分类： 地球科学 >> 空间物理学 提交时间： 2017-03-10
摘要： An one-dimensional variational retrieval system was developed to retrieve the clear sky atmospheric temperature and humidity profiles over land using the measurements of microwave humidity-temperature sounder (MWHTS) on Chinese FY-3C satellite. The system parameters are configured by analyzing the MWHTS channel properties and the climate condition over land. The retrieval results are evaluated by root mean square error (rmse) with respect to European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis data. The validated results show that the maximum root mean square error of temperature and humidity are 2.59K and 11.87%, respectively. The retrieval results, compared with National Centers for Environmental Prediction (NCEP) 6 hour forecast profiles, show that the background profiles can affect the accuracy of retrieval profiles and FY-3C/MWHTS measurements can improve forecast precision of humidity. �2016 IEEE.
分类： 地球科学 >> 空间物理学 提交时间： 2017-03-10
摘要： 针对风云三号C星微波湿温探测仪(FY-3C/MWHTS)的陆地晴空观测资料，建立了一维变分反演系统，对大气的温湿廓线进行反演。为了更好的描述温湿廓线的相关性，同时减小温度和湿度在反演过程中相互之间的误差传递，提出了使用背景协方差矩阵的联合矩阵和单独矩阵进行组合反演的方法。对于MWHTS模拟亮温和观测亮温之间的偏差，使用逐扫描点的统计回归方法进行校正。选择我国部分陆地区域的晴空观测亮温进行温湿廓线的反演，并利用欧洲中期天气预报中心(ECMWF)再分析数据、美国国家环境预报中心(NCEP)分析数据以及无线电探空观测(RAOB)数据对反演结果进行验证，温湿廓线的反演结果与ECMWF再分析数据验证的最大均方根误差分别是2.59 K和11.87%，与NCEP分析数据验证的最大均方根误差分别是1.88 K和21.50%，与RAOB数据验证的最大均方根误差分别是3.43 K和25.48%，验证结果表明了反演结果的可靠性。另外与国外同类载荷AMSU观测亮温的物理方法和统计方法反演精度进行了对比，结果表明：MWHTS具有较强的湿度廓线以及高空温度廓线的探测能力，且针对MWHTS的观测亮温建立的一维变分反演系统具有较高的反演精度。与NCEP 6小时预报廓线的验证结果表明：反演的湿度廓线可以提高预报廓线的精度。
分类： 地球科学 >> 空间物理学 提交时间： 2017-03-10
摘要： A passive sub-millimeter precipitation retrievals algorithm is provided based on Microwave Humidity and Temperature Sounder (MWHTS) onboard the Chinese Feng Yun 3C (FY-3C) satellite. Using the validated global reference physical model NCEP/WRF/ VDISORT), NCEP data per 6 hours are downloaded to run the Weather Research and Forecast model WRF, and derive the typical precipitation data from the whole world. The precipitation retrieval algorithm can operate either on land or on seawater for global. To simply the calculation procedure and save the training time, principle component analysis (PCA) was adapted to filter out the redundancy caused by scanning angle and surface effects, as well as system noise. According to the comparison and validation combing with other precipitation sources, it is demonstrated that the retrievals are reliable for surface precipitation rate higher than 0.1 mm/h at 15km resolution.
分类： 地球科学 >> 空间物理学 提交时间： 2017-03-10
摘要： For Microwave Humidity and Temperature sounder (MWHTS) measurements over 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.
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