Evaluation of dynamically downscaled ensemble climate simulations for Vietnam

Abstract

This article presents an assessment of the skill of regional climate model PRECIS in simulating seasonal climate over Vietnam. The simulations were conducted at a horizontal resolution of 25 km × 25 km. The model simulations were forced by the ERA-Interim reanalysis and five members of the Hadley Centre's perturbed physics ensemble (PPE). CRU, APHRODITE, ERA40 datasets and observations recorded at 61 meteorological stations over Vietnam were used to validate the model. The analysis compared seasonal averages of observed and simulated precipitation, temperature, 850 hPa wind speed and direction, as well as the 99th percentile of daily precipitation and the 95th and 5th percentile of daily minimum and maximum temperatures. Annual cycles of temperature and precipitation, and the interannual variability of precipitation were also assessed. The reanalysis-driven simulation accurately reproduced most of the important characteristics of the observed spatial patterns and annual cycles of circulation rainfall and temperature as well as capturing key characteristics of interannual variability in rainfall and of extremes in precipitation and temperature. Some apparent systematic cool biases were found most likely to be an artefact of inadequacies in the CRU-gridded temperature observations. The regional model was found to introduce some systematic wet-biases in rainfall. The five GCM driven simulations demonstrated errors with similar characteristics to the ERA-Interim-driven simulations, although with diversity in the magnitude of those errors resulting from the differences in the characteristics of the different members of the HadCM3-based PPE. By assessing the skill of these models at producing realistic baseline simulations, we gain valuable contextual information to guide the application and interpretation of the future projections over Vietnam generated using these models.

Projections of tropical cyclones affecting Vietnam under climate change: downscaled HadGEM2‐ES using PRECIS 2.1

“…It employs a rotated latitude/longitude horizontal grid with Arakawa B (Arakawa and Lamb, ) staggering and a terrain‐following hybrid‐pressure vertical coordinate described in Simmons and Burridge (). The model horizontal resolution is 25 km with 19 vertical levels (with the lowest level at ∼50 m and the highest at 0.5 hPa), which is the standard model configuration of PRECIS 2.1 as distributed to users (Rao et al ., ; Van Khiem et al ., ; Redmond et al ., ). The Lateral Boundary Conditions (LBC) scheme uses the relaxation method (Davies and Turner, ).…”

“…Previous studies have shown a good ability of RCMs to simulate the regional climate and extreme climate events in Vietnam (Van Khiem et al ., ; Raghavan et al ., ). RCMs have also been used for regional climate projections over Vietnam and found an increase in high‐temperature events and extreme rainfall over most of the country under climate change (Ho et al ., ; Ngo‐Duc et al ., ).…”

“…Therefore, this study analyses TCs in a historical simulation and explores possible future changes in TCs affecting Vietnam in different seasons up to the year 2100 using an RCM at a horizontal resolution of 25 km and explores the mechanisms involved. The RCM used in this study is Providing Regional Climates to Impact Studies (PRECIS), version 2.1, which is used widely for climate change impact studies in developing countries (Xu et al ., ; Rao et al ., 2014; Van Khiem et al ., ). Although this is a single‐model study, such studies (e.g.…”

Climate Analog Locations of Cities and Disappearing Climate in Viet Nam

“…In [7][8][9][10][11][12][13][14][15][16][17][18][19] [23][24][25]). Projected disappearing climate in the future in Viet Nam is also analyzed in the study.…”

Evaluation of tropical cyclones over the South China Sea simulated by the 12 km MetUM regional climate model

“…The RCM system known as 'PRECIS' (Providing Regional Climates to Impact Studies), developed from the Met Office Unified Model (MetUM version 4.7), has been widely used for climate change impact studies in developing countries (Xu et al, 2006;McSweeney et al, 2012;Rao et al, 2014;Van Khiem et al, 2014). A recent study by Redmond et al (2015) used this model, at 25 km resolution, to project the TC activity affecting the SCS and Vietnam under climate change.…”