China Meteorological Administration(CMA) recently released its 40-yr(1979–2018) global Chinese reanalysis(CRA-40) dataset. To assess performance of the CRA-40 data in quantifying the regional water cycle, contributio...China Meteorological Administration(CMA) recently released its 40-yr(1979–2018) global Chinese reanalysis(CRA-40) dataset. To assess performance of the CRA-40 data in quantifying the regional water cycle, contributions of local and remote atmospheric moisture fluxes to precipitation in East China derived from CRA-40 are compared with those derived from the ECMWF reanalysis version 5(ERA-5). Observed precipitation and evaporation data are also used for validation. As for mean precipitation, CRA-40 matches the observation better in winter and spring than in summer, with a larger wet bias(1.41 mm day^(-1)) in summer than that in ERA-5(0.97 mm day^(-1)), particularly over South China. The conservation of atmospheric water vapor over East China measured by CRA-40 is comparable to that of ERA-5. Both reanalyses show a dominant role of the remote moisture transport in the East China precipitation.In comparison, the annual precipitation induced by the moisture influx from the west of the study domain in CRA-40 is 80 mm less than that in ERA-5. The recycling ratio of annual mean precipitation in CRA-40 is approximately21.1%, slightly larger than that in ERA-5(20.1%). The maximum difference of each hydrological component between the two datasets appears in the summer horizontal moisture influx(3.57 ×10^(7) kg s^(-1);ERA-5 is larger) and winter runoff(1.84 ×10^(7) kg s^(-1);CRA-40 is larger). CRA-40 shows better performance than ERA-5 in capturing the interannual variability of precipitation over East China, as evinced by a higher correlation coefficient with the observation(0.77 versus 0.33). The trend of summer precipitation since 2011 is better reproduced in CRA-40. Both reanalyses show prominent contribution of the southern moisture influx to the interannual variation of precipitation. This study demonstrates the reliability of CRA-40 in representing the hydrological cycle over East China and provides a useful reference for future application of CRA-40 in water cycle studies.展开更多
Understanding the spatio-temporal changes of vegetation and its climatic control factors can provide an important theoretical basis for the protection and restoration of eco-environments.In this study,we analyzed the ...Understanding the spatio-temporal changes of vegetation and its climatic control factors can provide an important theoretical basis for the protection and restoration of eco-environments.In this study,we analyzed the normalized difference vegetation index(NDVI)in the Chinese Loess Plateau(CLP)from 2002 to 2018 via trend analysis,stability analysis,and Mann-Kendall mutation test to investigate the change of vegetation.In addition,we also used the skewness analysis and correlation analysis to explore the contribution of climate change and human activities on regional vegetation changes.The results indicated that the overall increasing trend of NDVI from 2002 to 2018 was significant The areas showing increased NDVI were mainly distributed in the south-eastern CLP and the irrigation districts of the Yellow River to the north and west of the CLP,while the areas showing decreased NDVl were concentrated in the desert of the westem Ordos Plateau,Longzhong Loess Plateau,and the built-up and adjacent areas.Precipitation was the dominant factor contributing to vegetation growth in the CLP,while vegetation was less dependent onprecipitation in the irigation districts.The increasement of NDVI has led to a prolonged responsetime of vegetation to water stress and a lag effect of less than two months in the CLP.The effect of temperature on NDVI was not significant;significant negative correlations between NDVI and temperature were found only in the desert,the Guanzhong Plain,the southem Liupan Mountains,and the southeastem Taihang Mountains,owing to high temperatures,urban heat islands,and large cloud cover in mountainous areas.Affected by the"Grain for Green Program"(GGP),NDVIin the CLP increased from 2002 to 2018;however,the increasing trends of NDNI for differentvegetation cover types were significantly different owing to the difference in background status.The increasing contribution rate of NDVI in the CLP mainly came from crops and steppes.Urban not only led to the destruction of vegetation but also had radiation effect ca展开更多
With the popularity of the automatic precipitation gauges in national weather stations,testing their performance and adjusting their measurements are top priorities. Additionally,because different climatic conditions ...With the popularity of the automatic precipitation gauges in national weather stations,testing their performance and adjusting their measurements are top priorities. Additionally,because different climatic conditions may have different effects on the performance of the precipitation gauges, it is also necessary to test the gauges in different areas. This study mainly analyzed precipitation measurements from the single-Altershielded TRwS204 automatic weighing gauge(TRwS_(SA)) relative to the adjusted manual measurements(reference precipitation) from the Chinese standard precipitation gauge in a doublefence wind shield(CSPG_(DF)) in the Hulu watershed in the Qilian Mountains, China. The measurements were compared over the period from August 2014 to July2017, and the transfer function derived from the work by Kochendorfer et al.(2017 a) for correcting windinduced losses was applied to the TRwS_(SA) measurements. The results show that the average loss of TRwS_(SA) measurements relative to the reference precipitation decreased from 0.55 mm(10.7%) to 0.51 mm(9.9%) for rainfall events, from 0.35 mm(8.5%)to 0.22 mm(5.3%) for sleet events, and from 0.49 mm(18.9%) to 0.33 mm(12.7%) for snowfall events after adjustment. The uncorrected large biases of TRwS_(SA) measurements are considered to be mainly caused by specific errors of TRwS_(SA), different gauge orifice area and random errors. These types of errors must be considered when comparing precipitation measurements for different gauge types, especially in the mountains.展开更多
Precipitation data is vital fundamental data for climate change.However,obtaining precise gauge-measured precipitation in high-altitude mountains is challenging,and the precipitation obtained from various gauge types ...Precipitation data is vital fundamental data for climate change.However,obtaining precise gauge-measured precipitation in high-altitude mountains is challenging,and the precipitation obtained from various gauge types at the same station may vary.To understand the differences in precipitation observations among the three commonly used gauges in China(Chinese Standard Precipitation Gauges(CSPG),Total Rain weighing Sensor(TRwS),and Geonor T-200B(T200B))in high-altitude mountains and to recommend a stable and cost-effective weighing gauge,a precipitation intercomparison experiment was conducted at Hulu-1 station in the Qilian Mountains.The wind-induced error in measurement was corrected with the‘universal’transfer function recommended by the Word Meteorological Organization.The comparison results,adjusted for systematic errors,showed that the rain,snow and mixed precipitation of CSPG and TRwS equipped with the same octagonal vertical double fence shields(CSPGDF and TRwSDF)and single-Alter shields(CSPG_(s)and TRwSs)were close,while the precipitation of Tretyakov-shielded T200B was notably higher than that of CSPG_(s)and TRwSs.The average differences in annual and daily precipitation between CSPGDF and TRwSDF from 2017 to 2021 were 12.9 mm and 0.10 mm,respectively.The daily precipitation difference between CSPG_(s)and TRwSs from April 2019–December 2021 was 0.10 mm,while the differences between T200Bs and CSPG_(s)and TRwSs was 0.28 mm and 0.38 mm,respectively.The wind shield performance of Alter and Tretyakov was not much different at Hulu-1 site with low wind speed,thus the measurement principle of T200Bs was the primary cause of the high observations.Taking the corrected CSPGDF measurement as the standard,the dynamic loss of CSPG_(s)was 17.6%,while that of CSPGUn was 55.6%,indicating that the single-Alter shield could effectively reduce the impact of wind on precipitation measurement.Considering the comparison results and the price difference of the instruments,it was recommended to use a single-Alter shielded 展开更多
This paper reports the analysis results (including pH,conductivity and ion concentrations) of the precipitation samples collected at the Chinese Great Wall Station,Antarctica (62°13′S, 58°58′W,ASL10.0 m) i...This paper reports the analysis results (including pH,conductivity and ion concentrations) of the precipitation samples collected at the Chinese Great Wall Station,Antarctica (62°13′S, 58°58′W,ASL10.0 m) in 1998.The average pH value and conductivity were 5.62 and 85.16 μS/cm,respectively.The pH value and conductivity of precipitation were higher during autumn, but lower during other seasons.The major ions in the precipitation were C1- and Na+,followed by SO_4^(2-),Mg^(2+),Ca^(2+),K^+,NO_3^-,NH_4^+ with the lower concentrations in order.The positive correlation significantly existing between the major ions,except NO_3^- and NH_4^+,indicated that those major ions might come from same sources.The fact that the relative abundances of ions in precipitation were very close to that of seawater of Antarctic Ocean indicated that marine aerosol was the dominant source of the ions of precipitation.However,there were yet other sources which may contribute to Ca^(2+) ion in the precipitation.The precipitation at the area was characterized by marine type chemically.展开更多
Based on the statistics of glacier area variation measured in the Chinese Tianshan Mountains since 1960, the response of glacier area variation to climate change is discussed systematically. As a result, the total are...Based on the statistics of glacier area variation measured in the Chinese Tianshan Mountains since 1960, the response of glacier area variation to climate change is discussed systematically. As a result, the total area of the glaciers has been reduced by 11.5% in the past 50 years, which is a weighted percentage according to the glacier area variations of 10 drainage basins separated by the Glacier Inventory of China （GIC）. The annual percentage of area changes （APAC） of glaciers in the Chinese Tianshan Mountains is 0.31% after the standardization of the study period. The APAC varies widely for different drainage basins, but the glaciers are in a state of rapid retreat, generally. According to the 14 meteorological sta- tions in the Chinese Tianshan Mountains, both the temperature and precipitation display a marked increasing tendency from 1960 to 2009 at a rate of 0.34℃·（10a）^-1 and 11 mm·（10a）^-1, respectively. The temperature in the dry seasons （from November to March） increases rapidly at a rate of 0.46℃·（10a）^-1, but the precipitation grows slowly at 2.3 mm·（10a）^-1. While the temperature in the wet seasons （from April to October） grows at a rate of 0.25℃·（10a）^-1, but the precipitation increases at 8.7 mm·（10a）^-1, The annual and seasonal climatic trends accelerate the retreat of glaciers.展开更多
基金Supported by the National Natural Science Foundation of China (41675076)Program of International S&T Cooperation of Chinese Academy of Sciences (2018YFE0196000)Innovative Team Project of Lanzhou Institute of Arid Meteorology (GHSCXTD-2020-2)。
文摘China Meteorological Administration(CMA) recently released its 40-yr(1979–2018) global Chinese reanalysis(CRA-40) dataset. To assess performance of the CRA-40 data in quantifying the regional water cycle, contributions of local and remote atmospheric moisture fluxes to precipitation in East China derived from CRA-40 are compared with those derived from the ECMWF reanalysis version 5(ERA-5). Observed precipitation and evaporation data are also used for validation. As for mean precipitation, CRA-40 matches the observation better in winter and spring than in summer, with a larger wet bias(1.41 mm day^(-1)) in summer than that in ERA-5(0.97 mm day^(-1)), particularly over South China. The conservation of atmospheric water vapor over East China measured by CRA-40 is comparable to that of ERA-5. Both reanalyses show a dominant role of the remote moisture transport in the East China precipitation.In comparison, the annual precipitation induced by the moisture influx from the west of the study domain in CRA-40 is 80 mm less than that in ERA-5. The recycling ratio of annual mean precipitation in CRA-40 is approximately21.1%, slightly larger than that in ERA-5(20.1%). The maximum difference of each hydrological component between the two datasets appears in the summer horizontal moisture influx(3.57 ×10^(7) kg s^(-1);ERA-5 is larger) and winter runoff(1.84 ×10^(7) kg s^(-1);CRA-40 is larger). CRA-40 shows better performance than ERA-5 in capturing the interannual variability of precipitation over East China, as evinced by a higher correlation coefficient with the observation(0.77 versus 0.33). The trend of summer precipitation since 2011 is better reproduced in CRA-40. Both reanalyses show prominent contribution of the southern moisture influx to the interannual variation of precipitation. This study demonstrates the reliability of CRA-40 in representing the hydrological cycle over East China and provides a useful reference for future application of CRA-40 in water cycle studies.
基金supported by the Natural Science Foundation for Young Scientists of Shanxi Province of China(201801D221043)the Science and Technology Innovation Fund of Shanxi Agricultural University(2016YJ16,2017022).
文摘Understanding the spatio-temporal changes of vegetation and its climatic control factors can provide an important theoretical basis for the protection and restoration of eco-environments.In this study,we analyzed the normalized difference vegetation index(NDVI)in the Chinese Loess Plateau(CLP)from 2002 to 2018 via trend analysis,stability analysis,and Mann-Kendall mutation test to investigate the change of vegetation.In addition,we also used the skewness analysis and correlation analysis to explore the contribution of climate change and human activities on regional vegetation changes.The results indicated that the overall increasing trend of NDVI from 2002 to 2018 was significant The areas showing increased NDVI were mainly distributed in the south-eastern CLP and the irrigation districts of the Yellow River to the north and west of the CLP,while the areas showing decreased NDVl were concentrated in the desert of the westem Ordos Plateau,Longzhong Loess Plateau,and the built-up and adjacent areas.Precipitation was the dominant factor contributing to vegetation growth in the CLP,while vegetation was less dependent onprecipitation in the irigation districts.The increasement of NDVI has led to a prolonged responsetime of vegetation to water stress and a lag effect of less than two months in the CLP.The effect of temperature on NDVI was not significant;significant negative correlations between NDVI and temperature were found only in the desert,the Guanzhong Plain,the southem Liupan Mountains,and the southeastem Taihang Mountains,owing to high temperatures,urban heat islands,and large cloud cover in mountainous areas.Affected by the"Grain for Green Program"(GGP),NDVIin the CLP increased from 2002 to 2018;however,the increasing trends of NDNI for differentvegetation cover types were significantly different owing to the difference in background status.The increasing contribution rate of NDVI in the CLP mainly came from crops and steppes.Urban not only led to the destruction of vegetation but also had radiation effect ca
基金supported primarily by the National Basic Research Program of China (2013CBA01806)the National Natural Sciences Foundation of China (41671029, 41690141, 41401040 and 41501040)
文摘With the popularity of the automatic precipitation gauges in national weather stations,testing their performance and adjusting their measurements are top priorities. Additionally,because different climatic conditions may have different effects on the performance of the precipitation gauges, it is also necessary to test the gauges in different areas. This study mainly analyzed precipitation measurements from the single-Altershielded TRwS204 automatic weighing gauge(TRwS_(SA)) relative to the adjusted manual measurements(reference precipitation) from the Chinese standard precipitation gauge in a doublefence wind shield(CSPG_(DF)) in the Hulu watershed in the Qilian Mountains, China. The measurements were compared over the period from August 2014 to July2017, and the transfer function derived from the work by Kochendorfer et al.(2017 a) for correcting windinduced losses was applied to the TRwS_(SA) measurements. The results show that the average loss of TRwS_(SA) measurements relative to the reference precipitation decreased from 0.55 mm(10.7%) to 0.51 mm(9.9%) for rainfall events, from 0.35 mm(8.5%)to 0.22 mm(5.3%) for sleet events, and from 0.49 mm(18.9%) to 0.33 mm(12.7%) for snowfall events after adjustment. The uncorrected large biases of TRwS_(SA) measurements are considered to be mainly caused by specific errors of TRwS_(SA), different gauge orifice area and random errors. These types of errors must be considered when comparing precipitation measurements for different gauge types, especially in the mountains.
基金This study was funded by the National Natural Sciences Foundation of China(42101120,42171145,41971041)the Joint Research Project of Three-River Headwaters National Park,Chinese Academy of Sciences and the People's Government of Qinghai Province(LHZX-2020-11)the Gansu Natural Science Foundation(22JR5RA071).
文摘Precipitation data is vital fundamental data for climate change.However,obtaining precise gauge-measured precipitation in high-altitude mountains is challenging,and the precipitation obtained from various gauge types at the same station may vary.To understand the differences in precipitation observations among the three commonly used gauges in China(Chinese Standard Precipitation Gauges(CSPG),Total Rain weighing Sensor(TRwS),and Geonor T-200B(T200B))in high-altitude mountains and to recommend a stable and cost-effective weighing gauge,a precipitation intercomparison experiment was conducted at Hulu-1 station in the Qilian Mountains.The wind-induced error in measurement was corrected with the‘universal’transfer function recommended by the Word Meteorological Organization.The comparison results,adjusted for systematic errors,showed that the rain,snow and mixed precipitation of CSPG and TRwS equipped with the same octagonal vertical double fence shields(CSPGDF and TRwSDF)and single-Alter shields(CSPG_(s)and TRwSs)were close,while the precipitation of Tretyakov-shielded T200B was notably higher than that of CSPG_(s)and TRwSs.The average differences in annual and daily precipitation between CSPGDF and TRwSDF from 2017 to 2021 were 12.9 mm and 0.10 mm,respectively.The daily precipitation difference between CSPG_(s)and TRwSs from April 2019–December 2021 was 0.10 mm,while the differences between T200Bs and CSPG_(s)and TRwSs was 0.28 mm and 0.38 mm,respectively.The wind shield performance of Alter and Tretyakov was not much different at Hulu-1 site with low wind speed,thus the measurement principle of T200Bs was the primary cause of the high observations.Taking the corrected CSPGDF measurement as the standard,the dynamic loss of CSPG_(s)was 17.6%,while that of CSPGUn was 55.6%,indicating that the single-Alter shield could effectively reduce the impact of wind on precipitation measurement.Considering the comparison results and the price difference of the instruments,it was recommended to use a single-Alter shielded
基金Sponsored by the Youth Meteorological Science Fund in the Ninth Five-Year Plan from China Meteorological Administration
文摘This paper reports the analysis results (including pH,conductivity and ion concentrations) of the precipitation samples collected at the Chinese Great Wall Station,Antarctica (62°13′S, 58°58′W,ASL10.0 m) in 1998.The average pH value and conductivity were 5.62 and 85.16 μS/cm,respectively.The pH value and conductivity of precipitation were higher during autumn, but lower during other seasons.The major ions in the precipitation were C1- and Na+,followed by SO_4^(2-),Mg^(2+),Ca^(2+),K^+,NO_3^-,NH_4^+ with the lower concentrations in order.The positive correlation significantly existing between the major ions,except NO_3^- and NH_4^+,indicated that those major ions might come from same sources.The fact that the relative abundances of ions in precipitation were very close to that of seawater of Antarctic Ocean indicated that marine aerosol was the dominant source of the ions of precipitation.However,there were yet other sources which may contribute to Ca^(2+) ion in the precipitation.The precipitation at the area was characterized by marine type chemically.
基金Foundation： National Natural Science Foundation of China, No.40701035 No.40631001+9 种基金 No.40571033 No.40701034 No.J0630966 Program for New Century Excellent Talents in University by the Ministry of Education, No.NCET-10-0019 Foundation for Young Innovative Scientists in Gansu Province National Basic Research Program of China, No.2010CB951003 No.2007CB411501 Knowledge Innovation Project of Chinese Academy of Sciences, No.KZCX2-YW-127 Independent Research Program of State Key Laboratory of Cryospheric Sciences of Chinese Academy of Sciences Knowledge and Technological Innovation Project of Northwest Normal University, No.NWNU-KJCXGC-03-66 Acknowledgement The authors would like to thank Arthur Wen for useful suggestions and language editing.
文摘Based on the statistics of glacier area variation measured in the Chinese Tianshan Mountains since 1960, the response of glacier area variation to climate change is discussed systematically. As a result, the total area of the glaciers has been reduced by 11.5% in the past 50 years, which is a weighted percentage according to the glacier area variations of 10 drainage basins separated by the Glacier Inventory of China （GIC）. The annual percentage of area changes （APAC） of glaciers in the Chinese Tianshan Mountains is 0.31% after the standardization of the study period. The APAC varies widely for different drainage basins, but the glaciers are in a state of rapid retreat, generally. According to the 14 meteorological sta- tions in the Chinese Tianshan Mountains, both the temperature and precipitation display a marked increasing tendency from 1960 to 2009 at a rate of 0.34℃·（10a）^-1 and 11 mm·（10a）^-1, respectively. The temperature in the dry seasons （from November to March） increases rapidly at a rate of 0.46℃·（10a）^-1, but the precipitation grows slowly at 2.3 mm·（10a）^-1. While the temperature in the wet seasons （from April to October） grows at a rate of 0.25℃·（10a）^-1, but the precipitation increases at 8.7 mm·（10a）^-1, The annual and seasonal climatic trends accelerate the retreat of glaciers.
