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Regional climate simulations from the Southeast Asia Regional Climate Downscaling/Coordinated Regional Climate Downscaling Experiment – Southeast Asia (SEA) indicated model biases in temperature and rainfall over SEA. Given the influence of sea surface temperature (SST) variability on SEA climate, this study examines SST representation in climate models to investigate its potential contribution to the resulting model biases over the Philippines. Observed SST over SEA is first characterized by its spatial patterns and temporal variability. An analysis of the SST representation over SEA and its potential influence on modelled climate over the Philippines in Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models (GCMs) is then conducted, followed by an assessment of the potential influence of SST representation in CMIP5 GCMs on downscaled regional climate output. Our results show that GCMs with well represented SSTs (i.e., low bias, well captured variability, and pattern) can produce climate simulations well over the Philippines. Whether or not the GCMs with poor SST representation can perform well is inconclusive. During boreal winter (summer), climate variables with high (low) spatial correlation with model SST get poor (better) spatial correlation with observed climate. Over west of the Philippines, where model SST seasonal variability is captured well, models also adequately simulate climate variables. Results suggest that the negative temperature biases, and positive precipitation and wind speed biases, in both GCMs and downscaled simulations, are associated with negative model SST biases. These findings give a better understanding on how SST potentially influences modelled climatology over the Philippines. [ABSTRACT FROM AUTHOR]

In this study, the projected drought characteristics over Vietnam for the future periods of the middle (2046–2065) and end of the 21st century (2080–2099) were investigated under the Representative Concentration Pathway (RCP) scenarios RCP4.5 and RCP8.5. The drought characteristics (duration, severity, intensity, inter‐arrival time, and geographic extent) were estimated based on the Palmer Drought Severity Index (PDSI). The PDSI was calculated using temperature and precipitation data from six regional climate downscaling experiments and their ensemble conducted by the Coordinated Regional Climate Downscaling Experiment‐Southeast Asia (CORDEX‐SEA) project. Projected changes of drought characteristics in the future periods were determined with respect to those in the baseline period 1986–2005. Results show biases in the regional climate model (RCM) outputs, namely an underestimation of temperature and an overestimation of precipitation, which also affect the representation of drought characteristics by overestimating the PDSI. In terms of projections, substantial increases of drought duration, severity and intensity, and decreases in the inter‐arrival time are found over the Red River Delta, northern parts of the North Central sub‐region, parts of the Central Highlands and over southern Vietnam. The droughts are projected to be more widespread under scenario RCP8.5 than RCP4.5, especially in southern Vietnam. With the increasing likelihood of droughts in Vietnam as a result of climate change, sustainable water resources management should be taken into account for agriculture, natural ecosystems and social development. [ABSTRACT FROM AUTHOR]

This study uses six regional climate model (RCM) experiments from the Coordinated Regional Climate Downscaling Experiment—Southeast Asia (CORDEX‐SEA) and their driving global climate models (GCM) to investigate the model performance and the time of emergence (ToE) of temperature and precipitation over Vietnam and its seven sub‐climatic regions. A simple delta (multiplicative) bias correction (BC) method has been applied to the model temperature (precipitation). Results show clear added values of the BC downscaled products compared to their driving GCMs, particularly for temperature. The projected trends of RCM temperature during 2006–2100 under two representative concentration pathway (RCP) RCP4.5 and RCP8.5 scenarios are similar to those of their driving GCMs. Consequently, the RCM‐based ToE and GCM‐based ToE are generally consistent for temperature, occurring in the beginning of the 21st century. The earliest and latest ToE occur in summer and winter, respectively. The seasonal differentiation for temperature‐ToEs is stronger in the northern areas compared to the southern areas of Vietnam. The ToE difference between two RCPs increases from the south to the north. As for precipitation, ToE occurs quite late, in the latter half of the 21st century at the earliest. Results from ToE estimations also indicate an opposite precipitation trend between the GCMs and RCMs. The largest difference is in summer over the southern region of Vietnam. The opposite trend between the GCM and RCM precipitation under a similar increasing temperature implies the uncertainty in assessing the impact of warming on hydrological cycles in Vietnam. [ABSTRACT FROM AUTHOR]

This study identified the analogue locations of five big cities and the future appearance of novel climate in Southeast Asia (SEA) at the end of the 21st century under the Representative Concentration Pathways 8.5 (RCP8.5) and 4.5 (RCP4.5) scenarios. A modified version of an existing formulation to estimate climate distance is introduced, using the monthly means of temperature and precipitation from six regional climate experiments and from six global climate models (GCMs). Results showed that regional downscaling allowed a more accurate representation of temperature but displayed a higher variability in rainfall over SEA compared to the GCM performance. The ensemble mean (ENS) experiment had a relatively better performance compared to each individual experiment in representing the monthly time series of temperature and precipitation. The common tendency of climatic relocation towards warmer regions for the five big cities in SEA (Hanoi, Bangkok, Manila, Kuala Lumpur and Jakarta) was prominent with the regional ENS experiment. At the end of the 21st century, the ratio of novel climate areas over SEA, mainly located in low elevation, coastal, equatorial regions, and islands, was less than 2% under RCP4.5, but increased to 24 and 21% under RCP8.5 for the ensemble regional and global experiments, respectively. [ABSTRACT FROM AUTHOR]

This study examines the projected precipitation extremes for the end of 21st century (2081–2100) over Southeast Asia (SEA) using the output of the Southeast Asia Regional Climate Downscaling/Coordinated Regional Climate Downscaling Experiment – Southeast Asia (SEACLID/CORDEX-SEA). Eight ensemble members, representing a subset of archived CORDEX-SEA simulations at 25 km spatial resolution, were examined for emission scenarios of RCP4.5 and RCP8.5. The study utilised four different indicators of rainfall extreme, i.e. the annual/seasonal rainfall total (PRCPTOT), consecutive dry days (CDD), frequency of extremely heavy rainfall (R50mm) and annual/seasonal maximum of daily rainfall (RX1day). In general, changes in extreme indices are more pronounced and covering wider area under RCP8.5 than RCP4.5. The decrease in annual PRCPTOT is projected over most of SEA region, except for Myanmar and Northern Thailand, with magnitude as much as 20% (30%) under RCP4.5 (RCP8.5) scenario. The most significant and robust changes were noted in CDD, which is projected to increase by as much as 30% under RCP4.5 and 60% under RCP8.5, particularly over Maritime Continent (MC). The projected decrease in PRCPTOT over MC is significant and robust during June to August (JJA) and September to November (SON). During March to May (MAM) under RCP8.5, significant and robust PRCPTOT decreases are also projected over Indochina. The CDD changes during JJA and SON over MC are even higher, more robust and significant compared to the annual changes. At the same time, a wetting tendency is also projected over Indochina. The R50mm and RX1day are projected to increase, during all seasons with significant and robust signal of RX1day during JJA and SON. • Future changes of Southeast Asia precipitation extremes were examined. • The result was derived from the CORDEX-SEA simulations experiments. • The dry tendency is projected over the maritime continent. • Increasing extreme rainfall frequency and intensity over the mainland Indo-China. • Significant and robust change signals during JJA and SON. [ABSTRACT FROM AUTHOR]