By means of ERA-40, JRA-25, NCEP/NCAR and NCEP/DOE reanalysis data, empirical relations between precipitable water and surface vapor pressure in spatial and temporal scale were calculated. The reliabilities of precipi...By means of ERA-40, JRA-25, NCEP/NCAR and NCEP/DOE reanalysis data, empirical relations between precipitable water and surface vapor pressure in spatial and temporal scale were calculated. The reliabilities of precipitable water from reanalysis data were validated based on comparing different W-e empirical relations of various reanalysis data, in order to provide basis and reference for reasonable application. The results showed that W-e empirical relation of ERA-40 was closest to that of sounding data in China, and precipitable water from ERA-40 was the most credible. The worldwide comparison among W-e empirical relations of four reanalysis data showed that there was little difference in annual mean W-e empirical relations in the middle latitudes and great differences in low and high latitudes. Seasonal mean W-e empirical relations in the middle latitudes of the northern Hemisphere had little difference in spring, autumn and winter, but great difference in summer. Therefore, the reliabilities of precipitable water from reanalysis data in spring, autumn and winter in the middle latitudes of the northern hemisphere were higher than other areas and seasons. W-e empirical relations of NCEP/NCAR and NCEP/DOE had good stability in different years, while there was poor stability in ERA-40 and JRA-25.展开更多
Concordance study between two laboratories testing clinical samples is important to a clinical program to assess the comparability of test results, especially when the two laboratories performed the same test at diffe...Concordance study between two laboratories testing clinical samples is important to a clinical program to assess the comparability of test results, especially when the two laboratories performed the same test at different locations. Assays that measure immune response should not be compared using the simple linear regression model; instead literature publications recommend an ＂errors-in-variables＂ model that accounts for the variability in these assays （Home, 1998）. In this paper, concordance slope and intercept was estimated using the statistical linear relationship （Tan and Iglewicz, 1999） for various tests between laboratories. The confidence bounds for the concordance line were used to assess the impact on vaccine booster thresholds when a consistent bias was observed between the results generated by two laboratories.展开更多
Alpine cold ecosystem with permafrost environment is quite sensitive to climatic changes and the changes in permafrost can significantly affect the alpine ecosystem.The vegetation coverage,grassland biomass and soil n...Alpine cold ecosystem with permafrost environment is quite sensitive to climatic changes and the changes in permafrost can significantly affect the alpine ecosystem.The vegetation coverage,grassland biomass and soil nutrient and texture are selected to indicate the regime of alpine cold ecosystems in the Qinghai-Tibet Plateau.The interactions between alpine ecosystem and permafrost were investigated with the depth of active layer,permafrost thickness and mean annual ground temperature(MAGTs).Based on the statistics model of GPTR for MAGTs and annual air temperatures,an analysis method was developed to analyze the impacts of permafrost changes on the alpine ecosystems.Under the climate change and human engineering activities,the permafrost change and its impacts on alpine ecosystems in the permafrost region between the Kunlun Mountains and the Tanggula Range of Qinghai-Tibet Plateau are studied in this paper.The results showed that the per-mafrost changes have a different influence on different alpine ecosystems.With the increase in the thickness of active layer,the vegetation cover and biomass of the alpine cold meadow exhibit a significant conic reduction,the soil organic matter content of the alpine cold meadow ecosystem shows an exponential decrease,and the surface soil materials become coarse and gravelly.The alpine cold steppe ecosystem,however,seems to have a relatively weak relation to the permafrost environment.Those relationships resulted in the fact that the distribution area of alpine cold meadow decreased by 7.98%and alpine cold swamp decreased by 28.11%under the permafrost environment degradation during recent 15 years.In the future 50 years the alpine cold meadow ecosystems in different geomorphologic units may have different responses to the changes of the permafrost under different climate warming conditions,among them the alpine cold meadow and swamp ecosystem located in the low mountain and plateau area will have a relatively serious degradation.Furthermore,from the angles of grassland coverage and biological production the variation characteristics of high-cold eco-systems in different representative regions and different geomorphologic units under different climatic conditions were quantitatively assessed.In the future,adopting effective measures to protect permafrost is of vital importance to maintaining the stability of permafrost engineering and alpine cold eco-systems in the plateau.展开更多
基金Supported by National Natural Science Foundation of China (40775048)Major State Basic Research Development Program (2006CB400504)National Key Technology R & D Program (2007BAC294)
文摘By means of ERA-40, JRA-25, NCEP/NCAR and NCEP/DOE reanalysis data, empirical relations between precipitable water and surface vapor pressure in spatial and temporal scale were calculated. The reliabilities of precipitable water from reanalysis data were validated based on comparing different W-e empirical relations of various reanalysis data, in order to provide basis and reference for reasonable application. The results showed that W-e empirical relation of ERA-40 was closest to that of sounding data in China, and precipitable water from ERA-40 was the most credible. The worldwide comparison among W-e empirical relations of four reanalysis data showed that there was little difference in annual mean W-e empirical relations in the middle latitudes and great differences in low and high latitudes. Seasonal mean W-e empirical relations in the middle latitudes of the northern Hemisphere had little difference in spring, autumn and winter, but great difference in summer. Therefore, the reliabilities of precipitable water from reanalysis data in spring, autumn and winter in the middle latitudes of the northern hemisphere were higher than other areas and seasons. W-e empirical relations of NCEP/NCAR and NCEP/DOE had good stability in different years, while there was poor stability in ERA-40 and JRA-25.
文摘Concordance study between two laboratories testing clinical samples is important to a clinical program to assess the comparability of test results, especially when the two laboratories performed the same test at different locations. Assays that measure immune response should not be compared using the simple linear regression model; instead literature publications recommend an ＂errors-in-variables＂ model that accounts for the variability in these assays （Home, 1998）. In this paper, concordance slope and intercept was estimated using the statistical linear relationship （Tan and Iglewicz, 1999） for various tests between laboratories. The confidence bounds for the concordance line were used to assess the impact on vaccine booster thresholds when a consistent bias was observed between the results generated by two laboratories.
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.30270255 and No.90511003)the"Hundred Talents"Project of the Chinese Academy of Sciences under the leadership of Wang Genxuthe State Key Project(973)(Grant No.2003CB415201).
文摘Alpine cold ecosystem with permafrost environment is quite sensitive to climatic changes and the changes in permafrost can significantly affect the alpine ecosystem.The vegetation coverage,grassland biomass and soil nutrient and texture are selected to indicate the regime of alpine cold ecosystems in the Qinghai-Tibet Plateau.The interactions between alpine ecosystem and permafrost were investigated with the depth of active layer,permafrost thickness and mean annual ground temperature(MAGTs).Based on the statistics model of GPTR for MAGTs and annual air temperatures,an analysis method was developed to analyze the impacts of permafrost changes on the alpine ecosystems.Under the climate change and human engineering activities,the permafrost change and its impacts on alpine ecosystems in the permafrost region between the Kunlun Mountains and the Tanggula Range of Qinghai-Tibet Plateau are studied in this paper.The results showed that the per-mafrost changes have a different influence on different alpine ecosystems.With the increase in the thickness of active layer,the vegetation cover and biomass of the alpine cold meadow exhibit a significant conic reduction,the soil organic matter content of the alpine cold meadow ecosystem shows an exponential decrease,and the surface soil materials become coarse and gravelly.The alpine cold steppe ecosystem,however,seems to have a relatively weak relation to the permafrost environment.Those relationships resulted in the fact that the distribution area of alpine cold meadow decreased by 7.98%and alpine cold swamp decreased by 28.11%under the permafrost environment degradation during recent 15 years.In the future 50 years the alpine cold meadow ecosystems in different geomorphologic units may have different responses to the changes of the permafrost under different climate warming conditions,among them the alpine cold meadow and swamp ecosystem located in the low mountain and plateau area will have a relatively serious degradation.Furthermore,from the angles of grassland coverage and biological production the variation characteristics of high-cold eco-systems in different representative regions and different geomorphologic units under different climatic conditions were quantitatively assessed.In the future,adopting effective measures to protect permafrost is of vital importance to maintaining the stability of permafrost engineering and alpine cold eco-systems in the plateau.
