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Dependence of the Accuracy of Precipitation and Cloud Simulation on Temporal and Spatial Scales

Advances in Atmospheric Sciences 2009年第6期26卷 1108-1114页

作者：高守亭 Xiaofan LI Laboratory of Cloud-Precipitation Physics and Severe Storms Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 Joint Center for Satellite Data Assimilation and NOAA/NESDIS/Center for Satellite Application and Research Camp Springs Maryland USA

Precipitation and associated cloud hydrometeors have large temporal and spatial variability, which makes accurate quantitative precipitation forecasting difficult. Thus, dependence of accurate precipitation and associated cloud simulation on temporal and spatial scales becomes an important issue. We report a cloud- resolving modeling analysis on this issue by comparing the control experiment with experiments perturbed by initial temperature, water vapor, and cloud conditions. The simulation is considered to be accurate only if the root-mean-squared difference between the perturbation experiments and the control experiment is smaller than the standard deviation. The analysis may suggest that accurate precipitation and cloud simulations cannot be obtained on both fine temporal and spatial scales simultaneously, which limits quanti- tative precipitation forecasting. The accurate simulation of water vapor convergence could lead to accurate precipitation and cloud simulations on daily time scales, but it may not be beneficial to precipitation and cloud simulations on hourly time scales due to the dominance of cloud processes.

关键词： temporal and spatial scales cloud and rainfall simulations cloud-resolving model initial con-ditions

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Bias characterization of ATMS low-level channels under clearsky and cloudy conditions

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Frontiers of Earth Science 2019年第2期13卷 277-289页

作者： Qi LI Xiaolei ZOU Joint Center of Data Assimilation for Research and Application College of Atmospheric ScienceNanjing University of Information Science and Technology (NUIST)Nanjing 210044China Earth System Science Interdisciplinary Center (ESSIC) University of MarylandCollege ParkMD 20740-3823USA

The Advanced Technology Microwave Soun? der (ATMS) onboard the Suomi National Polar-Orbiting Partnership satellite is a cross-track scanning instrument containing 22 sounding channels in *** this study,the bias characteristics of channels 1-6,which could have significant cloud contamination in heavy precipitation,are first analyzed based on the differences between ATMS observations (O) and model simulations (B) under clearsky conditions over *** dependencies of the biases of window channels 1-3 are greater than those of channels *** of all nadir-only observations examined in different latitudinal bands[μ1(φ)]are positive and no more than 7.0 *** at higher latitudes are *** 1-5 have a generally symmetric scan bias pattern [μ2(α)].The global distributions of brightness temperature differences after subtracting the biases,i.e.,O-B-μ1(φ)-μ2(α),for channels 3-6 spatially match the liquid water path *** ice-affected observations,channel 3-6 O-B differences systematically increase as the liquid water path increases under cloudy *** investigation is needed to apply these findings for ATMS data assimilation under both clear-sky and cloudy conditions.

关键词： ATMS O-B clear-sky bias characteristics impact of clouds on biases

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Detection of radio-frequency interference signals from AMSR-E data over the United States with snow cover

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Frontiers of Earth Science 2016年第2期10卷 195-204页

作者： Chengcheng FENG Xiaolei ZOU Juan ZHAO Center of Data Assimilation for Research and Application Nanjing University of Information Science & Technology Nanjing 210044 China Earth System Science Interdisciplinary Center University of Maryland College Park MD 20740-3823 USA China Meteorological Administration Training Centre Beijing 100081 China

Radio Frequency Interference （RFI） causes severe contamination to passive and active microwave sensing observations and corresponding retrieval products. RFI signals should be detected and filtered before applying the microwave data to retrieval and data assimilation. It is difficult to detect RFI over land surfaces covered by snow because of the scattering effect of snow surface. The double principal component analysis （DPCA） method is adopted in this study, and its ability in identifying RFI signals in AMSR-E data over snow covered regions is investigated. Results show that the DPCA method can detect RFI signals effectively in spite of the impact of snow scattering, and the detected RFI signals persistent over time. Compared to other methods, such as PCA and normalized PCA, DPCA is more robust and suitable for operational application.

关键词： Radio Frequency Interference (RFI) AMSR-E double principal component analysis (DPCA)

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Liquid Water Path Retrieval Using the Lowest Frequency Channels of Fengyun-3C Microwave Radiation Imager(MWRI)

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Journal of Meteorological research 2017年第6期31卷 1109-1122页

作者： Fei TANG Xiaolei ZOU Joint Center of Data Assimilation for Research and Application College of Atmospheric ScienceNanjing University of Information Science &Technology State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological Administration Earth System Science Interdisciplinary Center University of Maryland College Park

The Microwave Radiation Imager （MWRI） on board Chinese Fengyun-3 （FY-3） satellites provides measurements at 10.65, 18.7, 23.8, 36.5, and 89.0 GHz with both horizontal and vertical polarization channels. Brightness temperature measurements of those channels with their central frequencies higher than 19 GHz from satellite-based microwave imager radiometers had traditionally been used to retrieve cloud liquid water path （LWP） over ocean. The results show that the lowest frequency channels are the most appropriate for retrieving LWP when its values are large. Therefore, a modified LWP retrieval algorithm is developed for retrieving LWP of different magnitudes involving not only the high frequency channels but also the lowest frequency channels of FY-3 MWRI. The theoretical estimates of the LWP retrieval errors are between 0.11 and 0.06 mm for 10.65- and 18.7-GHz channels and between 0.02 and 0.04 mm for 36.5- and 89.0-GHz channels. It is also shown that the brightness temperature observations at 10.65 GHz can be utilized to better retrieve the LWP greater than 3 mm in the eyewall region of Super Typhoon Neoguri （2014）. The spiral structure of clouds within and around Typhoon Neoguri can be well captured by combining the LWP retrievals from different frequency channels.

关键词： microwave remote sensing Fengyun-3C Microwave Radiation Imager (MWRI) liquid water path (LWP) retrieval

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Polarization signature from the FengYun-3 Microwave Humidity Sounder

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Frontiers of Earth Science 2014年第4期8卷 625-633页

作者： Xiaolei ZOU Xu CHEN Fuzhong WENG Center of Data Assimilation for Research and Application Nanjing University of Information Science & Technology Nanjing 210044 China Department of Earth Ocean and Atmospheric Sciences Florida State University FL 32306 USA National Environmental Satellite Data & Information Service National Oceanic and Atmospheric Administration College Park MD 20740 USA

Microwave Humidity Sounders （MHS） onboard NOAA- 15, - 16, - 17, - 18, - 19, and EUMETSAT MetOp-A/B satellites provide radiance measurements at a single polarization state at any of five observed frequen- cies. The Microwave Humidity Sounder （MWHS） onboard the FengYun-3 （FY-3） satellite has a unique instrument design that provides dual polarization measurements at 150 GHz. In this study, the MWHS polarization signal was investigated using observed and modeled data. It is shown that the quasi-polarization brightness temperatures at 150GHz display a scan angle dependent bias. Under calm ocean conditions, the polarization difference at 150 GHz becomes non-negligible when the scan angle varies from 10° to 45° and reaches a maximum when the scan angle is about 30°. Also, the polarization state is sensitive to surface parameters such as surface wind speed. Under clear-sky conditions, the differences between horizontal and vertical polarization states at 150GHz increase with decreasing surface wind speed. Therefore, the polarization signals from the cross-track scanning microwave measurements at window channels contain useful information about surface parameters. In addition, the availability of dual polarization measurements allows a one-to-one conversion from antenna brightness temperature to sensor brightness temperature ifa cross-polarization spill-over exists.

关键词： Microwave Humidity Sounder (MWHS),polarization remote sensing surface properties

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Quality control of AIRS total column ozone data within tropical cyclones

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Frontiers of Earth Science 2016年第2期10卷 222-235页

作者： Yin LIU Xiaolei ZOU Center of Data Assimilation for Research and Application Nanjing University of Information Science & Technology Nanjing 210044 China Key Laboratory of Meteorological Disaster of Ministry of Education Nanjing University of Information Science & Technology Nanjing 210044 China Earth System Science Interdisciplinary Center University of Maryland College Park MD 20740-3823 USA

The Atmospheric Infrared Sounder （AIRS） provides infrared radiance observations twice daily, which can be used to retrieve total column ozone with high spatial resolution. However, it was found that almost all of the ozone data within typhoons and hurricanes were flagged to be of bad quality by the AIRS original quality control （QC） scheme. This determination was based on the ratio of total precipitable water （TPW） error divided by TPW value, where TPW was an AIRS retrieval product. It was found that the difficulty in finding total column ozone data that could pass AIRS QC was related to the low TPW employed in the AIRS QC algorithm. In this paper, a new two-step QC scheme for AIRS total column ozone is developed. A new ratio is defined which replaces the AIRS TPW with the zonal mean TPW retrieved from the Advanced Microwave Sounding Unit. outliers when the new The first QC step is to remove ratio exceeds 33%. Linear regression models between total column ozone and mean potential vorticity are subsequently developed with daily updates, which are required for future applications of the proposed total ozone QC algorithm to vortex initialization and assimilation of AIRS data. In the second QC step, observations that significantly deviate from the models are further removed using a biweighting algorithm. Numerical results for two typhoon cases and two hurricane cases show that a large amount of good quality AIRS total ozone data is kept within Tropical Cyclones after implementing the proposed QC algorithm.

关键词： AIRS total column ozone total precipitablewater mean potential vorticity quality control

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Modeling aerosol radiance for NCEP data assimilation

Modeling aerosol radiance for NCEP data assimilation

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Hyperspectral Imaging and Sounding of the Environment, HISE 2007

作者： Liu, Quanhua Han, Yong Delst, Paul Van Weng, Fuzhong Joint Center for Satellite Data Assimilation 5200 Auth Road Camp Springs MD 20746 United States NOAA/NESDIS Office of Research and Application 5200 Auth Road Camp Springs MD 20746 United States

CRTM can quantitatively simulate the aerosol effect on satellite radiances. Sensitivity studies show that the dust aerosol may reduce modeling brightness temperature by 1 Kelvin at 11 μm and 4 Kelvin at 3.7 μm. ... 详细信息

ISBN: (纸本)1557528284

关键词： Aerosols

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ANALYSIS OF THE EFFECT OF 3DVAR AND ENSRF DIRECT assimilation OF RADAR data ON THE FORECAST OF A HEAVY RAINFALL EVENT

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Journal of Tropical Meteorology 2016年第3期22卷 413-425页

作者：刘寅何光鑫刘佳伟赵虹燕成玉 Jiangsu Meteorological Observation Center Nanjing 210009 China Jiangsu Institute of Meteorological Sciences Nanjing 210009 China Center for Data Assimilation Research and Application Nanjing University of Information Science & Technology Nanjing 210044 China Luhe Meteorological Bureau Nanjing 211599 China Qinhuangdao Municipal Meteorological Observatory Qinhuangdao 066000 China

The present study designs experiments on the direct assimilation of radial velocity and reflectivity data collected by an S-band Doppler weather radar(CINRAD WSR-98D) at the Hefei Station and the reanalysis data produced by the United States National centers for Environmental Prediction using the Weather research and Forecasting(WRF) model,the WRF model with a three-dimensional variational(3DVAR) data assimilation system and the WRF model with an ensemble square root filter(EnSRF) data assimilation *** addition,the present study analyzes a Meiyu front heavy rainfall process that occurred in the Yangtze-Huaihe River Basin from July 4 to July 5,2003,through numerical *** results show the following.(1) The assimilation of the radar radial velocity data can increase the perturbations in the low-altitude atmosphere over the heavy rainfall region,enhance the convective activities and reduce excessive simulated precipitation.(2) The 3DVAR assimilation method significantly adjusts the horizontal wind *** assimilation of the reflectivity data improves the microphysical quantities and dynamic fields in the *** addition,the assimilation of the radial velocity and reflectivity data can better adjust the wind fields and improve the intensity and location of the simulated radar echo bands.(3) The EnSRF assimilation method can assimilate more small-scale wind field information into the *** assimilation of the reflectivity data alone can relatively accurately forecast the rainfall *** addition,the assimilation of the radial velocity and reflectivity data can improve the location of the simulated radar echo bands.(4) The use of the 3DVAR and EnSRF assimilation methods to assimilate the radar radial velocity and reflectivity data can improve the forecast of precipitation,rain-band areal coverage and the center location and intensity of precipitation.

关键词： assimilation radar data heavy rainfall forecast numerical simulation

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Propagation and Mechanisms of the Quasi-Biweekly Oscillation over the Asian Summer Monsoon Region

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Journal of Meteorological research 2017年第2期31卷 321-335页

作者： Meirong WANG Jun WANG Anmin DUAN Center of Data Assimilation for Research and Application/Key Laboratory of Meteorological Disaster of Ministry of Education Nanjing University of Information Science & TechnologyNanjing 210044 Plateau Atmosphere and Environment Key Laboratory of Sichuan Province Chengdu 610225 International Institute for Earth System Science Nanjing UniversityNanjing 210023 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029

The propagation and underlying mechanisms of the boreal summer quasi-biweekly oscillation（QBWO）over the entire Asian monsoon region are investigated,based on ECMWF Interim reanalysis（ERA-Interim）data,GPCP precipitation data,and an atmospheric general circulation model（AGCM）.Statistical analyses indicate that the QBWO over the Asian monsoon region derives its main origin from the equatorial western Pacific and moves northwestward to the Bay of Bengal and northern India,and then northward to the Tibetan Plateau（TP）area,with a baroclinic vertical *** propagation of the QBWO is promoted by three main mechanisms：barotropic vorticity,boundary moisture advection,and surface sensible heating（SSH）.It is dominated by the barotropic vorticity effect when the QBWO signals are situated to the south of 20°*** the propagation taking place farther north toward the TP,the boundary moisture advection and SSH are the leading *** use an AGCM to verify the importance of SSH on the northward propagation of the *** simulations confirm the diagnostic conclusion that the equatorial western Pacific is the source of the ***,the model can accurately simulate the propagation pathway of the QBWO signals over the Asian monsoon ***,sensitivity experiments demonstrate that the SSH over northern India and the southern slope of the TP greatly contributes to the northward propagation of the QBWO as far as the TP area.

关键词： quasi-biweekly oscillation Asian monsoon region northward-propagating mechanism surface sensible heating atmospheric general circulation model

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applications of the Three-cornered Hat Method to the Error Variance Estimations of FY-4A Atmospheric Temperature Profiles

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Atmosphere 2023年第1期61卷 12-24页

作者： Yue Zhang Yudong Gao Xu Xu Fang Zhao 1 Chongqing Institute of Meteorological Sciences Chongqing 401147 People’s Republic of China2 Chongqing Engineering Research Center of Agrometeorology and Satellite Remote Sensing Chongqing 401147 People’s Republic of China 3 Joint Center of Data Assimilation for Research and Application Nanjing University of Information Science & Technology Nanjing 210044 People’s Republic of China 4 Chongqing Meteorological Information and Technology Support center Chongqing 401147 People’s Republic of China

ABSTRACTABSTRACTThis study applied the three-cornered hat method to the error variance estimations of temperature profiles retrieved from the Geosynchronous Interferometric Infrared Sounder (GIIRS), the first hyperspectral infrared sounder onboard Fengyun-4A (FY-4A) geostationary satellite. An accurate observational error is a crucial input parameter for FY-4A temperature profile assimilation. Using multiple data sets from 2020, this study examined the error variances of FY-4A temperature profiles in clear-sky and cloudy-sky respectively. Because of the effects of clouds on GIIRS, the error variances in cloudy-sky are much larger than in clear-sky. Provided that error variances less than 4K2are significant for data assimilation, the FY-4A temperature profiles in clear-sky from 900 to 150 hPa are meaningful to be assimilated. Results reveal that the latitudinal dependency of error variances is strong at 100 hPa. Encouraged by the vertical distributions of the temperature profile differences between FY-4A and other data sets, the error variance of total potential energy is also examined in this study. Although the detailed structures of temperature profiles are removed, the vertical integration obtains a more minor percentage error. Further studies on data assimilation are worth discussing if total potential energy is more meaningful than the FY-4A temperature profiles.RÉSUMÉLa présente étude a appliqué la méthode du chapeau à trois angles aux estimations de la variance d’erreur des profils de température récupérés par le sondeur infrarouge interférométrique géosynchrone (GIIRS), le premier sondeur infrarouge hyperspectral à bord du satellite géostationnaire Fengyun-4A (FY-4A). Une erreur d’observation précise est un paramètre d’entrée crucial pour l’assimilation du profil de température de FY-4A. En utilisant plusieurs ensembles de données de 2020, cette étude a examiné les variances d’erreur des profils de température de FY-4A par ciel clair et par ciel nuageux resp

关键词： error variance estimation FY-4A GIIRS temperature profiles total potential energy

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