复杂地形任意天气情形下太阳直接辐射量模拟   总被引：2，自引：1，他引：1  

张海龙  刘高焕  姚玲  解修平 《中国沙漠》2010,30(6):1469-1476

以太阳辐射传输参数化模型为基础,结合MODIS影像两次白天的云产品和水汽产品及DEM,构建了复杂地形任意天气情形下每日太阳直接辐射量模型。选取代表不同气候类型与地形起伏状况的3个典型站点（拉萨、北京、额济纳旗）,以2007年每日实测值对模拟结果进行了验证,其相关系数分别为0.77、0.77和0.85。研究表明:有云天气下,云是影响地表太阳直接辐射数量和空间分布的主要因子;模型对时间步长不敏感。引起误差的原因主要是MODIS云产品的时空分辨率较低以及云的3D效应导致模拟的困难,对地形起伏较大地区,小比例尺的DEM也会导致较大的误差,同时实测值与模拟值的空间尺度不匹配也引起了一定误差。  相似文献   

A Study of the Atmospheric Boundary Layer Structure During a Clear Day in the Arid Region of Northwest China          下载免费PDF全文

ZHANG Qiang  WANG Sheng 《Acta Meteorologica Sinica》2009,23(3):327-337

The local climate and atmospheric circulation pattern exert a clear influence on the atmospheric boundary layer （ABL） formation and development in Northwest China. In this paper, we use field observational data to analyze the distribution and characteristics of the ABL in the extremely arid desert in Dunhuang, Northwest China. These data show that the daytime convective boundary layer and night time stable boundary layer in this area extend to higher altitudes than in other areas. In the night time, the stable boundary layer exceeds 900 m in altitude and can sometimes peak at 1750 m, above which the residual layer may reach up to about 4000 m. The daytime convective boundary layer develops rapidly after entering the residual layer, and exceeds 4000 m in thickness. The results show that the deep convective boundary layer in the daytime is a pre-requisite for maintaining the deep residual mixed layer in the night time. Meanwhile, the deep residual mixed layer in the night time provides favorable thermal conditions for the development of the convective boundary layer in the daytime. The prolonged periods of clear weather that often occurs in this area allow the cumulative effect of the atmospheric residual layer to develop fully, which creates thermal conditions beneficial for the growth of the daytime convective boundary layer. At the same time, the land surface process and atmospheric motion within the surface layer in this area also provide helpful support for forming the particular structure of the thermal ABL. High surface temperature is clearly the powerful external thermal forcing for the deep convective boundary layer. Strong sensible heat flux in the surface layer provides the required energy. Highly convective atmosphere and strong turbulence provide the necessary dynamic conditions, and the accumulative effect of the residual layer provides a favorable thermal environment.  相似文献   

基于LBP算法的全天空红外云图的分类研究     

孙学金  刘磊  高太长  赵世军 《南京气象学院学报》2009,32(4):490-497

利用局部二值模式（Local Binary Patterns,LBP）,结合局部云图的方差信息（VAR）,对全天空红外测云系统获得的红外云图进行了分类研究。首先建立了器测云状分类与传统分类的对应关系,其次分析了层状云、积状云、波状云、卷云和晴空5种类型天空的LBP谱和VAR特征,最后对274个样本进行了分类识别,并与人工观测结果比较,结果表明,层状云、积状云、波状云、卷云和晴空的识别正确率分别为100．0％、84．2％、70．3％、64．7％、99．0％,平均正确率达到87．2％。  相似文献   

基于模糊纹理光谱的全天空红外图像云分类   总被引：6，自引：1，他引：5       下载免费PDF全文

孙学金  刘磊  高太长  赵世军  刘剑  毛节泰 《应用气象学报》2009,20(2):157-163

为了对全天空红外测云系统获得的红外图像进行云类自动识别, 提出了基于模糊纹理光谱结合云物理属性的全天空云类识别方法。首先根据不同滤波窗口的模糊纹理光谱图像特征, 确定了滤波窗口大小, 然后通过分析不同天空类型下的FUTS谱 (fuzzy uncertainty texture spectrum) 以及同一种天空类型下的FUTS谱, 考察了FUTS进行云类识别的适用性, 最后利用最小距离分类法和云基本物理属性对全天空红外图像进行了分类测试。在200个测试样本中, 层状云、积云、高积云、卷云和晴空的识别率分别为100%, 100%, 90%, 100%, 100%, 平均识别率达到98%。基于模糊纹理光谱的云分类算法对单一云空具有很好的分类效果, 可进一步应用于全天空红外图像的云分类识别。  相似文献   

FY-2E分裂窗晴空沙尘区导风初步研究   总被引：2，自引：2，他引：0  

詹奕哲  王振会  张治国 《遥感学报》2012,16(4):738-750

干旱半干旱沙尘爆发区风场信息作为沙尘监测的一个重要组成部分,能够为沙尘移向预报提供宝贵的资料。结合目前日趋成熟的红外分裂窗差值监测沙尘及卫星导风技术,针对FY-2E气象卫星,首先利用MODTRAN辐射传输模式对沙尘晴空区特征进行敏感性分析,再将经过图像掩膜及线性处理后的分裂窗差值图像代入导风计算程序计算,获得了传统卫星导风所无法得到的水汽含量低值区风场信息。实际个例分析表明,得到的沙尘区风场与NCEP再分析资料850hPa风场有很好的一致性,能够为监测沙尘移动提供良好的风场信息。  相似文献   

长波天波授时可行性分析     

靳建新 《全球定位系统》2012,37(3):5-8,15

为扩展现有长河二号系统的授时覆盖范围,提出利用天波实现远距离授时。结合实测数据以及长波天波场强和时延理论算法,分析了天波场强和时延随传播路径及昼夜变化的规律,并通过天地波场强的对比验证了利用天波授时的可行性。  相似文献   

多普勒雷达晴空回波识别与应用   总被引：2，自引：0，他引：2  

冷亮  黄兴友  杨洪平  张思进 《气象科技》2012,40(4):534-541

在现有多普勒天气雷达资料质量控制基础上,采用徐州雷达站2009年4月和9月雷达资料,统计并对比几种常见的降水回波与非降水回波特性,找出一种有效地识别晴空回波的方法。该方法在不同径向距离区间(小于25km及25～200km)采用不同的识别参数,能够较好地将非降水回波中对临近预报有用的晴空回波信息保留,而将其他非降水回波信息(地物回波、超折射回波等)剔除。依据该方法识别的晴空回波区域所对应Doppler速度可用于判别大气平流状况,从而为预报工作提供帮助。  相似文献   

Ultraviolet radiation in overcast sky at the surface     

BAI Jianhui  WANG Gengchen  HU Fei 《大气科学进展》2003,20(6):1007-1009

Based on the analysis of one year of observation data of solar radiation at the ground in Beijing in 1990, a simple empirical formula for calculating UV radiation in overcast sky is established. The formula is Qlw/Quvo = A1S Ao, where Quv and Quvo are monthly mean daily sums of UV exposure in overcast sky and clear sky, respectively. S is the daily sunshine hours. The calculated results agree well with the observed. The maximum and minimum relative biases are 9.9% and 0.1%, respectively, and the yearly relative bias is 2.9%. The ratio of ultraviolet radiation of overcast sky to clear sky in 1990 is between 44.6% and 61.8%, and the yearly average is 53.9%. Thus, almost half of the UV energy is lost in the atmosphere in overcast sky in 1990.  相似文献   

云量定量测算     

韩通  王广玉 《气象》1996,22(6):39-41

现行云量观测各种误差较大，本文提出了天空（即天空视野）为半球形，把无法器测的云量转换成可以器测的云块视高度和视宽度角的测量，利用数学方法定量计算云量，以减小观测误差，提高观测精度。  相似文献   

STUDYING THE SKY RADIANCE AND DEGREE OF POLARIZATION AND SOUNDING THE OPTICAL CHARACTERISTICS OF ATMOSPHERIC AEROSOL          下载免费PDF全文

Zhao Xuepeng  Zhou Xiuji  Xue Qingyu  Guo Song 《Acta Meteorologica Sinica》1991,5(3):360-369

The sky radiance and degree of polarization with multiple scattering process considered were calculated inthis paper by solving vector form radiative transfer equation iteratively. Numerical experiment for simultaneouslyretriving the size distribution (SD) and the complex refractive index (CRI) of aerosol particle was conductedwith the degree of polarization of skylight (DPS) and the library method used. It is shown from the resultsthat the real part of CRI is always sensitive to DPS. But situation is somewhat complicated for the imaginarypart of CRI. Therefore, it is expected that the real part of CRI can be retrieved from DPS and its imaginarypart should be retrieved as the particle is large in size. In this paper, seven sets of DPS measurements on 6 January,1990 in Beijing were given and the optical characteristics of aerosol were retrieved.  相似文献