FY-3A气象卫星大气垂直探测仪器数据几何位置匹配试验

随着卫星搭载的有效载荷数目的增加,卫星数据种类也不断增加,利用有限的数据资源获得多种卫星或多种仪器遥感数据源的信息,可以增强对目标物的检测与识别能力,提高卫星遥感应用的精度、范围和效率。以风云三号气象卫星L1级模拟数据为基础,用建立匹配查找表的方法进行红外分光计、微波温度计、微波湿度计三个大气垂直探测仪器的数据几何位置匹配技术研究,把三个仪器的观测资料统一匹配到红外分光计的观测格点上,并对匹配前后的资料进行了分析。匹配结果表明,当微波湿度计观测资料匹配到与其分辨率相差不大的红外分光计格点上时,其探测资料的精度损失不大,基本上保持了原有分辨率上观测资料的数据分布信息。而当微波湿度计观测资料匹配到与其分辨率相差较大的微波温度计格点上时(从15km分辨率匹配到50km分辨率上),总的数据信息损失不大,只有一些较细致的数据纹理信息有所损失,匹配后的观测资料为卫星大气垂直探测提供了良好的数据基础。     

风云三号微波湿度计航空校飞辐射定标原理及数据分析

风云三号微波湿度计是我国首次在轨定量应用于大气探测的星载被动微波辐射计，为验证载荷辐射性能，发射前于2007年9月至11月开展了航空校飞试验，历时2个月共转场青海湖、敦煌和云南普洱3个试验场，地面同步实施了辐射校正测量。在阐述星载微波大气探测载荷航空校飞辐射定标原理基础上，开展航空校飞数据分析，并与同步辐射校正测量结果进行了比对验证，结果表明风云三号微波湿度计初样产品探测结果符合设计指标要求。风云三号微波湿度计航空校飞试验为其资料在轨业务定量应用奠定了基础，其中航空校飞辐射定标模型支撑了后续风云三号卫星微波湿度计在轨业务定标。     

风云三号微波湿度计航空校飞辐射定标原理及数据分析

风云三号微波湿度计是我国首次在轨定量应用于大气探测的星载被动微波辐射计，为验证载荷辐射性能，发射前于2007年9月至11月开展了航空校飞试验，历时2个月共转场青海湖、敦煌和云南普洱3个试验场，地面同步实施了辐射校正测量。在阐述星载微波大气探测载荷航空校飞辐射定标原理基础上，开展航空校飞数据分析，并与同步辐射校正测量结果进行了比对验证，结果表明风云三号微波湿度计初样产品探测结果符合设计指标要求。风云三号微波湿度计航空校飞试验为其资料在轨业务定量应用奠定了基础，其中航空校飞辐射定标模型支撑了后续风云三号卫星微波湿度计在轨业务定标。     

人工神经网络反演算法反演北京地区湿度廓线

微波湿度计（MWHS）是风云三号卫星的主要有效载荷之一,其频率为150GHz（双极化）和183.3lGHz（三通道）,分别用于探测大气窗区和水汽廓线。采用垂直于飞行方向的交轨扫描方式,科学目标是探测大气湿度的垂直分布。本文简要介绍微波大气湿度探测的基本原理,阐述了湿度廓线反演的各种方法,着重运用人工神经网络算法,反演北京地区的大气湿度的垂直分布。结果表明,运用风云三号微波湿度计数据,大气湿度垂直分布反演值与已知的探空数据相比,虽有误差,但在可接受范围之内,反演结果可应用于气象,通信等领域,并具有重要应用价值。     

风云三号微波大气探测载荷辐射定标

风云三号气象卫星是我国第二代极轨业务气象卫星,具有全球、全天候和多光谱探测能力,装载有微波温度计和微波湿度计2台微波大气探测载荷,自2008年首发星升空后,风云三号微波大气探测载荷资料在防灾减灾和数值天气预报同化应用中发挥了积极作用。风云三号气象卫星微波载荷辐射定标是从原始观测计数值出发获取目标亮温的数据处理技术过程,包括发射前定标、在轨星上定标、综合辐射定标和历史资料再定标4个技术环节。精确的辐射定标是星载被动微波辐射计遥感资料定量应用的基础。本文综述了风云三号气象卫星微波大气探测载荷综合辐射定标技术,介绍了风云三号微波大气探测载荷综合辐射定标基本原理及技术现状,展望了风云气象卫星微波大气探测载荷综合辐射定标技术未来发展。     

An alternative method for in-flight absolute radiometric calibration of thermal infrared channels of Chinese geostationary meteorological satellites

The aim of this study was to explore the feasibility of an alternative method for in-flight absolute radiometric calibration of the thermal infrared (TIR) channels of the Chinese meteorological satellites FengYun-2B (FY-2B) and FengYun-2C (FY-2C). The alternative method substituted radiosonde atmospheric profiles with those from the National Centers for Environmental Prediction (NCEP) reanalysis and the water surface brightness temperatures from TIR radiometers (CE312) with those from an automated hydrometeorological buoy (AHMB) system over Qinghai Lake (QHL), China. These data were then used to calculate the calibration coefficients and their uncertainty for the TIR channels of FY-2B and FY-2C. The at-sensor radiance (ASR) and at-sensor brightness temperature (ASBT) of the TIR channels of FY-2B and FY-2C were calculated by using 14 atmospheric profiles as measured by radiosonde over QHL in August 2003 and the corresponding NCEP reanalysis data, respectively. In addition, we conducted sensitivity tests to different atmospheric profiles of varying relative humidity and air temperatures on the ASR and ASBT of the TIR channels of FY-2B and FY-2C. Differences in gains between the regular and alternative methods are less than 0.005 mW m^–2 sr^?1 cm^?1 DN^?1. The sensitivity tests show that the ASR and ASBT are more sensitive to the relative humidity than the temperature in the atmospheric profile. Our results show that the proposed alternative method, of which the uncertainty is about 1.5 K for the TIR channels of FY-2B and FY-2C, is feasible for the TIR channels of various remote sensors. One of the major benefits of this alternative method is the potential for more frequent, reliable and inexpensive calibrations of the TIR sensors in operational conditions.     

小卫星大气微波探测仪及其应用模拟研究

小卫星大气微波探测仪技术是目前微波遥感技术的一个研究热点.通过研制一台小卫星大气微波探测仪(以下简称大气微波探测仪,英文简称SAMS)并搭载在我国的商业小卫星上,实现对大气温湿度、极端天气和降雨的快速测量.介绍了 SAMS的应用方面设计的特点,并结合目前的灵敏度测试数据,分析了在轨应用性能,尤其是在海面气压、大气湿路径...     

移动通讯信号对星载微波辐射计的影响分析-以风云三号气象卫星微波湿度计为例

以风云三号气象卫星微波湿度计为例，通过手机信号对183.31GHz接收机的干扰实验，找到了干扰途径，进行了机理分析，并定量分析了移动通讯基站对在轨运行的星载微波辐射计的影响，给出在星载微波辐射计中预防和解决干扰的措施，并进行了实验验证。
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FY-3A/MWHS辐射传递及冷空偏差修正

为了推进FY-3A/MWHS数据与国外同类载荷遥感数据的同化应用,针对FY-3A/MWHS业务L1数据尝试开展大气吸收通道在轨辐射校验,通过瞬时星下点交叉比对(SNO)方法,完成MWHS与美国NOAA卫星同类载荷AMSU-B轨辐射基准的交叉传递。两个同类载荷遥感数据的对比分析表明:MWHS大气水汽吸收线附近的主探测通道与AMSU-B对应通道天线亮温变化特征一致;以辐射校验为基础,可以将AMSU-B在轨辐射基准传递到MWHS冷空辐射修正量,实现微波探测器在轨辐射基准的归一化。辐射交叉校验技术,为两个同类微波探测器在轨遥感数据的融合应用以及在数值天气预报中多源数据的同化应用奠定了基础。     

FY-3A气象卫星VIRR云检测产品与IRAS的匹配

通过查找表方法进行FY-3A气象卫星可见光红外扫描辐射计(Visible and InfraRed Radiometer, VIRR)云检测产品与红外分光计(Infrared Atmospheric Sounder, IRAS)之间的匹配实验,使VIRR云检测产品与IRAS具有一致的空间分辨率,为IRAS大气温湿度廓线的反演提供可靠的云检测信息。实验中分别采用模拟的VIRR云检测结果与IRAS数据进行匹配,并将匹配结果与原始云检测信息进行对比分析,验证查找表方法进行两者之间匹配处理的可行性。     

A new generation of Chinese FY-3C microwave sounding measurements and the initial assessments of its observations

A new Chinese satellite, FY-3C, carrying second-generation microwave sounding instruments, was introduced and the observations were evaluated. On board FY-3C are the Microwave Temperature Sounder ?2 (MWTS-2) and Microwave Humidity Sounder?2 (MWHS-2), and these devices are more advanced than those on board the previous satellites, FY-3A/B; the spectral and spatial resolutions of the devices are also higher than the Advanced Microwave Sounding Unit-A (AMSU-A) and the Microwave Humidity Sounder (MHS). The 50–60 GHz and 183 GHz sounding abilities are similar to Advanced Technology Microwave Sounder (ATMS) on board the Suomi National Polar-orbiting Partnership (SNPP). FY-3C and SNPP were launched in different orbits but are complementary in observation area. In addition, MWHS-2 is the first operational polar-orbiting, satellite-based sensor which has 118 GHz channels. Assessment of MWTS-2 and MWHS-2 observations indicate that striping noises are apparent from the observations. A technique combining principal component analysis (PCA) with Ensemble Empirical Mode Decomposition (EEMD) is used to extract the noise. The striping noise in the first PCA component is extracted from the data. It was determined that the bias and standard deviation (SD) of MWTS-2 noise was larger than that of the ATMS corresponding channels. The biases and SDs of the MWHS-2 noise were comparable in magnitude with ATMS moisture channels. After removing the noise, the biases and SDs of the difference between observation and simulation (O–B) for MWTS-2 were slightly larger than the ATMS. Biases of MWHS-2 were close to the ATMS. The O–B biases of MWHS-2 118 GHz channels were within the range from ?0.6 to 0.2 K, and the SDs were approximately 0.5–1.2 K.     

Validation of INSAT-3D temperature and moisture sounding retrievals using matched radiosonde measurements

An evaluation of temperature and moisture profiles retrieved from a geostationary Indian National Satellite (INSAT-3D) sounder, launched in 2013, is performed against collocated radiosonde (RAOB) observation measurements of more than 1 year. This evaluation is carried out in terms of bias and root mean square error (RMSE) in temperature and relative humidity. An error analysis is carried out for different surface types, different seasons and day/night cases. The key finding of this study is that INSAT-3D retrievals show good agreement with RAOB measurements with overall RMSE accuracies ~1–2 K and 10–20%, respectively, for temperature and relative humidity in the troposphere. However, the temperature and relative humidity retrievals over land or in dry atmosphere show degraded performance. This degradation might be related to uncertainty in surface emissivity over land and possibility of undetected cloud in dry atmospheric condition. In addition to it, a similar analysis is carried out to assess the relative performance of INSAT-3D-retrieved profiles, Atmospheric Infrared Sounder (AIRS) L2 Standard Physical Retrieval (AIRS-only) version 6 (AIRS2RET) profiles and European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-Interim) reanalysis with respect to spatially and temporally collocated RAOBs. In this analysis, temperature and moisture profiles from RAOBs serve as reference measurements and all retrievals and ERA-interim are compared with RAOBs. AIRS and INSAT-3D temperature retrievals gave comparable accuracies in upper and lower troposphere where as the quality degrades in middle troposphere resulting in larger errors. This may be due to improper bias correction coefficients used for brightness temperature of clear sky pixels before physical retrievals. In case of relative humidity, INSAT-3D profiles have comparable accuracies as AIRS in troposphere.     

星载微波大气湿度探测仪再定标共性技术分析

探测大气水汽的星载微波大气湿度探测仪是国内外气象卫星上的关键载荷之一。多台星载微波大气湿度探测仪观测数据构成的长时间序列数据集在天气预报、数据同化和全球气候监测与评估中有着非常重要的作用。由于微波辐射没有绝对基准,并且不同卫星平台上的微波大气湿度探测仪的系统响应特性和定标方法不尽相同,因此,再定标是提高多台星载微波大气湿度探测仪的长时间序列观测数据的长期一致性和稳定性的关键技术。我国的四台星载微波大气湿度探测仪自2008年以来已经积累了超过10 a的重要观测数据集,亟待通过再定标技术实现4台载荷在轨历史观测数据长期一致性和稳定性并有效应用。为此,详细总结了国内外星载微波大气湿度探测仪研究现状,并对国内外星载微波大气湿度探测仪再定标共性技术研究现状进行总结分析,然后给出我国星载微波大气湿度探测仪再定标方案的构想,为再定标处理提供关键共性技术参考。     

星载微波大气湿度探测仪再定标共性技术分析

探测大气水汽的星载微波大气湿度探测仪是国内外气象卫星上的关键载荷之一。多台星载微波大气湿度探测仪观测数据构成的长时间序列数据集在天气预报、数据同化和全球气候监测与评估中有着非常重要的作用。由于微波辐射没有绝对基准，并且不同卫星平台上的微波大气湿度探测仪的系统响应特性和定标方法不尽相同，因此，再定标是提高多台星载微波大气湿度探测仪的长时间序列观测数据的长期一致性和稳定性的关键技术。我国的四台星载微波大气湿度探测仪自2008年以来已经积累了超过10 a的重要观测数据集，亟待通过再定标技术实现4台载荷在轨历史观测数据长期一致性和稳定性并有效应用。为此，详细总结了国内外星载微波大气湿度探测仪研究现状，并对国内外星载微波大气湿度探测仪再定标共性技术研究现状进行总结分析，然后给出我国星载微波大气湿度探测仪再定标方案的构想，为再定标处理提供关键共性技术参考。     

Influence of Assimilating the Sea Surface Pressure Fields Retrieved from FY-3C/MWHTS Data on Typhoon Forecasting

Using measurements with the Microwave Temperature and Humidity Sounder (MWHTS) onboard the Chinese Fengyun-3C satellite, real-time and high resolution sea surface pressure information can be retrived. Based on the three-dimensional variational assimilation (3DVAR) method, the retrieved sea pressure fields from FY-3C/MWHTS observations are assimilated into the Weather Research and Forecasting (WRF) model. The influence of the retrieved pressure fields on typhoon forecasting is discussed through the comparison between control experiment and assimilation experiment. Sensitivity experiments of typhoon Maria and Noru show that the assimilation of sea surface pressure fields makes the central pressure and central location closer to the actual value, and adjusts the structure and distribution of initial temperature fields and wind fields. The numerical prediction results show that the assimilation of the sea surface pressure fields can improve the accuracy of typhoon track and intensity prediction.     

Retrieval of meteorological parameters from ROSA on-board Megha Tropiques satellite: evaluation with COSMIC GPS RO,ERA-Interim and radiosonde data

The Indian Space Research Organization (ISRO), in collaboration with Centre National d’Etudes Spatiales, France, launched radio occultation sounder for atmosphere (ROSA) on-board Megha Tropiques (MT) satellite. In this article, the retrieval of atmospheric parameters from ROSA and its evaluation with a network of in situ (radiosonde), similar satellite (Constellation Observational System for Meteorology, Ionosphere and Climate (COSMIC) GPS RO), and re-analysis (ERA-Interim) data sets are presented. The refractivity is retrieved from the bending angle as a function of impact parameter, and pressure and temperature profiles are derived from the profiles of refractivity. The algorithm has been successfully applied to COSMIC data. We have applied and validated this algorithm for the first time to ROSAon board MT. The algorithm retrieves the refractivity and pressure information from surface to 40 km whereas temperature profiles are restricted between 10 and 40 km. The ROSA algorithm refractivity, pressure, and temperature profiles compare well with independent data sets mentioned above. The mean fractional difference between ROSA and COSMIC, ERA-Interim and radiosonde refractivity and the temperature is found to be 0.1% with a standard deviation of 0.5%. It is shown that the algorithm derives the atmospheric parameters with good accuracies from the ROSA instrument and provides the atmospheric community new data from GPS RO at the verge of existing COSMIC GPS RO and in between upcoming GPS RO missions.     

同化FY-3C/MWHTS观测资料反演的海面气压场对台风数值预报的影响

由中国风云三号C星（FY-3C）搭载的微波温湿探测仪（MWHTS）的亮温观测资料能够实时反演得到高分辨率、高精度的海面气压场。基于三维变分同化方法将FY-3C/MWHTS观测资料反演的海面气压场同化进入中尺度天气研究与预报（Weather Research and Forecasting, WRF）模式,以台风“Maria”和“Noru”为例,通过控制实验和同化试验的对比分析,探讨了同化反演的海面气压场对台风数值预报的影响。初始化敏感性试验结果表明,同化海面气压场使初始时刻台风中心气压与位置更接近实况,并且调整了台风初始温度场和风场的结构和分布。台风的数值预报结果表明:同化反演的海面气压场能够改进台风的路径和强度预报精度。     

Exploring the need to revise atmospheric correction algorithms of satellite sensor images for the area of Greece

A New Model Atmosphere was constructed for the area of Southern Greece in an effort to support atmospheric correction of satellite sensor images. The impact of the New Model Atmosphere on incident solar radiation was examined using the MODTRAN radiative transfer code to calculate spectral transmittances at the surface. Results were compared to the respective spectral transmittances as these resulted from the use of the 1976 U.S. Standard Atmosphere in the MODTRAN radiative transfer code. Significant differences in transmittance calculations in the spectral region from 0·8 to 1·0μm, around 6·0 μm, and from 8·45 to 12μm were observed, indicating potential errors in the atmospheric (radiometric) correction of satellite sensor images.     

新型地基大气廓线微波探测仪及其参数反演

介绍的新型地基大气廓线微波探测仪样机,对进口并普遍使用的MP3000地基大气探测仪进行了结构创新,采用温度廓线测量的V波段（50~59 GHz）和湿度廓线测量的K波段（22~31 GHz）,每个频段采用7个通道。与MP3000不同,采用独立反射面,而非共享反射面的形式。接收机采用直接检波方式,而不采用超外差检波方式,避免了接收机下变频部分,结构上更简单,空间分辨率更高,维修更容易。这种新型设备具有体积小、质量轻、空间分辨率高和非线性误差低的特点。利用辐射传输方程和已知探空资料相关数据,计算各通道加权函数,计算各通道亮温,采用神经网络算法进行大气温度廓线的反演,结果证明,此样机在结构改进的基础上完全满足地基大气廓线仪结构简单,对时间分辨率和空间分辨率,温度廓线反演结果达到预期要求。     

风云三号卫星微波探测仪定标原理及算法

微波探测仪是搭载于气象卫星上的重要载荷，可全天候获取大气温度、湿度垂直廓线、降雨等重要大气参数，为气象预报、气候变化研究和灾害性天气现象监测等提供重要数据。定标是星载微波探测仪定量化应用的基础。详细阐述了星载微波探测仪定标基本原理，给出了定标相关基础概念，并根据星载微波探测仪仪器特性，系统地梳理了发射前热真空定标、发射后在轨定标/真实性检验技术和定标算法，同时对定标试验实施方案和定标算法实现的关键点进行了总结，从而建立了完整的星载微波探测仪定标流程和基准，对星载微波探测仪的统一化定标和定量化应用具有重要意义。