Recent studies identify large uncertainties in the projections of tropical cyclone(TC)activity due to discrepancies in tropical Pacific sea surface temperature(SST)warming patterns.While observational datasets consist...Recent studies identify large uncertainties in the projections of tropical cyclone(TC)activity due to discrepancies in tropical Pacific sea surface temperature(SST)warming patterns.While observational datasets consistently reveal a La Niña-like warming pattern[0.15℃-0.25℃(10 yr)^(−1) relative cooling in the eastern equatorial Pacific],over 80%of CMIP6 models project an erroneous El Niño-like trend.These discrepancies arise from biases in cloud feedbacks,Walker circulation strength,and oceanic upwelling processes.This review examines the key mechanisms shaping observed versus modeled warming patterns,evaluates the complex link between tropical SST patterns and TC activity,and explores the feasibility of storm-resolving models for improving TC projections.We propose that pattern-conditioned TC projections using convection-permitting models,alongside physics-informed interpretations,offer a path forward in reducing uncertainties in future climate predictions.展开更多
Based on the recognition framework of the outermost closed contours of cyclones, an automated identification algorithm capable of identifying the multi-scale cyclones that occur during spring in the Changjiang River-H...Based on the recognition framework of the outermost closed contours of cyclones, an automated identification algorithm capable of identifying the multi-scale cyclones that occur during spring in the Changjiang River-Huaihe River valleys （CHV） were developed. We studied the characteristics of the multi-scale cyclone activity that affects CHV and its relationship with rainfall during spring since 1979. The results indicated that the automated identification algorithm for cyclones proposed in this paper could intuitively identify multi-scale cyclones that affect CHV. The algorithm allows for effectively describing the shape and coverage area of the closed contours around the periphery of cyclones. We found that, compared to the meso- and sub-synoptic scale cyclone activities, the synoptic-scale cyclone activity showed more intimate correlation with the overall activity intensity of multi-scale CHV cyclones during spring. However, the frequency of occurrence of sub-synoptic scale cyclones was the highest, and their effect on changes in CHV cyclone activity could not be ignored. Based on the area of impact and the depth of the cyclones, the sub-synoptic scale, synoptic scale and comprehensive cyclone intensity indices were further defined, which showed a positive correlation with rainfall in CHV during spring. Additionally, the comprehensive cyclone intensity index was a good indicator of strong rainfall events.展开更多
Prediction skill for the seasonal tropical cyclone(TC)activity in the Northern Hemisphere is investigated using the coupled climate forecast system(version 1.0)of Nanjing University of Information Science and Technolo...Prediction skill for the seasonal tropical cyclone(TC)activity in the Northern Hemisphere is investigated using the coupled climate forecast system(version 1.0)of Nanjing University of Information Science and Technology(NUISTCFS1.0).This assessment is based on the seven-month(May to November)hindcasts consisting of nine ensemble members during 1982–2019.The predictions are compared with the Japanese 55-year Reanalysis and observed tropical storms in the Northern Hemisphere.The results show that the overall distributions of the TC genesis and track densities in model hindcasts agree well with the observations,although the seasonal mean TC frequency and accumulated cyclone energy(ACE)are underestimated in all basins due to the low resolution(T106)of the atmospheric component in the model.NUIST-CFS1.0 closely predicts the interannual variations of TC frequency and ACE in the North Atlantic(NA)and eastern North Pacific(ENP),which have a good relationship with indexes based on the sea surface temperature.In the western North Pacific(WNP),NUIST-CFS1.0 can closely capture ACE,which is significantly correlated with the El Ni?o–Southern Oscillation(ENSO),while it has difficulty forecasting the interannual variation of TC frequency in this area.When the WNP is further divided into eastern and western subregions,the model displays improved TC activity forecasting ability.Additionally,it is found that biases in predicted TC genesis locations lead to inaccurately represented TC–environment relationships,which may affect the capability of the model in reproducing the interannual variations of TC activity.展开更多
This study investigates the effects of El Niño dissipation(ELD)and La Niña dissipation(LAD)phases on tropical cyclone(TC)activity over the North Atlantic.Unlike ELD events,LAD events are associated with incr...This study investigates the effects of El Niño dissipation(ELD)and La Niña dissipation(LAD)phases on tropical cyclone(TC)activity over the North Atlantic.Unlike ELD events,LAD events are associated with increased frequency,longer lifetime,and stronger intensity of TCs over the North Atlantic.Besides,more TCs pass through the Caribbean Sea,Mississippi River,and eastern main development region(MDR)during LAD events than during ELD events.We used a clustering method to separate the track data during the ELD and LAD events into 4 clusters.Over the eastern MDR,the number of cluster-1 and cluster-3 TCs during LAD events exceeded twice that during ELD events;however,the LAD and ELD events did not differ greatly in terms of the cluster-2 and cluster-4 TCs.Composite analysis and genesis potential index diagnosis revealed that the weaker vertical wind shear(VWS)and higher sea surface temperature(SST)over the eastern MDR favored the genesis of cluster-1 and cluster-3 TCs during LAD events than ELD events.However,environmental factors such as VWS,relative humidity,and SST play a weak role in the genesis of cluster-2 and cluster-4 TCs over the Gulf of Mexico and subtropical North Atlantic during both LAD and ELD events.Regression analysis showed that the difference in TC season SST(VWS)between LAD and ELD events was dominated by the different El Niño-Southern Oscillation phases in the preceding winter(the TC seasons).展开更多
Tropical cyclones(TCs)in the South China Sea(SCS)cause serious disasters and loss every year to the coastal and inland areas of southern China.The types of TCs are usually difficult to forecast,and studies on the unde...Tropical cyclones(TCs)in the South China Sea(SCS)cause serious disasters and loss every year to the coastal and inland areas of southern China.The types of TCs are usually difficult to forecast,and studies on the understanding of the TCs affecting the SCS are lacking.In this study,the authors use the TC data during 1965–2017 from two best-track datasets to analyse the climatic characteristics in terms of the frequency,the track activity,and the influencing indexes of the TCs affecting the SCS and investigate the possible causes.The results show that,during 1965–2017,there were 535 TCs affecting the SCS,mainly occurring from June to November of each year,with the annual average frequency exhibiting a significant downward trend.Meanwhile,the frequency of the track activity in most areas of the SCS also demonstrate a remarkable decreasing trend but an increase in the Gulf of Tonkin and the Taiwan Strait.The large-scale environmental anomalous westerlies and the decrease of humidity in the mid-and low-level over the northern part of the SCS are likely the main causes for the decrease in frequency and the track activity.In addition,the analysis using the cyclone activity index shows that the influence of the before mentioned TCs in southern China gradually decreases,while the influence of TCs in the SCS show a decreasing trend during past decades.展开更多
Poleward atmospheric moisture transport(AMT) into the Arctic Ocean can change atmospheric moisture or water vapor content and cause cloud formation and redistribution, which may change downward longwave radiation and,...Poleward atmospheric moisture transport(AMT) into the Arctic Ocean can change atmospheric moisture or water vapor content and cause cloud formation and redistribution, which may change downward longwave radiation and, in turn, surface energy budgets, air temperatures, and sea-ice production and melt. In this study, we found a consistently enhanced poleward AMT across 60?N since 1959 based on the NCAR–NCEP reanalysis. Regional analysis demonstrates that the poleward AMT predominantly occurs over the North Atlantic and North Pacific regions, contributing about 57% and 32%, respectively, to the total transport. To improve our understanding of the driving force for this enhanced poleward AMT, we explored the role that extratropical cyclone activity may play. Climatologically, about 207 extratropical cyclones move across 60?N into the Arctic Ocean each year, among which about 66(32% of the total) and 47(23%) originate from the North Atlantic and North Pacific Ocean, respectively. When analyzing the linear trends of the time series constructed by using a 20-year running window, we found a positive correlation of 0.70 between poleward yearly AMT and the integrated cyclone activity index(measurement of cyclone intensity, number, and duration). This shows the consistent multidecadal changes between these two parameters and may suggest cyclone activity plays a driving role in the enhanced poleward AMT. Furthermore, a composite analysis indicates that intensification and poleward extension of the Icelandic low and accompanying strengthened cyclone activity play an important role in enhancing poleward AMT over the North Atlantic region.展开更多
基金supported partly by the AORI visiting professorship programsupported in part by a Moonshot R&D grant(Grant No.JPMJMS2282-02)from the Japan Science and Technology Agency+1 种基金the JSPS Core-to-Core Program,“International Core-to-Core Project on Global Storm Resolving Analysis”(Grant No.JPJSCCA20220001)JSPS KAKENHI(Grant Nos.20B202,20H05728,and 24K00703)。
文摘Recent studies identify large uncertainties in the projections of tropical cyclone(TC)activity due to discrepancies in tropical Pacific sea surface temperature(SST)warming patterns.While observational datasets consistently reveal a La Niña-like warming pattern[0.15℃-0.25℃(10 yr)^(−1) relative cooling in the eastern equatorial Pacific],over 80%of CMIP6 models project an erroneous El Niño-like trend.These discrepancies arise from biases in cloud feedbacks,Walker circulation strength,and oceanic upwelling processes.This review examines the key mechanisms shaping observed versus modeled warming patterns,evaluates the complex link between tropical SST patterns and TC activity,and explores the feasibility of storm-resolving models for improving TC projections.We propose that pattern-conditioned TC projections using convection-permitting models,alongside physics-informed interpretations,offer a path forward in reducing uncertainties in future climate predictions.
基金jointly sponsored by the National Natural Science Foundation of China(Grant No.41575081)the National Basic Research Program of China(Grant No.2015CB953904)+3 种基金the Public Sector(Meteorology)Special Research Foundation(Grant Nos.GYHY201406024 and GYHY201306022)the Special Fund for Core Operational Development of Forecast and Prediction of the China Meteorological Administration(Grant No.CMAHX20160405)the Natural Science Foundation of Jiangsu Province(Grant No.BK20161603,BK2012465)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Based on the recognition framework of the outermost closed contours of cyclones, an automated identification algorithm capable of identifying the multi-scale cyclones that occur during spring in the Changjiang River-Huaihe River valleys （CHV） were developed. We studied the characteristics of the multi-scale cyclone activity that affects CHV and its relationship with rainfall during spring since 1979. The results indicated that the automated identification algorithm for cyclones proposed in this paper could intuitively identify multi-scale cyclones that affect CHV. The algorithm allows for effectively describing the shape and coverage area of the closed contours around the periphery of cyclones. We found that, compared to the meso- and sub-synoptic scale cyclone activities, the synoptic-scale cyclone activity showed more intimate correlation with the overall activity intensity of multi-scale CHV cyclones during spring. However, the frequency of occurrence of sub-synoptic scale cyclones was the highest, and their effect on changes in CHV cyclone activity could not be ignored. Based on the area of impact and the depth of the cyclones, the sub-synoptic scale, synoptic scale and comprehensive cyclone intensity indices were further defined, which showed a positive correlation with rainfall in CHV during spring. Additionally, the comprehensive cyclone intensity index was a good indicator of strong rainfall events.
基金supported in part by the National Key Research and Development Program of China(Grant No.2020YFA0608000)the Nature Science Foundation of China(Grant Nos.42005002,42030605,and 42105003)。
文摘Prediction skill for the seasonal tropical cyclone(TC)activity in the Northern Hemisphere is investigated using the coupled climate forecast system(version 1.0)of Nanjing University of Information Science and Technology(NUISTCFS1.0).This assessment is based on the seven-month(May to November)hindcasts consisting of nine ensemble members during 1982–2019.The predictions are compared with the Japanese 55-year Reanalysis and observed tropical storms in the Northern Hemisphere.The results show that the overall distributions of the TC genesis and track densities in model hindcasts agree well with the observations,although the seasonal mean TC frequency and accumulated cyclone energy(ACE)are underestimated in all basins due to the low resolution(T106)of the atmospheric component in the model.NUIST-CFS1.0 closely predicts the interannual variations of TC frequency and ACE in the North Atlantic(NA)and eastern North Pacific(ENP),which have a good relationship with indexes based on the sea surface temperature.In the western North Pacific(WNP),NUIST-CFS1.0 can closely capture ACE,which is significantly correlated with the El Ni?o–Southern Oscillation(ENSO),while it has difficulty forecasting the interannual variation of TC frequency in this area.When the WNP is further divided into eastern and western subregions,the model displays improved TC activity forecasting ability.Additionally,it is found that biases in predicted TC genesis locations lead to inaccurately represented TC–environment relationships,which may affect the capability of the model in reproducing the interannual variations of TC activity.
基金The study was supported by the National Natural Science Foundation(41776004)the Fundamental Research Funds for the Central Universities(B210203041,2016B12514)+1 种基金the Opening Project of Key Laboratory of Marine Environmental Information Technology,the Fundamental Research Funds for the Central Universities(2019B62914)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(SJKY19_0416).
文摘This study investigates the effects of El Niño dissipation(ELD)and La Niña dissipation(LAD)phases on tropical cyclone(TC)activity over the North Atlantic.Unlike ELD events,LAD events are associated with increased frequency,longer lifetime,and stronger intensity of TCs over the North Atlantic.Besides,more TCs pass through the Caribbean Sea,Mississippi River,and eastern main development region(MDR)during LAD events than during ELD events.We used a clustering method to separate the track data during the ELD and LAD events into 4 clusters.Over the eastern MDR,the number of cluster-1 and cluster-3 TCs during LAD events exceeded twice that during ELD events;however,the LAD and ELD events did not differ greatly in terms of the cluster-2 and cluster-4 TCs.Composite analysis and genesis potential index diagnosis revealed that the weaker vertical wind shear(VWS)and higher sea surface temperature(SST)over the eastern MDR favored the genesis of cluster-1 and cluster-3 TCs during LAD events than ELD events.However,environmental factors such as VWS,relative humidity,and SST play a weak role in the genesis of cluster-2 and cluster-4 TCs over the Gulf of Mexico and subtropical North Atlantic during both LAD and ELD events.Regression analysis showed that the difference in TC season SST(VWS)between LAD and ELD events was dominated by the different El Niño-Southern Oscillation phases in the preceding winter(the TC seasons).
基金This work was jointly supported by General Project of Technological Innovation and Application Demonstration of Chongqing Municipality[cstc2018jscx-msybX0165]Special Project for Development of Key Technology for Meteorological Forecast Service of China Meteorological Administration[YBGJXM(2018)04-08]+1 种基金National Natural Science Foundation of China[41875111]Innovation Team Project of Intelligent Meteorological Technology of Chongqing Meteorological Bureau[ZHCXTD-201804].
文摘Tropical cyclones(TCs)in the South China Sea(SCS)cause serious disasters and loss every year to the coastal and inland areas of southern China.The types of TCs are usually difficult to forecast,and studies on the understanding of the TCs affecting the SCS are lacking.In this study,the authors use the TC data during 1965–2017 from two best-track datasets to analyse the climatic characteristics in terms of the frequency,the track activity,and the influencing indexes of the TCs affecting the SCS and investigate the possible causes.The results show that,during 1965–2017,there were 535 TCs affecting the SCS,mainly occurring from June to November of each year,with the annual average frequency exhibiting a significant downward trend.Meanwhile,the frequency of the track activity in most areas of the SCS also demonstrate a remarkable decreasing trend but an increase in the Gulf of Tonkin and the Taiwan Strait.The large-scale environmental anomalous westerlies and the decrease of humidity in the mid-and low-level over the northern part of the SCS are likely the main causes for the decrease in frequency and the track activity.In addition,the analysis using the cyclone activity index shows that the influence of the before mentioned TCs in southern China gradually decreases,while the influence of TCs in the SCS show a decreasing trend during past decades.
基金This work was supported by the NSF(Grant Nos.ARC1023592,ARC-1107509,and PLR-1304684)
文摘Poleward atmospheric moisture transport(AMT) into the Arctic Ocean can change atmospheric moisture or water vapor content and cause cloud formation and redistribution, which may change downward longwave radiation and, in turn, surface energy budgets, air temperatures, and sea-ice production and melt. In this study, we found a consistently enhanced poleward AMT across 60?N since 1959 based on the NCAR–NCEP reanalysis. Regional analysis demonstrates that the poleward AMT predominantly occurs over the North Atlantic and North Pacific regions, contributing about 57% and 32%, respectively, to the total transport. To improve our understanding of the driving force for this enhanced poleward AMT, we explored the role that extratropical cyclone activity may play. Climatologically, about 207 extratropical cyclones move across 60?N into the Arctic Ocean each year, among which about 66(32% of the total) and 47(23%) originate from the North Atlantic and North Pacific Ocean, respectively. When analyzing the linear trends of the time series constructed by using a 20-year running window, we found a positive correlation of 0.70 between poleward yearly AMT and the integrated cyclone activity index(measurement of cyclone intensity, number, and duration). This shows the consistent multidecadal changes between these two parameters and may suggest cyclone activity plays a driving role in the enhanced poleward AMT. Furthermore, a composite analysis indicates that intensification and poleward extension of the Icelandic low and accompanying strengthened cyclone activity play an important role in enhancing poleward AMT over the North Atlantic region.
