Based on regular surface meteorological observations and NCEP/DOE reanalysis data, this study investigates the evolution of surface sensible heat（SH） over the central and eastern Tibetan Plateau（CE-TP） under the r...Based on regular surface meteorological observations and NCEP/DOE reanalysis data, this study investigates the evolution of surface sensible heat（SH） over the central and eastern Tibetan Plateau（CE-TP） under the recent global warming hiatus. The results reveal that the SH over the CE-TP presents a recovery since the slowdown of the global warming. The restored surface wind speed together with increased difference in ground-air temperature contribute to the recovery in SH.During the global warming hiatus, the persistent weakening wind speed is alleviated due to the variation of the meridional temperature gradient. Meanwhile, the ground surface temperature and the difference in ground-air temperature show a significant increasing trend in that period caused by the increased total cloud amount, especially at night. At nighttime, the increased total cloud cover reduces the surface effective radiation via a strengthening of atmospheric counter radiation and subsequently brings about a clear upward trend in ground surface temperature and the difference in ground-air temperature.Cloud–radiation feedback plays a significant role in the evolution of the surface temperature and even SH during the global warming hiatus. Consequently, besides the surface wind speed, the difference in ground-air temperature becomes another significant factor for the variation in SH since the slowdown of global warming, particularly at night.展开更多
[目的]评价黄河下游水资源生态承载状态,为地区水资源管理与规划提供理论依据。[方法]运用水资源生态足迹理论结合对数均值迪式指数分解法(logarithmic mean divisia index,LMDI)对2007—2020年黄河下游水资源生态足迹的时空分布特征及...[目的]评价黄河下游水资源生态承载状态,为地区水资源管理与规划提供理论依据。[方法]运用水资源生态足迹理论结合对数均值迪式指数分解法(logarithmic mean divisia index,LMDI)对2007—2020年黄河下游水资源生态足迹的时空分布特征及驱动机制进行核算分析,并通过灰色预测模型GM(1,1)对2021—2030年的水资源生态足迹变化趋势进行预测。[结果]黄河下游历年水资源生态足迹远高于生态承载力,水资源生态赤字现象严重;水资源生态足迹与生态赤字年际间均呈波动降低趋势,用水效率逐渐提高,农业用水是最大的水资源生态足迹账户;黄河三角洲是黄河下游水资源生态压力最大的区域,淄博、济南、郑州和泰安4市的生态压力相对较小;经济效应对黄河下游水资源生态足迹变化起正向主导作用,技术效应起负向主导作用;预测结果表明,2021—2030年黄河下游人均水资源生态赤字由0.387 hm^(2)/人降至0.359 hm^(2)/人。[结论]在生产力快速发展和用水结构优化调整等综合作用下,黄河下游地区用水效率逐渐提高,水资源生态压力有一定幅度的缓解。但由于该区域水资源生态赤字基数较大,未来水资源可持续利用形势依旧十分严峻,亟待进一步加强水资源的统筹管理,助力黄河下游地区高质量可持续发展。展开更多
The intensification of estrogen non-point source pollution has drawn global attention due to their contribution to ecological environment problems worldwide,and it is critical to develop effective,economic and eco-fri...The intensification of estrogen non-point source pollution has drawn global attention due to their contribution to ecological environment problems worldwide,and it is critical to develop effective,economic and eco-friendly methods for reducing estrogens pollution.To address the agglomeration and oxidation of nano zero-valent iron(nZVI),biochar-nanoscale zero-valent iron composite(nZVI-biochar)could be a feasible choice for estrogens removal.This study summarized biochar and nZVI-biochar preparation,characterization,and unusual applications for estrone(E1),17β-estradiol(E2),and estriol(E3)removal.The properties of biochar and nZVI-biochar in characterization,effects of influencing factors on the removal efficiency,adsorption kinetics,isotherm and thermodynamics were investigated.The experiment results showed that nZVI-biochar exhibited the superior removal performance for estrogens pollutants compared to biochar.Based on the quasi-second-order model,estrogens adsorption kinetics were observed,which supported the mechanism that chemical and physical adsorption existed simultaneously on estrogens removal.The adsorption isotherm of estrogens could be well presented by the Freundlich model and thermodynamics studies explained that nZVI-biochar could spontaneously remove estrogens pollutants and the main mechanisms involvedπ-πinteraction,hydrophobic interaction,hydrogen bonding and degradation through ring rupture.The products analyzed by GC-MS showed that estrogens degradation was primarily attributed to the benzene ring broken,and Fe^(3+)promoted the production of free radicals,which further proved that nZVI-biochar had the excellent adsorption performances.Generally,nZVI-biochar could be employed as a potential material for removing estrogens from wastewater.展开更多
The spatial and temporal variations of the vegetation carbon flux in China from 1901 to 2005 were studied using the vegetation net primary production(NPP)values from seven Earth-system models.In addition,the temporal ...The spatial and temporal variations of the vegetation carbon flux in China from 1901 to 2005 were studied using the vegetation net primary production(NPP)values from seven Earth-system models.In addition,the temporal and spatial changes in the nitrogen deposition flux in China were studied using the NHx and NOy fluxes from 1901 to 2005.The relationship between changes in the carbon flux,nitrogen flux and climate was analyzed.The results show that(1)over the past 100 years,NPP in China has shown an upward trend.The average trend coefficient is 0.88 and the NPP distribution trend is generally low in the north and high in the south,with a gradual increase from the northwest to the southeast.Temperature,precipitation and radiation are all conducive to plant growth in the direction of the gradient.The correlation coefficients between the ensemble model mean NPP and temperature,precipitation,longwave radiation and shortwave radiation are 0.88,0.73,0.91 and 0.67,respectively.(2)In the past 100 years,the NHx and NOy fluxes in China have shown an upward trend,with trend coefficients of 0.98 and 0.98,respectively,which pass the 99.9%confidence level of the t-test.NHx and NOy fluxes are also generally low in the north and high in the south,with a gradual increase from the northwest to the southeast in a step-like pattern.(3)The spatial distribution of the correlation coefficients between the NHx and NOy fluxes and air temperature is similar,with only slight differences in values.The spatial distribution of the correlation coefficients between the NHx and NOy fluxes and precipitation is similar in overall pattern,but the pattern is relatively complicated,with a positive-negative-positive-negative-positive pattern occurring across the monsoon region from north to south,and a negative-positive-negative-positive pattern occurring beyond the monsoon region from east to west.(4)The spatial distribution of the correlation coefficients between the NHx and NOy fluxes and NPP shows a generally consistent pattern,but the pattern is re展开更多
Trends and uncertainties of surface air temperature over the Tibetan Plateau（TP）are evaluated by using observations at 100 meteorological stations during the period 1951–2013.The sampling error variances of gridded...Trends and uncertainties of surface air temperature over the Tibetan Plateau（TP）are evaluated by using observations at 100 meteorological stations during the period 1951–2013.The sampling error variances of gridded monthly data are estimated for every month and every grid box of data.The gridded data and their sampling error variances are used to calculate TP averages,their trends,and associated uncertainties.It is shown that large sampling error variances dominate northern and western TP,while small variances appear over southern and eastern TP.Every month from January to December has a positive linear trend during the study period.February has the largest trend of 0.34±0.18°C（10 yr）^（–1）,and April the smallest at 0.15±0.11°C（10 yr）^（–1）.The uncertainties decrease steadily with time,implying that they are not large enough to alter the TP warming trend.展开更多
Using daily temperature data from 599 Chinese weather stations during 1961-2007, the length change trends of four seasons dur- ing the past 47 years were analyzed. Results show that throughout the region, four seasons...Using daily temperature data from 599 Chinese weather stations during 1961-2007, the length change trends of four seasons dur- ing the past 47 years were analyzed. Results show that throughout the region, four seasons＇ lengths are： spring becomes shorter （-0.8 d/10yrs）, summer becomes longer （3.2 d/10yrs）, autumn （-0.5 d/10yrs） and winter （-1.6 d/10yrs） becomes shorter. This trend is different in spatial distribution, namely it is very obvious in northern than southern China, and also remarkable in eastern than western China. Summer change is most obvious, but autumn has little change comparatively. This trend is highly obvious in North, East, Central and South China. In the Southwest starting in the 21st century, summer becomes longer and winter shortens. The trend in the Plateau region since the 1980s is that spring becomes longer and winter shortens. The average annual temperature increased during the past 47 years, and the change of the average annual temperature precedes seasons＇ length. Thus, the average annual temperature has a certain influence on the length change of seasons.展开更多
Severe air pollution with visibility deterioration has long been a focus in the North China Plain(NCP).In this study,concentration and light extinction analysis of PM_(2.5)chemical components were carried out from 201...Severe air pollution with visibility deterioration has long been a focus in the North China Plain(NCP).In this study,concentration and light extinction analysis of PM_(2.5)chemical components were carried out from 2014 to 2017 to study the pollution characteristics in Baoding,a case city of the NCP.The annual average concentration of total PM_(2.5)components showed a declining trend,decreasing by 11μg m^(−3)(water-soluble inorganic ions),23μg m^(−3)(carbonaceous aerosols),and 1796 ng m^(−3)(inorganic elements).Contributing 82.9%to the concentration of total ions,the dominant components,NH 4+,NO 3−,and SO_(4)^(2−)became the main pollutants in PM_(2.5)pollution.Based on the IMPROVE algorithm,the average reconstructed PM_(2.5)mass concentration was 93±69μg m^(−3)during the observation period.Meanwhile,the light extinction coefficients were 373.8±233.6 M^(m−1),405.3±300.1M^(m−1),554.3±378.2M^(m−1)and 1005.2±750.3M^(m−1),in spring,summer,autumn,and winter,respectively.Ammonium sulfate,ammonium nitrate,and organic matter were the largest contributors to light extinction,accounting for a total of 55%–77%in the four seasons.The b sca(light scattering by particles and gases)reconstructed from PM_(2.5)components(Rb_(sca))and the b sca converted from visibility(Vb_(sca))were compared to evaluate the performance of the IMPROVE algorithm,revealing a high correlation coefficient of 0.84.The high values of Vb_(sca)were underestimated while the low values were overestimated,as determined through comparison with the one-to-ne line.Especially,when Rb_(sca)>1123M^(m−1)(corresponding to<2.0 km,approximately),Vb_(sca)was underestimated by 17.6%.PM_(2.5)mass concentration and relative humidity also had an impact on the estimation.展开更多
The North American Dipole(NAD)is a north-south seesaw pattern of sea level pressure anomalies over the western tropical North Atlantic and northeastern North America.Previous observational studies have demonstrated th...The North American Dipole(NAD)is a north-south seesaw pattern of sea level pressure anomalies over the western tropical North Atlantic and northeastern North America.Previous observational studies have demonstrated that the NAD can affect the outbreak of El Niño-Southern Oscillation(ENSO)events.The present study analyzed the NAD-ENSO relationship as simulated by a coupled ocean-atmosphere model-namely,the Flexible Global Ocean-Atmosphere-Land System model,gridpoint version 2(FGOALS-g2).Results indicated that the model can replicate a distinct dipole comprised of a low over northeastern North America and a high over the western tropical North Atlantic,which is the signature feature of the NAD.Further analysis verified that the winter NAD can initiate the central equatorial Pacific warming in the subsequent winter by effectively forcing an anticyclonic flow and sea surface temperature(SST)warming over the northeastern subtropical Pacific(NESP)during late winter or early spring.In addition,the probability of an El Niño event was increased by a factor of 1.8 in the assimilation experiment with the NAD.By comparison,the winter Northern Atlantic Oscillation had no significant impact on the occurrence of ENSO a year later owing to its failure to induce the SST and surface wind anomalies over the NESP.展开更多
The differences in the influences of the North Atlantic Oscillation (NAO) on the air–sea CO2 fluxes (fCO2) in the North Atlantic (NA) between different seasons and between different regions are rarely fully investiga...The differences in the influences of the North Atlantic Oscillation (NAO) on the air–sea CO2 fluxes (fCO2) in the North Atlantic (NA) between different seasons and between different regions are rarely fully investigated. We used observation-based data of fCO2, surface-ocean CO2 partial pressure (pCO2sea), wind speed and sea surface temperature (SST) to analyze the relationship between the NAO and fCO2 of the subtropical and subpolar NA in winter and summer on the interannual time scale. Based on power spectrum estimation, there are significant interannual signs with a 2–6 year cycle in the NAO indexes and area-averaged fCO2 anomalies in winter and summer from 1980 to 2015. Regression analysis with the 2–6 year filtered data shows that on the interannual scale the response of the fCO2 anomalies to the NAO has an obvious meridional wave-train-like pattern in winter, but a zonal distribution in summer. This seasonal difference is because in winter the fCO2 anomalies are mainly controlled by the NAO-driven wind speed anomalies, which have a meridional distribution pattern, while in summer they are dominated by the NAO-driven SST anomalies, which show distinct zonal difference in the subtropical NA. In addition, in the same season, there are different factors controlling the variation of pCO2sea in different regions. In summer, SST is important to the interannual variation of pCO2sea in the subtropical NA, while some biogeochemical variables probably control the pCO2sea variation in the subpolar NA.展开更多
Purposes: To observe the characteristics of local electroretinogram (LERG) in normal subjects and patients with maculopathies, and to evaluate the applied worth of LERG and pattern visual evoked potential (PVEP) in ma...Purposes: To observe the characteristics of local electroretinogram (LERG) in normal subjects and patients with maculopathies, and to evaluate the applied worth of LERG and pattern visual evoked potential (PVEP) in maculopathies. Methods: LERGs at 5° and 15° macular regions were recorded from 27 normal subjects (54 eyes). The factors of age, different eyes and stimulate areas for LERG influence were observed. Meanwhile, the LERG and PVEP were recorded from 25 patients (35 eyes) with maculopathies for making contrast study. Results: In normal subjects, there was no significant influence of age to LERG. As the stimulated areas increased, the a- and b-wave amplitudes of LERG increased. In the patients with maculopathies, the a- and b-wave amplitudes of LERG at 5°, 10°and 15° macular regions were significantly lowered and the mean values of P1 latency were prolonged and N1-P1 amplitudes of VEP were lowered, comparing with the control group. In the nearing stimulated area (5°LERG and 14. 9×19°PVEP.),展开更多
Knowledge of the structure of the Tibetan Plateau vortex （TPV） is of considerable importance for understanding the generation and development mechanisms of this mesoscale system. However, our understanding of vortex...Knowledge of the structure of the Tibetan Plateau vortex （TPV） is of considerable importance for understanding the generation and development mechanisms of this mesoscale system. However, our understanding of vortex struc- tures and our ability to classify them on a physical basis is limited due to insufficient observations. The high- resolution new-generation NCEP-CFSR （Climate Forecast System Reanalysis） dataset is used in the present paper to investigate the general structural features of various types of mature TPV through classification and composite struc- ture analysis. Results indicate that the dynamic and thermodynamic structures show regional and seasonal depend- ency, as well as being influenced by attributes of translation, associated precipitation, and the South Asian high （SAH）. The common precipitating TPV （type I）, frequently occurring in the west-east-oriented zonal region between 33° and 36°N, is a notably low-level baroclinic and asymmetric system. It resides within a large-scale confluent zone and preferentially travels eastward, potentially moving out of the plateau. The heavy rain vortex （type II） corresponds to a deep vortex circulation occurring in midsummer. The low-level baroclinic sub-category （type IIa） is associated with a low-level jet and mainly originates in the area 32°-35°N, 86°-94°E, preferentially moving east of 90°E and even away from the plateau; meanwhile, the nearly upright sub-category （type IIb）, which has a cold center at low levels and a warm center at mid-upper levels, is a quasi-stationary and quasi-symmetric system favorably occurring west of 92°E. A western-pattern SAH exists in the upper troposphere for these two sub-categories. The springtime dry vortex in the western plateau （type III） is warm and shallow （approximately 100 hPa deep）, and zonal circulation dominates the large-scale environmental flows in the middle and upper troposphere. The precipitating vortex in the southern plateau occurring during July-August （t展开更多
基金supported by the National Natural Science Foundation of China(41425019,41661144016,91537214)the Public Science and Technology Research Funds Projects of the Ocean(201505013)
文摘Based on regular surface meteorological observations and NCEP/DOE reanalysis data, this study investigates the evolution of surface sensible heat（SH） over the central and eastern Tibetan Plateau（CE-TP） under the recent global warming hiatus. The results reveal that the SH over the CE-TP presents a recovery since the slowdown of the global warming. The restored surface wind speed together with increased difference in ground-air temperature contribute to the recovery in SH.During the global warming hiatus, the persistent weakening wind speed is alleviated due to the variation of the meridional temperature gradient. Meanwhile, the ground surface temperature and the difference in ground-air temperature show a significant increasing trend in that period caused by the increased total cloud amount, especially at night. At nighttime, the increased total cloud cover reduces the surface effective radiation via a strengthening of atmospheric counter radiation and subsequently brings about a clear upward trend in ground surface temperature and the difference in ground-air temperature.Cloud–radiation feedback plays a significant role in the evolution of the surface temperature and even SH during the global warming hiatus. Consequently, besides the surface wind speed, the difference in ground-air temperature becomes another significant factor for the variation in SH since the slowdown of global warming, particularly at night.
基金Study on Colloidal Coagulation and Heavy Metal Adsorption Mechanism of Sediment River(No.42007158)Study on the distribution characteristics of birds and the reduction technology of typical pollutants in their habitats in the Yellow River basin(Henan section)(No.23B180008)supported this research.
文摘The intensification of estrogen non-point source pollution has drawn global attention due to their contribution to ecological environment problems worldwide,and it is critical to develop effective,economic and eco-friendly methods for reducing estrogens pollution.To address the agglomeration and oxidation of nano zero-valent iron(nZVI),biochar-nanoscale zero-valent iron composite(nZVI-biochar)could be a feasible choice for estrogens removal.This study summarized biochar and nZVI-biochar preparation,characterization,and unusual applications for estrone(E1),17β-estradiol(E2),and estriol(E3)removal.The properties of biochar and nZVI-biochar in characterization,effects of influencing factors on the removal efficiency,adsorption kinetics,isotherm and thermodynamics were investigated.The experiment results showed that nZVI-biochar exhibited the superior removal performance for estrogens pollutants compared to biochar.Based on the quasi-second-order model,estrogens adsorption kinetics were observed,which supported the mechanism that chemical and physical adsorption existed simultaneously on estrogens removal.The adsorption isotherm of estrogens could be well presented by the Freundlich model and thermodynamics studies explained that nZVI-biochar could spontaneously remove estrogens pollutants and the main mechanisms involvedπ-πinteraction,hydrophobic interaction,hydrogen bonding and degradation through ring rupture.The products analyzed by GC-MS showed that estrogens degradation was primarily attributed to the benzene ring broken,and Fe^(3+)promoted the production of free radicals,which further proved that nZVI-biochar had the excellent adsorption performances.Generally,nZVI-biochar could be employed as a potential material for removing estrogens from wastewater.
基金the National Natural Science Foundation of China[grant number 42275022]the Second Tibetan Plateau Scientific Expedition and Research Program[grant number 2019QZKK010203]+1 种基金the Sichuan Natural Science Foundation[grant number 2022NSFSC1092]the Scientific and Technological Innovation Capacity Improvement Project of Chengdu University of Information Technology[KYQN202202].
基金supported by the National Natural Science Foundation of China(Grant Nos.41630532&41575093)the National Key Research and Development Program of China(Grant Nos.2016YFA0602501&2018YFA0606004).
文摘The spatial and temporal variations of the vegetation carbon flux in China from 1901 to 2005 were studied using the vegetation net primary production(NPP)values from seven Earth-system models.In addition,the temporal and spatial changes in the nitrogen deposition flux in China were studied using the NHx and NOy fluxes from 1901 to 2005.The relationship between changes in the carbon flux,nitrogen flux and climate was analyzed.The results show that(1)over the past 100 years,NPP in China has shown an upward trend.The average trend coefficient is 0.88 and the NPP distribution trend is generally low in the north and high in the south,with a gradual increase from the northwest to the southeast.Temperature,precipitation and radiation are all conducive to plant growth in the direction of the gradient.The correlation coefficients between the ensemble model mean NPP and temperature,precipitation,longwave radiation and shortwave radiation are 0.88,0.73,0.91 and 0.67,respectively.(2)In the past 100 years,the NHx and NOy fluxes in China have shown an upward trend,with trend coefficients of 0.98 and 0.98,respectively,which pass the 99.9%confidence level of the t-test.NHx and NOy fluxes are also generally low in the north and high in the south,with a gradual increase from the northwest to the southeast in a step-like pattern.(3)The spatial distribution of the correlation coefficients between the NHx and NOy fluxes and air temperature is similar,with only slight differences in values.The spatial distribution of the correlation coefficients between the NHx and NOy fluxes and precipitation is similar in overall pattern,but the pattern is relatively complicated,with a positive-negative-positive-negative-positive pattern occurring across the monsoon region from north to south,and a negative-positive-negative-positive pattern occurring beyond the monsoon region from east to west.(4)The spatial distribution of the correlation coefficients between the NHx and NOy fluxes and NPP shows a generally consistent pattern,but the pattern is re
基金Supported by the National Natural Science Foundation of China(41405069,91537214,41275079,41305077,41605063,and41505078)Key Foundation of the Education Department of Sichuan Province(16ZA0203)+1 种基金China Meteorological Administration Special Public Welfare Research Fund(GYHY201506001)Scientific Research Fund of Chengdu University of Information Technology(KYTZ201517,J201516,and J201518)
文摘Trends and uncertainties of surface air temperature over the Tibetan Plateau（TP）are evaluated by using observations at 100 meteorological stations during the period 1951–2013.The sampling error variances of gridded monthly data are estimated for every month and every grid box of data.The gridded data and their sampling error variances are used to calculate TP averages,their trends,and associated uncertainties.It is shown that large sampling error variances dominate northern and western TP,while small variances appear over southern and eastern TP.Every month from January to December has a positive linear trend during the study period.February has the largest trend of 0.34±0.18°C（10 yr）^（–1）,and April the smallest at 0.15±0.11°C（10 yr）^（–1）.The uncertainties decrease steadily with time,implying that they are not large enough to alter the TP warming trend.
基金supported by the National Natural Science Foundation of China (Grant No. 40875053)
文摘Using daily temperature data from 599 Chinese weather stations during 1961-2007, the length change trends of four seasons dur- ing the past 47 years were analyzed. Results show that throughout the region, four seasons＇ lengths are： spring becomes shorter （-0.8 d/10yrs）, summer becomes longer （3.2 d/10yrs）, autumn （-0.5 d/10yrs） and winter （-1.6 d/10yrs） becomes shorter. This trend is different in spatial distribution, namely it is very obvious in northern than southern China, and also remarkable in eastern than western China. Summer change is most obvious, but autumn has little change comparatively. This trend is highly obvious in North, East, Central and South China. In the Southwest starting in the 21st century, summer becomes longer and winter shortens. The trend in the Plateau region since the 1980s is that spring becomes longer and winter shortens. The average annual temperature increased during the past 47 years, and the change of the average annual temperature precedes seasons＇ length. Thus, the average annual temperature has a certain influence on the length change of seasons.
基金supported by the National Key Research and Development Program of China grant number 2016YFC0202001the Chinese Academy of Sciences Strategic Priority Research Program grant number XDA23020301+1 种基金the National Natural Science Foundation of China grant numbers 41375036 and 91644226the National Key Research and Development Program of China grant number2018YFC0214002。
文摘Severe air pollution with visibility deterioration has long been a focus in the North China Plain(NCP).In this study,concentration and light extinction analysis of PM_(2.5)chemical components were carried out from 2014 to 2017 to study the pollution characteristics in Baoding,a case city of the NCP.The annual average concentration of total PM_(2.5)components showed a declining trend,decreasing by 11μg m^(−3)(water-soluble inorganic ions),23μg m^(−3)(carbonaceous aerosols),and 1796 ng m^(−3)(inorganic elements).Contributing 82.9%to the concentration of total ions,the dominant components,NH 4+,NO 3−,and SO_(4)^(2−)became the main pollutants in PM_(2.5)pollution.Based on the IMPROVE algorithm,the average reconstructed PM_(2.5)mass concentration was 93±69μg m^(−3)during the observation period.Meanwhile,the light extinction coefficients were 373.8±233.6 M^(m−1),405.3±300.1M^(m−1),554.3±378.2M^(m−1)and 1005.2±750.3M^(m−1),in spring,summer,autumn,and winter,respectively.Ammonium sulfate,ammonium nitrate,and organic matter were the largest contributors to light extinction,accounting for a total of 55%–77%in the four seasons.The b sca(light scattering by particles and gases)reconstructed from PM_(2.5)components(Rb_(sca))and the b sca converted from visibility(Vb_(sca))were compared to evaluate the performance of the IMPROVE algorithm,revealing a high correlation coefficient of 0.84.The high values of Vb_(sca)were underestimated while the low values were overestimated,as determined through comparison with the one-to-ne line.Especially,when Rb_(sca)>1123M^(m−1)(corresponding to<2.0 km,approximately),Vb_(sca)was underestimated by 17.6%.PM_(2.5)mass concentration and relative humidity also had an impact on the estimation.
基金jointly supported by the National Natural Science Foundation of China[grant number 41975070]the State Key Labo-ratory of Tropical Oceanography,South China Sea Institute of Oceanol-ogy,Chinese Academy of Sciences[project number LTO1901].
文摘The North American Dipole(NAD)is a north-south seesaw pattern of sea level pressure anomalies over the western tropical North Atlantic and northeastern North America.Previous observational studies have demonstrated that the NAD can affect the outbreak of El Niño-Southern Oscillation(ENSO)events.The present study analyzed the NAD-ENSO relationship as simulated by a coupled ocean-atmosphere model-namely,the Flexible Global Ocean-Atmosphere-Land System model,gridpoint version 2(FGOALS-g2).Results indicated that the model can replicate a distinct dipole comprised of a low over northeastern North America and a high over the western tropical North Atlantic,which is the signature feature of the NAD.Further analysis verified that the winter NAD can initiate the central equatorial Pacific warming in the subsequent winter by effectively forcing an anticyclonic flow and sea surface temperature(SST)warming over the northeastern subtropical Pacific(NESP)during late winter or early spring.In addition,the probability of an El Niño event was increased by a factor of 1.8 in the assimilation experiment with the NAD.By comparison,the winter Northern Atlantic Oscillation had no significant impact on the occurrence of ENSO a year later owing to its failure to induce the SST and surface wind anomalies over the NESP.
基金supported jointly by the National Key Research and Development Program of China (Grant No. 2016YFB0200800)the National Natural Science Foundation of China (Grant No. 41530426)
文摘The differences in the influences of the North Atlantic Oscillation (NAO) on the air–sea CO2 fluxes (fCO2) in the North Atlantic (NA) between different seasons and between different regions are rarely fully investigated. We used observation-based data of fCO2, surface-ocean CO2 partial pressure (pCO2sea), wind speed and sea surface temperature (SST) to analyze the relationship between the NAO and fCO2 of the subtropical and subpolar NA in winter and summer on the interannual time scale. Based on power spectrum estimation, there are significant interannual signs with a 2–6 year cycle in the NAO indexes and area-averaged fCO2 anomalies in winter and summer from 1980 to 2015. Regression analysis with the 2–6 year filtered data shows that on the interannual scale the response of the fCO2 anomalies to the NAO has an obvious meridional wave-train-like pattern in winter, but a zonal distribution in summer. This seasonal difference is because in winter the fCO2 anomalies are mainly controlled by the NAO-driven wind speed anomalies, which have a meridional distribution pattern, while in summer they are dominated by the NAO-driven SST anomalies, which show distinct zonal difference in the subtropical NA. In addition, in the same season, there are different factors controlling the variation of pCO2sea in different regions. In summer, SST is important to the interannual variation of pCO2sea in the subtropical NA, while some biogeochemical variables probably control the pCO2sea variation in the subpolar NA.
文摘Purposes: To observe the characteristics of local electroretinogram (LERG) in normal subjects and patients with maculopathies, and to evaluate the applied worth of LERG and pattern visual evoked potential (PVEP) in maculopathies. Methods: LERGs at 5° and 15° macular regions were recorded from 27 normal subjects (54 eyes). The factors of age, different eyes and stimulate areas for LERG influence were observed. Meanwhile, the LERG and PVEP were recorded from 25 patients (35 eyes) with maculopathies for making contrast study. Results: In normal subjects, there was no significant influence of age to LERG. As the stimulated areas increased, the a- and b-wave amplitudes of LERG increased. In the patients with maculopathies, the a- and b-wave amplitudes of LERG at 5°, 10°and 15° macular regions were significantly lowered and the mean values of P1 latency were prolonged and N1-P1 amplitudes of VEP were lowered, comparing with the control group. In the nearing stimulated area (5°LERG and 14. 9×19°PVEP.),
基金Supported by the National Natural Science Foundation of China(41305042)Major Research Plan of the National Natural Science Foundation of China(91537214 and 91644226)Scientific Research Talents Fund of Chengdu University of Information Technology(J201412)
文摘Knowledge of the structure of the Tibetan Plateau vortex （TPV） is of considerable importance for understanding the generation and development mechanisms of this mesoscale system. However, our understanding of vortex struc- tures and our ability to classify them on a physical basis is limited due to insufficient observations. The high- resolution new-generation NCEP-CFSR （Climate Forecast System Reanalysis） dataset is used in the present paper to investigate the general structural features of various types of mature TPV through classification and composite struc- ture analysis. Results indicate that the dynamic and thermodynamic structures show regional and seasonal depend- ency, as well as being influenced by attributes of translation, associated precipitation, and the South Asian high （SAH）. The common precipitating TPV （type I）, frequently occurring in the west-east-oriented zonal region between 33° and 36°N, is a notably low-level baroclinic and asymmetric system. It resides within a large-scale confluent zone and preferentially travels eastward, potentially moving out of the plateau. The heavy rain vortex （type II） corresponds to a deep vortex circulation occurring in midsummer. The low-level baroclinic sub-category （type IIa） is associated with a low-level jet and mainly originates in the area 32°-35°N, 86°-94°E, preferentially moving east of 90°E and even away from the plateau; meanwhile, the nearly upright sub-category （type IIb）, which has a cold center at low levels and a warm center at mid-upper levels, is a quasi-stationary and quasi-symmetric system favorably occurring west of 92°E. A western-pattern SAH exists in the upper troposphere for these two sub-categories. The springtime dry vortex in the western plateau （type III） is warm and shallow （approximately 100 hPa deep）, and zonal circulation dominates the large-scale environmental flows in the middle and upper troposphere. The precipitating vortex in the southern plateau occurring during July-August （t
