In this paper, an objective technique for estimating the tropical cyclone （TC） precipitation from station observations is proposed. Based on a comparison between the Original Objective Method （OOM） and the Expert ...In this paper, an objective technique for estimating the tropical cyclone （TC） precipitation from station observations is proposed. Based on a comparison between the Original Objective Method （OOM） and the Expert Subjective Method （ESM）, the Objective Synoptic Analysis Technique （OSAT） for partitioning TC precipitation was developed by analyzing the western North Pacific （WNP） TC historical track and the daily precipitation datasets. Being an objective way of the ESM, OSAT overcomes the main problems in OOM, by changing two fixed parameters in OOM, the thresholds for the distance of the absolute TC precipitation （D0） and the TC size （D1）, into variable parameters.Case verification for OSAT was also carried out by applying CMORPH （Climate Prediction Center MORPHing technique） daily precipitation measurements, which is NOAA＇s combined satellite precipitation measurement system. This indicates that OSAT is capable of distinguishing simultaneous TC precipitation rain-belts from those associated with different TCs or with middle-latitude weather systems.展开更多
Tropical Cyclone (TC) activity is an important feature of China's climate that can have important impacts on precipitation and can cause extensive property damage. In particular, precipitation from TCs contributes...Tropical Cyclone (TC) activity is an important feature of China's climate that can have important impacts on precipitation and can cause extensive property damage. In particular, precipitation from TCs contributes a significant portion of overall precipitation. This study deals with typhoons that influence China and focuses on their impact on China's precipitation. Four aspects are examined in this research. Firstly, the study of influencing typhoon frequency reveals that the main season that typhoons affect China is from May to November, especially between July and September. The frequency of influencing typhoons was steady during the past 40 years. Secondly, inspection of the climatology of station typhoon precipitation shows that Hainan and the southeastern coastalmost regions are most frequently affected by typhoons, and most of the regions south of the Yangtze River are affected by typhoons each year. Meanwhile, during 1957-1996, most of the typhoon-influenced regions show decreasing trends in typhoon precipitation but only the trends in southern Northeast China are significant. Thirdly, examination of the typhoon cases shows that there exists it significant linear relationship between the precipitation volume and impacted area. Finally, study of variations of typhoon impacts on China's precipitation suggests that there exists a decreasing trend in the contribution of typhoon precipitation to overall precipitation, while total annual volume of typhoon precipitation decreases significantly during the period.展开更多
The outputs of the Chinese Academy of Sciences(CAS) Flexible Global Ocean–Atmosphere–Land System(FGOALS-f3-L) model for the baseline experiment of the Atmospheric Model Intercomparison Project simulation in the Diag...The outputs of the Chinese Academy of Sciences(CAS) Flexible Global Ocean–Atmosphere–Land System(FGOALS-f3-L) model for the baseline experiment of the Atmospheric Model Intercomparison Project simulation in the Diagnostic,Evaluation and Characterization of Klima common experiments of phase 6 of the Coupled Model Intercomparison Project(CMIP6) are described in this paper. The CAS FGOALS-f3-L model, experiment settings, and outputs are all given. In total,there are three ensemble experiments over the period 1979–2014, which are performed with different initial states. The model outputs contain a total of 37 variables and include the required three-hourly mean, six-hourly transient, daily and monthly mean datasets. The baseline performances of the model are validated at different time scales. The preliminary evaluation suggests that the CAS FGOALS-f3-L model can capture the basic patterns of atmospheric circulation and precipitation well, including the propagation of the Madden–Julian Oscillation, activities of tropical cyclones, and the characterization of extreme precipitation. These datasets contribute to the benchmark of current model behaviors for the desired continuity of CMIP.展开更多
Relationships between tropical cyclone(TC)precipitation,wind,and storm damage are analyzed for China based on TCs over the period from 1984 to 2013.The analysis shows that the maximum daily areal precipitation from st...Relationships between tropical cyclone(TC)precipitation,wind,and storm damage are analyzed for China based on TCs over the period from 1984 to 2013.The analysis shows that the maximum daily areal precipitation from stations with daily precipitation of ≥50 mm and the sum of wind gusts of ≥13.9 m/s can be used to estimate the main damage caused by TCs,and an index combining the precipitation and wind gust of a TC(IPWT)is defined to assess the severity of the combined impact of precipitation and wind.The correlation coefficient between IPWT and the damage index for affecting TCs is 0.80,which is higher than that for only precipitation or wind.All TCs with precipitation and wind affecting China are divided intofive categories,Category 0 to Category 4,based on IPWT,where higher categories refer to higher combined impacts of precipitation and wind.The combined impact category is closely related to damage category and it can be used to estimate the potential damage category in operational work.There are 87.7%,72.9%,69.8%,and 73.4%of cases that have the same or one category difference between damage category and combined impact category for Categories 1,2,3,and 4,respectively.IPWT and its classification can be used to assess the severity of the TC impact and of combined precipitation and wind conveniently and accurately,and the potential damage caused by TCs.The result will be a good supplementary data for TC intensity,precipitation,wind,and damage.In addition,IPWT can be used as an index to judge the reliability of damage data.Further analysis of the annual frequency of combined precipitation-wind impact categories reveals no significant increasing or decreasing trend in impact over China over the past 30 years.展开更多
The precipitation distributions associated with two landfalling tropical cyclones（TCs） during extratropical transition（ET） were examined in this study.Their distinction is that the bulk of precipitation fell to th...The precipitation distributions associated with two landfalling tropical cyclones（TCs） during extratropical transition（ET） were examined in this study.Their distinction is that the bulk of precipitation fell to the left of the TC track in one TC and to the right in the other.The analyses indicate that,for the TC Haima（2004） case,accompanied by the approach of a deep midlatitude trough throughout the depth of the troposphere,the warm and moist air advection by the southeasterly flow north of TC was favorable for warm advection and frontogenesis to the northwest of the TC.Due to the steepening of equivalent potential temperature（θ e）,the air-parcel uplift along the θ e surface,in collaboration with thermally direct circulation related to frontogenesis,led to enhanced precipitation northwest of the TC.In contrast,for TC Matsa（2005） embedded within a moister environment,a weak midlatitude trough was situated at the mid-upper level.The convection was triggered by the conditional instability at the lower level and then sustained by dynamic forcing at the mid-upper level so that the heavy precipitation occurred to the northeast of TC.For the two TC cases,the precipitation enhancement was also linked to the upper-level anomalous divergence associated with the jet-related forcing on the right side of the jet entrance.From the quasigeostrophic perspective,the advection of geostrophic absolute vorticity by the thermal wind most likely served as an indication reflecting the displacement of the vertical motion relative to the center of the TC.展开更多
文摘In this paper, an objective technique for estimating the tropical cyclone （TC） precipitation from station observations is proposed. Based on a comparison between the Original Objective Method （OOM） and the Expert Subjective Method （ESM）, the Objective Synoptic Analysis Technique （OSAT） for partitioning TC precipitation was developed by analyzing the western North Pacific （WNP） TC historical track and the daily precipitation datasets. Being an objective way of the ESM, OSAT overcomes the main problems in OOM, by changing two fixed parameters in OOM, the thresholds for the distance of the absolute TC precipitation （D0） and the TC size （D1）, into variable parameters.Case verification for OSAT was also carried out by applying CMORPH （Climate Prediction Center MORPHing technique） daily precipitation measurements, which is NOAA＇s combined satellite precipitation measurement system. This indicates that OSAT is capable of distinguishing simultaneous TC precipitation rain-belts from those associated with different TCs or with middle-latitude weather systems.
文摘Tropical Cyclone (TC) activity is an important feature of China's climate that can have important impacts on precipitation and can cause extensive property damage. In particular, precipitation from TCs contributes a significant portion of overall precipitation. This study deals with typhoons that influence China and focuses on their impact on China's precipitation. Four aspects are examined in this research. Firstly, the study of influencing typhoon frequency reveals that the main season that typhoons affect China is from May to November, especially between July and September. The frequency of influencing typhoons was steady during the past 40 years. Secondly, inspection of the climatology of station typhoon precipitation shows that Hainan and the southeastern coastalmost regions are most frequently affected by typhoons, and most of the regions south of the Yangtze River are affected by typhoons each year. Meanwhile, during 1957-1996, most of the typhoon-influenced regions show decreasing trends in typhoon precipitation but only the trends in southern Northeast China are significant. Thirdly, examination of the typhoon cases shows that there exists it significant linear relationship between the precipitation volume and impacted area. Finally, study of variations of typhoon impacts on China's precipitation suggests that there exists a decreasing trend in the contribution of typhoon precipitation to overall precipitation, while total annual volume of typhoon precipitation decreases significantly during the period.
基金funded by the National Key Research and development Program of China (Grant No. 2017YFA0604004)the National Natural Science Foundation of China (Grant Nos. 91737306, U1811464, 41530426, 91837101, 41730963, and 91637312)
文摘The outputs of the Chinese Academy of Sciences(CAS) Flexible Global Ocean–Atmosphere–Land System(FGOALS-f3-L) model for the baseline experiment of the Atmospheric Model Intercomparison Project simulation in the Diagnostic,Evaluation and Characterization of Klima common experiments of phase 6 of the Coupled Model Intercomparison Project(CMIP6) are described in this paper. The CAS FGOALS-f3-L model, experiment settings, and outputs are all given. In total,there are three ensemble experiments over the period 1979–2014, which are performed with different initial states. The model outputs contain a total of 37 variables and include the required three-hourly mean, six-hourly transient, daily and monthly mean datasets. The baseline performances of the model are validated at different time scales. The preliminary evaluation suggests that the CAS FGOALS-f3-L model can capture the basic patterns of atmospheric circulation and precipitation well, including the propagation of the Madden–Julian Oscillation, activities of tropical cyclones, and the characterization of extreme precipitation. These datasets contribute to the benchmark of current model behaviors for the desired continuity of CMIP.
基金This study was sponsored by the National Basic Research Program of China(Grant No.2015CB452806)the National Natural Science Foundations of China(Grant Nos.41475082 and 41875114)+1 种基金Shanghai Science&Technology Research Program(Grant No.19dzl 200101)the Fundamental Research Funds of the STI/CMA(Grant No.2019JB06).
文摘Relationships between tropical cyclone(TC)precipitation,wind,and storm damage are analyzed for China based on TCs over the period from 1984 to 2013.The analysis shows that the maximum daily areal precipitation from stations with daily precipitation of ≥50 mm and the sum of wind gusts of ≥13.9 m/s can be used to estimate the main damage caused by TCs,and an index combining the precipitation and wind gust of a TC(IPWT)is defined to assess the severity of the combined impact of precipitation and wind.The correlation coefficient between IPWT and the damage index for affecting TCs is 0.80,which is higher than that for only precipitation or wind.All TCs with precipitation and wind affecting China are divided intofive categories,Category 0 to Category 4,based on IPWT,where higher categories refer to higher combined impacts of precipitation and wind.The combined impact category is closely related to damage category and it can be used to estimate the potential damage category in operational work.There are 87.7%,72.9%,69.8%,and 73.4%of cases that have the same or one category difference between damage category and combined impact category for Categories 1,2,3,and 4,respectively.IPWT and its classification can be used to assess the severity of the TC impact and of combined precipitation and wind conveniently and accurately,and the potential damage caused by TCs.The result will be a good supplementary data for TC intensity,precipitation,wind,and damage.In addition,IPWT can be used as an index to judge the reliability of damage data.Further analysis of the annual frequency of combined precipitation-wind impact categories reveals no significant increasing or decreasing trend in impact over China over the past 30 years.
基金supported by National Basic Research Program of China (Grant No.2009CB421505)Special Scientific Research project for Public Interest (Grant No. GYHY201006021)National Natural Science Foundation of China (Grant No.40921160379),respectively
文摘The precipitation distributions associated with two landfalling tropical cyclones（TCs） during extratropical transition（ET） were examined in this study.Their distinction is that the bulk of precipitation fell to the left of the TC track in one TC and to the right in the other.The analyses indicate that,for the TC Haima（2004） case,accompanied by the approach of a deep midlatitude trough throughout the depth of the troposphere,the warm and moist air advection by the southeasterly flow north of TC was favorable for warm advection and frontogenesis to the northwest of the TC.Due to the steepening of equivalent potential temperature（θ e）,the air-parcel uplift along the θ e surface,in collaboration with thermally direct circulation related to frontogenesis,led to enhanced precipitation northwest of the TC.In contrast,for TC Matsa（2005） embedded within a moister environment,a weak midlatitude trough was situated at the mid-upper level.The convection was triggered by the conditional instability at the lower level and then sustained by dynamic forcing at the mid-upper level so that the heavy precipitation occurred to the northeast of TC.For the two TC cases,the precipitation enhancement was also linked to the upper-level anomalous divergence associated with the jet-related forcing on the right side of the jet entrance.From the quasigeostrophic perspective,the advection of geostrophic absolute vorticity by the thermal wind most likely served as an indication reflecting the displacement of the vertical motion relative to the center of the TC.
