Lidar has been used extensively in the area of atmospheric aerosol measurement.Two unknowns at the reference altitude,the lidar ratio and the backscatter coefficient,need to be resolved from the lidar equation.In the ...Lidar has been used extensively in the area of atmospheric aerosol measurement.Two unknowns at the reference altitude,the lidar ratio and the backscatter coefficient,need to be resolved from the lidar equation.In the actual application,these two values are difficult to obtain,particularly the backscatter coefficient.To better characterize the optical properties of aerosols,optical thickness,and attenuated backscatter obtained by other instruments are usually used as the input for joint inversion.However,this method is limited by location and time.In this study,the authors propose a new method for aerosol retrieval by using Mie scattering lidar data to solve this problem.The authors take the horizontal aerosol extinction coefficient as the constraint to begin the iteration until a self-consistent aerosol vertical profile was obtained.By comparing their results with Aerosol Robotic Network(AERONET) data,the authours determine that the aerosol extinction coefficient obtained by combining horizontal and vertical lidar observations is more precise than that obtained by using the traditional Fernald method.This new method has been adopted for retrieving the extinction coefficient of aerosols during the observation days.展开更多
The combination of photovoltaic system with a thermal to form the hybrid PVT （photovoltaic thermal）, which together will generate electricity and heat. This energy depends on the input that is to say the energy of s...The combination of photovoltaic system with a thermal to form the hybrid PVT （photovoltaic thermal）, which together will generate electricity and heat. This energy depends on the input that is to say the energy of solar radiation, temperature and speed wind and output which is the operating temperature of the system. This production also depends on the mode of heat removal. The authors present in this article; a study by a numerical simulation of the thermal behavior of a prototype hybrid sensor through the development of an energy balance that involves heat exchange between the different components of the hybrid sensor, and it will allow us to study the influence of internal and external parameters on the temperature variation in the different layers of the prototype PV/T studied.展开更多
We developed a sophisticated method to depict the spatial and seasonal characterization of net primary productivity (NPP) and climate variables. The role of climate variability in the seasonal variation of NPP exerts ...We developed a sophisticated method to depict the spatial and seasonal characterization of net primary productivity (NPP) and climate variables. The role of climate variability in the seasonal variation of NPP exerts delayed and continuous effects. This study expands on this by mapping the seasonal characterization of NPP and climate variables from space using geographic information system (GIS) technology at the pixel level. Our approach was developed in southeastern China using moderate-resolution imaging spectroradiometer (MODIS) data. The results showed that air temperature,precipitation and sunshine percentage contributed significantly to seasonal variation of NPP. In the northern portion of the study area,a significant positive 32-d lagged correlation was observed between seasonal variation of NPP and climate (P<0.01),and the influences of changing climate on NPP lasted for 48 d or 64 d. In central southeastern China,NPP showed 16-d,48-d,and 96-d lagged correlation with air temperature,precipitation,and sunshine percentage,respectively (P<0.01); the influences of air temperature and precipitation on NPP lasted for 48 d or 64 d,while sunshine influence on NPP only persisted for 16 d. Due to complex topography and vegetation distribution in the southern part of the study region,the spatial patterns of vegetation-climate relationship became complicated and diversiform,especially for precipitation influences on NPP. In the northern part of the study area,all vegetation NPP had an almost similar response to seasonal variation of air temperature except for broad crops. The impacts of seasonal variation of precipitation and sunshine on broad and cereal crop NPP were slightly different from other vegetation NPP.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.41127901)
文摘Lidar has been used extensively in the area of atmospheric aerosol measurement.Two unknowns at the reference altitude,the lidar ratio and the backscatter coefficient,need to be resolved from the lidar equation.In the actual application,these two values are difficult to obtain,particularly the backscatter coefficient.To better characterize the optical properties of aerosols,optical thickness,and attenuated backscatter obtained by other instruments are usually used as the input for joint inversion.However,this method is limited by location and time.In this study,the authors propose a new method for aerosol retrieval by using Mie scattering lidar data to solve this problem.The authors take the horizontal aerosol extinction coefficient as the constraint to begin the iteration until a self-consistent aerosol vertical profile was obtained.By comparing their results with Aerosol Robotic Network(AERONET) data,the authours determine that the aerosol extinction coefficient obtained by combining horizontal and vertical lidar observations is more precise than that obtained by using the traditional Fernald method.This new method has been adopted for retrieving the extinction coefficient of aerosols during the observation days.
文摘The combination of photovoltaic system with a thermal to form the hybrid PVT （photovoltaic thermal）, which together will generate electricity and heat. This energy depends on the input that is to say the energy of solar radiation, temperature and speed wind and output which is the operating temperature of the system. This production also depends on the mode of heat removal. The authors present in this article; a study by a numerical simulation of the thermal behavior of a prototype hybrid sensor through the development of an energy balance that involves heat exchange between the different components of the hybrid sensor, and it will allow us to study the influence of internal and external parameters on the temperature variation in the different layers of the prototype PV/T studied.
基金Project supported by the National High-Tech Research and Development Program (863) of China (No. 2006AA120101)the National Natural Science Foundation of China (Nos. 40871158 and 40875070)the Key Technologies Research and Development Program of China (No. 2006BAD10A01)
文摘We developed a sophisticated method to depict the spatial and seasonal characterization of net primary productivity (NPP) and climate variables. The role of climate variability in the seasonal variation of NPP exerts delayed and continuous effects. This study expands on this by mapping the seasonal characterization of NPP and climate variables from space using geographic information system (GIS) technology at the pixel level. Our approach was developed in southeastern China using moderate-resolution imaging spectroradiometer (MODIS) data. The results showed that air temperature,precipitation and sunshine percentage contributed significantly to seasonal variation of NPP. In the northern portion of the study area,a significant positive 32-d lagged correlation was observed between seasonal variation of NPP and climate (P<0.01),and the influences of changing climate on NPP lasted for 48 d or 64 d. In central southeastern China,NPP showed 16-d,48-d,and 96-d lagged correlation with air temperature,precipitation,and sunshine percentage,respectively (P<0.01); the influences of air temperature and precipitation on NPP lasted for 48 d or 64 d,while sunshine influence on NPP only persisted for 16 d. Due to complex topography and vegetation distribution in the southern part of the study region,the spatial patterns of vegetation-climate relationship became complicated and diversiform,especially for precipitation influences on NPP. In the northern part of the study area,all vegetation NPP had an almost similar response to seasonal variation of air temperature except for broad crops. The impacts of seasonal variation of precipitation and sunshine on broad and cereal crop NPP were slightly different from other vegetation NPP.
