EFFECTS OF A CLOUD FILTERING METHOD FOR FENGYUN-3C MICROWAVE HUMIDITY AND TEMPERATURE SOUNDER MEASUREMENTS OVER OCEAN ON RETRIEVALS OF TEMPERATURE AND HUMIDITY     

贺秋瑞  王振占  何杰颖 《热带气象学报(英文版)》2018,24(1):29-41

For Microwave Humidity and Temperature sounder (MWHTS) measurements over the ocean, a cloud filtering method is presented to filter out cloud- and precipitation-affected observations by analyzing the sensitivity of the simulated brightness temperatures of MWHTS to cloud liquid water, and using the root mean square error (RMSE) between observation and simulation in clear sky as a reference standard. The atmospheric temperature and humidity profiles are retrieved using MWHTS measurements with and without filtering by multiple linear regression (MLR), artificial neural networks (ANN) and one- dimensional variational (1DVAR) retrieval methods, respectively, and the effects of the filtering method on the retrieval accuracies are analyzed. The numerical results show that the filtering method can improve the retrieval accuracies of the MLR and the 1DVAR retrieval methods, but have little influence on that of the ANN. In addition, the dependencies of the retrieval methods upon the testing samples of brightness temperature are studied, and the results show that the 1DVAR retrieval method has great stability due to that the testing samples have great impact on the retrieval accuracies of the MLR and the ANN, but have little impact on that of the 1DVAR.  相似文献   

基于卫星辐射率资料的两种三维云反演方法对比研究     

许冬梅  沈菲菲  闵锦忠  张备 《大气科学》2018,42(2):411-420

基于格点统计插值分析系统（Gridpoint Statistical Interpolation analysis system,简称GSI）,利用粒子滤波（Particle Filter,简称PF）方法对卫星红外辐射率资料进行了云覆盖、云高等三维云图产品的反演研究。选取了具有高时空分辨率的静止卫星GOES（Geostationary Operational Environmental Satellites）-Imager辐射率资料进行了云反演试验,初步评估了PF云反演方法的可行性及其与多元极小残差（Multivariate and Minimum Residual,简称MMR）云反演方法的异同。结果表明:两种方法反演得到的云覆盖和云顶气压与NASA基于CO₂切片法反演得到的GOES云产品一致性较高。PF和MMR方法反演产品的优点是云图信息是三维分布的,相对于NASA提供的GOES云产品能提供更全方位立体的云信息。MMR方法需要利用一维变分逐步拟合观测来反演三维云图产品;PF方法采用不同模式垂直层的云覆盖比例作为不同粒子来近似后验概率分布,计算效率大大提高。进一步提出了一种新的基于“扰动粒子”的粒子滤波云反演方法,结果表明:在滤波过程中采用足够多的粒子样本（样本数量约为250）可以改进后验概率密度函数的估计,有效地避免了粒子发散问题,改善了云反演的结果。  相似文献   

Describing and comparing landscapes using tags,texts, and free lists: an interdisciplinary approach     

Flurina M. Wartmann  Elise Acheson  Ross S. Purves 《International journal of geographical information science》2018,32(8):1572-1592

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Sensitivity Studies for Monitoring Tropospheric Ozone from Space Using the Ultraviolet,Visible,and Polarization Bands          下载免费PDF全文

CAI Zhao-Nan  LIU Yi  LIU Xiong 《大气和海洋科学快报》2014,(3):198-202

The authors analyzed the retrieval sensitivity of tropospheric ozone using simulated the Global Ozone Monitoring Experiment-2 （GOME-2） measurements. The retrieval sensitivity was evaluated by the degree of free- dom for signal （DFS）. The combination of the ultraviolet （UV）, UV polarization （UVPOL）, and visible （VIS） bands enhances DFS of tropospheric ozone and improves the vertical resolution of the retrieved ozone profile. UVPOL reduces the dependence on solar zenith angle, mainly in- creases the sensitivity in upper troposphere. Polarization increased the DFS by 20% on the eastern side of the GOME-2 orbit, with little improvement on the western side because the increase in DFS due to polarization is depend- ent on the relative azimuth angle. The inclusion of the visi- ble band reduces significantly the dependence on viewing geometry, and mainly increases the DFS in the lower tro- posphere （0-6 kin） by a factor of two. It was possible to retrieve several independent pieces of tropospheric ozone information from GOME-2 UV/UVPOL/VIS measure- ments, especially in the lower troposphere.  相似文献   

Are opinions expressed in land-use planning documents?     

Eric Kergosien  Bernard Laval  Mathieu Roche 《International journal of geographical information science》2014,28(4):739-762

A great deal of research on information extraction from textual datasets has been performed in specific data contexts, such as movie reviews, commercial product evaluations, campaign speeches, etc. In this paper, we raise the question on how appropriate these methods are for documents related to land-use planning. The kind of information sought concerns the stakeholders, sentiments, geographic information, and everything else related to the territory. However, it is extremely challenging to link sentiments to the three dimensions that constitute geographic information (location, time, and theme). After highlighting the limitations of existing proposals and discussing issues related to textual data, we present a method called OPILAND (OPinion mIning from LAND-use planning documents) designed to semi-automatically mine opinions related to named-entities in specialized contexts. Experiments are conducted on a Thau lagoon dataset (France), and then applied on three datasets that are related to different areas in order to highlight the relevance and the broader applications of our proposal.  相似文献   

升降轨PSInSAR观测反演沉降与水平向位移试验     

王艳  张玲  葛大庆  张学东  李曼 《国土资源遥感》2014,(4)

In SAR观测的解算值为雷达视线向形变量,在具备多个方向独立观测的条件下可利用最小二乘方法反演垂直、东西甚至南北方向的形变量。由于难以同时获取上下、东西和南北3个方向上的独立观测值,因而可利用升降轨模式实现对垂向和东西方向移动量的估计。以PSIn SAR监测所获取的形变速率为观测值,利用二维简化模型求解地面沉降量和东西方向移动量。结果表明,研究区形变以沉降为主,水平方向移动微小,证明了升降轨PSIn SAR在地面沉降中的适用性和可靠性。  相似文献   

基于AMSR-E数据的多年冰密集度反演算法研究   总被引：2，自引：1，他引：1  

郝光华  苏洁 《海洋学报(英文版)》2015,34(9):102-109

In recent years, the rapid decline of Arctic sea ice area(SIA) and sea ice extent(SIE), especially for the multiyear(MY) ice, has led to significant effect on climate change. The accurate retrieval of MY ice concentration retrieval is very important and challenging to understand the ongoing changes. Three MY ice concentration retrieval algorithms were systematically evaluated. A similar total ice concentration was yielded by these algorithms, while the retrieved MY sea ice concentrations differs from each other. The MY SIA derived from NASA TEAM algorithm is relatively stable. Other two algorithms created seasonal fluctuations of MY SIA, particularly in autumn and winter. In this paper, we proposed an ice concentration retrieval algorithm, which developed the NASA TEAM algorithm by adding to use AMSR-E 6.9 GHz brightness temperature data and sea ice concentration using 89.0GHz data. Comparison with the reference MY SIA from reference MY ice, indicates that the mean difference and root mean square(rms) difference of MY SIA derived from the algorithm of this study are 0.65×106 km2 and0.69×106 km2 during January to March, –0.06×106 km2 and 0.14×106 km2 during September to December respectively. Comparison with MY SIE obtained from weekly ice age data provided by University of Colorado show that, the mean difference and rms difference are 0.69×106 km2 and 0.84×106 km2, respectively. The developed algorithm proposed in this study has smaller difference compared with the reference MY ice and MY SIE from ice age data than the Wang's, Lomax' and NASA TEAM algorithms.  相似文献   

星载双频测雨雷达航空校飞试验降水反演分析   总被引：4，自引：2，他引：2  

吴琼  杨虎  商建  郭杨  尹红刚  卢乃锰 《气象学报》2013,71(1):159-166

2010年9月6日到10月20日,在江苏东台黄海附近进行了中国首次星载双频(Ku和Ka波段)测雨雷达的外场校飞试验,获得了宝贵的机载雷达数据。利用所探测的有效降水资料,对机载雷达的降水探测能力进行了性能分析。对比机载测雨雷达和同步星载测雨雷达(Precipation Radar,PR)探测的反射率因子廓线可以发现,机载雷达反射率因子廓线在1.55 km高度的探测结果和PR较为一致,尤其是融化层一致性更好,表明机载雷达有探测降水垂直结构的能力。为了进行Ka波段机载雷达的降水反演,利用卫星数据模拟器(Satellite Data Simulator Unit,SDSU)计算了k-Z_e和R-Z_e关系的系数,并在此基础上进行了衰减订正以及雨强的反演。结果表明,Ku和Ka波段反演的雨强廓线基本一致,证实了反演系数的合理性。  相似文献   

传播运动在对流风暴合并过程中的作用          下载免费PDF全文

侯淑梅  闵锦忠  王改利  吕博  王俊  孙晶  景安华 《大气科学学报》2020,43(2):347-357

2012年8月18日下午,山东省境内飑线在形成过程中发生多次合并,强度增强,造成章丘和宁阳分别出现9级和10级雷暴大风。基于多普勒天气雷达反演风场和地面加密自动气象站资料,分析了传播运动在对流风暴合并过程中的作用。结果表明:1)地面冷池前沿阵风锋强度大,垂直厚度达2 km。受其影响,飑线向东移动的同时向东传播(前向传播),北段逐渐演变为弓形回波。2)弓形回波与单体E分别具有独立的垂直环流,均为前向传播,但位于上游的弓形回波传播速度快,二者最终合并,垂直环流合二为一。3)弓形回波与单体E合并过程中,水平风速与上升运动明显增大,气压降低,尺度减小,最终形成强烈旋转上升的小尺度低气压柱,造成章丘大风。4)飑线尾部水汽充沛,阵风锋辐合造成飑线前侧的暖湿空气抬升,不断产生新的对流单体并逐渐合并增强,导致飑线向西南方向传播(后向传播)。5)位于下游的对流单体传播方向与平流方向相反,在3 km高度产生云桥,最终与上游单体整层合并。飑线尾部对流风暴多次合并,强度持续增强,造成宁阳大风。  相似文献   

基于神经网络的太赫兹冰云探测反演算法研究     

陈柯  张兰  张幼明  董杉彬  刘艳  吴琼  商建 《遥感学报》2022,26(10):2043-2059

太赫兹频段在冰云探测上具有独特优势,但是目前的太赫兹冰云反演算法将不同种类冰相粒子（主要是冰和霰）视为冰粒子统一计算。本文根据冰云太赫兹辐射特性实现了一种预分类的神经网络算法,能够从太赫兹亮温中分别反演得到冰、霰两种粒子的统计参数和廓线分布。首先,基于WRF数值模式和ATMS载荷真实观测的冰云霰数据构建了包含冰、霰粒子密度廓线的混合冰云数据库,然后,使用DOTLRT辐射传输模式模拟183 GHz、243 GHz、325 GHz、448 GHz、664 GHz和874 GHz这6个频段的星载太赫兹冰云探测亮温,最后,开展冰云参数探测仿真试验,验证反演算法性能。仿真试验中反演得到的冰和霰的路径总量均方根误差分别为8.97 g/m²和10.90 g/m²,等效粒径均方根误差分别为7.54 μm和25.38 μm,反演的冰、霰密度廓线也具有较高的精度。研究结果表明本文算法能够以较好的精度从多频太赫兹冰云探测亮温数据中分别反演得到冰、霰两种粒子的路径总量、等效粒径、等效云高和密度廓线,突破现有研究仅仅计算单一冰粒子的局限,更加符合冰云真实情况。  相似文献