北京晴天紫外波段气溶胶光学厚度反演与分析

利用太阳一大气紫外光谱辐射计(SAUVS)，测量到达北京地表的太阳直接和散射紫外光谱辐射，给出反演大气气溶胶光学厚度的一种方法。结果表明：在紫外波段，大气气溶胶的光学厚度随波长的增加而单调减小，用指数函数可以很好地拟合反演结果。统计得到了3个水平能见度状况下拟合函数的系数值，与全球气溶胶监测网络(AERONET)北京站的资料对比，表明反演结果基本合理。     

基于直射辐射遥感图象的地物双向反射特性研究(英文)

该文讨论了一种在ＧＩＳ支持下利用直射辐射遥感图象研究地物双向反射特性的原理和方法。其主要依据是象元地面的坡度和坡向的不同，同时改变了象元地面与太阳之间、象元地面与卫星传感器之间的相对位置，并且造成了同类象元太阳直射辐射遥感分量的差异。而正是这种差异体现了该类地物双向反射特性。在ＧＩＳ的支持下利用卫星直射辐射遥感数字图象，研究卫片象元同类地物的这种差异的规律以及它们与对应坡面上的太阳位置、卫星位置的关系，便可进行该类地物的双向反射特性研究。     

一种改进的MODIS影像BRDF辐射校正方法

针时二向性造成的辐射失真，在核驱动模型的基础上提出了一种改进的二向性反射分布模型，并通过时MODIS影像的试验，得到了减弱辐射差异的较好效果，并对试验结果进行了分析和评价。     

热红外波段大气透过率和程辐射的估算方法

文中对M ONTRAN模型内嵌6种大气模式的主要特性差异进行分析,并以中纬度夏季大气模式为例,分析了主要参数(如水汽、臭氧以及气温等)对估算热红外波段大气透过率和程辐射的影响。论文最后对利用探空数据构造完整大气模式进行了研究。     

云顶以下臭氧对TOMS反演臭氧总量的影响及反演方法的理论研究

目前紫外后向散射反演臭氧总量的所有算法,都将云考虑成不透明的Lambertian反射体,并假定云顶有效反照率不随波长的变化而变化.然而本文通过模拟计算发现,由于云散射、瑞利散射、臭氧吸收三种作用的综合结果,云顶的有效反照率是与波长相关的,即使光学厚度比较大的云,辐射也可由云顶继续向下传输,因而会受到云顶以下臭氧吸收的影响.用V7方法进行反演,模拟计算结果表明：云的出现使得云顶以下,特别是云内光程增强,导致紫外波段的臭氧吸收衰减增大,所以反演出的臭氧总量值比真实值偏大,本文称这种现象为“云吸收效应”,并讨论了该效应的影响因子.最后,在辐射传输模拟的基础上建立一套反演算法,大大减弱了“云吸收效应”的影响.     

Matrix expression of thermal radiative characteristics for an open complex

The directionality of thermal radiance of a homogeneous isothermal non-black plane surface is totally decided by its directional emissivity, which depends on the complex dielectric constant and roughness of surface. It can be expressed by This paper proves that it is necessary to express emissivity by a matrix when a target becomes an inhomogeneous non-isothermal open complex with complicated inner geometric structure. The matrix describes the inner radiative interaction among components accurately and also expresses its thermal radiative directionality and structural characteristics completely. Advantages of matrix expression are as follows: first, the physical mechanics of effective emissivity of an open complex is described in a simple and perfect way; second, it becomes easy to understand the principle and method to retrieve components temperature from multi-angle thermal remotely sensed data; and third, the differences of directionalities between an open complex and a homogeneous isothermal non-black plane body are expressed by just using an effective emissivity matrix instead of an emissivity vector. Formula in classic physics is only the special case of matrix expression; therefore, the matrix is a universal unconditional expression to describe the directionality of thermal radiance.     

MODIS 1B数据与物理量计算

弄清楚HDF-EOS数据结构和内容及其基本物理量的计算方法是MODIS应用的基础。HDF是NCSA开发、适用于多种计算机平台、易于扩展、主要用来存储各种类型的科学数据。NASA在此基础上,对HDF进行了扩展,开发了专门处理EOS产品的数据格式HDF-EOS。MODIS 1B产品采用HDF-EOS格式存储数据,数据文件包括250、500、1000 m分辨率的定标后的资料以及星载定标器数据及其他工程数据。白天MODIS资料有36个波段,夜间只有17个波段。MODIS 1B产品将MODIS探测得到的数据信号按一定比例缩放为16位整数保存,根据数据集保存的缩放比和截距参数,可以算出反射率和辐射率。     

Impact of Assimilating Radiances with the WRFDA ETKF/3DVAR Hybrid System on Prediction of Two Typhoons in 2012

The impacts of AMSU-A and IASI (Infrared Atmospheric Sounding Interferometer) radiances assimila-tion on the prediction of typhoons Vicente and Saola (2012) are studied by using the ensemble transform ...     

FY-3D卫星MWHS-2辐射率资料直接同化对台风“米娜”预报的影响*

文章基于天气研究和预报(weather research and forecasting, WRF)模式中的FY-3D卫星微波湿度计Ⅱ(micro-wave humidity sounder 2, MWHS-2)辐射率资料的直接同化模块, 采用三维变分(three dimensional variation, 3DVar)方法在晴空条件下同化MWHS-2辐射率资料, 考察MWHS-2辐射率资料同化对台风“米娜”(2019)预报的影响。文中设计了4组试验, 第一组试验不同化任何资料, 第二组试验同化了单独的全球通信系统(global telecommunications system, GTS)常规资料, 第三组试验联合同化了GTS常规资料和MWHS-2辐射率资料, 第四组试验将MWHS-2辐射率资料换成先进技术微波探测计(advanced technology microwave sounder, ATMS)辐射率资料同化。研究结果表明: 偏差订正后各通道观测和背景场差值的均值趋于0, 同化后分析场相对观测的标准差与均方根误差较背景场显著减小, 同化过程是有效的。与仅同化GTS常规资料和同化ATMS资料的试验相比, 同化晴空MWHS-2辐射率资料后的增量场在台风中心附近有负的高度增量和正的温度增量, 从动力与热力上有助于台风的维持。在确定性预报最后的12h, 同化晴空MWHS-2辐射率资料的试验能够改进500hPa环流形势的模拟, 加强西南方向引导气流的强度, 从而最终减小台风路径预报的误差。     

Month-Long Simulations of Gravity Waves over North America and North Atlantic in Comparison with Satellite Observations

Mesoscale simulations of gravity waves in the upper troposphere and lower stratosphere over North America and North Atlantic Ocean in January 2003 are compared with satellite radiance measurements from the Advanced Microwave Sounding Unit-A (AMSU-A). Four regions of strong gravity wave (GW) activities are found in the model simulations and the AMSU-A observations: the northwestern Atlantic, the U.S. Rockies, the Appalachians, and Greenland. GWs over the northwestern Atlantic Ocean are associated with the midlatitude baroclinic jet-front system, while the other three regions are apparently related to high topography. Model simulations are further used to analyze momentum fluxes in the zonal and meridional directions. It is found that strong westward momentum fluxes are prevalent over these regions over the whole period. Despite qualitative agreement between model simulations and satellite measurements, sensitivity experiments demonstrate that the simulated GWs are sensitive to the model spin-up time.