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evaluation of Global Gridded Precipitation and Temperature Datasets against Gauged Observations over the Upper Tekeze River Basin,Ethiopia

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Journal of Meteorological Research 2021年第4期35卷 673-689页

作者： Kidane Welde REDA Xingcai LIU Qiuhong TANG Tesfay Gebretsadkan GEBREMICAEL Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Tigray Agricultural Research Institute Mekelle 492Ethiopia

The availability of satellite and reanalysis climate datasets and their applicability have been greatly promoted in hydro-climatic studies.However,such climatic products are still subject to considerable uncertainties and an evaluation of the products is necessary for applications in specific regions.This study aims to evaluate the reliability of nine gridded precipitation and temperature datasets against ground-based observations in the upper Tekeze River basin(UTB)of Ethiopia from 1982 to 2016.Precipitation,maximum temperature(Tmax),minimum temperature(Tmin),and mean temperature(Tmean)were evaluated at daily and monthly timescales.The results show that the best estimates of precipitation are from the Eart H2 Observe,WFDEI,and ERA-Interim reanalysis data Merged and Bias-corrected for the Inter-Sectoral Impact Model Intercomparison Project(EWEMBI),and the Climate Hazards Group Infra Red Precipitation with Station data(CHIRPS)datasets.The percentage biases and correlation coefficients(CCs)are within±15%and>0.5,respectively,for both EWEMBI and CHIRPS at the two timescales.All products underestimate the drought conditions indicated by the standardized precipitation index(SPI),while the EWEMBI and CHIRPS datasets show higher agreement with the observations than other datasets.The Tmean estimates produced by the ECMWF ReAnalysis version 5(ERA5)and the Climate Hazards Group Infra Red Temperature with Station data(CHIRTS)are the closest to the observations,with CCs of 0.65 and 0.55,respectively,at the daily timescale.The CHIRTS and EWEMBI datasets show better representations of Tmax(T_(min)),with CCs of 0.69(0.72)and 0.62(0.68),respectively,at the monthly timescale.The temperature extremes are better captured by the ERA5(T_(mean)),CHIRTS(T_(max)),and EWEMBI(T_(min))datasets.The findings of this study provide useful information to select the most appropriate dataset for hydrometeorological studies in the UTB and could help to improve the regional representation of global datasets.

关键词： climatic datasets evaluation rainfall temperature Tekeze River basin

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evaluation model for service life of dam based on time-varying risk probability

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Science China(Technological Sciences) 2009年第7期52卷 1966-1973页

作者： SU HuaiZhi WEN ZhiPing HU Jiang WU ZhongRu College of Water Conservancy and Hydropower Engineering of Hohai University Nanjing 210098China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Nanjing 210098China College of Computer Engineering Nanjing Institute of TechnologyNanjing 211167China

For many dam projects in China, the 50-year designed life time is coming to an end. It is urgent to study the theory and method to evaluate the dam service life. In this paper, firstly, the probability theory of fuzzy event and time-varying effect theory are used to analyze the time-variety of various risk factors in the process of dam operations. A method is proposed to quantify the above time-variety and a model to describe the fuzzy time-varying risk probability for the dam structure is also built. Secondly, the information entropy theory is used to analyze the uncertain degree relationship between the characteristic value of membership function and fuzzy risk probability, and a mathematical method is presented to calculate the time-varying risk probability accordingly. Thirdly, the relation mode between time-varying risk probability and service life is discussed. Based on this relation mode and the acceptable risk probability of dams in China, a method is put forward to evaluate and forecast the dam service life. Finally, the proposed theory and method are used to analyze one concrete dam. The dynamic variability and mutation feature of the dam risk probability are analyzed. The remaining service life of this dam is forecasted. The obtained results can provide technology support for the project management department to make treatment measures of engineering and reasonably arrange reinforce cost. The principles in this paper have wide applicability and can be used in risk analysis for slope instability and other fields.

关键词： dam service life evaluation time-varying risk probability fuzzy probability theory information entropy theory

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evaluation of monthly turbulent heat fluxes from WHOI analysis and NCEP reanalysis in the tropical Atlantic

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Acta Oceanologica Sinica 2005年第5期24卷 14-26页

作者： JIANG Hua WANG Hui WU Dexing Institute of Climate System Chinese Academy of Meteorological Sciences Beijing 100081 China Chinese Academy of Meteorological Sciences Beijing 100081 China Institute of Physical Oceanography Ocean University of China Qingdao 266003 China

The biases and their sources in monthly turbulent heat fluxes from the Woods Hole Oceanographic Institution （WHOI） analysis, and the National Centers for Environmental Prediction-National Center for Atmospheric Research reanalyses 1 and 2 （NCEPI and NCEP2） are checked in the climatically representative regions in the tropical Atlantic using the fluxes from the Southampton Oceanographic Centre （SOC） and the pilot research moored array in the tropical Atlantic （PIRATA） as references. For the WHOI analysis, the biases in turbulent heat fluxes mainly exist in equatorial regions which are due to the overestimated sea surface temperature and the underestimated 2 m air humidity. For the NCEP2 reanalysis, the maximum biases, about （40±5） W/m^2, exist in southeast and northeast trade wind regions, which are mainly caused by the flux algorithm used because the biases in wind speed and air-sea humidity difference are relatively small. In the equatorial regions, the flux biases in the NCEP2 derived from both flux-related basic variables and algorithm are equally large. Although the estimations of time series trends and air-sea humidity difference of the NCEPI are improved greatly in the NCEP2, the biases of latent heat flux in the NCEP2 are about 20 W/m^2 greater than those from the NCEP1 in the trade wind regions. The result shows that the climatologies and monthly variabilities of the turbulent heat fluxes from the WHOI are more accurate than those from the NCEP1 and NCEP2 in the tropical Atlantic, especially on outside of the equatorial regions.

关键词： turbulent heat fluxes evaluation the tropical Atlantic

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evaluation of social network conservation in historical areas of mountainous towns in Chongqing, China

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Journal of Mountain Science 2020年第7期17卷 1763-1775页

作者： SHI Ya-ling HUANG Yong HU Dong-yang WAN Dan Faculty of Architecture and Urban Planning Chongqing UniversityChongqing400030China The Bartlett School of Construction and Project Management University College London1-19 Torrington PlaceLondonWC1E 7HBUK Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityChongqing400030China Chongqing University Planning&Design Institute Co. LtdChongqing400044China

Over recent decades,historical areas conservation has become an important strategy to improve urban competitiveness in the global economy.As shown in existing studies that the conservation of historical areas mainly focused on the physical environment,there is still room for the non-physical study,and researches on the social network conservation in mountainous historical areas are particularly insufficient.Therefore,this paper aims to establish an evaluation system which is helpful for the social network conservation of historical areas.The evaluation system is based on social network analysis and the information of social relationships gathered in field surveys using a specifically designed questionnaire method in four mountainous towns in Chongqing,China.And it was analyzed from three perspectives,i.e.,by the basic statistical properties,condensate subgroup,and centrality.Then five analysis indicators were conceived,including density,lambda set,k-core,degree centrality,and betweenness centrality.The analysis results demonstrate that the social networks of the four towns show different indicators,which are respectively relevant to completeness degree,edgerelatedness level,local stability,structural balance,and concentrated trend of social relationships.Results from SNA modeling indicate that neighborhood residents of historical areas who have more stable and healthier social relationships are relatively not easily be destroyed.The results also illustrate that the social networks structure is influenced by the terrain,form,and function of historical areas,and the change of historical areas is caused by"individual-family-society".Finally,the strategies guiding the social network conservation are put forward from two aspects.These findings suggest that the conservation and management of social network and aborigines in historical areas should be emphasized to increase the collective benefits and vitality.

关键词： Historical areas Social network analysis Physical environment evaluation Conservation Mountainous towns

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evaluation Methods of Profitable Tight Oil Reservoir of Lacustrine Coquina: A Case Study of Da'anzhai Member of Jurassic in the Sichuan Basin

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Acta Geologica Sinica(English Edition) 2020年第2期94卷 418-429页

作者： PANG Zhenglian TAO Shizhen ZHANG Qin ZHANG Bin ZHANG Tianshu YANG Xiaoping WU Yinye FAN Jianwei YUAN Miao Research Institute of Petroleum Exploration&Development PetrochinaBeijing 100083China

Based on core observation,cast and fluorescent thin sections,FESEM and ESEM,coquina in Da'anzhai Member of Jurassic in Sichuan Basin were examined systematically.Together with production data and logging evaluation,a method for lacustrine coquina evaluation based on geological theory was established up.In the article,two aspects of the study were elaborated,characteristics of favorable reservoirs,and a"five-step"evaluation method for favorable coquina reservoir.According to the correlation between porosity and production data,porosity is not effective in finding high quality coquina reservoir of this area.Whereas micro research of reservoir samples from a high productivity well revealed that sparry coquina is the best lithofacies,with the most developed micro storage space of various kinds.After the favorable reservoir was sorted out,a five-step method evaluating the coquina reservoir was worked out.Correlation ofGR value and rock types suggests that GRevaluation parameter in identifying profitable reservoir lithofacies.Meanwhile,the combination of profitable reservoir rock thickness and production data revealed that the reservoirs with the highest potentiality are those with thickness of 3-18 m.Fractures are more developed in faults,folds and structural noses in the study area.Organic acid is discharged massively before the peak of hydrocarbon generation,leading to the formation of dissolution pores in the reservoir.The evaluation of organic acid was made by using the source rock indexes.After evaluating the four factors,and compiling their distribution maps,the maps were overlapped to predict favorable reservoir zones,and 7 first class and 9 second class favorable zones of coquina were picked out.

关键词： coquina lithofacies logging evaluation favorable areas Sichuan Basin

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evaluation on monthly sea surface wind speed of four reanalysis data sets over the China seas after 1988

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Acta Oceanologica Sinica 2020年第1期39卷 83-90页

作者： Guosong Wang Xidong Wang Hui Wang Min Hou Yan Li Wenjing Fan Yulong Liu College of Oceanography Hohai University Nanjing 210098China National Marine Data and Information Service Tianjin 300171China Tianjin Binhai New Area Meteorology Administration Tianjin 300457China

This study investigates the long-term changes of monthly sea surface wind speeds over the China seas from 1988 to 2015. The 10-meter wind speeds products from four major global reanalysis datasets with high resolution are used: Cross-Calibrated Multi-Platform data set(CCMP), NCEP climate forecast system reanalysis data set(CFSR),ERA-interim reanalysis data set(ERA-int) and Japanese 55-year reanalysis data set(JRA55). The monthly sea surface wind speeds of four major reanalysis data sets have been investigated through comparisons with the longterm and homogeneous observation wind speeds data recorded at ten stations. The results reveal that(1) the wind speeds bias of CCMP, CFSR, ERA-int and JRA55 are 0.91 m/s, 1.22 m/s, 0.62 m/s and 0.22 m/s, respectively.The wind speeds RMSE of CCMP, CFSR, ERA-int and JRA55 are 1.38 m/s, 1.59 m/s, 1.01 m/s and 0.96 m/s,respectively;(2) JRA55 and ERA-int provides a realistic representation of monthly wind speeds, while CCMP and CFSR tend to overestimate observed wind speeds. And all the four data sets tend to underestimate observed wind speeds in Bohai Sea and Yellow Sea;(3) Comparing the annual wind speeds trends between observation and the four data sets at ten stations for 1988-1997, 1988–2007 and 1988–2015, the result show that ERA-int is superior to represent homogeneity monthly wind speeds over the China seaes.

关键词： monthly sea surface wind speeds China Sea reanalysis data inhomogeneity evaluation trend analysis

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evaluation of Precipitation Datasets from TRMM Satellite and Down-scaled Reanalysis Products with Bias-correction in Middle Qilian Mountain,China

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Chinese Geographical Science 2021年第3期31卷 474-490页

作者： ZHANG Lanhui HE Chansheng TIAN Wei ZHU Yi Key Laboratory of West China's Environmental System(Ministry of Education) College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China Department of Geography Western Michigan UniversityKalamazoo Michigan 49008USA

Accurate estimates of precipitation are fundamental for hydrometeorological and ecohydrological studies,but are more difficult in high mountainous areas because of the high elevation and complex terrain.This study compares and evaluates two kinds of precipitation datasets,the reanalysis product downscaled by the Weather Research and Forecasting(WRF)output,and the satellite product,the Tropical Rainfall Measuring Mission(TRMM)Multisatellite Precipitation Analysis(TMPA)product,as well as their bias-corrected datasets in the Middle Qilian Mountain in Northwest China.Results show that the WRF output with finer resolution perfonns well in both estimating precipitation and hydrological simulation,while the TMPA product is unreliable in high mountainous areas.Moreover,bias-corrected WRF output also performs better than bias-corrected TMPA product.Combined with the previous studies,atmospheric reanalysis datasets are more suitable than the satellite products in high mountainous areas.Climate is more important than altitude for the\falseAlarms'events of the TRMM product.Designed to focus on the tropical areas,the TMPA product mistakes certain meteorological situations for precipitation in subhumid and semiarid areas,thus causing significant"falseAlarms"events and leading to significant overestimations and unreliable performance.Simple linear bias correction method,only removing systematical errors,can significantly improves the accuracy of both the WRF output and the TMPA product in arid high mountainous areas with data scarcity.Evaluated by hydrological simulations,the bias-corrected WRF output is more reliable than the gauge dataset.Thus,data merging of the WRF output and gauge observations would provide more reliable precipitation estimations in arid high mountainous areas.

关键词： evaluation Weather Research and Forecasting(WRF) Tropical Rainfall Measuring Mission(TRMM) precipitation bias correction high mountainous areas

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evaluation of sugar and organic acid composition and their levels in highbush blueberries from two regions of China

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Journal of Integrative Agriculture 2020年第9期19卷 2352-2361页

作者： ZHANG Jia NIE Ji-yun LI Jing ZHANG Hui LI Ye Saqib FAROOQ Syed Asim Shah BACHA WANG Jie Laboratory of Quality&Safety Risk Assessment for Fruit(Xingcheng) Ministry of Agriculture and Rural Affairs/Institute of PomologyChinese Academy of Agricultural SciencesXingcheng 125100P.R.China College of Horticulture Qingdao Agricultural UniversityQingdao 266109P.R.China Institude of Crop Science Chinese Academy of Agricultural SciencesBeijing 100081P.R.China

Sweet and sour are the most important taste of blueberries,and they are produced by sugar and acid,respectively.Their contributions to the taste depend not only on the levels of sugar and acid,but also on the types and relative proportions of sugar and acid.Therefore,it is very important to evaluate the composition and levels of sugar and acid in blueberries.Regional differences and variety diversity also affect the sugar and acid characteristics of fruits.Therefore,this study selected two main producing regions in northern China(Weihai and Yingkou)to examine the sugar and acid characteristics of 11 common blueberry cultivars.The indexes measured included soluble sugars,organic acids,soluble solid content and titratable acidity.The results showed that glucose and fructose were the major sugars,and citric acid and quinic acid were the major organic acids.Correlation analysis showed that glucose,fructose,and sucrose were positively correlated with total sugar content;the citric acid content was positively correlated with the titratable acidity and total organic acids.Titratable acidity,glucose,fructose,sucrose,total sugar content,citric acid,shikimic acid and total acid content of the blueberries varied significantly between regions(Pevaluation of sweet and sour flavors and cultivar selection of blueberries.

关键词： blueberry sugar organic acid level evaluation

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evaluation of the Global and Regional Assimilation and Prediction System for Predicting Sea Fog over the South China Sea

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Advances in Atmospheric Sciences 2019年第6期36卷 623-642页

作者： Huijun HUANG Bin HUANG Li YI Chunxia LIU Jing TU Guanhuan WEN Weikang MAO Institute of Tropical and Marine Meteorology China Meteorological Administration National Meteorological Centre Ocean University of China Guangdong Meteorological Observatory

In the South China Sea, sea fog brings severe disasters every year, but forecasters have yet to implement an effective seafog forecast. To address this issue, we test a liquid-water-content-only(LWC-only) operational sea-fog prediction method based on a regional mesoscale numerical model with a horizontal resolution of about 3 km, the Global and Regional Assimilation and Prediction System(GRAPES), hereafter GRAPES-3 km. GRAPES-3 km models the LWC over the sea, from which we infer the visibility that is then used to identify fog. We test the GRAPES-3 km here against measurements in 2016 and 2017 from coastal-station observations, as well as from buoy data, data from the Integrated Observation Platform for Marine Meteorology, and retrieved fog and cloud patterns from Himawari-8 satellite data. For two cases that we examine in detail, the forecast region of sea fog overlaps well with the multi-observational data within 72 h. Considering forecasting for0–24 h, GRAPES-3 km has a 2-year-average equitable threat score(ETS) of 0.20 and a Heidke skill score(HSS) of 0.335,which is about 5.6%(ETS) and 6.4%(HSS) better than our previous method(GRAPES-MOS). Moreover, the stations near the particularly foggy region around the Leizhou Peninsula have relatively high forecast scores compared to other sea areas.Overall, the results show that GRAPES-3 km can roughly predict the formation, evolution, and dissipation of sea fog on the southern China coast.

关键词： sea fog operational GRAPES model southern China coast forecast evaluation

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evaluation of TIGGE Ensemble Forecasts of Precipitation in Distinct Climate Regions in Iran

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Advances in Atmospheric Sciences 2018年第4期35卷 457-468页

作者： Saleh AMINYAVARI Bahram SAGHAFIAN Majid DELAVAR Department of Technical and Engineering Science and Research Branch Islamic Azad University Department of Water Resources Engineering Tarbiat Modares University

The application of numerical weather prediction （NWP） products is increasing dramatically. Existing reports indicate that ensemble predictions have better skill than deterministic forecasts. In this study, numerical ensemble precipitation forecasts in the TIGGE database were evaluated using deterministic, dichotomous （yes/no）, and probabilistic techniques over Iran for the period 2008-16. Thirteen rain gauges spread over eight homogeneous precipitation regimes were selected for evaluation. The Inverse Distance Weighting and Kriging methods were adopted for interpolation of the prediction values, downscaled to the stations at lead times of one to three days. To enhance the forecast quality, NWP values were post-processed via Bayesian Model Averaging. The results showed that ECMWF had better scores than other products. However, products of all centers underestimated precipitation in high precipitation regions while overestimating precipitation in other regions. This points to a systematic bias in forecasts and demands application of bias correction techniques. Based on dichotomous evaluation, NCEP did better at most stations, although all centers overpredicted the number of precipitation events. Compared to those of ECMWF and NCER UKMO yielded higher scores in mountainous regions, but performed poorly at other selected stations. Furthermore, the evaluations showed that all centers had better skill in wet than in dry seasons. The quality of post-processed predictions was better than those of the raw predictions. In conclusion, the accuracy of the NWP predictions made by the selected centers could be classified as medium over Iran, while post-processing of predictions is recommended to improve the quality.

关键词： ensemble forecast NWP TIGGE evaluation post-processing

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