Solar radiation, which varies over multiple temporal scales, modulates remarkably the evolution of the ionosphere. The solar activity dependence of the ionosphere is a key and fundamental issue in ionospheric physics,...Solar radiation, which varies over multiple temporal scales, modulates remarkably the evolution of the ionosphere. The solar activity dependence of the ionosphere is a key and fundamental issue in ionospheric physics, providing information essential to understanding the variations in the ionosphere and its processes. Selected recent studies on solar activity effects of the ionosphere are briefly reviewed in this report. This report focuses on (1) observations of solar irradiance at X-ray and extreme ultraviolet wavelengths and the outstanding problems of solar proxies, in the view of ionospheric studies, (2) new findings and improved representations of the features of the solar activity dependence of ionospheric key parameters and the corresponding physical processes, (3) possible phenomena in the ionosphere under extremely high and low solar activity conditions that are unique, as indicated by historical solar datasets and the deep solar minimum of solar cycle 23/24, and (4) statistical studies and model simulations of the ionosphere response to solar flares. The above-mentioned studies provide new clues for comprehensively explaining basic processes in the ionosphere and improving the prediction capability of ionospheric models and related applications.展开更多
Based on the infrared radiation transfer model, the outgoing longwave radiation (OLR) and Channel 5 radiance of Fengyun-3B (FY-3B) satellite visible infrared radiometer (VIRR) were simulated for 3812 global soundings....Based on the infrared radiation transfer model, the outgoing longwave radiation (OLR) and Channel 5 radiance of Fengyun-3B (FY-3B) satellite visible infrared radiometer (VIRR) were simulated for 3812 global soundings. Using regression analysis of the simulations, an inverse model, which connected the flux equivalent brightness temperature with the channel brightness temperature, was derived. By applying the model to the FY-3B VIRR L1 data, the global OLR data at the time of the passing of the FY-3B were processed. The quality of the data was validated by comparing it with that of the NOAA-18 satellite's advanced very high resolution radiometer (AVHRR). The validation results show root mean square errors in the range 10-13 W/M 2 when comparing the daily average OLR of the VIRR with that of the NOAA-18 AVHRR, and the correlation coefficients were in the range 0.97-0.98. The larger RMSE is mainly due to the different passing times of the two satellites for the specific locations on the Earth. An example of the OLR data and its preliminary applications are given.展开更多
茶树、小麦和樟树群体叶面积垂直分布的差异显著,但在一定精度内,它们可用相同的函数形式描述,具有理论意义。茶树叶倾角基本服从正态分布,方差较大。不同的植物群体中,太阳辐射的垂直分布有别,与群体叶面积垂直分布密切相关。光合有效...茶树、小麦和樟树群体叶面积垂直分布的差异显著,但在一定精度内,它们可用相同的函数形式描述,具有理论意义。茶树叶倾角基本服从正态分布,方差较大。不同的植物群体中,太阳辐射的垂直分布有别,与群体叶面积垂直分布密切相关。光合有效辐射(PAR)的消光系数大于总辐射(TSR)的消光系数;一天中,群体下部的光照条件以中午前后为佳,消光系数(k)最小;k 值与太阳高度角的正弦成反比。考虑到 k 值的日变化,指数衰减律仍不失为一种简单实用的数学模型。展开更多
The cloud-detection procedure developed by McNally and Watts(MW03) was added to the Weather Research and Forecasting Data Assimilation System. To provide some guidelines for setting up cloud-detection schemes, this st...The cloud-detection procedure developed by McNally and Watts(MW03) was added to the Weather Research and Forecasting Data Assimilation System. To provide some guidelines for setting up cloud-detection schemes, this study compares the MW03 scheme to the Multivariate and Minimum Residual(MMR) scheme for both simulated and real Advanced Infrared Sounder(AIRS) radiances. Results show that there is a high level of consistency between the results from simulated and real AIRS data. As expected, both cloud-detection schemes perform well in finding the cloud-contaminated channels based on the channels' peak levels. The clouddetection results from MW03 are sensitive to the prescribed brightness temperature innovation threshold and brightness temperature gradient threshold. When increasing the brightness temperature innovation threshold for MW03 to roughly eight times the default threshold, the two cloud-detection schemes produce consistent data rejection distributions overall for high channels. MMR generally retains more data for long-wave channels. For both cloud-detection schemes, there is a high level of consistency between the cloud-free pixels and the visible/near-IR(Vis/NIR) cloud mask.展开更多
基金supported by the National Natural Science Foundation of China (40725014)the Specialized Research Fund for State Key Laboratories
文摘Solar radiation, which varies over multiple temporal scales, modulates remarkably the evolution of the ionosphere. The solar activity dependence of the ionosphere is a key and fundamental issue in ionospheric physics, providing information essential to understanding the variations in the ionosphere and its processes. Selected recent studies on solar activity effects of the ionosphere are briefly reviewed in this report. This report focuses on (1) observations of solar irradiance at X-ray and extreme ultraviolet wavelengths and the outstanding problems of solar proxies, in the view of ionospheric studies, (2) new findings and improved representations of the features of the solar activity dependence of ionospheric key parameters and the corresponding physical processes, (3) possible phenomena in the ionosphere under extremely high and low solar activity conditions that are unique, as indicated by historical solar datasets and the deep solar minimum of solar cycle 23/24, and (4) statistical studies and model simulations of the ionosphere response to solar flares. The above-mentioned studies provide new clues for comprehensively explaining basic processes in the ionosphere and improving the prediction capability of ionospheric models and related applications.
文摘Based on the infrared radiation transfer model, the outgoing longwave radiation (OLR) and Channel 5 radiance of Fengyun-3B (FY-3B) satellite visible infrared radiometer (VIRR) were simulated for 3812 global soundings. Using regression analysis of the simulations, an inverse model, which connected the flux equivalent brightness temperature with the channel brightness temperature, was derived. By applying the model to the FY-3B VIRR L1 data, the global OLR data at the time of the passing of the FY-3B were processed. The quality of the data was validated by comparing it with that of the NOAA-18 satellite's advanced very high resolution radiometer (AVHRR). The validation results show root mean square errors in the range 10-13 W/M 2 when comparing the daily average OLR of the VIRR with that of the NOAA-18 AVHRR, and the correlation coefficients were in the range 0.97-0.98. The larger RMSE is mainly due to the different passing times of the two satellites for the specific locations on the Earth. An example of the OLR data and its preliminary applications are given.
文摘茶树、小麦和樟树群体叶面积垂直分布的差异显著,但在一定精度内,它们可用相同的函数形式描述,具有理论意义。茶树叶倾角基本服从正态分布,方差较大。不同的植物群体中,太阳辐射的垂直分布有别,与群体叶面积垂直分布密切相关。光合有效辐射(PAR)的消光系数大于总辐射(TSR)的消光系数;一天中,群体下部的光照条件以中午前后为佳,消光系数(k)最小;k 值与太阳高度角的正弦成反比。考虑到 k 值的日变化,指数衰减律仍不失为一种简单实用的数学模型。
基金sponsored by the National Basic Research Program of China (973 Program, 2013CB430102)the Program of Scientific Innovation Research of College Graduate in Jiangsu Province (Grant Nos. CXZZ12-0490 and CXZZ11-0606)The National Center for Atmospheric Research is sponsored by the National Science Foundation
文摘The cloud-detection procedure developed by McNally and Watts(MW03) was added to the Weather Research and Forecasting Data Assimilation System. To provide some guidelines for setting up cloud-detection schemes, this study compares the MW03 scheme to the Multivariate and Minimum Residual(MMR) scheme for both simulated and real Advanced Infrared Sounder(AIRS) radiances. Results show that there is a high level of consistency between the results from simulated and real AIRS data. As expected, both cloud-detection schemes perform well in finding the cloud-contaminated channels based on the channels' peak levels. The clouddetection results from MW03 are sensitive to the prescribed brightness temperature innovation threshold and brightness temperature gradient threshold. When increasing the brightness temperature innovation threshold for MW03 to roughly eight times the default threshold, the two cloud-detection schemes produce consistent data rejection distributions overall for high channels. MMR generally retains more data for long-wave channels. For both cloud-detection schemes, there is a high level of consistency between the cloud-free pixels and the visible/near-IR(Vis/NIR) cloud mask.
