Juneng et al, ; Ngo‐Duc et al, ). Similarly, many simulations were completed locally by developing and emerging country scientists over other CORDEX domains (e.g., South Asia, East Asia, South America) or as part of regional intercomparison projects such as CLARIS (Boulanger et al, ) and RMIP (Fu et al, ).…”

Projected future changes in mean precipitation over Thailand based on multi‐model regional climate simulations of CORDEX Southeast Asia

“…The RegCM4.3 simulations used the MIT-Emanuel cumulus parameterization scheme (Emanuel and Živkovi c-Rothman, 1999), the BATS1e land scheme (Dickinson et al, 1993), the planetary boundary layer (PBL) scheme of Holtslag (Holtslag et al, 1990), the Subgrid Explicit Moisture scheme (SUBEX) (Sundqvist et al, 1989;Pal et al, 2007), and the Zeng ocean flux scheme (Zeng et al, 1998). The suitability of these optimal configurations was determined in an earlier sensitivity experiment involving countries in the Southeast Asia region (Juneng et al, 2016;Cruz et al, 2017;Ngo-Duc et al, 2017).…”

“…In order to overcome this challenge, especially for developing countries, collaboration among different institutions and countries is encouraged under the Coordinated Regional Climate Downscaling Experiment (CORDEX) (Giorgi et al, 2009), so that downscaling tasks can be shared. The Southeast Asia Regional Climate Downscaling (SEACLID)/CORDEX Southeast Asia (hereafter referred as CORDEX-SEA) was established involving collaborators from a number of institutions and countries within and outside the region to conduct multi-model regional climate downscaling experiments to a resolution of 25 km × 25 km (Juneng et al, 2016;Ngo-Duc et al, 2017;Cruz et al, 2017;Chung et al, 2018;Tangang et al, 2018;http://www.ukm.edu.my/seaclid-cordex).…”

Evaluation of regional climate model simulated rainfall over Indonesia and its application for downscaling future climate projections

“…Data are obtained from the European Center for Medium-Range Weather Forecast (ECMWF), with T255 (~0.8 × 0.8 or 80 km) horizontal resolution and 60 vertical levels. This product has been widely used by various analyses and as boundary condition for several RCM simulations (Giorgi et al, 2009;Kendon et al, 2012;Nikulin et al, 2012;Rauniyar and Walsh, 2013;Juneng et al, 2016;Cruz et al, 2017;Ngo-Duc et al, 2017).…”