Pub Date : 2025-03-01DOI: 10.1016/j.tcrr.2025.02.008
M.V. Subrahmanyam
Two typhoons, Saola and Damrey, moved across the Northwest Pacific Ocean (NPO) between July 27, 2012, and August 4, 2012. During this period, the oceanographic response was studied. The study examined variations in Sea Surface Temperature (SST) and Mix Layer Depth (MLD) in response to twin typhoons using satellite data from QuickSCAT wind, reanalysis data from OISST, and Argo data. On August 1, 2012, typhoon Damrey's right side experienced the greatest SST dip of 3.6 °C because of mixing. Typhoon Damrey had an influence on typhoon Saola, which caused a weaker SST cooling of 2.5 °C. During the passage of the twin typhoons, the area around typhoon Saola observed the most noticeable change in MLD, which went from 15 m to 85 m. The Ekman pumping effect led to modifications in the subsurface layer, which improved SST cooling and caused MLD deepening.
{"title":"Impact of twin typhoons on the upper ocean environment across the Northwest Pacific ocean","authors":"M.V. Subrahmanyam","doi":"10.1016/j.tcrr.2025.02.008","DOIUrl":"10.1016/j.tcrr.2025.02.008","url":null,"abstract":"<div><div>Two typhoons, Saola and Damrey, moved across the Northwest Pacific Ocean (NPO) between July 27, 2012, and August 4, 2012. During this period, the oceanographic response was studied. The study examined variations in Sea Surface Temperature (SST) and Mix Layer Depth (MLD) in response to twin typhoons using satellite data from QuickSCAT wind, reanalysis data from OISST, and Argo data. On August 1, 2012, typhoon Damrey's right side experienced the greatest SST dip of 3.6 °C because of mixing. Typhoon Damrey had an influence on typhoon Saola, which caused a weaker SST cooling of 2.5 °C. During the passage of the twin typhoons, the area around typhoon Saola observed the most noticeable change in MLD, which went from 15 m to 85 m. The Ekman pumping effect led to modifications in the subsurface layer, which improved SST cooling and caused MLD deepening.</div></div>","PeriodicalId":44442,"journal":{"name":"Tropical Cyclone Research and Review","volume":"14 1","pages":"Pages 71-81"},"PeriodicalIF":2.4,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.tcrr.2025.02.004
Guanbo Zhou , Longsheng Liu , Bin Huang
In this paper, the ERA-Interim reanalysis data at six-hourly intervals (with a horizontal resolution of 0.25° × 0.25°) and typhoon best track datasets are used to conduct a comparative kinetic energy budget analysis of Typhoon Yagi and Rumbia during their lifecycles in 2018. At the same time, the contributions of divergent wind and rotating wind to the kinetic energy budget in different quadrants are analyzed, and the relative importance of the components of rotating wind energy and divergent wind energy represented by Kr and Kd in the kinetic energy budget is studied. Different from the previous kinetic energy budget analysis of the whole target area, this paper studies Kr and Kd in the four quadrants around the typhoon center to reveal their respective contributions to the development of the typhoon. The results show that: (1) On the whole, the rotational wind energy Kr is the largest, and the distribution is relatively consistent with the total kinetic energy K0. (2) The variation trend of divergent wind energy Kd in the lower layer can better reflect the intensity change of TCs. (3) From the comparative analysis of the deviation term vr∗vd, "Rumbia" weakens to the lowest in the northwest, while the corresponding northeast direction is the maximum at this time, which corresponds to the beginning of the Northeast turning of "Rumbia". (4) Through further analysis and comparison, it is found that T1 and T3 are mainly positive in the low layer, and their contributions mainly come from T1d and T3d.
{"title":"Comparative analysis of kinetic energy budget of Typhoons Yagi and Rumbia","authors":"Guanbo Zhou , Longsheng Liu , Bin Huang","doi":"10.1016/j.tcrr.2025.02.004","DOIUrl":"10.1016/j.tcrr.2025.02.004","url":null,"abstract":"<div><div>In this paper, the ERA-Interim reanalysis data at six-hourly intervals (with a horizontal resolution of 0.25° × 0.25°) and typhoon best track datasets are used to conduct a comparative kinetic energy budget analysis of Typhoon Yagi and Rumbia during their lifecycles in 2018. At the same time, the contributions of divergent wind and rotating wind to the kinetic energy budget in different quadrants are analyzed, and the relative importance of the components of rotating wind energy and divergent wind energy represented by Kr and Kd in the kinetic energy budget is studied. Different from the previous kinetic energy budget analysis of the whole target area, this paper studies Kr and Kd in the four quadrants around the typhoon center to reveal their respective contributions to the development of the typhoon. The results show that: (1) On the whole, the rotational wind energy Kr is the largest, and the distribution is relatively consistent with the total kinetic energy K0. (2) The variation trend of divergent wind energy Kd in the lower layer can better reflect the intensity change of TCs. (3) From the comparative analysis of the deviation term vr∗vd, \"Rumbia\" weakens to the lowest in the northwest, while the corresponding northeast direction is the maximum at this time, which corresponds to the beginning of the Northeast turning of \"Rumbia\". (4) Through further analysis and comparison, it is found that T1 and T3 are mainly positive in the low layer, and their contributions mainly come from T1d and T3d.</div></div>","PeriodicalId":44442,"journal":{"name":"Tropical Cyclone Research and Review","volume":"14 1","pages":"Pages 13-26"},"PeriodicalIF":2.4,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.tcrr.2025.03.001
John G. Miller, Guilherme Vieira da Silva, Darrell Strauss
Here we present a mean and extreme tropical cyclone (TC)-generated wave climate for the Coral Sea (the oceanic basin east of Australia), for 1979–2020. An available WAVEWATCH III® hindcast model dataset with surface wind forcing from the National Centres for Environmental Prediction supplied Climate Forecasts System Version 2 was used. The resolution of this wind field is 0.3°, increasing to 0.2° from 2011, among the highest available to better represent TC vortices. The spatial and temporal resolution of the wave model was sufficient to produce TC wave climates, although a limitation in representing TCs at both ends of the intensity scale was apparent. Model performance was validated using wave buoy data at three coastal locations. The area near the Tropic of Capricorn, around 155° E, experienced the largest TC-generated mean waves with the locations of the primary swell height maxima shifted slightly north-west, in comparison with combined waves. There was an interdecadal increase (decrease) in TC significant wave height with positive (negative) IPO phase in three of the four decades. TC extreme wave maxima were situated further east, compared to the TC generated mean waves. The 50 and 100-year average return intervals indicated high extreme waves near the northeastern tip of Australia and northwest of New Caledonia. For the east Australian coast, extreme waves from TCs showed a decreasing trend in the south only. This study presents a unique mapping of TC wave characteristics over the entire Coral Sea and validates the use of a globally applicable method, for such applications.
{"title":"The mean and extreme tropical cyclone wave climate throughout the Coral Sea, from 1979 to 2020","authors":"John G. Miller, Guilherme Vieira da Silva, Darrell Strauss","doi":"10.1016/j.tcrr.2025.03.001","DOIUrl":"10.1016/j.tcrr.2025.03.001","url":null,"abstract":"<div><div>Here we present a mean and extreme tropical cyclone (TC)-generated wave climate for the Coral Sea (the oceanic basin east of Australia), for 1979–2020. An available WAVEWATCH III® hindcast model dataset with surface wind forcing from the National Centres for Environmental Prediction supplied Climate Forecasts System Version 2 was used. The resolution of this wind field is 0.3°, increasing to 0.2° from 2011, among the highest available to better represent TC vortices. The spatial and temporal resolution of the wave model was sufficient to produce TC wave climates, although a limitation in representing TCs at both ends of the intensity scale was apparent. Model performance was validated using wave buoy data at three coastal locations. The area near the Tropic of Capricorn, around 155° E, experienced the largest TC-generated mean waves with the locations of the primary swell height maxima shifted slightly north-west, in comparison with combined waves. There was an interdecadal increase (decrease) in TC significant wave height with positive (negative) IPO phase in three of the four decades. TC extreme wave maxima were situated further east, compared to the TC generated mean waves. The 50 and 100-year average return intervals indicated high extreme waves near the northeastern tip of Australia and northwest of New Caledonia. For the east Australian coast, extreme waves from TCs showed a decreasing trend in the south only. This study presents a unique mapping of TC wave characteristics over the entire Coral Sea and validates the use of a globally applicable method, for such applications.</div></div>","PeriodicalId":44442,"journal":{"name":"Tropical Cyclone Research and Review","volume":"14 1","pages":"Pages 40-59"},"PeriodicalIF":2.4,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.tcrr.2025.02.007
Sunil Kumar , Shashi Kant , Rizwan Ahmed
The investigation of extreme weather phenomena is an important scientific field that incorporates multiple disciplines due to their significant impacts on various sectors and society as a whole. There is evidence to support the occurrence of severe weather events in different regions of the world. In India, major precipitation events, such as the Mumbai floods in 2005 and the Kerala floods in 2018, often occur during the south-west monsoon season, leading to significant impacts. This statement is also applicable to states like Arunachal Pradesh, Nagaland, and Manipur in the northeast region. Intense precipitation events caused significant impacts in Meghalaya from June 16th to June 18th, 2022.These events resulted in a significant socio-economic and human impact, including infrastructure damage, displacement of communities, and around 90 reported fatalities in Assam and Meghalaya. These two states are susceptible to flooding and erosion, and they consistently face intense and periodic floods on an annual basis. Analysis of the 2022 rainfall data reveals that over 4.8 million individuals were adversely impacted in the majority of districts in Assam and Meghalaya. Specifically, 79 % of the total 43 districts were affected.
This study analyzed the meteorological aspects of exceptional heavy rainfall events in Meghalaya from June 16th to 18th, 2022, to understand their significant impact on the environment and society. The extreme weather event in Meghalaya was a result of a well-marked low pressure area, a significant influx of moisture from the Bay of Bengal (BoB), favourable dynamics and thermodynamics conditions, and a supportive cloud top temperature (CTT) that collectively intensified the heavy rainfall. The study's findings can provide valuable insights for disaster managers and forecasters, enabling them to better prepare for and respond to extreme rainfall events in the northeast region of the country.
{"title":"Assessment of an Extreme Heavy Rainfall over Meghalaya, India on 16th& 17th June 2022: A case study using Meteorological and Remote Sensing observations","authors":"Sunil Kumar , Shashi Kant , Rizwan Ahmed","doi":"10.1016/j.tcrr.2025.02.007","DOIUrl":"10.1016/j.tcrr.2025.02.007","url":null,"abstract":"<div><div>The investigation of extreme weather phenomena is an important scientific field that incorporates multiple disciplines due to their significant impacts on various sectors and society as a whole. There is evidence to support the occurrence of severe weather events in different regions of the world. In India, major precipitation events, such as the Mumbai floods in 2005 and the Kerala floods in 2018, often occur during the south-west monsoon season, leading to significant impacts. This statement is also applicable to states like Arunachal Pradesh, Nagaland, and Manipur in the northeast region. Intense precipitation events caused significant impacts in Meghalaya from June 16th to June 18th, 2022.These events resulted in a significant socio-economic and human impact, including infrastructure damage, displacement of communities, and around 90 reported fatalities in Assam and Meghalaya. These two states are susceptible to flooding and erosion, and they consistently face intense and periodic floods on an annual basis. Analysis of the 2022 rainfall data reveals that over 4.8 million individuals were adversely impacted in the majority of districts in Assam and Meghalaya. Specifically, 79 % of the total 43 districts were affected.</div><div>This study analyzed the meteorological aspects of exceptional heavy rainfall events in Meghalaya from June 16th to 18th, 2022, to understand their significant impact on the environment and society. The extreme weather event in Meghalaya was a result of a well-marked low pressure area, a significant influx of moisture from the Bay of Bengal (BoB), favourable dynamics and thermodynamics conditions, and a supportive cloud top temperature (CTT) that collectively intensified the heavy rainfall. The study's findings can provide valuable insights for disaster managers and forecasters, enabling them to better prepare for and respond to extreme rainfall events in the northeast region of the country.</div></div>","PeriodicalId":44442,"journal":{"name":"Tropical Cyclone Research and Review","volume":"14 1","pages":"Pages 60-70"},"PeriodicalIF":2.4,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-17DOI: 10.1016/j.tcrr.2025.02.003
Roger K. Smith , Michael T. Montgomery
Conceptual frameworks are discussed for understanding the physics of the tropical cyclone life cycle in an idealized, three-dimensional, numerical simulation in a quiescent environment. Both axisymmetric and three-dimensional frameworks are discussed. A central feature of one of the two axisymmetric frameworks is the assumption that absolute angular momentum is materially conserved above the frictional boundary layer, at least in the classical Eliassen balance formulation. Such conservation implies that vortex spin up requires radial inflow above the friction layer, while radial outflow there leads to spin down. Many of the ideas are illustrated by two simple laboratory experiments.
In the other axisymmetric framework, the so-called WISHE framework the material conservation of absolute angular momentum is dispensed with in favour of assuming that the saturated moist equivalent potential vorticity is everywhere zero. This assumption limits the applicability of the WISHE framework at best to a small portion of the storm’s life cycle, even if one were able to justify the implicit angular momentum source thereby introduced. Analysis of a recent three-dimensional numerical simulation of the tropical cyclone life cycle unveils a causality problem with the assumptions underlying these models.
In a three-dimensional framework, the rotating-convection paradigm highlights the importance for vortex spin up of the deep, convectively-induced overturning circulation being strong enough to generate inflow above the frictional boundary layer in the presence of the ubiquitous tendency of the boundary layer to generate outflow there. When deep convection is too weak to ventilate all the mass that is converging in the boundary layer to the upper troposphere, there is net outflow above the boundary layer and the vortex weakens. This behaviour appears to be ruled out in the WISHE models by their assumption of global moist neutrality, but is a feature of the classical Eliassen model.
{"title":"Towards understanding the tropical cyclone life cycle","authors":"Roger K. Smith , Michael T. Montgomery","doi":"10.1016/j.tcrr.2025.02.003","DOIUrl":"10.1016/j.tcrr.2025.02.003","url":null,"abstract":"<div><div>Conceptual frameworks are discussed for understanding the physics of the tropical cyclone life cycle in an idealized, three-dimensional, numerical simulation in a quiescent environment. Both axisymmetric and three-dimensional frameworks are discussed. A central feature of one of the two axisymmetric frameworks is the assumption that absolute angular momentum is materially conserved above the frictional boundary layer, at least in the classical Eliassen balance formulation. Such conservation implies that vortex spin up requires radial inflow above the friction layer, while radial outflow there leads to spin down. Many of the ideas are illustrated by two simple laboratory experiments.</div><div>In the other axisymmetric framework, the so-called WISHE framework the material conservation of absolute angular momentum is dispensed with in favour of assuming that the saturated moist equivalent potential vorticity is everywhere zero. This assumption limits the applicability of the WISHE framework at best to a small portion of the storm’s life cycle, even if one were able to justify the implicit angular momentum source thereby introduced. Analysis of a recent three-dimensional numerical simulation of the tropical cyclone life cycle unveils a causality problem with the assumptions underlying these models.</div><div>In a three-dimensional framework, the rotating-convection paradigm highlights the importance for vortex spin up of the deep, convectively-induced overturning circulation being strong enough to generate inflow above the frictional boundary layer in the presence of the ubiquitous tendency of the boundary layer to generate outflow there. When deep convection is too weak to ventilate all the mass that is converging in the boundary layer to the upper troposphere, there is net outflow above the boundary layer and the vortex weakens. This behaviour appears to be ruled out in the WISHE models by their assumption of global moist neutrality, but is a feature of the classical Eliassen model.</div></div>","PeriodicalId":44442,"journal":{"name":"Tropical Cyclone Research and Review","volume":"14 2","pages":"Pages 119-131"},"PeriodicalIF":2.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144138230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01DOI: 10.1016/j.tcrr.2024.11.003
Rijin Wan , Mengqi Yang
In the operational forecasting of tropical cyclones (TCs), decoding TC warning messages from global centers, along with extracting, organizing, and storing useful track observations and forecasts, are fundamental tasks. The technical core lies in accurately identifying distinct TC individuals through automated programming methods. Based on the statistical characteristics of historical distances between TC individuals, this study designs a novel method for automatic identification of TC individuals and establishes a database of TC track observations and forecasts by integrating the persistent features from various elements in TC warning messages. This method accurately identifies each TC individual and assigns it a unique database number through a two-step process: initially, through the 'Same Center same Number Comparison(SCNC)' identification method, followed by the 'Spatio-Temeporal Distance Comparison(STDC)' identification method.On this basis, we obtain a well-organized and comprehensive dataset that covers entire TC life time. Over the past decade,the operational practice has demonstrated that this method is accurate and efficient, providing solid data support for the TC forecasting operation, the assessment of TC forecasting accuracy, the compilation of TC yearbook, and TC-related research.
{"title":"A method to automatically ascertain the identities of tropical cyclones in tropical cyclone warning messages","authors":"Rijin Wan , Mengqi Yang","doi":"10.1016/j.tcrr.2024.11.003","DOIUrl":"10.1016/j.tcrr.2024.11.003","url":null,"abstract":"<div><div>In the operational forecasting of tropical cyclones (TCs), decoding TC warning messages from global centers, along with extracting, organizing, and storing useful track observations and forecasts, are fundamental tasks. The technical core lies in accurately identifying distinct TC individuals through automated programming methods. Based on the statistical characteristics of historical distances between TC individuals, this study designs a novel method for automatic identification of TC individuals and establishes a database of TC track observations and forecasts by integrating the persistent features from various elements in TC warning messages. This method accurately identifies each TC individual and assigns it a unique database number through a two-step process: initially, through the 'Same Center same Number Comparison(SCNC)' identification method, followed by the 'Spatio-Temeporal Distance Comparison(STDC)' identification method.On this basis, we obtain a well-organized and comprehensive dataset that covers entire TC life time. Over the past decade,the operational practice has demonstrated that this method is accurate and efficient, providing solid data support for the TC forecasting operation, the assessment of TC forecasting accuracy, the compilation of TC yearbook, and TC-related research.</div></div>","PeriodicalId":44442,"journal":{"name":"Tropical Cyclone Research and Review","volume":"13 4","pages":"Pages 286-292"},"PeriodicalIF":2.4,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143307919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The forecast probability of tropical cyclone (TC) genesis in the western North Pacific from 2017 to 2020 was investigated using global ensembles from the Japan Meteorological Agency (JMA), the European Centre for Medium-Range Weather Forecasts (ECMWF), the U.S. National Centers for Environmental Prediction (NCEP), and the Met Office in the United Kingdom (UKMO). The time of TC genesis was defined as the time the TCs were first recorded in the best-track data (Case 1) and as the time they reached the intensity of a Tropical Storm (Case 2). The results in Case 1 showed that differences between the forecast probability based on each global ensemble were large, even for a 1-day forecast, and that mean probability were from 18 % to 74 %. The forecasts based on the NCEP had a large frequency bias and overpredicted TC genesis events. The results indicated that the representation of genesis events differed greatly between global ensembles. The effectiveness of multiple ensembles was investigated. The results from the threat score and the false alarm ratio indicated that multiple ensembles had skillful forecasts. When the forecast probability was examined for environmental patterns of synoptic low-level flow, the mean 5-day forecast probability was highest for the pattern in the confluence region. The results also showed that the forecast probability was much larger in Case 2 than in Case 1. In all global ensembles, the mean probability with a lead time of up to 1-week was below 10 % for both Case 1 and 2. This result indicates that even with today's operational forecasting systems, it is difficult to regularly predict TC genesis events with a 1-week lead time with high confidence. These results provide a better understanding of TC genesis forecast products in each global ensemble and will be useful information when multiple-ensemble products are created.
{"title":"Assessing global ensemble systems’ forecasts of tropical cyclone genesis in differing environmental flow regimes in the western North Pacific","authors":"Yasuhiro Kawabata , Munehiko Yamaguchi , Hironori Fudeyasu , Ryuji Yoshida","doi":"10.1016/j.tcrr.2024.11.007","DOIUrl":"10.1016/j.tcrr.2024.11.007","url":null,"abstract":"<div><div>The forecast probability of tropical cyclone (TC) genesis in the western North Pacific from 2017 to 2020 was investigated using global ensembles from the Japan Meteorological Agency (JMA), the European Centre for Medium-Range Weather Forecasts (ECMWF), the U.S. National Centers for Environmental Prediction (NCEP), and the Met Office in the United Kingdom (UKMO). The time of TC genesis was defined as the time the TCs were first recorded in the best-track data (Case 1) and as the time they reached the intensity of a Tropical Storm (Case 2). The results in Case 1 showed that differences between the forecast probability based on each global ensemble were large, even for a 1-day forecast, and that mean probability were from 18 % to 74 %. The forecasts based on the NCEP had a large frequency bias and overpredicted TC genesis events. The results indicated that the representation of genesis events differed greatly between global ensembles. The effectiveness of multiple ensembles was investigated. The results from the threat score and the false alarm ratio indicated that multiple ensembles had skillful forecasts. When the forecast probability was examined for environmental patterns of synoptic low-level flow, the mean 5-day forecast probability was highest for the pattern in the confluence region. The results also showed that the forecast probability was much larger in Case 2 than in Case 1. In all global ensembles, the mean probability with a lead time of up to 1-week was below 10 % for both Case 1 and 2. This result indicates that even with today's operational forecasting systems, it is difficult to regularly predict TC genesis events with a 1-week lead time with high confidence. These results provide a better understanding of TC genesis forecast products in each global ensemble and will be useful information when multiple-ensemble products are created.</div></div>","PeriodicalId":44442,"journal":{"name":"Tropical Cyclone Research and Review","volume":"13 4","pages":"Pages 344-355"},"PeriodicalIF":2.4,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143355039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01DOI: 10.1016/j.tcrr.2024.11.006
Jeff Callaghan
Recent intensifying tropical cyclones around the globe are analysed to examine the observed winds structure in their inner core. The winds in sectors with strong bands of thunderstorms were observed from analysed vector winds in weather forecasting computer models to turn in an anticyclonic fashion from the 850 hPa level up to the 500 hPa level. This wind structure resembles Quasi-Geostrophic warm air advection and from Hysplit the trajectory analysis was in areas of ascending air currents suitable for the initiation of thunderstorms. The rapid intensification occurred as the cyclonic circulation extends up to at least 200 hPa.
{"title":"Development of strong asymmetric convection leading to rapid intensification of tropical cyclones","authors":"Jeff Callaghan","doi":"10.1016/j.tcrr.2024.11.006","DOIUrl":"10.1016/j.tcrr.2024.11.006","url":null,"abstract":"<div><div>Recent intensifying tropical cyclones around the globe are analysed to examine the observed winds structure in their inner core. The winds in sectors with strong bands of thunderstorms were observed from analysed vector winds in weather forecasting computer models to turn in an anticyclonic fashion from the 850 hPa level up to the 500 hPa level. This wind structure resembles Quasi-Geostrophic warm air advection and from Hysplit the trajectory analysis was in areas of ascending air currents suitable for the initiation of thunderstorms. The rapid intensification occurred as the cyclonic circulation extends up to at least 200 hPa.</div></div>","PeriodicalId":44442,"journal":{"name":"Tropical Cyclone Research and Review","volume":"13 4","pages":"Pages 239-260"},"PeriodicalIF":2.4,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143307916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01DOI: 10.1016/j.tcrr.2024.11.002
Zeng Jinyu , Lian Chenfang , Yin Siyu , Sun Chaofeng
<div><div>Based on wind profile radar data, this paper aims at different typhoon processes landed and affected Fujian from 2011 to 2019, according to the nature of typhoon rainstorm, it can be classified into outer precipitation before typhoon landed, main body precipitation and precipitation at the rear of typhoon, the change of the characteristic quantities in approaching time of the occurrence of short-term heavy rainfall was analyzed, and the typhoon case in 2020 was back calculated. The results show that, the characteristics of low-level jet streams (maximum wind speed at low altitude, minimum height of jet streams, and low-level jet stream index), as well as the magnitude of vertical wind shear below 700 hPa, have important indicative significance for the occurrence of short-term heavy rainfall. (1) More than 80 % of short-term heavy rainfall occurred 3 h before the low-level jet stream already existed. The maximum wind speed below 2 km was basically close to a normal distribution, and the occurrence of heavy precipitation showed a bimodal pattern. The percentage of wind speed between 8 and 32 m/s was the highest, exceeding 85 %. The wind direction of the strong wind is mainly NE, SE, and SW. Classification analysis showed that the distribution characteristics of wind speed of the main precipitation were the same as before, but the wind direction SE was higher than NE. The wind speed of pre-landfall precipitation was basically skewed, and the occurrence time of heavy precipitation followed a normal distribution. The percentage of wind speed between 16 and 32 m/s was the highest, and the wind direction was the same as before classification. The maximum wind speed of precipitation in the rear was basically bimodal distribution, with a relatively even distribution, and the wind direction was mainly SE and SW. (2) In the 3 h before the occurrence of short-term heavy precipitation, there was an increase in the maximum wind speed value, a decrease in the minimum extension height, and an increase in the low-level jet stream index I. As short-term heavy rainfall approached, the intensity of the low-level jet stream remained high and its proportion increased. The minimum achievable extension height gradually decreased and remained stable at a low value. In the first 2 h of heavy rainfall, the wind speed reached its maximum, the extension height was the lowest, and the low-level jet stream index I was the highest. Classifying and discussing it, the precipitation in the rear was different, and the lowest height decreased to the lowest at the time of occurrence, at which point the I value reached its maximum. The characteristics of the other two categories were the same as before the classification. (3) The vertical wind shear from the ground to different isobaric surfaces gradually decreased with the increase of height. With the approach of short-term heavy rainfall, the vertical wind shear of each layer basically decreased gradually, after the beginn
{"title":"Application research of wind profile radar in short-term heavy rainfall forecast of typhoon in Fujian Province","authors":"Zeng Jinyu , Lian Chenfang , Yin Siyu , Sun Chaofeng","doi":"10.1016/j.tcrr.2024.11.002","DOIUrl":"10.1016/j.tcrr.2024.11.002","url":null,"abstract":"<div><div>Based on wind profile radar data, this paper aims at different typhoon processes landed and affected Fujian from 2011 to 2019, according to the nature of typhoon rainstorm, it can be classified into outer precipitation before typhoon landed, main body precipitation and precipitation at the rear of typhoon, the change of the characteristic quantities in approaching time of the occurrence of short-term heavy rainfall was analyzed, and the typhoon case in 2020 was back calculated. The results show that, the characteristics of low-level jet streams (maximum wind speed at low altitude, minimum height of jet streams, and low-level jet stream index), as well as the magnitude of vertical wind shear below 700 hPa, have important indicative significance for the occurrence of short-term heavy rainfall. (1) More than 80 % of short-term heavy rainfall occurred 3 h before the low-level jet stream already existed. The maximum wind speed below 2 km was basically close to a normal distribution, and the occurrence of heavy precipitation showed a bimodal pattern. The percentage of wind speed between 8 and 32 m/s was the highest, exceeding 85 %. The wind direction of the strong wind is mainly NE, SE, and SW. Classification analysis showed that the distribution characteristics of wind speed of the main precipitation were the same as before, but the wind direction SE was higher than NE. The wind speed of pre-landfall precipitation was basically skewed, and the occurrence time of heavy precipitation followed a normal distribution. The percentage of wind speed between 16 and 32 m/s was the highest, and the wind direction was the same as before classification. The maximum wind speed of precipitation in the rear was basically bimodal distribution, with a relatively even distribution, and the wind direction was mainly SE and SW. (2) In the 3 h before the occurrence of short-term heavy precipitation, there was an increase in the maximum wind speed value, a decrease in the minimum extension height, and an increase in the low-level jet stream index I. As short-term heavy rainfall approached, the intensity of the low-level jet stream remained high and its proportion increased. The minimum achievable extension height gradually decreased and remained stable at a low value. In the first 2 h of heavy rainfall, the wind speed reached its maximum, the extension height was the lowest, and the low-level jet stream index I was the highest. Classifying and discussing it, the precipitation in the rear was different, and the lowest height decreased to the lowest at the time of occurrence, at which point the I value reached its maximum. The characteristics of the other two categories were the same as before the classification. (3) The vertical wind shear from the ground to different isobaric surfaces gradually decreased with the increase of height. With the approach of short-term heavy rainfall, the vertical wind shear of each layer basically decreased gradually, after the beginn","PeriodicalId":44442,"journal":{"name":"Tropical Cyclone Research and Review","volume":"13 4","pages":"Pages 261-275"},"PeriodicalIF":2.4,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143307917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01DOI: 10.1016/j.tcrr.2024.11.008
Zaine Perry , Ramontsheng Rapolaki , Sarah Roffe , Moagabo Ragoasha
During February–March 2023, the record-breaking tropical cyclone (TC) Freddy caused widespread flooding and damages across southeastern Africa. While <5 % of TCs make landfall into southern Africa, TC Freddy made landfall twice and is the only TC in the past two decades that has tracked over 8000 km across the entire southern Indian Ocean. To understand why TC Freddy was so unique, this study investigated the evolution, track and atmospheric-oceanic mechanisms driving TC Freddy using the ERA5, CFSv2, OSTIA, NCEP-NCAR datasets and track data from various sources. It was found that SSTs were >27 °C during TC Freddy’s lifetime, while TC Dingani and a split Mascarene High played a role in steering TC Freddy across the southern Indian Ocean. Leading up to the development of TC Freddy, conditions were favourable for TC genesis, as indicated by the levels of the Genesis Potential Parameter (GPP) and its modified version (GPPI), the tropical cyclone heat potential levels, and elevated SSTs. Ridging subtropical anticyclones and the Mascarene High alongside favourable steering flow and GPP (and GPPI) conditions resulted in Freddy’s double landfall in Mozambique. In assessing the tracks, it was found that there are discrepancies in the track of the commonly used IBTrACS when compared to ERA5 and RSMC tracks, which has implications for impact studies due to the underestimation of landfall considerations. This study reveals the unique characteristics and atmospheric-oceanic mechanisms driving TC Freddy, emphasising the importance of accurate representation of favourable conditions and track data for enhancing TC forecasting and impact assessments.
{"title":"Analysing the atmospheric-oceanic conditions driving the sustained long track and intensity of Tropical Cyclone Freddy","authors":"Zaine Perry , Ramontsheng Rapolaki , Sarah Roffe , Moagabo Ragoasha","doi":"10.1016/j.tcrr.2024.11.008","DOIUrl":"10.1016/j.tcrr.2024.11.008","url":null,"abstract":"<div><div>During February–March 2023, the record-breaking tropical cyclone (TC) Freddy caused widespread flooding and damages across southeastern Africa. While <5 % of TCs make landfall into southern Africa, TC Freddy made landfall twice and is the only TC in the past two decades that has tracked over 8000 km across the entire southern Indian Ocean. To understand why TC Freddy was so unique, this study investigated the evolution, track and atmospheric-oceanic mechanisms driving TC Freddy using the ERA5, CFSv2, OSTIA, NCEP-NCAR datasets and track data from various sources. It was found that SSTs were >27 °C during TC Freddy’s lifetime, while TC Dingani and a split Mascarene High played a role in steering TC Freddy across the southern Indian Ocean. Leading up to the development of TC Freddy, conditions were favourable for TC genesis, as indicated by the levels of the Genesis Potential Parameter (GPP) and its modified version (GPPI), the tropical cyclone heat potential levels, and elevated SSTs. Ridging subtropical anticyclones and the Mascarene High alongside favourable steering flow and GPP (and GPPI) conditions resulted in Freddy’s double landfall in Mozambique. In assessing the tracks, it was found that there are discrepancies in the track of the commonly used IBTrACS when compared to ERA5 and RSMC tracks, which has implications for impact studies due to the underestimation of landfall considerations. This study reveals the unique characteristics and atmospheric-oceanic mechanisms driving TC Freddy, emphasising the importance of accurate representation of favourable conditions and track data for enhancing TC forecasting and impact assessments.</div></div>","PeriodicalId":44442,"journal":{"name":"Tropical Cyclone Research and Review","volume":"13 4","pages":"Pages 356-388"},"PeriodicalIF":2.4,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143308166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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