Sky radiance might be influenced by the multiple reflectance between the earth＇s albedo surface and the atmosphere. Based on the Lambert＇s law and the radiative transfer equation （RTE）, a model is developed to cal...Sky radiance might be influenced by the multiple reflectance between the earth＇s albedo surface and the atmosphere. Based on the Lambert＇s law and the radiative transfer equation （RTE）, a model is developed to calculate the additional sky radiance at wavelengths of 0.4-3μm due to the reflectance contribution of the underlying surface. The iterative method is used to calculate sky radiance without the reflectance from underlying surface. The hybrid modified delta-Eddington approximation is used to compute the atmospheric reflection of the radiation from the earth＇s surface. An interaction factor is introduced to deal with the multiple reflectance between the atmosphere and the underlying surface. The sky radiance increment is evaluated for some different albedos of the earth＇s surface. The results show that the sky radiance increment rises rapidly while viewing zenith angle is near to 90°and the larger the albedo of the earth＇s surface is, the more obvious this effect appears.展开更多
Using ECWMF ERA-40 and Interim reanalysis data, the planetary wave fluxes associated with the February extreme stratospheric polar vortex were studied. Using the three-dimensional Eliassen-Palm (EP) flux as a measure ...Using ECWMF ERA-40 and Interim reanalysis data, the planetary wave fluxes associated with the February extreme stratospheric polar vortex were studied. Using the three-dimensional Eliassen-Palm (EP) flux as a measure of the wave activity propagation, the authors show that the unusual warm years in the Arctic feature an anomalous weak stratosphere-troposphere coupling and weak downward wave flux at the lower stratosphere, especially over the North America and North Atlantic (NANA) region. The extremely cold years are characterized by strong stratosphere-troposphere coupling and strong downward wave flux in this region. The refractive index is used to examine the conception of planetary wave reflection, which shows a large refractive index (low reflection) for the extremely warm years and a small refractive index (high reflection) for the extremely cold years. This study reveals the importance of the downward planetary wave propagation from the stratosphere to the troposphere for explaining the unusual state of the stratospheric polar vortex in February.展开更多
基金This work was supported by the National Natural Science Foundation of China under Grant No. 10376007.
文摘Sky radiance might be influenced by the multiple reflectance between the earth＇s albedo surface and the atmosphere. Based on the Lambert＇s law and the radiative transfer equation （RTE）, a model is developed to calculate the additional sky radiance at wavelengths of 0.4-3μm due to the reflectance contribution of the underlying surface. The iterative method is used to calculate sky radiance without the reflectance from underlying surface. The hybrid modified delta-Eddington approximation is used to compute the atmospheric reflection of the radiation from the earth＇s surface. An interaction factor is introduced to deal with the multiple reflectance between the atmosphere and the underlying surface. The sky radiance increment is evaluated for some different albedos of the earth＇s surface. The results show that the sky radiance increment rises rapidly while viewing zenith angle is near to 90°and the larger the albedo of the earth＇s surface is, the more obvious this effect appears.
基金supported by the National Basic Research Program of China (973Program) (Grant No. 2010CB428603)the National Natural Science Foundation of China (Grant Nos. 40805017 and 41175041)
文摘Using ECWMF ERA-40 and Interim reanalysis data, the planetary wave fluxes associated with the February extreme stratospheric polar vortex were studied. Using the three-dimensional Eliassen-Palm (EP) flux as a measure of the wave activity propagation, the authors show that the unusual warm years in the Arctic feature an anomalous weak stratosphere-troposphere coupling and weak downward wave flux at the lower stratosphere, especially over the North America and North Atlantic (NANA) region. The extremely cold years are characterized by strong stratosphere-troposphere coupling and strong downward wave flux in this region. The refractive index is used to examine the conception of planetary wave reflection, which shows a large refractive index (low reflection) for the extremely warm years and a small refractive index (high reflection) for the extremely cold years. This study reveals the importance of the downward planetary wave propagation from the stratosphere to the troposphere for explaining the unusual state of the stratospheric polar vortex in February.
