对基于RegCM4降尺度的中国区域性暴雨事件模拟评估     

蔡怡亨  韩振宇  周波涛 《气候变化研究进展》2021,17(4):420-429

基于区域气候模式RegCM4对4个全球气候模式动力降尺度模拟（分别记为CdR、EdR、HdR、MdR）以及高分辨率格点观测数据CN05.1的日降水数据,利用“追踪式”客观识别方法,对1981—2005年中国区域性暴雨事件进行了识别,并评估了模式对其气候特征的模拟性能。结果表明：4个动力降尺度模拟以及多模式集合能较好地模拟区域性暴雨事件发生频次、平均持续时间、平均降水量、平均影响范围和综合强度的年内分布特征以及气候平均值。观测的区域性暴雨事件持续时间、平均降水量、平均影响范围和综合强度在不同区间的频率分布特征以及区域性暴雨事件的累计频次、累计持续时间和累计降水量的空间分布特征也能得到很好地再现。模拟值与观测的空间相关系数都在0.9以上,且均方根误差不超过0.4。不过,相对而言,模式模拟的区域性暴雨事件频次略少,主要由对中度区域性暴雨事件低估所致;模拟的平均持续时间和平均降水量略偏高,而平均影响范围略偏小。综合强度方面,除HdR外,其余模拟均有所高估,尤其是MdR。在频率分布特征和空间分布方面,CdR的模拟性能低于其他模拟。多模式集合模拟的平均持续时间、平均降水量、平均影响范围和综合强度的相对误差分别为13%、2%、-11%和3%。  相似文献   

匹配域投影降尺度方法在黄河流域夏季降水预测中的应用     

史恒斌  常军  梁俊平 《气象》2016,42(11):1364-1371

文章采用黄河流域夏季降水数据和BCC-CGCM模式资料,利用匹配域投影降尺度方法对黄河流域夏季降水进行预测,得到以下结论:(1)交叉验证期,匹配域投影降尺度方法对黄河流域夏季降水的预测效果要好于原始模式预测,且较模式直接输出的要素预测稳定;分月预测比夏季整体预测效果要好。(2)匹配域投影降尺度方法对各个区域的预测能力不同,在夏季(6—8月)预测中,预测较好区域比较分散,而分月预测中,预测较好的区域比较集中。月份不同,降尺度方法对于不同地区的预测能力也不同。(3)2009—2013年的独立样本检验表明,匹配域投影降尺度方法对于黄河流域夏季降水的预测效果要明显好于模式直接输出的要素预测。尤其6和7月的降尺度预测较模式直接输出的要素预测有较大提高。  相似文献   

Blunt extension of discrete universal multifractal cascades: development and application to downscaling     

Auguste Gires  Ioulia Tchiguirinskaia  Daniel Schertzer 《水文科学杂志》2020,65(7):1204-1220

ABSTRACT

Scale issues are ubiquitous in geosciences. Because of their simplicity and intuitiveness, and despite strong limitations, notably its non-stationarity features, discrete random multiplicative cascade processes are very often used to address these scale issues. A novel approach based on the parsimonious framework of Universal Multifractals (UM) is introduced to tackle this issue while preserving the simple structure of discrete cascades. It basically consists in smoothing at each cascade step the random multiplicative increments with the help of a geometric interpolation over a moving window. The window size enables to introduce non-conservativeness in the simulated fields. It is established theoretically,] and numerically confirmed, that the simulated fields also exhibit a multifractal behaviour with expected features. It is shown that such an approach remains valid over a limited range of UM parameters. Finally, we test downscaling of rainfall fields with the help of this blunt discrete cascade process, and we discuss challenges for future developments.  相似文献   

复杂山区地形条件下ERA5再分析地表气温降尺度方法     

于法川  祝善友  张桂欣  朱佳恒  张南  徐永明 《地球信息科学学报》2022,24(4):750-765

高时空分辨率的气温栅格数据是多种地学模型和气候模型的重要输入。山区地形复杂,气温空间异质性强,如何获取高时空分辨率的山区地表气温数据一直是研究热点与难点。本文选择地形复杂的河北省张家口市作为试验区,基于局部薄盘样条函数对ERA5再分析日均近地表气温（2 m高度）进行空间插值,并利用随机森林算法,结合少量气象站观测气温数据、地形地表参数数据构建日均气温订正模型和气温逐时化模型,实现空间分辨率由0.1 °（约11 km）到30 m的逐时气温降尺度,最后将该模型拓展应用于其他时间与区域,检验本文发展的降尺度方法在没有站点观测数据条件下的时空移植性。结果显示,本文降尺度方法得到的高时空分辨率山区气温数据精度较高,1月均方根误差（RMSE）平均值为2.4 ℃,明显优于气象站点插值结果,且气温相对高低的空间分布更为合理、纹理更加丰富;将该方法应用到其他时间与区域的RMSE平均值分别为2.9 ℃与2.5 ℃,均小于再分析资料直接插值所产生的误差。研究结果总体表明,在气象站点较少甚至没有时,可利用本文方法通过ERA5再分析气温准确获取复杂地形条件下的山区高时空分辨率气温数据。  相似文献   

基于BCC_CSM模式的山西省盛夏降水降尺度预测     

张冬峰  王永光  张国宏 《气象科技》2019,47(4):622-630

降尺度方法是目前弥补气候系统模式预测结果不足的重要手段,为获得具有较高预测技巧的山西盛夏降水客观化预测产品,本文选取1990—2017年6月起报的BCC_CSM气候系统模式输出盛夏结果和同期NCEP/NCAR再分析资料同时与山西盛夏降水异常典型模态具有统计显著的因子,利用逐步回归方法建立了山西盛夏降水降尺度模型。进一步研究发现,降尺度模型的预测能力与BCC_CSM对影响山西盛夏降水关键区海温的预测技巧密切相关。检验回报与观测的时间和空间距平相关系数(TCC和ACC)、回报与观测的距平符号一致率(PC)以及趋势异常综合评分(PS),表明降尺度模型对山西盛夏降水的预测技巧较BCC_CSM输出有明显改进,BCC_CSM模拟降水TCC在山西全区没有通过95%信度检验,降尺度模型回报TCC在山西大部分地区通过95%信度检验,中南部通过99%信度检验;相应的ACC由-0.02提高到0.35,PC由53.3%提高到66.8%,PS由65.6%提高到78.9%。2018年盛夏业务试运行,ACC为0.42,PS为70.8%。  相似文献   

2018年夏季我国极端降水及滑坡泥石流灾害预测   总被引：1，自引：0，他引：1       下载免费PDF全文

马洁华  孙建奇  汪君  于恩涛  何爽爽 《大气科学学报》2019,42(1):93-99

基于动力降尺度预测系统,中国科学院大气物理研究所竺可桢-南森国际研究中心对2018年夏季我国极端降水日数及滑坡泥石流灾害的发生风险进行了超前4个月的实时预测试验。与实测结果相比,该系统对2018年夏季我国极端降水日数空间分布的预测与实况基本相符,但大部分地区存在明显低估;滑坡泥石流的预测结果与目前统计的由于降水引发的滑坡泥石流灾害事件的分布基本吻合。此次预测试验表明,中国科学院大气物理研究所竺可桢-南森国际研究中心发展的动力降尺度预测系统对我国夏季极端降水和滑坡泥石流灾害具有一定的预测能力,具有实时预测价值。  相似文献   

Assessment of Temperature Extremes in China Using RegCM4 and WRF     

Xianghui KONG  Aihui WANG  Xunqiang BI  Dan WANG 《大气科学进展》2019,36(4):363-377

This study assesses the performance of temperature extremes over China in two regional climate models(RCMs),RegCM4 and WRF, driven by the ECMWF's 20 th century reanalysis. Based on the advice of the Expert Team on Climate Change Detection and Indices(ETCCDI), 12 extreme temperature indices(i.e., TXx, TXn, TNx, TNn, TX90 p, TN90 p,TX10 p, TN10 p WSDI, ID, FD, and CSDI) are derived from the simulations of two RCMs and compared with those from the daily station-based observational data for the period 1981–2010. Overall, the two RCMs demonstrate satisfactory capability in representing the spatiotemporal distribution of the extreme indices over most regions. RegCM performs better than WRF in reproducing the mean temperature extremes, especially over the Tibetan Plateau(TP). Moreover, both models capture well the decreasing trends in ID, FD, CSDI, TX10 p, and TN10 p, and the increasing trends in TXx, TXn, TNx, TNn, WSDI, TX90 p,and TN90 p, over China. Compared with observation, RegCM tends to underestimate the trends of temperature extremes,while WRF tends to overestimate them over the TP. For instance, the linear trends of TXx over the TP from observation,RegCM, and WRF are 0.53?C(10 yr)^-1, 0.44?C(10 yr)^-1, and 0.75?C(10 yr)^-1, respectively. However, WRF performs better than RegCM in reproducing the interannual variability of the extreme-temperature indices. Our findings are helpful towards improving our understanding of the physical realism of RCMs in terms of different time scales, thus enabling us in future work to address the sources of model biases.  相似文献   

Dynamical Downscaling of the Arctic Climate with a Focus on Polar Cyclone Climatology     

Minghong Zhang  Zhenxia Long 《大气与海洋》2019,57(1):41-60

We present a dynamical downscaling of the Arctic climatology using a high-resolution implementation of the Polar Weather Research and Forecasting, version 3.6 (WRF3.6) model, with a focus on Arctic cyclone activity. The study period is 1979–2004 and the driving fields are data from the Hadley Centre Global Environmental Model, version 2, with an Earth System component (HadGEM2-ES) simulations. We show that the results from the Polar WRF model provide significantly improved simulations of the frequency, intensity, and size of cyclones compared with the HadGEM2-ES simulations. Polar WRF reproduces the intensity of winter cyclones found in ERA-Interim, the global atmospheric reanalysis produced by the European Centre for Medium-range Weather Forecasts (ECMWF), and suggests that the average minimum central pressure of the cyclones is about 10?hPa lower than that derived from HadGEM2-ES simulations. Although both models underestimate the frequency of summer Arctic cyclones, Polar WRF simulations suggest there are 10.5% more cyclones per month than do HadGEM2-ES results. Overall, the Polar WRF model captures more intense and smaller cyclones than are obtained in HadGEM2-ES results, in better agreement with the ERA-Interim reanalysis data. Our results also show that the improved simulations of Arctic synoptic weather systems contribute to better simulations of atmospheric surface fields. The Polar WRF model is better able to simulate both the spatial patterns and magnitudes of the ERA-Interim reanalysis data than HadGEM2-ES is; in particular, the latter overestimates the absorbed solar radiation in the Arctic basin by as much as 30?W?m^?2 and underestimates longwave radiation by about 10?W?m^?2 in summer. Our results suggest that the improved simulations of longwave and solar radiation are partly associated with a better simulation of cloud liquid water content in the Polar WRF model, which is linked to improvements in the simulation of cyclone frequency and intensity and the resulting transient eddy transports of heat and water vapour.  相似文献   

Hydrological impacts of climate change on streamflow of Dongliao River watershed in Jilin Province, China     

Lei Zhang  Wenxi Lu  Qingchun Yang  Yongkai An  Di Li  Lei Gong 《中国地理科学(英文版)》2012,22(5):522-530

The impacts of future climate change on streamflow of the Dongliao River Watershed located in Jilin Province,China have been evaluated quantitatively by using a general circulation model(HadCM3)coupled with the Soil and Water Assessment Tool(SWAT)hydrological model.The model was calibrated and validated against the historical monitored data from 2005 to 2009.The streamflow was estimated by downscaling HadCM3 outputs to the daily mean temperature and precipitation series,derived for three 30-year time slices,2020s,2050s and 2080s.Results suggest that daily mean temperature increases with a changing rate of 0.435℃per decade,and precipitation decreases with a changing rate of 0.761 mm per decade.Compared with other seasons,the precipitation in summer shows significant downward trend,while a significant upward trend in autumn.The annual streamflow demonstrates a general downward trend with a decreasing rate of 0.405 m3/s per decade.The streamflow shows significant downward and upward trends in summer and in autumn,respectively.The decreasing rate of streamflow in summer reaches 1.97 m 3 /s per decade,which contributes primarily to the decrease of streamflow.The results of this work would be of great benifit to the design of economic and social development planning in the study area.  相似文献   

Statistical downscaling of extreme daily precipitation,evaporation, and temperature and construction of future scenarios   总被引：4，自引：0，他引：4  

Tao Yang  Huihui Li  Weiguang Wang  Chong‐Yu Xu  Zhongbo Yu 《水文研究》2012,26(23):3510-3523

Generally, the statistical downscaling approaches work less perfectly in reproducing precipitation than temperatures, particularly for the extreme precipitation. This article aimed to testify the capability in downscaling the extreme temperature, evaporation, and precipitation in South China using the statistical downscaling method. Meanwhile, the linkages between the underlying driving forces and the incompetent skills in downscaling precipitation extremes over South China need to be extensively addressed. Toward this end, a statistical downscaling model (SDSM) was built up to construct future scenarios of extreme daily temperature, pan evaporation, and precipitation. The model was thereafter applied to project climate extremes in the Dongjiang River basin in the 21st century from the HadCM3 (Hadley Centre Coupled Model version 3) model under A2 and B2 emission scenarios. The results showed that: (1) The SDSM generally performed fairly well in reproducing the extreme temperature. For the extreme precipitation, the performance of the model was less satisfactory than temperature and evaporation. (2) Both A2 and B2 scenarios projected increases in temperature extremes in all seasons; however, the projections of change in precipitation and evaporation extremes were not consistent with temperature extremes. (3) Skills of SDSM to reproduce the extreme precipitation were very limited. This was partly due to the high randomicity and nonlinearity dominated in extreme precipitation process over the Dongjiang River basin. In pre‐flood seasons (April to June), the mixing of the dry and cold air originated from northern China and the moist warm air releases excessive rainstorms to this basin, while in post‐flood seasons (July to October), the intensive rainstorms are triggered by the tropical system dominated in South China. These unique characteristics collectively account for the incompetent skills of SDSM in reproducing precipitation extremes in South China. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献