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Assessing Hourly Precipitation Forecast Skill with the Fractions Skill Score

Journal of Meteorological Research 2018年第1期32卷 135-145页

作者： Bin ZHAO Bo ZHANG National Meteorological Center Beijing 100081 China Meteorological Administration Numerical Weather Prediction Center Beijing 100081

Statistical methods for category（yes/no） forecasts, such as the Threat Score, are typically used in the verification of precipitation forecasts. However, these standard methods are affected by the so-called ＂double-penalty＂ problem caused by slight displacements in either space or time with respect to the observations. Spatial techniques have recently been developed to help solve this problem. The fractions skill score（FSS）, a neighborhood spatial verification method, directly compares the fractional coverage of events in windows surrounding the observations and forecasts.We applied the FSS to hourly precipitation verification by taking hourly forecast products from the GRAPES（Global/Regional Assimilation Prediction System） regional model and quantitative precipitation estimation products from the National Meteorological Information Center of China during July and August 2016, and investigated the difference between these results and those obtained with the traditional category score. We found that the model spin-up period affected the assessment of stability. Systematic errors had an insignificant role in the fraction Brier score and could be ignored. The dispersion of observations followed a diurnal cycle and the standard deviation of the forecast had a similar pattern to the reference maximum of the fraction Brier score. The coefficient of the forecasts and the observations is similar to the FSS; that is, the FSS may be a useful index that can be used to indicate correlation.Compared with the traditional skill score, the FSS has obvious advantages in distinguishing differences in precipitation time series, especially in the assessment of heavy rainfall.

关键词： neighborhood spatial verification method fractions skill score traditional category score hourly precipitation heavy rainfall

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Moisture Transport over the Arabian Sea Associated with Summer rainfall over Pakistan in 1994 and 2002

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Advances in Atmospheric Sciences 2012年第3期29卷 501-508页

作者： Kalim ULLAH 高守亭 Laboratory of Cloud-Precipitation Physics and Severe Storms Institute of Atmospheric Physics Chinese Academy of Sciences Graduate University of the Chinese Academy of Sciences Department of Meteorology COMSATS Institute of Information TechnologyIslamabadPakistan

In this study, we aimed to elucidate the critical role of moisture transport affecting monsoon activity in two contrasting summers over the Arabian Sea during the years 1994, a relatively wet year, and 2002, a relatively dry year. A comprehensive diagnostic evaluation and comparisons of the moisture fields were con- ducted; we focused on the precipitation and evaporation as well as the moisture transport and its divergence or convergence in the atmosphere. Monthly mean reanalysis data were obtained from the National Centers for Environmental Prediction （NCEP-I and -II）. A detailed evaluation of the moisture budgets over Pak- istan during these two years was made by calculating the latent energy flux at the surface （E - P） from the divergence of the total moisture transport. Our results confirm the moisture supply over the Arabian Sea to be the major source of rainfall in Pakistan and neighboring regions. In 1994, Pakistan received more rainfall compared to 2002 during the summer monsoon. Moisture flow deepens and strengthens over Arabian Sea during the peak summer monsoon months of July and August. Our analysis shows that vertically integrated moisture transport flux have a significant role in supplying moisture to the convective centers over Pakistan and neighboring regions from the divergent regions of the Arabian Sea and the Bay of Bengal. Moreover, in 1994, a deeper vertically integrated moisture convergence progression occurred over Pakistan compared to that in 2002. Perhaps that deeper convergence resulted in a more intense moisture depression over Pakistan and also caused more rainfall in 1994 during the summer monsoon. Finally, from the water budget analysis, it has been surmised that the water budget was larger in 1994 than in 2002 during the summer monsoon.

关键词： moisture flux moisture convergence convection heavy rainfall

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Application of ATOVS Microwave Radiance Assimilation to rainfall Prediction in Summer 2004

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Advances in Atmospheric Sciences 2006年第5期23卷 815-830页

作者：齐琳琳孙建华 Chinese Academy of Meteorological Sciences Beijing 100081 Institute of Aviation Meteorology Beijing 100085 Laboratory of Cloud Physics and Severe Storms Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029

Experiments are performed in this paper to understand the influence of satellite radiance data on the initial field of a numerical prediction system and rainfall prediction. First, Advanced Microwave Sounder Unit A （AMSU-A） and Unit B （AMSU-B） radiance data are directly used by three-dimensional variational data assimilation to improve the background field of the numerical model. Then, the detailed effect of the radiance data on the background field is analyzed. Secondly, the background field, which is formed by application of Advanced Television and Infrared Observation Satellite Operational Vertical Sounder （ATOVS） microwave radiance assimilation, is employed to simulate some heavy rainfall cases. The experiment results show that the assimilation of AMSU-A （B） microwave radiance data has a certain impact on the geopotential height, temperature, relative humidity and flow fields. And the impacts on the background field are mostly similar in the different months in summer. The heavy rainfall experiments reveal that the application of AMSU-A （B） microwave radiance data can improve the rainfall prediction significantly. In particular, the AMSU-A radiance data can significantly enhance the prediction of rainfall above 10 mm within 48 h, and the AMSU-B radiance data can improve the prediction of rainfall above 50 mm within 24 h. The present study confirms that the direct assimilation of satellite radiance data is an effective way to improve the prediction of heavy rainfall in the summer in China.

关键词： heavy rainfall satellite radiance data direct assimilation rainfall prediction experiments

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Numerical simulation of topography effects on the “00.7” severe rainfall in Beijing

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Progress in Natural Science:Materials International 2005年第9期15卷 818-826页

作者： ZHANG Chaolin1**, JI Chongping1, KUO Yinghwa2, FAN Shuiyong1, XUAN Chunyi3 and CHEN Min1(1. Institute of Urban Meteorology, China Meteorological Administration, Beijing 100089, China 2. Mesoscale and Microscale Meteorology Division, National Center for Atmospheric Research, Boulder, CO 80307-3000, USA 3. Beijing Meteorological Bureau, Beijing 100089, China) Institute of Urban Meteorology China Meteorological Administration Beijing 100089 China Mesoscale and Microscale Meteorology Division National Center for Atmospheric Research Boulder CO 80307-3000 United States Beijing Meteorological Bureau Beijing 100089 China

In an effort to study the severe rainfall event of 4—5th July 2000 in Beijing (with 24h accumulated precipitation of 240 mm), we perform numerical simulations to investigate this event using the MM5v3.6 model. The model is initialized with the MM5/WRF 3DVAR analysis, which incorporates the ground-based GPS precipitable water vapor, automatic and conventional meteorological observations in its assimilation step. For 24 h accumulated precipitation forecast, the threat scores are 0.72, 0.76, 0.67 and 0.63, for thresholds of 1, 5, 10, and 20 mm, respectively. Holding other factors unchanged, sensitivity experiments were conducted with different topographic resolutions of 110, 50 and 3.7 km to investigate the topographic effects on precipitation over the Beijing area. In these sensitivity experiments, we attempt to preserve the realistic orographic distribution in the model topography under the condition of keeping the dynamic-thermodynamic consistency of the initial model atmosphere to the extent possible. Results indicate that the unique topographic distribution and variations in the Beijing area play an important role in determining the location, distribution and intensity of heavy precipitation.

关键词： topography heavy rainfall 3DVAR ground-based GPS numerical simulation.

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An Overview of Research and Forecasting on rainfall Associated with Landfalling Tropical Cyclones

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Advances in Atmospheric Sciences 2010年第5期27卷 967-976页

作者：陈联寿李英程正泉 State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences Guangzhou Central Meteorological Observatory

The ability to forecast heavy rainfall associated with landfalling tropical cyclones （LTCs） can be improved with a better understanding of the mechanism of rainfall rates and distributions of LTCs. Research in the area of LTCs has shown that associated heavy rainfall is related closely to mechanisms such as moisture transport, extratropical transition （ET）, interaction with monsoon surge, land surface processes or topographic effects, mesoscale convective system activities within the LTC, and boundary layer energy transfer etc.. LTCs interacting with environmental weather systems, especially the westerly trough and mei-yu front, could change the rainfall rate and distribution associated with these mid-latitude weather systems. Recently improved technologies have contributed to advancements within the areas of quantitative precipitation estimation （QPE） and quantitative precipitation forecasting （QPF）. More specifically, progress has been due primarily to remote sensing observations and mesoscale numerical models which incorporate advanced assimilation techniques. Such progress may provide the tools necessary to improve rainfall forecasting techniques associated with LTCs in the future.

关键词： landfalling tropical cyclones heavy rainfall research and forecasting

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An Analysis of a Meso-β System in a Mei-yu Front Using the Intensive Observation Data During CHeRES 2002

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Advances in Atmospheric Sciences 2005年第2期22卷 278-289页

作者：孙建华张小玲齐琳琳赵思雄 Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 National Meteorological Center China Meteorological Administration Beijing 100081 Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 Chinese Academy of Meteorological Sciences Beijing 100081

The conventional and intensive observational data of the China heavy Rain Experiment and Study (CHeRES) are used to specially analyze the heavy rainfall process in the mei-yu front that occurred during 20-21 June 2002, focusing on the meso-β system. A mesoscale convective system (MCS) formed in the warm-moist southwesterly to the south of the shear line over the Dabie Mountains and over the gorge between the Dabie and Jiuhua Mountains. The mei-yu front and shear line provide a favorable synoptic condition for the development of convection. The GPS observation indicates that the precipitable water increased obviously about 2-3 h earlier than the occurrence of rainfall and decreased after that. The abundant moisture transportation by southwesterly wind was favorable to the maintenance of convective instability and the accumulation of convective available potential energy (CAPE). Radar detection reveals that meso-β and -γ systems were very active in the MaCS. Several convection lines developed during the evolution of the MaCS, and these are associated with surface convergence lines. The boundary outflow of the convection line may have triggered another convection line. The convection line moved with the mesoscale surface convergence line, but the convective cells embedded in the convergence line propagated along the line. On the basis of the analyses of the intensive observation data, a multi-scale conceptual model of heavy rainfall in the mei-yu front for this particular case is proposed.

关键词： mei-yu front heavy rainfall mesoscale convergence line conceptual model Doppler radar

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Can Natural Farming Help to Combat Climate Variability? A Comparison of Natural and Chemical Farming in Andhra Pradesh, India

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Agricultural Sciences 2023年第9期14卷 1321-1342页

作者： Zakir Hussain Vijay Kumar Thallam Reshma Soma Kiranmai Jirra Himabindu Anisetti Bhavana Boppana Neelima Dendeti Rythu Sadhikara Samstha (RySS) Guntur AP India

A study was conducted to compare the potential of natural farming versus conventional chemical farming to withstand adverse climate effects. The study investigated two cyclones, namely cyclone Pethai and cyclone Titli of 2018, which caused significant damage to Andhra Pradesh’s coastal corridor. In addition, the impact of heavy rainfall in 2021 on two different farming systems was studied. The worst-affected Paddy crop regions where these cyclones caused severe damage were surveyed. Multiple linear regression was utilized to investigate predictors including crop damage, wind damage, submergence, and yield loss in these two agricultural systems during these two cyclonic and heavy rainfall events. The study indicated that natural farming practices were more resilient to climate variability than conventional chemical farming techniques. The study showed a statistically significant difference (p < 0.001) between these two farming systems in terms of damage caused due to climate variabilities.

关键词： Natural Farming Climate Resilience Cyclones heavy rainfall

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Assimilation of Polarimetric Radar Data Using an Ensemble Kalman Filter for the Analysis and Forecast of Tropical Storm Ewiniar(2018)

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Journal of Tropical Meteorology 2021年第2期27卷 94-108页

作者：黎慧琦刘显通肖辉万齐林 Guangzhou Institute of Tropical and Marine Meteorology China Meteorological AdministrationGuangzhou 510640 China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081 China

This study explores the potential for directly assimilating polarimetric radar data(including reflectivity Z and differential reflectivity Z_(DR))using an ensemble Kalman filter(EnKF)based on the Weather Research and Forecasting model to improve analysis and forecast of Tropical Storm Ewiniar(2018).Ewiniar weakened but brought about heavy rainfall over Guangdong,China after its final landfall.In the present study,two experiments are performed,one assimilating only Z and the other assimilating both Z and Z_(DR).Assimilation of Z_(DR)together with Z effectively modifies hydrometeor fields,and improves the forecast of the intensity,shape and position of rainbands.Forecast of 24-hour extraordinary rainfall≥250 mm is significantly improved.Improvement can also be seen in the wind fields because of cross-variable covariance.The current study shows the possibility of applying polarimetric radar data to improve forecasting of tropical cyclones,which deserves more research in the future.

关键词： data assimilation polarimetric radar EnKF tropical cyclone heavy rainfall

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NUMERICAL SIMULATION OF A MESOSCALE CONVECTIVE SYSTEM(MCS)DURING THE FIRST RAINY SEASON OVER SOUTH CHINA

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Acta meteorologica Sinica 2003年第1期17卷 79-92页

作者：蒙伟光王安宇李江南冯瑞权古志明 Department of Atmospheric Sciences Zhongshan University Macao Meteorological and Geophysical Services

Based on the NCEP/NCAR reanalysis data and observations collected during the SCSMEX,a mesoscale convective system (MCS) occurring over South China during 23-24 May 1998 has been studied with a numerical simulation using the Fifth Generation Penn-State/NCAR Mesoseale Modeling System (MMS).The successful simulations present us some interesting findings.The simulated MCS was a kind of meso-β scale system with a life cycle of about 11 hours.It generated within a small vortex along a cold front shear line.The MCS was characterized by severe convection.The simulated maximum vertical velocity was greater than 90 cm s^(-1),and the maximum divergence at about 400 hPa.The rainfall rate of MCS exceeded 20 mm h^(-1).To the right of the simulated MCS,a mesoscale low-level jet (mLLJ) was found.A strong southwesterly current could also be seen to the right of MCS above the mLLJ.This strong southwesterly current might extend up to 400 hPa.A column of cyclonic vorticity extended through most part of the MCS in the vertical direction.Additionally,the simulated MCS was compared favorably with the observational data in terms of location,precipitation intensity and evolution.

关键词： mesoscale convective system (MCS) mesoscale low-level jet (mLLJ) heavy rainfall South China first rainy season numerical simulation

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MESOSCALE CONVECTIVE SYSTEMS DURING 20-23 JUNE 2002 REVEALED BY SATELLITE OBSERVATION

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Acta meteorologica Sinica 2004年第1期18卷 1-16页

作者：覃丹宇江吉喜马岚方宗义 Nanjing Institute of Meteorology National Satellite Meteorological Center

The 20-23 June 2002 mesoscale convective systems,which produced heavy rainfalls over the middle and lower reaches of the Changjiang River Basin,are studied using satellite imagery, satellite products and conventional sounding data. Results demonstrate that the torrential rain was caused by three MαCSs (Meso-a scale Convective System) and some MβCS (Meso-β-scale Convective System) activities in succession. The TBB (black-body temperature) analysis depicts that several meso-β-scale cloud clusters and convective cells were embedded and alternately developed within an MαCS.As the strongest convection gradually decreased,the cold TBB area expanded quickly in hours before dissipation. However,the heavy rainfall occurred in MαCS developing and maturing stages.And the minimum TBB fluctuation matched well to the precipitation trend with the lower TBB for the heavier rainfall. A kind of favorable synoptic environment for MαCS genesis and activities could be described as follows.The West Pacific subtropical high is stable with its western ridge reaching to the west region of South China.To its south and west sides,there is the robust ITCZ (Intertropical Convergence Zone),the active Indian-Bengal monsoon cloud surges carry warm and moist air by low-level jet (LLJ) to mid-latitudes where a frontal zone existed for days,meanwhile a 500 hPa short-wave trough moved eastward.At the upper troposphere,the southeasterly divergent flow dominates the environment due to the South-Asian high enhancing and moving eastward,and a monsoon water vapor plume (WVP) is stretched from the Bay of Bengal to the Changjiang River Basin.With a certain favorable configuration including a monsoon WVP,a frontal cloud system,a shortwave trough cloud system,and monsoon cloud clusters,MαCSs could initiate and develop successively in the same region.

关键词： satellite data heavy rainfall mesoscale convective system (MCS)

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