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1. chinaXiv:201703.00286 [pdf]

Temperature and humidity profiles retrieving over land using clear sky measurements of microwave humidity-temperature sounder on Chinese FY-3C satellite

He, Qiurui; Wang, Zhenzhan; He, Jieying
Subjects: Geosciences >> Space Physics

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.

submitted time 2017-03-10 Hits3695Downloads652 Comment 0

2. chinaXiv:201703.00254 [pdf]

Effects of a cloud filtering method for Fengyun-3C Microwave Humidity and Temperature Sounder measurements over ocean on retrievals of temperature and humidity

HE Qiurui; WANG Zhenzhan; HE Jieying
Subjects: Geosciences >> Space Physics

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.

submitted time 2017-03-10 Hits782Downloads396 Comment 0

3. chinaXiv:201605.01581 [pdf]

A method for correcting regional bias in SMOS global salinity products

Tong Xiaolin; Wang Zhenzhan); Li Qingxia
Subjects: Geosciences >> Space Physics

Soil Moisture and Ocean Salinity (SMOS) Level 3 (L3) sea surface salinity (SSS) products are provided by the Barcelona Expert Centre (BEC). Strong biases were observed on the SMOS SSS products, thus the data from the Centre Aval de Traitement des Donn,es SMOS (CATDS) were adjusted for biases using a large-scale correction derived from observed differences between the SMOS SSS and World Ocean Atlas (WOA) climatology data. However, this large-scale correction method is not suitable for correcting the large gradient of salinity biases. Here, we present a method for the correction of SSS regional bias of the monthly L3 products. Based on the stable characteristics of the large SSS biases from month to month in some regions, corrected SMOS SSS maps can be obtained from the monthly mean values after removing the regional biases. The accuracy of the SMOS SSS measurements is greatly improved, especially near the coastline, at high latitudes, and in some open ocean regions. The SMOS and ISAS SSS data are also compared with Aquarius SSS to verify the corrected SMOS SSS data. The correction method presented here only corrects annual mean biases. The measurement accuracy of the SSS may be improved by considering the influence of atmospheric and ocean circulation in different seasons and years.

submitted time 2016-05-12 Hits437Downloads249 Comment 0

4. chinaXiv:201605.00279 [pdf]


Zhang, Dehai; Wang, Zhenzhan; Li, Yun; Zhao, Jin; Liu, Yalong
Subjects: Geosciences >> Space Physics

Water vapor and cloud liquid water can influence the accuracy of sea surface height that spaceborne altimeter measures. Atmospheric correction microwave radiometer (ACMR) can be used to retrieve the amount of water vapor and cloud liquid water by measuring radiation from atmosphere and earth's surface. HY-2 satellite is a Chinese satellite for ocean dynamic environmental monitoring. ACMR is one payload of HY-2 satellite. Up to now, ACMR has been in operation for more than three years. In-orbit system stability of three years is assessed. The data of ACMR brightness temperature are matched to that of ECMWF wet tropospheric path delay in same space and time. The water vapor and cloud liquid water retrieval algorithm is derived The wet tropospheric path delay deviations are less than 1.5cm. Brightness temperatures and path delay of ACMR were compared with that of AMR. The average and standard deviations of wet tropospheric path delay are 1.27mm and 0.68mm.

submitted time 2016-05-03 Hits767Downloads424 Comment 0

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