Measurements of ocean wave spectrum from airborne radar at small incidence angles

This paper proposes the retrieval method of ocean wave spectrum for airborne radar observations at small incidence angles, which is slightly modified from the method developed by Hauser. Firstly, it makes use of integration method to estimate total mean square slope instead of fitting method, which aims to reduce the affects of fluctuations superposed on normalized radar cross-section by integration. Secondly, for eliminating the noise spectrum contained in signal spectrum, the method considers the signal spectrum in certain look direction without any long wave components as the assumed noise spectrum, which would be subtracted from signal spectrum in any look direction for linear wave spectrum retrieval. Estimated ν from the integration method are lower than the one from fitting method and have a standard deviation of 0.004 between them approximately. The assumed noise spectrum energy almost has no big variations along with the wave number and is slightly lower to the high wave number part of signal spectrum in any look direction, which follows that the assumption makes sense. The retrieved directional spectra are compared with the buoy records in terms of peak wavelength, peak direction and the significant wave height. Comparisons show that the retrieved peak wavelength and significant wave height are slightly higher than the buoy records but don’t differs significantly (error less than 10%). For peak direction, the swell waves in first case basically propagate in the wind direction 6 hours ago and the wind-generated waves in second case also propagate in the wind direction, but the 180? ambiguity remains. Results show that the modified method can carry out the retrieval of directional wave spectrum.     

利用环境一号卫星热红外影像反演渤海海表温度

针对环境卫星热红外遥感影像,结合美国环境预报中心(NCEP)再分析数据,运用覃志豪单窗算法(MW),修订了该算法的主要参数计算公式,建立了反演海洋表面温度的流程.利用2009年10月4日渤海上空的热红外遥感影像进行反演试验,同时对比反演结果和美国中等分辨率成像光谱仪(MODIS)的海表温度产品(MOD28)之间的差异....     

Retrieval of vertical wind profiles during monsoon from satellite observed winds over the Indian ocean using complex EOF analysis

The aim of this paper is to study the feasibility of deriving vertical wind profiles from current satellite observations. With this aim, we carried out complex empirical orthogonal function (CEOF) analysis of a large number of radiosonde observations of wind profiles over the Indian Ocean during the monsoon months. It has been found that the first two CEOFs explain 67% of the total variance in wind fields. While the first principal component is well correlated with the winds at 850 mb (r = 0:80), the second one is highly correlated with winds at 200 mb (r = 0:89). This analysis formed the basis of a retrieval algorithm which ensures the retrieval of vertical profiles of winds using satellite tracked cloud motion vector winds. Under the assumption that accurate measurements of wind are available at the above mentioned levels, the r.m.s. error of retrieval of each component of wind is estimated to range between 2 ms^-1 and 6 ms^-1 at different levels, which is much less than the natural variance of winds at these levels. For a better visualization of retrieval, we have provided retrieved and true wind profiles side by side for four typical synoptic conditions during the monsoon season.     

分析测试标准方法目录数据库检索系统

应用dBASEⅢ数据库建成了分析测试标准方法目录数据库检索系统。数据库内已录入九个国家及组织最新发布的有关地质、冶金、煤炭、环保、建材及水分析等方面的分析测试标准4000多个,并已将库内所有标准以分类号及标准号顺序打印装订成分析测试标准检索手册。本数据库的建成为有关部门获得最新的标准情报提供了工具。     

遥感植被双向反射光谱的理论研究与应用展望

本文首先分析了传统的垂直测量方法在定量遥感中的局限性及多角度倾斜光谱在估算地物三维空间结构等方面的优越性。通过总结近年来国际上在植被双向反射领域所取得的主要成果,对计算植被双向反射系数的四类物理模型进行了简要评述。然后,从模式的选取、地物方向谱的结构及最佳的多角度资料的获取、观测波段的选择和模式的数学反演等方面出发,详细地讨论了利用上述理论模型实现植被结构参数的定量估算、再生资源的定量遥感的主要过程,以及使多角度遥感的潜在优势得以真正实现的可能途径。     

全国测绘资料档案管理系统SMIS的设计与实现

本文介绍了全国测绘资料档案管理系统SMIS的主要功能、设计思想与实现方法。重点叙述了SMIS的系统结构,测绘资料档案综合数据库的设计,测绘资料档案多途经检索与提供、图形及数据交换接口程序的实现原理。文中还提出了一种新的索引地图检索方法,该方法适用于任何具有地理分布特征的信息管理领域。     

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

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.