The stratification of the atmospheric surface layer(ASL)plays an important role in regulating the water vapor and heat exchange across the lake–air interface.Based on one year of data measured by the eddy covariance ...The stratification of the atmospheric surface layer(ASL)plays an important role in regulating the water vapor and heat exchange across the lake–air interface.Based on one year of data measured by the eddy covariance technique over Erhai Lake in 2015,the ASL stability(ζ)was divided into six ranges,including unstable(-1ζ<-0:1),weakly unstable(-0:1ζ<-0:01),near-neutral1(-0:01ζ<0),near-neutral2(0ζ<0:01),weakly stable(0:01ζ<0:1),and stable(0:1ζ<1).The characteristics of ASL stability conditions and factors controlling the latent(LE)and sensible heat(H)fluxes under different stability conditions were analyzed in this study.The stability conditions of Erhai Lake have noticeably seasonal and diurnal variation,with the nearneutral and(weakly)stable stratification usually occurring before July,with frequencies of 51.7%and 23.3%,respectively,but most of the(weakly)unstable stratification was observed after July,with a frequency of 59.8%.Large evaporation occurred even in stable atmospheric conditions,due to the coupled effects of the relatively larger lake–air vapor pressure difference and wind speed.The relative controls of LE and H by different atmospheric variables are largely dependent on the stability conditions.In stable and unstable ranges,LE is closely correlated with the vapor pressure difference,whereas in weakly unstable to weakly stable ranges,it is primarily controlled by wind speed.H is related to wind speed and the lake–air temperature difference under stable conditions,but shows no obvious relationship under unstable conditions.展开更多
The instrumentation, method and measurement results used for measurements of CO2 concentrations in surface air of Obninsk （55.1° N, 36.9° E, 183 m above the sea level） located at a distance of 105 km to th...The instrumentation, method and measurement results used for measurements of CO2 concentrations in surface air of Obninsk （55.1° N, 36.9° E, 183 m above the sea level） located at a distance of 105 km to the south-west of Moscow are presented. Proposed is a method of experimental data filtering allowing one to separate natural and anthropogenic variations of CO2 concentrations. It is shown that minimal concentrations of CO2 registered in Obninsk and at the continental stations of GAW WMO characterize not only the ＂regional background＂ but also coincide with the data from GAW WMO background stations located in the oceanic regions. In this connection, one can assume that the excess in measured CO2 concentration over its minimal values, making about 5-6 ppm, is connected with an anthropogenic emission, and the continent should be considered as an anthropogenic source of C02.展开更多
Reconstruction of ancient atmospheric conditions through the analysis of precipitation patterns is a novel endeavor in the study of paleoclimate. A new approach is now available for a quantitative reconstruction of Pa...Reconstruction of ancient atmospheric conditions through the analysis of precipitation patterns is a novel endeavor in the study of paleoclimate. A new approach is now available for a quantitative reconstruction of Paleogene atmospheric hydrological conditions in High Arctic. It is based on 1） the discovery of exceptionally-preserved Paleogene plant fossils from the Canadian Arctic which yielded in situ labile biomolecules 2） the development of compound-specific hydrogen isotope analysis which can be applied to small amount of plant material and 3） taxon-specific apparent hydrogen isotope fractionation factors obtained from empirical measurement. A new moisture recycling model is established to explain the reconstructed paleohydrologic pattern in the High Arctic during Paleogene.展开更多
基金supported by the National Key Research and Development Program of China (No. 2017YFC1502101)National Natural Science Foundation of China (Nos. 91537212 and 41775018)。
文摘The stratification of the atmospheric surface layer(ASL)plays an important role in regulating the water vapor and heat exchange across the lake–air interface.Based on one year of data measured by the eddy covariance technique over Erhai Lake in 2015,the ASL stability(ζ)was divided into six ranges,including unstable(-1ζ<-0:1),weakly unstable(-0:1ζ<-0:01),near-neutral1(-0:01ζ<0),near-neutral2(0ζ<0:01),weakly stable(0:01ζ<0:1),and stable(0:1ζ<1).The characteristics of ASL stability conditions and factors controlling the latent(LE)and sensible heat(H)fluxes under different stability conditions were analyzed in this study.The stability conditions of Erhai Lake have noticeably seasonal and diurnal variation,with the nearneutral and(weakly)stable stratification usually occurring before July,with frequencies of 51.7%and 23.3%,respectively,but most of the(weakly)unstable stratification was observed after July,with a frequency of 59.8%.Large evaporation occurred even in stable atmospheric conditions,due to the coupled effects of the relatively larger lake–air vapor pressure difference and wind speed.The relative controls of LE and H by different atmospheric variables are largely dependent on the stability conditions.In stable and unstable ranges,LE is closely correlated with the vapor pressure difference,whereas in weakly unstable to weakly stable ranges,it is primarily controlled by wind speed.H is related to wind speed and the lake–air temperature difference under stable conditions,but shows no obvious relationship under unstable conditions.
文摘The instrumentation, method and measurement results used for measurements of CO2 concentrations in surface air of Obninsk （55.1° N, 36.9° E, 183 m above the sea level） located at a distance of 105 km to the south-west of Moscow are presented. Proposed is a method of experimental data filtering allowing one to separate natural and anthropogenic variations of CO2 concentrations. It is shown that minimal concentrations of CO2 registered in Obninsk and at the continental stations of GAW WMO characterize not only the ＂regional background＂ but also coincide with the data from GAW WMO background stations located in the oceanic regions. In this connection, one can assume that the excess in measured CO2 concentration over its minimal values, making about 5-6 ppm, is connected with an anthropogenic emission, and the continent should be considered as an anthropogenic source of C02.
基金funded in part by the CAS/SAFEA International Partnership Program for Creatine Research Teams,the Pilot Project of Knowledge Innovation,CAS the Major Basis Research Projects(2006CB806400)+1 种基金the National Science Foundation of China(40402002)the American Chemical Society Petroleum Research Funds,and a NASA RI Space Grant
文摘Reconstruction of ancient atmospheric conditions through the analysis of precipitation patterns is a novel endeavor in the study of paleoclimate. A new approach is now available for a quantitative reconstruction of Paleogene atmospheric hydrological conditions in High Arctic. It is based on 1） the discovery of exceptionally-preserved Paleogene plant fossils from the Canadian Arctic which yielded in situ labile biomolecules 2） the development of compound-specific hydrogen isotope analysis which can be applied to small amount of plant material and 3） taxon-specific apparent hydrogen isotope fractionation factors obtained from empirical measurement. A new moisture recycling model is established to explain the reconstructed paleohydrologic pattern in the High Arctic during Paleogene.
