RegCM4: Model description and preliminary tests over multiple CORDEX domains

Climate Research (Impact Factor: 2.5). 01/2011; 936:577X. DOI: 10.3354/cr01018


A new version of the RegCM regional climate modeling system, RegCM4, has been recently developed and made available for public use. Compared to previous versions, RegCM4 includes new land surface, planetary boundary layer, and air-sea flux schemes, a mixed convection and tropical band configuration, modifications to the pre-existing radiative transfer and boundary layer schemes, and a full upgrade of the model code towards improved flexibility, portability, and user friendliness. The model can be interactively coupled to a 1D lake model, a simplified aerosol scheme (including organic carbon, black carbon, SO4, dust, and sea spray), and a gas phase chemistry module (CBM-Z). After a general description of the model, a series of test experiments are presented over 4 domains prescribed under the CORDEX framework (Africa, South America, East Asia, and Europe) to provide illustrative examples of the model behavior and sensitivities under different climatic regimes. These experiments indicate that, overall, RegCM4 shows an improved performance in several respects compared to previous versions, although further testing by the user community is needed to fully explore its sensitivities and range of applications.

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    • "Nevertheless, after all such advancements the simulation models need a long way to go to simulate regional precipitation and cloud and aerosol interactions properly. As far as the involvement of these climate models to carry out the hydrological studies is related both the Regional Climate Models (RCMs) as was studied by Wang et al. (2004) and Block (2009), Haddeland et al. (2011), Ghosh and Katkar (2012), Giorgi and Coppola (2012)and Hagemann et al. (2013) reported that the GCMs are generally taken resort to. These climate models are coupled with the Hydrological Models and help simulating input of the regional weather parameters being translated into the changes in the hydrological processes. "
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    ABSTRACT: In the wake of changing climate the present water crisis seems to tighten its hold on the Mankind hence water resources estimation is integral part of planning, development and management of water resources of the country and the estimation of water resource is based on several hydrological and meteorological parameters. Rainfall is the main source of the ground and surface water resources. Recently due to anticipated climate change it is projected that spatial and temporal pattern of rainfall in different part of the country will be change and there will be increase in intensity of rainfall greater monsoon variability. This unprecedented change is expected to have severe impact on the on the water resource and finally on water resource estimation for future planning and management. Apart from climate change, both the ever increasing population and the rapidly changing land use patterns have left the major river basins of the India in a bleak uncertainty to keep up the required runoff. For planning and management, the climate and the hydrological modellers have begun working out runoff projections. During recent years, the Global Climate Models (GCMs) and Regional Climate Models (RCMs) driven hydrological models are in frequent use to draw such projections. But the projections have been often found to lack of reliability. Very recently, there is another emerging field of multi-model ensembles that has added feather to cap of the climate modeling community but this field is yet to be tried in many of the basin runoff-studies especially in the Indian perspective. There is a dire need for more research input assessing the future runoff as far as the Indian River basins are concerned. The climate models are being improved day by day so are the hydrological models. The multi-model ensembles are expected to bring out more reliability in the model outputs regarding the future runoff regimes of the basins than that could be brought about using individual models. The present study is a brief reviewof the model-based projections made for the some of the major river basins of the world. This attempt also seeks to bring forth the basin wise state-of-the-art research activities of such a kind so that the unexplored horizons of model based hydrological research could be taken up as newer research challenges like eg. in India there hasn’t yet been much basin scale studies conducted using multi-model ensembles. Therefore it is suggested that detailed studies to be taken up to assess the impact of climate change on the various parameters involved in estimation of water resources and asses water resource keeping in view the climate change for more realistic future planning and integrated water resource management.
    12/2015; 4:730-738. DOI:10.1016/j.aqpro.2015.02.094
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    • "Sản phẩm dự tính mưa từ mô hình khí hậu khu vực RegCM phiên bản 4 (RegCM4) [27] theo các kịch bản trung bình RCP4.5 và cao RCP4.8 cho các giai đoạn nền (1980-1999), giữa thế kỷ 21 (M21) và cuối thế kỷ 21 (E21) được sử dụng cho mô hình thủy văn. Mực NBD dự tính tương ứng với các kịch bản và giai đoạn theo báo cáo thứ 5 của IPCC [28] được sử dụng như biên mực nước tại cửa ra của lưu vực cho mô hình thủy lực. "
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    ABSTRACT: This study presents the climate change impact assessment on the flooding in the Nhatle river basin, in the North Central Vietnam. The regional climate model RegCM4 is used to downscale the global climate model CCAM outputs under the RCP4.5 and RCP8.5 of the Representative Concentration Pathway (RCP) scenarios. The maximum 3-day rainfall for the 10, 50 and, 100-year return periods based on the RegCM outputs was used as inputs for the hydrological model HEC-HMS to simulate the flood events for present (1980-1999) and future (2046-2065 and 2080-2099) climate conditions. The hydraulic model HEC-RAS combined with GIS analysis, the HEC-GeoRAS module, to simulate flood inundations and to generate the flood maps using flows from HEC-RAS and mean sea level rise scenarios (SLR) as boundary conditions. The comparison of the changes in the maximum 3-day rainfall, peak flows, depth and areas of flooding in the present and future climate conditions indicates that climate change has significantly impacted on the flood and might lead to increase its frequency and magnitude in the study area. Bài báo trình bày một số kết quả đánh giá tác động của biến đổi khí hậu (BĐKH) đến ngập lụt lưu vực sông Nhật Lệ. Mô hình khí hậu khu vực RegCM4 được sử dụng để hạ quy mô động lực từ sản phẩm của mô hình toàn cầu CCAM theo các kịch bản phát thải khí nhà kính (KNK) mới (đường nồng độ đại diện - RCP) của IPCC là RCP4.5 và RCP8.5. Lượng mưa 3 ngày cực đại (Rx3day) của RegCM4 theo các chu kỳ xuất hiện 10, 50 và 100 năm, sau đó được sử dụng như đầu vào cho mô hình thủy văn HEC-HMS để mô phỏng dòng chảy lũ cho điều kiện khí hậu hiện tại (1980-1999) và tương lai (giữa thế kỷ 21, 2046-2065 và cuối thế kỷ 21, 2080-2099). Mô hình thủy lực HEC-RAS kết hợp với modul HEC-GeoRAS được sử dụng để xây dựng bản đồ diện và độ sâu ngập lụt với biên là lưu lượng tính được từ HEC-HMS và mực nước biển dâng (NBD) theo các kịch bản tương ứng. So sánh giá trị của các đặc trưng ngập lụt gồm Rx3day, lưu lượng dòng chảy đỉnh lũ (Qp), diện và độ sâu ngập giữa điều kiện khí hậu tương lai và hiện tại (giai đoạn nền) cho thấy biến đổi khí hậu có tác động mạnh mẽ và là nguyên nhân dẫn đến sự gia tăng cả về tần suất và mức độ ngập lụt trên lưu vực sông này.
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    • "Previous studies also found that the Emanuel scheme tends to produce excessive rainfall over land while the Grell scheme cannot capture major events over ocean (Gianotti et al. 2012; Adeniyi 2014). Giorgi et al. (2012) suggests that Grell scheme can be used over land with Emanuel scheme over ocean to overcome these weaknesses. Here, it is further noticed from Table 2 that among the results of E-C-Z2, GAS-C-Z2 and GFC-C-Z2, GFC produces the smallest MAB and largest COR over land area, while the results from GAS have the largest MAB and smallest COR over land area. "
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    ABSTRACT: This study evaluates the sensitivity of summertime rainfall simulations over East-to-southeast Asia and the western north Pacific in the regional climate model version 4 (RegCM4) to cumulus (including Grell with Arakawa–Schubert type closure, Grell with Fritsch–Chappell type closure, and Emanuel), land surface (Biosphere–atmosphere transfer scheme or BATS, and the community land model or CLM) and ocean surface (referred to as Zeng1, Zeng2 and BATS1e in the model) schemes by running the model with different combinations of these parameterization packages. For each of these experiments, ensemble integration of the model was carried out in the extended boreal summer of May–October from 1998 to 2007. The simulated spatial distribution, intensity and inter-annual variation of the precipitation, latent heat flux, position of the subtropical high and tropical cyclone genesis patterns from these numerical experiments were analyzed. Examinations show that the combination of Emanuel, CLM and Zeng2 (E-C-Z2) yields the best overall results, consistent with the fact that physical mechanisms considered in E-C-Z2 tend to be more comprehensive in comparison with the others. Additionally, the rainfall quantity is found very sensitive to sea surface roughness length, and the reduction of the roughness length constant (from 2 × 10−4 to 5 × 10−5 m) in our modified BATS1e mitigates the drastic overestimation of latent heat flux and rainfall, and is therefore preferable to the default value for simulations in the western north Pacific region in RegCM4.
    Climate Dynamics 07/2015; DOI:10.1007/s00382-015-2714-y · 4.67 Impact Factor
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