Much attention has recently been focused on the effects of climate variability and human activities on the runoff. In this study, we analyzed 56-yr(1957–2012) runoff change and patterns in the Jinghe River Basin(JRB)...Much attention has recently been focused on the effects of climate variability and human activities on the runoff. In this study, we analyzed 56-yr(1957–2012) runoff change and patterns in the Jinghe River Basin(JRB) in the arid region of northwest China. The nonparametric Mann–Kendall test and the precipitation-runoff double cumulative curve(PRDCC) were used to identify change trend and abrupt change points in the annual runoff. It was found that the runoff in the JRB has periodically fluctuated in the past 56 yr. Abrupt change point in annual runoff was identified in the JRB, which occurred in the years around 1964 and 1996 dividing the long-term hydrologic series into a natural period(1957 – 1964) and a climate and man-induced period(1965 – 1996 and 1997 – 2012). In the 1965 – 1996 period, human activities were the main factor that decreased runoff with contribution of 88.9%, while climate variability only accounted for 11.1%. However,the impact of climate variability has been increased from 11.1% to 47.5% during 1997 – 2012, showing that runoff in JRB is more sensitive to climate variability during global warming. This study distinguishes theeffect of climate variability from human activities on runoff, which can do duty for a reference for regional water resources assessment and management.展开更多
Based on the climate factors data and surface vapor pressure(SVP) data of 44 weather stations in Tianshan Mountains during the years 1961-2011, this paper establishes a water vapor content(WVC) estimation model accord...Based on the climate factors data and surface vapor pressure(SVP) data of 44 weather stations in Tianshan Mountains during the years 1961-2011, this paper establishes a water vapor content(WVC) estimation model according to the relationship between monthly WVC of radiosonde and corresponding SVP and analyzes the spatial and temporal variability of WVC and their causes. The results show that the WVC is linearly and negatively related to the elevation and longitude(Vertical zonality and Longitude zonality), while it was not linearly related to the latitude. The westerly wind, geographical situation and sea level elevation composed complex surface conditions to influence the spatial distribution of WVC in the Tianshan Mountains. The Mann-Kendall(M-K) statistical test shows a significant increasing trend in the mean annual WVC in Tianshan Mountains during 1961-2011(P < 0.001), with a rate of 0.23 mm/decade, and indicates an abrupt turning point in 1985(P < 0.001). Correlation analysis shows that the WVC are significantly correlated to the temperature, especially during the winter, but the summer WVC are significantly correlated to the precipitation. In addition, the North Atlantic Oscillation Index(NAOI)and the Arctic Oscillation Index(AOI) are significantly correlated to the winter WVC in the Tianshan Mountains. As a new Microwave radiometric profilers(MWRPs) instrument, the MP-3000 A provides continuous, real-time and high temporal resolution atmospheric profiles up to 10 km. In order to monitor water vapor and atmosphere profiles in Tianshan Mountains, an MP-3000 A was established in Urumqi(43.8°N, 87.58°N) in May 2008. The results indicated that the MP-3000 A was applicable to this area, and the evolutionary process of water vapor and the WVC peak values of MP-3000 A were a strong signal for rainstorm and flood forecasts for Urumqi and the Tianshan Mountains.展开更多
Central Asia(CA)is one of the most drought-prone regions in the world with complex climate regimes,it is extremely vulnerable to water scarcity.Many studies on drought in CA,as a whole,have been carried out,whereas th...Central Asia(CA)is one of the most drought-prone regions in the world with complex climate regimes,it is extremely vulnerable to water scarcity.Many studies on drought in CA,as a whole,have been carried out,whereas there is a lack of studies on the drying and wetting trends of different climatic zones within CA.In this study,CA was divided into three different climatic zones based on the Koppen climate classification method,precipitation climatology,and aridity index.These were the temperate continental(Df),dry arid desert(BW),and Mediterranean continental(Ds)climatic zones.The regional drying and wetting trends during the years 1961—2015 were investigated using the monthly gridded Standardized Precipitation Evapotranspiration Index(SPEI).The empirical orthogonal function(EOF)was applied to analyze spatial and temporal variation patterns.EOF mode 1(EOF1)analysis found increasingly wet conditions throughout CA over the duration of the study,and EOF mode 2(EOF2)analysis found a contrast between northern and southern CA:as Df became drier and BW and Ds became wetter.EOF mode 3(EOF3)analysis found a western and eastern inverse phase distribution.The SPEI displayed a decreasing trend from 1961 to 1974 for CA as a whole,before increasing from 1975 to 2015,with a particularly significant increase over the first seven years of that period.On a regional scale,the BW and Ds zones experienced a wetting trend due to increased precipitation during 1961—2015,but the Df zone experienced a drying trend due to reduced evapotranspiration and an increasing temperature,particularly from 1961 to 1978.Thus,the spatio-temporal patterns in dryness and wetness across CA can be categorized according to climatic regions.展开更多
Precipitation is particularly scarce in arid Central Asia(CA),and is expected to be severely impacted by future warming,and the assessmentof the stationarity of precipitation variability is important for managing surf...Precipitation is particularly scarce in arid Central Asia(CA),and is expected to be severely impacted by future warming,and the assessmentof the stationarity of precipitation variability is important for managing surface water resources in this region.In this study,we investigated thestatistics of stationarity in the totals and extremes of precipitation in CA based on the longest observational records(1881e2006),tree-ringreconstructed records(1756e2012 and 1760e2015),and the Coupled Model Intercomparison Project 5(CMIP5)simulations,applying theautocorrelation function and testing criteria established based on the statistical definitions of stationarity.We analyzed the longest daily pre-cipitation record(Tashkent station,1881e2006)and found that the autocorrelation coefficient of the precipitation totals(PRCPTOT)and annualmaximum 1-day precipitation amount(Rx1day)were statistically insignificant for all lags,implying stationary behavior.Regionally,nearly allthe Global Historical Climatology Network-Daily Database(GHCN-D)observatory sites(1925e2005)indicated likely stationary behavior.Thereconstructed records were also indistinguishable from a random process.For the CMIP5 models,the simulated and projected PRCPTOT closelyapproximated a purely random process;however,the projected Rx1day maintained non-stationary means in most of the models under therepresentative concentration pathway(RCPs),implying that extreme events would increase in the future.The mean precipitation changes(DP)can be expressed as an exponential function depending on the length of the successive mean periods(m)and variance(s2).TheDPof the nextdecade is projected to be within±14.8%of the previous decades mean annual PRCPTOT over CA.The higher the RCPs,the higher theDP overCA.The results show that the detection and prediction of precipitation change will be challenging in arid CA.展开更多
目的探究糖化血红蛋白(HbA1c)诊断肥胖儿童糖尿病前期的最佳阈值,以期为我国肥胖儿童HbA1c诊断糖尿病前期的开展提供参考。方法本研究为回顾性样本的横断面研究。选取2018年6月-2021年5月在宁波市妇女儿童医院内分泌科住院部诊断为肥胖...目的探究糖化血红蛋白(HbA1c)诊断肥胖儿童糖尿病前期的最佳阈值,以期为我国肥胖儿童HbA1c诊断糖尿病前期的开展提供参考。方法本研究为回顾性样本的横断面研究。选取2018年6月-2021年5月在宁波市妇女儿童医院内分泌科住院部诊断为肥胖的儿童191例,均于空腹8 h后行口服葡萄糖耐量试验(OGTT),记录空腹血糖(FPG)、负荷后2 h血糖(2 h PG),并测定糖化血红蛋白(HbA1c)水平。根据2020年美国糖尿病学会的诊断标准分为非糖尿病前期组和糖尿病前期组,比较两组之间HbA1c水平,绘制HbA1c诊断糖尿病前期的ROC曲线,计算曲线下面积(AUC)及不同阈值的敏感度和特异度,揭示诊断的最佳阈值。结果根据OGTT结果,去除确诊为糖尿病的儿童并分组,183例中非糖尿病前期组142例(77.6%),糖尿病前期组41例(22.4%)。采用倾向评分匹配法校正混杂因素后共100例进入模型,其中非糖尿病前期组63例,糖尿病前期组37例。非糖尿病前期组HbA1c水平[(5.52±0.34)%]低于糖尿病前期组[(5.69±0.39)%],差异有统计学意义(t=2.247,P=0.027)。通过ROC曲线得出HbA1c诊断糖尿病前期的AUC为0.625。最佳阈值为5.45%,对应的敏感度73.0%,特异度66.7%。结论推测HbA1c在肥胖儿童中诊断糖尿病前期的最佳阈值为5.45%。展开更多
基金supported by the International S&T Cooperation Program of China (Grant No. 2010DFA92720-12)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-YW-GJ04)+2 种基金the Natural Science Foundation of China (Grant Nos. 41130531, 41375101)the Ministry of Water Resources Special Funds for Scientific Research on Public Causes (Grant No. 201301103)the Program for Innovative Research Team in University (Grant No. IRT1180)
文摘Much attention has recently been focused on the effects of climate variability and human activities on the runoff. In this study, we analyzed 56-yr(1957–2012) runoff change and patterns in the Jinghe River Basin(JRB) in the arid region of northwest China. The nonparametric Mann–Kendall test and the precipitation-runoff double cumulative curve(PRDCC) were used to identify change trend and abrupt change points in the annual runoff. It was found that the runoff in the JRB has periodically fluctuated in the past 56 yr. Abrupt change point in annual runoff was identified in the JRB, which occurred in the years around 1964 and 1996 dividing the long-term hydrologic series into a natural period(1957 – 1964) and a climate and man-induced period(1965 – 1996 and 1997 – 2012). In the 1965 – 1996 period, human activities were the main factor that decreased runoff with contribution of 88.9%, while climate variability only accounted for 11.1%. However,the impact of climate variability has been increased from 11.1% to 47.5% during 1997 – 2012, showing that runoff in JRB is more sensitive to climate variability during global warming. This study distinguishes theeffect of climate variability from human activities on runoff, which can do duty for a reference for regional water resources assessment and management.
基金sponsored by the Natural Science Foundation of China (Grant No. 41375101)the Special Fund for Meteorology-scientific Research in the Public Interest of China (Grant No. GYHY201006012)+2 种基金the Cooperation Program of National International Technological (Grant No. 2010DFA92720-14)Ministry of Water Resources Special Funds for Scientific Research on Public Causes (No.201301103)the Program for Innovative Research Team in University (Grant No. IRT1180)
文摘Based on the climate factors data and surface vapor pressure(SVP) data of 44 weather stations in Tianshan Mountains during the years 1961-2011, this paper establishes a water vapor content(WVC) estimation model according to the relationship between monthly WVC of radiosonde and corresponding SVP and analyzes the spatial and temporal variability of WVC and their causes. The results show that the WVC is linearly and negatively related to the elevation and longitude(Vertical zonality and Longitude zonality), while it was not linearly related to the latitude. The westerly wind, geographical situation and sea level elevation composed complex surface conditions to influence the spatial distribution of WVC in the Tianshan Mountains. The Mann-Kendall(M-K) statistical test shows a significant increasing trend in the mean annual WVC in Tianshan Mountains during 1961-2011(P < 0.001), with a rate of 0.23 mm/decade, and indicates an abrupt turning point in 1985(P < 0.001). Correlation analysis shows that the WVC are significantly correlated to the temperature, especially during the winter, but the summer WVC are significantly correlated to the precipitation. In addition, the North Atlantic Oscillation Index(NAOI)and the Arctic Oscillation Index(AOI) are significantly correlated to the winter WVC in the Tianshan Mountains. As a new Microwave radiometric profilers(MWRPs) instrument, the MP-3000 A provides continuous, real-time and high temporal resolution atmospheric profiles up to 10 km. In order to monitor water vapor and atmosphere profiles in Tianshan Mountains, an MP-3000 A was established in Urumqi(43.8°N, 87.58°N) in May 2008. The results indicated that the MP-3000 A was applicable to this area, and the evolutionary process of water vapor and the WVC peak values of MP-3000 A were a strong signal for rainstorm and flood forecasts for Urumqi and the Tianshan Mountains.
基金funded by National Key Research and Development Program of China(2018YFC1507101)National Natural Science Foundation of China(U1903113)+1 种基金China Desert Meteorological Science Research Foundation(SQJ2017012)Sichuan Science and Technology Program(2020JDJQ0050).
文摘Central Asia(CA)is one of the most drought-prone regions in the world with complex climate regimes,it is extremely vulnerable to water scarcity.Many studies on drought in CA,as a whole,have been carried out,whereas there is a lack of studies on the drying and wetting trends of different climatic zones within CA.In this study,CA was divided into three different climatic zones based on the Koppen climate classification method,precipitation climatology,and aridity index.These were the temperate continental(Df),dry arid desert(BW),and Mediterranean continental(Ds)climatic zones.The regional drying and wetting trends during the years 1961—2015 were investigated using the monthly gridded Standardized Precipitation Evapotranspiration Index(SPEI).The empirical orthogonal function(EOF)was applied to analyze spatial and temporal variation patterns.EOF mode 1(EOF1)analysis found increasingly wet conditions throughout CA over the duration of the study,and EOF mode 2(EOF2)analysis found a contrast between northern and southern CA:as Df became drier and BW and Ds became wetter.EOF mode 3(EOF3)analysis found a western and eastern inverse phase distribution.The SPEI displayed a decreasing trend from 1961 to 1974 for CA as a whole,before increasing from 1975 to 2015,with a particularly significant increase over the first seven years of that period.On a regional scale,the BW and Ds zones experienced a wetting trend due to increased precipitation during 1961—2015,but the Df zone experienced a drying trend due to reduced evapotranspiration and an increasing temperature,particularly from 1961 to 1978.Thus,the spatio-temporal patterns in dryness and wetness across CA can be categorized according to climatic regions.
基金the National Key Research andDevelopment Program of China(2018YFC1507101)NationalNatural Science Foundation of China(U1903113,41971023)the Open Research Fund of State Key Laboratory ofDesert and Oasis Ecology in Xinjiang Institute of Ecology andGeography of the Chinese Academy of Sciences.
文摘Precipitation is particularly scarce in arid Central Asia(CA),and is expected to be severely impacted by future warming,and the assessmentof the stationarity of precipitation variability is important for managing surface water resources in this region.In this study,we investigated thestatistics of stationarity in the totals and extremes of precipitation in CA based on the longest observational records(1881e2006),tree-ringreconstructed records(1756e2012 and 1760e2015),and the Coupled Model Intercomparison Project 5(CMIP5)simulations,applying theautocorrelation function and testing criteria established based on the statistical definitions of stationarity.We analyzed the longest daily pre-cipitation record(Tashkent station,1881e2006)and found that the autocorrelation coefficient of the precipitation totals(PRCPTOT)and annualmaximum 1-day precipitation amount(Rx1day)were statistically insignificant for all lags,implying stationary behavior.Regionally,nearly allthe Global Historical Climatology Network-Daily Database(GHCN-D)observatory sites(1925e2005)indicated likely stationary behavior.Thereconstructed records were also indistinguishable from a random process.For the CMIP5 models,the simulated and projected PRCPTOT closelyapproximated a purely random process;however,the projected Rx1day maintained non-stationary means in most of the models under therepresentative concentration pathway(RCPs),implying that extreme events would increase in the future.The mean precipitation changes(DP)can be expressed as an exponential function depending on the length of the successive mean periods(m)and variance(s2).TheDPof the nextdecade is projected to be within±14.8%of the previous decades mean annual PRCPTOT over CA.The higher the RCPs,the higher theDP overCA.The results show that the detection and prediction of precipitation change will be challenging in arid CA.
文摘目的探究糖化血红蛋白(HbA1c)诊断肥胖儿童糖尿病前期的最佳阈值,以期为我国肥胖儿童HbA1c诊断糖尿病前期的开展提供参考。方法本研究为回顾性样本的横断面研究。选取2018年6月-2021年5月在宁波市妇女儿童医院内分泌科住院部诊断为肥胖的儿童191例,均于空腹8 h后行口服葡萄糖耐量试验(OGTT),记录空腹血糖(FPG)、负荷后2 h血糖(2 h PG),并测定糖化血红蛋白(HbA1c)水平。根据2020年美国糖尿病学会的诊断标准分为非糖尿病前期组和糖尿病前期组,比较两组之间HbA1c水平,绘制HbA1c诊断糖尿病前期的ROC曲线,计算曲线下面积(AUC)及不同阈值的敏感度和特异度,揭示诊断的最佳阈值。结果根据OGTT结果,去除确诊为糖尿病的儿童并分组,183例中非糖尿病前期组142例(77.6%),糖尿病前期组41例(22.4%)。采用倾向评分匹配法校正混杂因素后共100例进入模型,其中非糖尿病前期组63例,糖尿病前期组37例。非糖尿病前期组HbA1c水平[(5.52±0.34)%]低于糖尿病前期组[(5.69±0.39)%],差异有统计学意义(t=2.247,P=0.027)。通过ROC曲线得出HbA1c诊断糖尿病前期的AUC为0.625。最佳阈值为5.45%,对应的敏感度73.0%,特异度66.7%。结论推测HbA1c在肥胖儿童中诊断糖尿病前期的最佳阈值为5.45%。
