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The uncertainties of two high-resolution satellite precipitation products (TRMM 3B42 v7.0 and GSMaP v5.222) were investigated by comparing them against rain gauge observations in Singapore on sub-daily scales. The satellite-borne precipitation products are assessed in terms of diurnal cycle and extreme precipitation for 10 years from Dec. 2000 to Nov. 2010. The satellite products agree well on the late afternoon maximum and heavier rainfall of gauge-based data in winter season when the ITCZ is located in Singapore. However, they fail in estimating diurnal cycle in summer. The disagreement in summer can be accounted for by the dominant satellite overpass time (about 14:00 SGT) later than the diurnal peak time (about 09:00 SGT) of gauge precipitation. According to analysis of extreme precipitation indices, both satellite datasets tend to overestimate the light rain and frequency but underestimate high intensity precipitation and the length of dry spell over all stations. In particular, the uncertainty of extreme precipitation is higher in GSMaP than in TRMM, possibly due to the several effects such as satellite merging algorithm, the finer spatio-temporal scale of high intensity precipitation, and swath time of satellite. Such discrepancies between satellite-born and gauge-based precipitations at sub-daily scale can possibly lead to distorting analysis of precipitation characteristics and/or application model results, this research on quantification of their uncertainty is useful in many respects, especially that the satellite products can stand scrutiny overplaces/stations where there are no good data to be compared against. [ABSTRACT FROM AUTHOR]

Climate change is one of the most serious challenges facing mankind in the 21st century. Extreme climatic events are expected to be more frequent and severe leading to various natural disasters. Vietnam, with more than 70% of the population working in agriculture and having a high density of inhabitants on the coastal plains, is one among those countries heavily impacted by climate change. The aim of this paper is to present a methodology to assess the impacts of climate change on a flood prone area of a coastal river basin in the central region of Vietnam. The hydrological simulations are based on a validated deterministic hydrological model MIKE SHE, which integrates geology, soil, topography, river systems and climate variables. The present-day climate, over the period of 1991–2010, was reasonably simulated by the hydrological model. Future climate (2091–2100) information was obtained from a dynamical downscaling of the global climate models, CCSM3.0, MIROC-medres and ECHAM5 under A2 scenario, using the Regional Climate Model: Weather Research and Forecasting Model. The result indicates that with this area, the ensemble future river flow under scenario A2 might increase up to 200% during rainy season and reduce to roughly 7–30% during dry season. The study also analyzed the changes in the flood dynamics of the study region, the hydrological shift and the uncertainties of climate change simulation. This paper showcases an operational approach to integrate the results from the impacts of climate change to flood protection measures that would help in devising resilience strategies. [ABSTRACT FROM AUTHOR]

An urban microclimate model integrated with the mesoscale, local scale, microscale and building scale models is presented for the urban thermal environment and urban heat island (UHI) mitigation study. This integrated multi-scale and multi-physics urban microclimate model takes the impacts on the urban microclimate of multiple physical processes of regional climate, urban climate, building and pavement material properties, and anthropogenic heat into account. This objective is achieved by coupling weather and energy models, the weather research forecasting (WRF), OpenFOAM and EnergyPlus. This study presents a method of distributing initial and boundary conditions from mesoscale into microscale through the integration of building thermal behaviour and microclimate. We further examine the integrated model by taking the Kent Ridge campus of National University of Singapore (NUS) as a test case. The preliminary application focuses on the assessment of weather conditions at the local scale and the feasibility of using mesoscale WRF outputs as inputs for the CFD model. • Integrations and interactions of multi-scale and multi-physics. • Coupling weather and energy models, the WRF and OpenFOAM and EnergyPlus. • Application with the 3D model of NUS campus. [ABSTRACT FROM AUTHOR]