CSAO和VSNIIFTRI等高仪合作观测纲要和试观测初步结果     

徐家岩  刘进梅 《时间频率学报》1996,19(1):14-17

ＣＳＡＯ和ＶＳＮＩＩＦＴＲＩ１９９３年秋正式签订了将陕台ＰＨＡＩ搬去伊尔库次克进行国际合作观测、研究的协议．为了执行此项合作协议，首先对仪器进行了改造，使其能工作在Ｚ＝４５°的等高圈上；同时编制了适合于伊尔库次克纬度和新天顶距的观测纲要，全纲要共包括１２个星组，含６６８星次。其中ＦＫＳ基本星为３２４星次；ＦＫＳ扩展星和补编星为３４４星次；两次过等高圈的有２０３颗星，一次过等高圈的有２６２颗星，极限星等为９．５ｍ．恒星的赤纬分布在＋８．９°～＋７４．４°之间，赤纬跨度达６５．５°，在此赤纬带内可以消除赤其测定中的盲区．  相似文献   

适应性观测研究现状和展望   总被引：4，自引：1，他引：3       下载免费PDF全文

马旭林  于月明  陈德辉 《Acta Meteorologica Sinica》2015,73(2):221-235

适应性观测是指为了有针对性地提高高影响天气数值预报的质量,在已有观测系统基础上对特定敏感区域/特定时段进行补充性加强观测。十多年来,这种旨在提高数值预报质量的新策略在国际上引起高度重视,成功开展了多个系列外场观测试验,并在适应性观测敏感区识别方法的发展和适应性观测资料同化后对数值预报质量影响的定量评估等方面均取得了重要的研究成果。文中简述了适应性观测问题及其目的,着重分析和总结了目标敏感区识别方法及其特点和适应性观测对数值预报质量的影响等方面的研究进展,并讨论了适应性观测资料改进未来数值预报质量需要解决的关键科学问题。  相似文献   

理解大气资料同化的内在逻辑和若干共性特征     

朱国富 《气象》2015,41(8):997-1006

大气资料同化已发展成为基于估计理论的一门学科。本文试图梳理资料同化学科内容从“性质上分析同化问题是什么”到“过程上资料同化如何实施”再到“结果上分析场有着什么内在要求”这一内在逻辑,相应地综合阐述“逆问题求解和所需要的先验信息”、“观测信息的输入及其权重与传播平滑”和“同化结果的准确性和协调性”等资料同化作为一门学科的这些基本方面;以期这一逐步递进的逻辑及其基本方面有益于对资料同化在条理脉络上的一个整体理解。此外,着重于具体同化方法中的一些等价性和共性特征,本文梳理和归纳了“变分方法分别与最优插值方法之间和与扩展卡尔曼滤波方法之间的等价性”、“同化方法中数学的主要作用”,以及“同化方法中要应用综合学科知识”和“业务同化系统实施中要做好系统工程”等内容;以期这些内容增加对资料同化方法及同化系统研发的理解和思考。  相似文献   

基于CLDAS资料的内蒙古干旱监测分析   总被引：5，自引：1，他引：4  

孙小龙  宋海清  李平  李云鹏  武荣盛 《气象》2015,41(10):1245-1252

以内蒙古地区为研究区域,对中国气象局陆面数据同化系统（CMA Land Data Assimilation System,CLDAS）的土壤湿度和降水数据进行了评估,使用土壤相对湿度法和连续无降水日数法监测2014年夏季干旱,并选择干旱年（2014年）和湿润年（2013年）与标准化降水指数和降水百分位指数法进行验证分析。结果表明：CLDAS资料能够很好地再现日土壤相对湿度动态变化情况和降水落区与量级,能够满足干旱监测的需求;基于CLDAS数据的土壤相对湿度法可以方便、快捷地监测干旱日变化和区域性变化,连续无有效降水日数法对评估长时间、持续性干旱较为有效;CLDAS同化数据在时效性、分辨率、代表性上能够满足气象服务的需求,可作为观测资料的重要补充广泛应用于业务和科研,特别是对于地广人稀且气象站点相对较少的内蒙古地区气象服务潜力巨大。  相似文献   

四维变分同化技术在风暴潮数值模拟中的应用     

王宗辰  于福江  原野 《海洋预报》2015,32(1)

利用区域海洋模式ROMS(Regional Ocean Modelling System)及其四维变分同化模块,建立了具有资料同化能力的东中国海风暴潮数值模式,通过将海洋站水位观测资料同化到风暴潮模式中,提高了模式对风暴潮的模拟精度。四维变分同化技术能够在整个同化时间窗口保持动力协调,使模拟结果在该时间窗口内最大程度的靠近观测,同时,得到了最优预报初始场。利用该模式,对两次温带风暴潮过程进行了数值模拟,结果表明:在同化窗口内,同化对模拟精度有明显的提高;结束同化之后,得到的最优预报初始场对临近预报精度也有一定提高。  相似文献   

天津港邻近海域精密潮汐模型的构建     

白亭颖 《海洋测绘》2015,35(3):8-10

基于POM模式的"blending"同化法,构建了天津港及附近海域分辨率为1'×1'、13个主分潮的精密潮汐模型。构建过程中重点关注水深数据格网化与潮汐模型的精度评估。水深数据格网化过程基于尽量扩大覆盖范围、分辨率与水深数据相匹配以及保持岸线形状基本不变等原则。潮汐数值模拟过程采用分批同化T/P点与验潮站,实现对潮汐模型精度的可靠评估。经估计,在天津港附近的9个主分潮RSS在10cm内。  相似文献   

Analysis of SARAL/AltiKa Wind and Wave over Indian Ocean and its Real-time Application in Wave Forecasting System at ISRO     

Suchandra Aich Bhowmick  Ruchi Modi  K. G. Sandhya  M. Seemanth  T. M. Balakrishnan Nair  Raj Kumar 《Marine Geodesy》2015,38(3):396-408

The current study aims to analyze the wind and wave parameters over Indian Ocean region obtained from first Ka –band altimeter AltiKa onboard SARAL, a collaborative mission of Indian Space Research Organization (ISRO) and Centre National d'Etudes Spatiales (CNES), France. It also demonstrates a real time application of SARAL data by assimilating the wave height in a wave model operational at the Space Applications Centre, ISRO. State-of–the art coastal wave model Simulating Wave Near shore (SWAN) is used for this purpose. The well-tested optimal interpolation technique is adopted for assimilation. Before proceeding to the assimilation per se, SARAL/AltiKa Wind and Significant Wave Height (SWH) have been validated using in- situ observations and WAVEWATCH III model. Apart from assessment of wind and wave data quality, this also served the purpose of providing error covariance to be used in assimilation. Supremacy of the assimilation run over parallel control run without assimilation has been judged by comparing the results with buoy observations at Indian National Centre for Ocean Information System (INCOIS). The statistics of validation of the assimilation run has been found to be extremely encouraging and interesting.  相似文献   

A Precipitation Detection Method for MWTS-Ⅱ Radiance Assimilation in Typhoon Simulation     

袁炳  马刚  张鹏  希爽  王庭芳 《热带气象学报(英文版)》2020,26(2):150-160

FY-3C Microwave Temperature Sounder Ⅱ(MWTS-Ⅱ) lacks observations at 23.8 GHz, 31 GHz and 89 GHz,making it difficult to remove the data contaminated by precipitation in assimilation. In this paper, a fast forward operator based on the Community Radiative Transfer Model(CRTM) was used to analyze the relationship between the observation minus background simulation(O-B) and the cloud fractions in different MWTS-Ⅱ channels. In addition,based on the community Gridpoint Statistical Interpolation(GSI) system, the radiation brightness temperature of the MWTS-Ⅱ was assimilated in the regional Numerical Weather Prediction(NWP) model. In the process of assimilation,Visible and Infrared Radiometer(VIRR) cloud detection products were matched to MWTS-Ⅱ pixels for precipitation detection. For typhoon No. 18 in 2014, impact tests of MWTS-Ⅱ data assimilation was carried out. The results show that,though the bias observation minus analysis(O-A) of assimilated data can be reduced by quality control only with | O-B| 3 K; however, the O-A becomes much smaller while the precipitation detection is performed with F_(virr) 0.9(VIRR cloud fraction threshold of 0.9). Besides, the change of the environmental field around the typhoon is more conducive to make the simulated track closer to the observation. The 72-hour typhoon track simulation error also shows that, after the precipitation detection, the error of simulated typhoon track is significantly reduced, which reflects the validity of a precipitation detection method based on a double criterion of | O-B | 3 K and F_(virr) 0.9.  相似文献   

Wind Speed and Altitude Dependent AMDAR Observational Error and Its Impacts on Data Assimilation and Forecasting     

陈耀登  周炳君  陈敏  王元兵 《热带气象学报(英文版)》2020,26(3):261-274

Aircraft Meteorological Data Relay (AMDAR) observations have been widely used in numerical weather prediction (NWP) because of its high spatiotemporal resolution. The observational error of AMDAR is influenced by aircraft flight altitude and atmospheric condition. In this study, the wind speed and altitude dependent observational error of AMDAR is estimated. The statistical results show that the temperature and the observational error in wind speeds slightly decrease as altitude increases, and the observational error in wind speed increases as wind speed increases. Pseudo single AMDAR observation assimilation tests demonstrate that the wind speed and altitude dependent observational error can provide more reasonable analysis increment. Furthermore, to assess the performance of wind speed and altitude dependent observational error on data assimilation and forecasting, two-month 3-hourly cycling data assimilation and forecast experiments based on the Weather Research and Forecasting Model (WRF) and its Data Assimilation system (WRFDA) are performed for the period during 1 September-31 October, 2017. The results of the two-month 3-hourly cycling experiments indicate that new observational error improves analysis and forecast of wind field and geo-potential height, and has slight improvements on temperature. The Fractions Skill Score (FSS) of the 6-h accumulated precipitation shows that new wind speed and altitude dependent observational error leads to better precipitation forecast skill than the default observational error in the WRFDA does.  相似文献   

往返式探空观测资料的质量控制及不确定性分析     

王丹  王金成  田伟红  郭启云 《大气科学》2020,44(4):865-884

为了推动新型探测资料在数值预报模式中的应用,本文进行了往返式探空资料同化应用前重要的基础性研究工作。基于国内首次往返式探空观测资料,首先建立了面向业务化应用的往返式探空资料质量控制方案,通过对比和分析质量控制前后观测样本的统计特征,论证了质量控制方案的合理性,质量控制后探测要素抽样分布更为合理,要素间一致性得到提高。进而以数值天气预报高时间分辨率的模式预报场和同站址业务常规探空观测资料为参考,分析质量控制后资料的不确定性,结果表明往返探空探测精度达到了世界气象组织WMO（World Meteorological Center）规定的突破目标,部分探测要素甚至实现了理想目标,探测资料具有可用性。最后结合数值模式背景场探讨往返探空资料的可同化性,研究表明往返探空的风场观测和夜间温度观测满足变分同化系统的高斯、无偏假定,可直接同化;气压、湿度和日间温度观测在资料同化前需要开展偏差订正工作,从而更有效的发挥资料价值。本文的研究工作为今后往返探空资料在模式中的同化应用奠定了基础。  相似文献