Intercomparison of CRA-Interim Precipitation Products with ERA5 and JRA-55     

叶梦姝  姚秀萍  张涛  许小峰  王式功 《热带气象学报(英文版)》2021,27(2):136-147

By using the hourly data from surface meteorological stations in China, the 3-hour precipitation data from CRA-Interim (Chinese Reanalysis-Interim), ERA5 (ECMWF Reanalysis 5) and JRA-55 (Japanese Reanalysis-55) are compared, both on the spatial-temporal distributions and on bias with observation precipitation in China. The results show that: (1) The three sets of reanalysis datasets can all reflect the basic spatial distribution characteristics of annual average precipitation in China. The simulation of topographic forced precipitation in complex terrain by CRA-interim is more detailed, while CRA-interim has larger negative bias in central and East China, and larger positive bias in southwest China. (2) In terms of seasonal precipitation, the three sets of reanalysis datasets overestimate the precipitation in the heavy rainfall zone of spring and summer, especially in southwest China. CRA interim’s location of the rain belt in the First Rainy Season in South China is west by south, the summer precipitation has positive bias in southwest and South China. (3) All of the reanalysis datasets can basically reflect the distribution difference of inter-annual variation of drought and flood, but the overall the CRA-Interim generally shows negative bias, while the ERA5 and JRA-55 exhibit positive bias. (4) For the diurnal variation of precipitation in summer, all the reanalysis datasets perform better in simulating the daytime precipitation than in the night, and bias of CRA-interim is less in southeast and northeast than elsewhere. (5) ERA5 generally performs the best on the evaluation of quantitative precipitation forecast, the JRA-55 is the next, followed by the CRA-Interim. CRA-Interim has higher missing rate and lower threat score for heavy rains; however, at the level of downpour, the CRA-Interim performs slightly better.  相似文献   

柱色谱分离-分子筛络合洗脱过程中正构烷烃单体碳同位素分馏研究     

董浩伟  赵佳玉  曾凡刚  谢曼曼  尚文郁  王淑贤  孙青 《岩矿测试》2021,(3):349-357

应用气相色谱-气体同位素质谱(GC-C-IRMS)分析正构烷烃单体碳同位素之前,需要对饱和烃样品中正构烷烃和异构烷烃进行预分离、富集,在预分离和富集过程中正构烷烃单体碳同位素是否发生分馏是高精度分析正构烷烃单体碳同位素比值(δ~(13)C)的关键。本文以正构烷烃混合溶液为对象,利用柱色谱、5■分子筛络合、环己烷-正戊烷混合溶剂两次洗脱,GC-C-IRMS分析正构烷烃单体碳同位素,研究前处理过程中正构烷烃单体碳同位素是否发生分馏。结果表明:使用柱色谱分离前后,多数正构烷烃单体碳同位素比值相差-0.2‰～0.2‰;当5■分子筛不完全络合时,未络合的正构烷烃单体碳同位素比值偏重约0.7‰,可能发生了微弱的碳同位素分馏,但并未影响洗脱后的正构烷烃单体碳同位素比值;使用环己烷-正戊烷混合溶剂洗脱前后,碳同位素比值相差-0.2‰～0.5‰,以同样方式洗脱第二次,获得的正构烷烃单体碳同位素比值与模拟样品相差-0.3‰～0.2‰。分析不同回收率(20%)正构烷烃的单体碳同位素比值,处理前后的差值基本在0.3‰以内,可见当正构烷烃回收率低至20%左右时,其单体碳同位素仍未发生明显分馏。柱色谱分离-5■分子筛络合-混合溶剂洗脱方法适用于回收率大于20%的正构烷烃单体碳同位素分析。  相似文献   

Effect of the Dry Ashing Method on Cadmium Isotope Measurements in Soil and Plant Samples     

Wei‐Xin Lv  Hao‐Ming Yin  Meng‐Shu Liu  Fang Huang  Hui‐Min Yu 《Geostandards and Geoanalytical Research》2021,45(1):245-256

A dry ashing method is commonly used to remove organic material from samples prior to geochemical analysis. In the course of this study, the Cd isotope ratios of a series of soil and plant reference materials and samples were studied to evaluate the effect of the dry ashing method on measurement results of Cd isotope ratios. The samples were pre‐treated using the dry ashing method and high‐pressure bomb for comparison. The results show that the digestion using high‐pressure bombs did not lead to Cd loss, but using the dry ashing method would cause different proportions of Cd loss. The whole range of Cd isotope difference between two methods was from ?0.07‰ to 3.01‰. There was also an obvious difference in measured Cd isotope ratios from the same leaf sample pre‐treated independently by the dry ashing method, indicating that the amount of Cd loss and the effect on Cd isotope measurement during dry ashing is related to the properties of the samples. Therefore, dry ashing may not be appropriate for the removal of organic material in Cd isotope ratio measurement, especially for samples with high organic contents. The δ^114/110Cd values of reference materials NIST SRM 1573a and GSD‐30 are reported for the first time in this study.  相似文献   

模式内部变率引起的1.5℃和2℃升温阈值出现时间模拟的不确定性研究     

季涤非  刘利  李立娟  孙超  于馨竹  李锐喆  张诚  王斌 《气候变化研究进展》2019,15(4):343-351

模式内部变率是模拟结果不确定性的重要来源,然而它对于1.5℃和2℃升温阈值出现时间不确定性的影响尚不清楚。因此,基于耦合模式比较计划第五阶段(CMIP5)的多模式数据研究了模式内部变率对1.5℃和2℃升温阈值出现时间不确定性的影响以及对未来排放情景的敏感性。结果表明,模式内部变率对升温阈值出现时间模拟的影响与外强迫的影响相当,单个模式内部不同成员达到全球平均1.5℃或2℃增温的年份相差2~12年;其影响具有明显的空间差异,影响极大值出现在欧亚大陆以北洋面、白令海峡周围区域、北美东北部及其与格陵兰岛之间的海域、南半球高纬地区等;低排放情景下模式内部变率的影响大于高排放情景。  相似文献   

Integrating downscaled CMIP5 data with a physically based hydrologic model to estimate potential climate change impacts on streamflow processes in a mixed‐use watershed          下载免费PDF全文

Michael G. Sunde  Hong S. He  Jason A. Hubbart  Michael A. Urban 《水文研究》2017,31(9):1790-1803

Climatic changes have altered surface water regimes worldwide, and climate projections suggest that such alterations will continue. To inform management decisions, climate projections must be paired with hydrologic models to develop quantitative estimates of watershed scale water regime changes. Such modeling approaches often involve downscaling climate model outputs, which are generally presented at coarse spatial scales. In this study, Coupled Model Intercomparison Project Phase 5 climate model projections were analyzed to determine models representing severe and conservative climate scenarios for the study watershed. Based on temperature and precipitation projections, output from GFDL‐ESM2G (representative concentration pathway 2.6) and MIROC‐ESM (representative concentration pathway 8.5) were selected to represent conservative (Δ_C) and severe (Δ_S) change scenarios, respectively. Climate data were used as forcing for the soil and water assessment tool to analyze the potential effects of climate change on hydrologic processes in a mixed‐use watershed in central Missouri, USA. Results showed annual streamflow decreases ranging from ?5.9% to ?26.8% and evapotranspiration (ET) increases ranging from +7.2% to +19.4%. During the mid‐21st century, sizeable decreases to summer streamflow were observed under both scenarios, along with large increases of fall, spring, and summer ET under Δ_S. During the late 21st century period, large decreases of summer streamflow under both scenarios, and large increases to spring (Δ_S), fall (Δ_S) and summer (Δ_C) ET were observed. This study demonstrated the sensitivity of a Midwestern watershed to future climatic changes utilizing projections from Coupled Model Intercomparison Project Phase 5 models and presented an approach that used multiple climate model outputs to characterize potential watershed scale climate impacts.  相似文献   

Seasonal evaluation of rainfall estimation by four cumulus parameterization schemes and their sensitivity analysis     

Asnor Muizan Ishak  Michaela Bray  Renji Remesan  Dawei Han 《水文研究》2012,26(7):1062-1078

Sustainable water resources management require scientifically sound information on precipitation, as it plays a key role in hydrological responses in a catchment. In recent years, mesoscale weather models in conjunction with hydrological models have gained great attention as they can provide high‐resolution downscaled weather variables. Many cumulus parameterization schemes (CPSs) have been developed and incorporated into three‐dimensional Pennsylvania State University/National Center for Atmospheric Research (PSU/NCAR) mesoscale model 5 (MM5). This study has performed a comprehensive evaluation of four CPSs (the Anthes–Kuo, Grell, Betts–Miller and Kain–Fritsch93 schemes) to identify how their inclusion influences the mesoscale model's precipitation estimation capabilities. The study has also compared these four CPSs in terms of variability in rainfall estimation at various horizontal and vertical levels. For this purpose, the MM5 was nested down to resolution of 81 km for Domain 1 (domain span 21 × 81 km) and 3 km for Domain 4 (domain span 16 × 3 km), respectively, with vertical resolutions at 23, 40 and 53 vertical levels. The study was carried out at the Brue catchment in Southwest England using both the ERA‐40 reanalysis data and the land‐based observation data. The performances of four CPs were evaluated in terms of their ability to simulate the amount of cumulative rainfall in 4 months in 1995 representing the four seasonal months, namely, January (winter), March (spring), July (summer) and October (autumn). It is observed that the Anthes–Kuo scheme has produced inferior precipitation values during spring and autumn seasons while simulations during winter and summer were consistently good. The Betts–Miller scheme has produced some reasonable results, particularly at the small‐scale domain (3 km grid size) during winter and summer. The KF2 scheme was the best scheme for the larger‐scale (81 km grid size) domain during winter season at both 23 and 53 vertical levels. This scheme tended to underestimate rainfall for other seasons including the small‐scale domain (3 km grid size) in the mesoscale. The Grell scheme was the best scheme in simulating rainfall rates, and was found to be superior to other three schemes with consistently better results in all four seasons and in different domain scales. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

钴—5—Br—PADNm络合物的光度性质研究及其应用     

张正奇  丁义平 《岩矿测试》1990,9(3):169-172

本文研究了钴(Ⅱ)-5-Br-PADNm络合物的光度性质。在pH5.0缓冲溶液中,有TritonX-100存在时,Co~(2 )与5-Br-PADNm形成1:2红色络合物,λ_(max)为547nm,ε为1.35×10~5l·mol~(-1)·cm~(-1)。所提出的方法用于矿石及茶叶中Co的测定,得到满意结果。  相似文献   

Primary cracking of kerogens. Experimenting and modelling C₁, C₂–C₅, C₆–C₁₅ and C₁₅₊ classes of hydrocarbons formed     

J. Espitali  P. Ungerer  I. Irwin  F. Marquis 《Organic Geochemistry》1988,13(4-6)

Mathematical models of hydrocarbon formation can be used to simulate the natural evolution of different types of organic matter and to make an overall calculation of the amounts of oil and/or gas produced during this evolution. However, such models do not provide any information on the composition of the hydrocarbons formed or on how they evolve during catagenesis.From the kinetic standpoint, the composition of the hydrocarbons formed can be considered to result from the effect of “primary cracking” reactions having a direct effect on kerogen during its evolution as well as from the effect of “secondary cracking” acting on the hydrocarbons formed.This report gives experimental results concerning the “primary cracking” of Types II and III kerogens and their modelling. For this, the hydrocarbons produced have been grouped into four classes (C₁, C₂–C₅, C₆–C₁₅ and C₁₅₊). Experimental data corresponding to these different classes were obtained by the pyrolysis of kerogens with temperature programming of 4°C/min with continuous analysis, during heating, of the amount of hydrocarbons corresponding to each of these classes.The kinetic parameters of the model were optimized on the basis of the results obtained. This model represents the first step in the creation of a more sophisticated mathematical model to be capable of simulating the formation of different hydrocarbon classes during the thermal history of sediments. The second step being the adjustment of the kinetic parameters of “secondary cracking”.  相似文献   

拟合法15°波动方程有限差分串联偏移     

陈静  赵振飞  张叔伦 《地球物理学报》1993,36(5):651-656

本文把最佳拟合算法（三点和五点差分格式）及串联偏移方法应用在15°波动方程偏移中。由于拟合法的差分因子随着采样间隔、步长、速度等参数的变化而变化,因此与原有的波动方程差分偏移法相比,串联偏移方法能有效的使大倾角归位,克服频散,速度及步长可以灵活变化,运算效率高等优点。  相似文献   

Fe（11）—5—Br—PADAP—Tritonx—100析相光度法测定痕量铁   总被引：1，自引：0，他引：1  

周发连  曾锋 《华东地质学院学报》1991,14(2):189-194

  相似文献