搜索、营救和通常的警戒任务向机组人员使用的常规成像系统提出严峻的挑战。这些系统通常必须在低光度，低能见度条件下发现并识别目标。为此已发展了一种新的机载成像技术以克服普通CCD摄像机，像增强器和热像仪所表现的诸多不足之处...搜索、营救和通常的警戒任务向机组人员使用的常规成像系统提出严峻的挑战。这些系统通常必须在低光度，低能见度条件下发现并识别目标。为此已发展了一种新的机载成像技术以克服普通CCD摄像机，像增强器和热像仪所表现的诸多不足之处。近年来激光二极管阵列、激光二极管波束准直和可门控微通道析增强器技术的进展，已使得构建结构紧凑的有源成像系统成为可能，这种系统被命名为机载激光增强探测和观察系统（ALBEDOS－Airborne Laser Based Enhanced Detection and Observation System)，试验证明，该系统在夜间和不良天气条件下工作特别有效。此外，还演示了距离门装置，除了抑制大部分气溶胶后向散射外，距离门还可以一定程度上消除高灵敏度摄像机产生的光晕效应。1995年10月已将其安装在直升机上进行不同情况下的飞行试验，以验证其潜力。为了增强其大面积警戒能力，优化对人和小目标的探测并改善对飞机的搜索能力，又研制了第二代改进型系统，即增强激光可见光和红外警戒系统（ELVISS）。展开更多
Surface albedo,as one of the important properties of the underlying surface,has a significant impact on the surface energy balance in cold regions.However,due to the complexity of the factors affecting surface albedo,...Surface albedo,as one of the important properties of the underlying surface,has a significant impact on the surface energy balance in cold regions.However,due to the complexity of the factors affecting surface albedo,existing calculations still contain inaccuracies.Therefore,this study conducted surface albedo experiments on loess with different water contents and temperatures.By analyzing the surface albedo measurements of samples with varying temperature and water content levels,as well as the soil freezing characteristic curve(SFCC)and soil-water characteristic curve(SWCC)of loess,the study explores the influence of soil temperature and water content on the surface albedo of loess.The results indicate that both the temperature and water content of loess jointly affect surface albedo.During the process of albedo change,there exists a water content threshold that alters the trend of surface albedo.Soil temperature influences surface albedo by affecting the content of pore ice and liquid water within the soil.When the water content of loess is relatively low,the surface albedo decreases as the unfrozen water content decreases.However,this trend changes as the water content of loess increases.Additionally,a decrease in soil temperature lowers the moisture content threshold during the changes in surface albedo.This study provides a reference for exploring and determining the surface energy balance in cold regions under the background of warm and humid climates,as well as for establishing thermal calculation boundaries.展开更多
This study investigates the complex heat transfer dynamics inmultilayer bifacial photovoltaic(bPV)solar modules under spectrally resolved solar irradiation.A novel numericalmodel is developed to incorporate internal h...This study investigates the complex heat transfer dynamics inmultilayer bifacial photovoltaic(bPV)solar modules under spectrally resolved solar irradiation.A novel numericalmodel is developed to incorporate internal heat generation resulting from optical absorption,grounded in the physical equations governing light-matter interactions within the module’smultilayer structure.The model accounts for reflection and transmission at each interface between adjacent layers,as well as absorption within individual layers,using the wavelength-dependent dielectric properties of constituent materials.These properties are used to calculate the spectral reflectance,transmittance,and absorption coefficients,enabling precise quantification of internal heat sources from irradiance incidents on both the front and rear surfaces of the module.The study further examines the influence of irradiance reflection on thermal behavior,evaluates the thermal impact of various supporting materials placed beneath the module,and analyzes the role of albedo in modifying heat distribution.By incorporating spectrally resolved heat generation across each layer often simplified or omitted in conventional models,the proposed approach enhances physical accuracy.The transient heat equation is solved using a one-dimensional finite difference(FD)method to produce detailed temperature profiles under multiple operating scenarios,including Standard Test Conditions(STC),Bifacial Standard Test Conditions(BSTC),Normal Operating Cell Temperature(NOCT),and Bifacial NOCT(BNOCT).The results offer valuable insights into the interplay between optical and thermal phenomena in bifacial systems,informing the design and optimization of more efficient photovoltaic technologies.展开更多
Antarctic coastal polynyas play a vital role in atmosphere-ocean interactions and local ecosystems.This study investigates the interannual variability of springtime coastal polynyas over the Ross Sea based on satellit...Antarctic coastal polynyas play a vital role in atmosphere-ocean interactions and local ecosystems.This study investigates the interannual variability of springtime coastal polynyas over the Ross Sea based on satellite-retrieved sea-ice concentration(SIC)data from 1992 to 2021.Firstly,the springtime coastal polynya areas display large interannual variability as well as a positive trend of about 2000 km^(2)(10 yr)^(-1) over the 30 years.Secondly,based on composite analysis,in spring,we find that a deepened Amundsen Sea Low(ASL)induces stronger meridional winds over the eastern Ross Sea,leading to stronger sea-ice advection and expansion of coastal polynya areas.This is accompanied by more solar radiation absorption in early summer(about 16 W m^(2)),resulting in upper-ocean warming(~0.4℃)and significant sea-ice loss in late summer(~50%SIC).Additionally,the physical processes are validated by 500-year piControl simulations of a state-of-the-art Earth system model.Based on the same composite analysis,the results show that the sea-ice decline is consistent with the deepening of the ASL and the increase of the meridional sea-ice advection of the preceding spring,which is highly consistent with that of observations.This further confirms the circulations-polynyas-sea-ice physical linkages.Since the springtime ASL is strongly modulated by the tropical Pacific variability and the stratospheric polar vortex,changes in the polynya areas of the Ross Sea can be traced back to remote regions.展开更多
The Van Allen radiation belts are doughnut-shaped zones surrounding Earth, filled with highly energetic charged particles whose sources or loss mechanisms have been investigated for decades. As for the inner belt, cos...The Van Allen radiation belts are doughnut-shaped zones surrounding Earth, filled with highly energetic charged particles whose sources or loss mechanisms have been investigated for decades. As for the inner belt, cosmic ray albedo neutron decay(CRAND),radial diffusion, and local acceleration have been considered principal sources of electrons, whereas protons are predominantly from CRAND and solar protons. In this article, lightning-induced neutrons from Earth's upper atmosphere are suggested as a possible source of protons and electrons in the inner radiation belt. These terrestrial neutrons can contribute to the inner belt population by undergoing nuclear decay. Several approaches are proposed and discussed to evaluate the potential contribution of lightning-induced neutrons to the inner belt, including magnitude estimation, Monte Carlo simulations, and in situ observations. This article discusses some avenues of further study to determine the contribution of lightning-induced neutrons to the inner radiation belt.展开更多
地表反照率直接影响地表辐射平衡,进而改变当地温度(2m气温,下同),然后还可能通过大气平流过程影响下游地区的温度。为揭示利用实时更新的地表反照率替换WRF(Weather Research and Forecasting)模式的静态地表反照率对中国大陆温度模拟...地表反照率直接影响地表辐射平衡,进而改变当地温度(2m气温,下同),然后还可能通过大气平流过程影响下游地区的温度。为揭示利用实时更新的地表反照率替换WRF(Weather Research and Forecasting)模式的静态地表反照率对中国大陆温度模拟结果的影响,本文进行了两组为期6年(2002-2007年)的连续积分试验:控制试验(CT试验)采用短波波段地表反照率,取自WRF模式推荐的地表参数数据集;敏感试验(MD试验)采用分波段的(可见光和近红外)地表反照率,取自MODIS BRDF/Albedo数据产品。试验结果表明,CT试验能够模拟中国温度的基本空间格局,但是模拟温度相对于观测温度有明显偏差,青藏高原南部的模拟温度偏低(负偏差),最大偏低幅度为1.03℃,出现在秋季,东部地区的模拟温度偏高(正偏差),最大偏高幅度达3.4℃,出现在春季;MD试验模拟结果的正、负偏差格局与CT试验基本相似,但是与CT试验相比,MD试验模拟的青藏高原南部温度的负偏差更大,最大为1.32℃,而模拟的东部地区温度的正偏差明显减小,最大为2.97℃,这说明MD试验比CT试验模拟的温度普遍偏低。在青藏高原,这主要归因于MD试验比CT试验的地表反照率大,使得地表净辐射少,地表感热少,致使温度偏低;在中国东部的黄淮海至江南丘陵区,这主要归因于MD试验中北方蒙古高原的地表反照率比CT试验的大,使得MD试验中该地区的地表净辐射少,地表感热少,温度低,然后通过南下冷平流过程致使位于其下游的黄淮海至江南丘陵区温度降低。展开更多
Characteristics of urban heat island （UHI） effect and its cause are investigated by using MODIS data in April 2004. Surface parameters from the MODIS data have surface temperature （ts） albedo（α）, and normalized...Characteristics of urban heat island （UHI） effect and its cause are investigated by using MODIS data in April 2004. Surface parameters from the MODIS data have surface temperature （ts） albedo（α）, and normalized difference vegetation index （NDVI）. Their heterogeneities over urban and rural area are analyzed based on land cover classification, and their relations are also presented in order to explain the UHI effect. The results show that there exists obvious the UHI effect. Ts over urban areas are by 10.83 % higher than those over rural area, and NDVI and α over urban area are by 62 % and 18.75 % less than those over rural area, respectively. Surface temperature has significantly negative correlation with NDVI and their correlation coefficient is -0.73. Correlation between NDVI and albedo is determined by the spectrum of light. Difference in vegetation cover is the primary cause of the UHI effect.展开更多
[Objective] Temporal and spatial variation of surface albedo in Tibetan Plateau were studied in our paper.[Method] Based on NOAA/AVHRR data,different algorithms were used to retrieve surface albedo in Tibetan Plateau,...[Objective] Temporal and spatial variation of surface albedo in Tibetan Plateau were studied in our paper.[Method] Based on NOAA/AVHRR data,different algorithms were used to retrieve surface albedo in Tibetan Plateau,and it showed that the result of Stroeve was mostly close to observed data.Based on retrieval algorithm from Stroeve,the spatial distribution of surface albedo in Tibetan Plateau was obtained by means of NOAA/AVHRR data in 1982-2000.[Result] The distribution of annual mean surface albedo in Tibetan Plateau was identical with that of geographical zone in plateau area;annual mean surface albedo in plateau area showed slight decrease trend which was different in various regions;monthly surface albedo in plateau area had obviously zonal distribution and changed with time evidently.[Conclusion] Our study will be helpful to improving the parameterization scheme of surface albedo in climate model,revealing the internal mechanism of local and regional climate change and enhancing the level of long-term climate forecast.展开更多
The surface albedo which is affected by the earth surface coverage or other surface characteristics is one of the important factors impacting remote sensing image information and therefore it can be calculated by inte...The surface albedo which is affected by the earth surface coverage or other surface characteristics is one of the important factors impacting remote sensing image information and therefore it can be calculated by integrating land coverage types with information of remote sensing images.Horqin sand land which was taken as an experimental area for study on Landsat-TM topography and atmospheric correction,then the Landsat-TM data inversion formula established by Liang was used to calculate the experimental zone albedo map;correlation analysis was performed to the surface albedo map and the land-use maps which was acquired by supervision and classification.The results revealed significant relations between land-use types and the surface albedo of study area.Additionally,the surface albedo and NDVI of the study area were statistically analyzed to obtain the study area's surface albedo and NDVI dependent equation.展开更多
文摘搜索、营救和通常的警戒任务向机组人员使用的常规成像系统提出严峻的挑战。这些系统通常必须在低光度，低能见度条件下发现并识别目标。为此已发展了一种新的机载成像技术以克服普通CCD摄像机，像增强器和热像仪所表现的诸多不足之处。近年来激光二极管阵列、激光二极管波束准直和可门控微通道析增强器技术的进展，已使得构建结构紧凑的有源成像系统成为可能，这种系统被命名为机载激光增强探测和观察系统（ALBEDOS－Airborne Laser Based Enhanced Detection and Observation System)，试验证明，该系统在夜间和不良天气条件下工作特别有效。此外，还演示了距离门装置，除了抑制大部分气溶胶后向散射外，距离门还可以一定程度上消除高灵敏度摄像机产生的光晕效应。1995年10月已将其安装在直升机上进行不同情况下的飞行试验，以验证其潜力。为了增强其大面积警戒能力，优化对人和小目标的探测并改善对飞机的搜索能力，又研制了第二代改进型系统，即增强激光可见光和红外警戒系统（ELVISS）。
基金supported by the National Natural Science Foundation of China(42261028)the Chinese Academy of Sciences“Light of West China”Program for Western Young Scholars(23JR6KA027)+3 种基金the Science Foundation for Distinguished Young Scholars of Gansu Province(24JRRA167)the Key Research and Development Program on Ecological Civilization Construction of Gansu Province(25YFFA012)Gansu Provincial Science and Technology Plan Fund Project(24CXGA063)Scientific Research Projects on Ecological and Environmental Protection in Heilongjiang Province in 2023(Grant No.:HST2023ZR005)。
文摘Surface albedo,as one of the important properties of the underlying surface,has a significant impact on the surface energy balance in cold regions.However,due to the complexity of the factors affecting surface albedo,existing calculations still contain inaccuracies.Therefore,this study conducted surface albedo experiments on loess with different water contents and temperatures.By analyzing the surface albedo measurements of samples with varying temperature and water content levels,as well as the soil freezing characteristic curve(SFCC)and soil-water characteristic curve(SWCC)of loess,the study explores the influence of soil temperature and water content on the surface albedo of loess.The results indicate that both the temperature and water content of loess jointly affect surface albedo.During the process of albedo change,there exists a water content threshold that alters the trend of surface albedo.Soil temperature influences surface albedo by affecting the content of pore ice and liquid water within the soil.When the water content of loess is relatively low,the surface albedo decreases as the unfrozen water content decreases.However,this trend changes as the water content of loess increases.Additionally,a decrease in soil temperature lowers the moisture content threshold during the changes in surface albedo.This study provides a reference for exploring and determining the surface energy balance in cold regions under the background of warm and humid climates,as well as for establishing thermal calculation boundaries.
文摘This study investigates the complex heat transfer dynamics inmultilayer bifacial photovoltaic(bPV)solar modules under spectrally resolved solar irradiation.A novel numericalmodel is developed to incorporate internal heat generation resulting from optical absorption,grounded in the physical equations governing light-matter interactions within the module’smultilayer structure.The model accounts for reflection and transmission at each interface between adjacent layers,as well as absorption within individual layers,using the wavelength-dependent dielectric properties of constituent materials.These properties are used to calculate the spectral reflectance,transmittance,and absorption coefficients,enabling precise quantification of internal heat sources from irradiance incidents on both the front and rear surfaces of the module.The study further examines the influence of irradiance reflection on thermal behavior,evaluates the thermal impact of various supporting materials placed beneath the module,and analyzes the role of albedo in modifying heat distribution.By incorporating spectrally resolved heat generation across each layer often simplified or omitted in conventional models,the proposed approach enhances physical accuracy.The transient heat equation is solved using a one-dimensional finite difference(FD)method to produce detailed temperature profiles under multiple operating scenarios,including Standard Test Conditions(STC),Bifacial Standard Test Conditions(BSTC),Normal Operating Cell Temperature(NOCT),and Bifacial NOCT(BNOCT).The results offer valuable insights into the interplay between optical and thermal phenomena in bifacial systems,informing the design and optimization of more efficient photovoltaic technologies.
基金supported by the National Key R&D Program of China(Grant No.2021YFC2802504)the National Outstanding Youth Grant(Grant No.41925027)+1 种基金the National Natural Science Foundation of China(Grant No.42206251)the Innovation Group Project of the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.311021008).
文摘Antarctic coastal polynyas play a vital role in atmosphere-ocean interactions and local ecosystems.This study investigates the interannual variability of springtime coastal polynyas over the Ross Sea based on satellite-retrieved sea-ice concentration(SIC)data from 1992 to 2021.Firstly,the springtime coastal polynya areas display large interannual variability as well as a positive trend of about 2000 km^(2)(10 yr)^(-1) over the 30 years.Secondly,based on composite analysis,in spring,we find that a deepened Amundsen Sea Low(ASL)induces stronger meridional winds over the eastern Ross Sea,leading to stronger sea-ice advection and expansion of coastal polynya areas.This is accompanied by more solar radiation absorption in early summer(about 16 W m^(2)),resulting in upper-ocean warming(~0.4℃)and significant sea-ice loss in late summer(~50%SIC).Additionally,the physical processes are validated by 500-year piControl simulations of a state-of-the-art Earth system model.Based on the same composite analysis,the results show that the sea-ice decline is consistent with the deepening of the ASL and the increase of the meridional sea-ice advection of the preceding spring,which is highly consistent with that of observations.This further confirms the circulations-polynyas-sea-ice physical linkages.Since the springtime ASL is strongly modulated by the tropical Pacific variability and the stratospheric polar vortex,changes in the polynya areas of the Ross Sea can be traced back to remote regions.
基金supported by the National Natural Science Foundation of China (No. 42225405 and No. 42350710200)。
文摘The Van Allen radiation belts are doughnut-shaped zones surrounding Earth, filled with highly energetic charged particles whose sources or loss mechanisms have been investigated for decades. As for the inner belt, cosmic ray albedo neutron decay(CRAND),radial diffusion, and local acceleration have been considered principal sources of electrons, whereas protons are predominantly from CRAND and solar protons. In this article, lightning-induced neutrons from Earth's upper atmosphere are suggested as a possible source of protons and electrons in the inner radiation belt. These terrestrial neutrons can contribute to the inner belt population by undergoing nuclear decay. Several approaches are proposed and discussed to evaluate the potential contribution of lightning-induced neutrons to the inner belt, including magnitude estimation, Monte Carlo simulations, and in situ observations. This article discusses some avenues of further study to determine the contribution of lightning-induced neutrons to the inner radiation belt.
文摘地表反照率直接影响地表辐射平衡,进而改变当地温度(2m气温,下同),然后还可能通过大气平流过程影响下游地区的温度。为揭示利用实时更新的地表反照率替换WRF(Weather Research and Forecasting)模式的静态地表反照率对中国大陆温度模拟结果的影响,本文进行了两组为期6年(2002-2007年)的连续积分试验:控制试验(CT试验)采用短波波段地表反照率,取自WRF模式推荐的地表参数数据集;敏感试验(MD试验)采用分波段的(可见光和近红外)地表反照率,取自MODIS BRDF/Albedo数据产品。试验结果表明,CT试验能够模拟中国温度的基本空间格局,但是模拟温度相对于观测温度有明显偏差,青藏高原南部的模拟温度偏低(负偏差),最大偏低幅度为1.03℃,出现在秋季,东部地区的模拟温度偏高(正偏差),最大偏高幅度达3.4℃,出现在春季;MD试验模拟结果的正、负偏差格局与CT试验基本相似,但是与CT试验相比,MD试验模拟的青藏高原南部温度的负偏差更大,最大为1.32℃,而模拟的东部地区温度的正偏差明显减小,最大为2.97℃,这说明MD试验比CT试验模拟的温度普遍偏低。在青藏高原,这主要归因于MD试验比CT试验的地表反照率大,使得地表净辐射少,地表感热少,致使温度偏低;在中国东部的黄淮海至江南丘陵区,这主要归因于MD试验中北方蒙古高原的地表反照率比CT试验的大,使得MD试验中该地区的地表净辐射少,地表感热少,温度低,然后通过南下冷平流过程致使位于其下游的黄淮海至江南丘陵区温度降低。
基金the project of National Natural Science Funding of China under grant No.40075004.
文摘Characteristics of urban heat island （UHI） effect and its cause are investigated by using MODIS data in April 2004. Surface parameters from the MODIS data have surface temperature （ts） albedo（α）, and normalized difference vegetation index （NDVI）. Their heterogeneities over urban and rural area are analyzed based on land cover classification, and their relations are also presented in order to explain the UHI effect. The results show that there exists obvious the UHI effect. Ts over urban areas are by 10.83 % higher than those over rural area, and NDVI and α over urban area are by 62 % and 18.75 % less than those over rural area, respectively. Surface temperature has significantly negative correlation with NDVI and their correlation coefficient is -0.73. Correlation between NDVI and albedo is determined by the spectrum of light. Difference in vegetation cover is the primary cause of the UHI effect.
基金Supported by Plateau Meteorology Open Laboratory Foundation of Institute of Plateau Meteorology,CMA,Chengdu(LPM2009018 and BROP201001)
文摘[Objective] Temporal and spatial variation of surface albedo in Tibetan Plateau were studied in our paper.[Method] Based on NOAA/AVHRR data,different algorithms were used to retrieve surface albedo in Tibetan Plateau,and it showed that the result of Stroeve was mostly close to observed data.Based on retrieval algorithm from Stroeve,the spatial distribution of surface albedo in Tibetan Plateau was obtained by means of NOAA/AVHRR data in 1982-2000.[Result] The distribution of annual mean surface albedo in Tibetan Plateau was identical with that of geographical zone in plateau area;annual mean surface albedo in plateau area showed slight decrease trend which was different in various regions;monthly surface albedo in plateau area had obviously zonal distribution and changed with time evidently.[Conclusion] Our study will be helpful to improving the parameterization scheme of surface albedo in climate model,revealing the internal mechanism of local and regional climate change and enhancing the level of long-term climate forecast.
基金Supported by Institute of Atmospheric Environment CMA,Shenyang
文摘The surface albedo which is affected by the earth surface coverage or other surface characteristics is one of the important factors impacting remote sensing image information and therefore it can be calculated by integrating land coverage types with information of remote sensing images.Horqin sand land which was taken as an experimental area for study on Landsat-TM topography and atmospheric correction,then the Landsat-TM data inversion formula established by Liang was used to calculate the experimental zone albedo map;correlation analysis was performed to the surface albedo map and the land-use maps which was acquired by supervision and classification.The results revealed significant relations between land-use types and the surface albedo of study area.Additionally,the surface albedo and NDVI of the study area were statistically analyzed to obtain the study area's surface albedo and NDVI dependent equation.
