南海局地生成的台风简称土台风,西北太平洋生成进入南海的台风简称洋台风。土台风具有突发性强、路径复杂、预报难度大等特点,给区域防灾减灾带来挑战,亟须开展系统性统计研究以提升对其发生发展规律的认知。当前对南海土台风的研究相...南海局地生成的台风简称土台风,西北太平洋生成进入南海的台风简称洋台风。土台风具有突发性强、路径复杂、预报难度大等特点,给区域防灾减灾带来挑战,亟须开展系统性统计研究以提升对其发生发展规律的认知。当前对南海土台风的研究相对零散,存在长期资料系统分析不足以及与洋台风对比不充分等问题,限制对其气候特征的深入理解。文章基于1949—2024年中国气象局热带气旋最佳路径数据集,系统分析了南海土台风的频数、强度、路径及源地分布特征,并与洋台风进行对比,揭示其时空变化模式。主要结论:1)土台风年均生成5.86个,年内分布呈单峰型,6—10月为高发期(78.9%),其中9月最多(21.7%),年频数存在显著下降线性趋势(-0.05个·年^(-1));2)土台风中心最低气压年均值位于965.0~999.5hPa,存在显著的下降线性趋势,路径以西/西北行为主,源地多位于南海中北部;3)与洋台风相比,土台风强度偏弱,仅13.7%的土台风为台风及以上等级,而洋台风可达61.7%,土台风累积气旋能量指数(accumulated cyclone energy index,ACE)和持续天数都更少,但变化迅速,登陆比例更高,更具突发性与局地性。展开更多
The Yellow Sea and Bohai Sea are among the global shelf seas susceptible to typhoons every year.Using observations and high-resolution numerical simulations,the current study investigates the dramatic changes in tempe...The Yellow Sea and Bohai Sea are among the global shelf seas susceptible to typhoons every year.Using observations and high-resolution numerical simulations,the current study investigates the dramatic changes in temperature and ocean heat content(OHC)of the Yellow Sea and Bohai Sea caused by Super Typhoon Maysak in early September 2020,which is representative of northward/northeastward-bypassing typhoons with centers just to the east of the study area.Temperature shows spatially coherent cooling in the upper mixed layer but warming in the subsurface layer in the majority of the offshore waters,due to wind-enhanced vertical mixing.In lower layers from the thermocline to sea bottom,temperature experiences significant warming in northeastern coastal waters of the Shandong Peninsula and in regions just off the Subei Shoal,but significant cooling in western coastal waters of the Korean Peninsula and southern coastal waters of the Shandong Peninsula.Significant temperature warming/cooling in lower layers is caused by coastal downwelling/upwelling.The total OHC of the study area decreases rapidly during Typhoon Maysak(2020)’s passage,which is generated comparably by latent heat loss at the sea surface and southward heat advection out of the study area at the southern boundary.Reduced shortwave radiation contributes positively but secondarily to the decreasing OHC during the first day.A numerical experiment suggests that Typhoon Maysak(2020)-induced OHC decline could have greatly affected the regional climate evolution in the following seasons.More studies are needed to fully understand the impacts of typhoons on regional climate changes in shelf seas at different time scales.展开更多
Explosive cyclones(ECs) are rapidly intensifying subtropical cyclones that can develop within a short time and pose considerable threats to coastal areas in middle and high latitudes.Gaining a comprehensive understand...Explosive cyclones(ECs) are rapidly intensifying subtropical cyclones that can develop within a short time and pose considerable threats to coastal areas in middle and high latitudes.Gaining a comprehensive understanding of their formation,evolution,and mechanisms of explosive development is essential for improving forecasts of extreme weather events and mitigating associated impacts.Potential vorticity(PV),which is closely related to cyclone dynamics,serves as a valuable diagnostic tool in the study of ECs.In this study,two wintertime ECs of differing intensity over the Northwestern Pacific Ocean are analyzed to examine how different atmospheric processes influence PV generation and the rapid development of ECs.The maximum deepening rates of the two ECs are 2.81 Bergeron(called EC1) and 1.52 Bergeron(referred to as EC2).Results indicate that different stages of EC evolution are closely associated with PV tendency changes at different atmospheric levels.Using the PV tendency equation,during the explosive development of EC1,latent heat release may trigger the downward propagation of upper-level PV.For EC2,latent heat release notably enhances low-level PV,directly contributing to its rapid intensification.To validate these findings,sensitivity tests are conducted using the Weather Research and Forecasting model,with latent heat release turned off in the microphysical scheme for both cases.The results confirm the crucial role of latent heat release in generating low-level PV,further revealing that latent heat release contributes more to the explosive development of EC2 than that of EC1.展开更多
This study describes a new bulk parameterization for sea salt aerosol(SSA)microphysics and investigates the impacts of SSA on an idealized tropical cyclone(TC)through numerical experiments.Results indicate that consid...This study describes a new bulk parameterization for sea salt aerosol(SSA)microphysics and investigates the impacts of SSA on an idealized tropical cyclone(TC)through numerical experiments.Results indicate that consideration of SSA microphysics enhances total precipitation and shifts its timing earlier,with opposite effects during the rapid intensification(RI)and mature(Mt)stages.During RI,SSA increases the maximum 10-m wind speed,strengthens eyewall updrafts,condensation,and cloud/rainwater content,while cooling mid-lower layers.In the Mt stage,SSA slightly reduces the wind speed,cools the warm core,elevates the latent heat release center to~500 m above the surface,and weakens the eyewall but enhances the outer rainband precipitation process.The findings reveal that SSA processes significantly strengthen TCs only during the RI stage,contrasting with previous studies showing continuous TC enhancement by SSA.展开更多
Energy transfers among internal waves in the northern South China Sea are not well characterized,particularly during typhoons,owing to the lack of in situ observations.Based on high-resolution mooring data collected d...Energy transfers among internal waves in the northern South China Sea are not well characterized,particularly during typhoons,owing to the lack of in situ observations.Based on high-resolution mooring data collected during Typhoon Trami(2024),this study reveals the occurrence of robust vertical energy redistribution among diurnal internal tides(D1 ITs)and near-inertial waves(NIWs).Strikingly,the typhoon not only amplified the NIW energy but also triggered an unexpected surge in the D1 IT energy.The observed average net energy transfer rate of 1×10^(-7) W kg^(−1) from typhoon-forced NIWs to D1 ITs occurred at water depths of 120-170 m.Further bispectral analysis indicated that the energy transfer is driven by nonlinear wave—wave interaction.These results reveal the existence of a new energy transfer pathway—from atmospheric forcing to D1 ITs—and redefine the redistribution of the internal wave energy during extreme weather events.展开更多
采用1958～2002年海洋同化资料SODA（Simple Ocean Data Assimilation）的海温场，定义了东印度洋。西太平洋永久性暖池（简称印．太暖池）指数，即不随季节变化的27．5℃等温面所包含的〉27．5℃的暖水体积或强度，并采用功率谱和小波...采用1958～2002年海洋同化资料SODA（Simple Ocean Data Assimilation）的海温场，定义了东印度洋。西太平洋永久性暖池（简称印．太暖池）指数，即不随季节变化的27．5℃等温面所包含的〉27．5℃的暖水体积或强度，并采用功率谱和小波分析的方法研究了其周期变化特征。结果表明，印度洋暖池和西太平洋暖池均具有显著的准10a的周期振荡和1976～1986年前后的年代际突变特征，暖池由1976年前的“冷”暖池转变为1986年后的“热”暖池；暖池指数的季节循环也存在显著的年代际突变特征，特别是西太平洋暖池在异常暖年代其季节变化还呈现出明显的增暖趋势；暖池三维结构的年代际变化主要表现为在暖年代热带南印度洋暖水的向西向南扩张和西太平洋暖池东边界的向东及北边界的向北扩张，暖异常主要分布在60m以浅的上混合层中暖池的东边界区域，而其下面的温跃层内则为更强的异常降温，垂向上表现出上暖下冷的斜压模态结构，而温跃层和混合层深度的变化在不同暖池区则有不同的特点，表明东印度洋暖池和西太平洋暖池的年代际变化可能由不同的机制引起，尚需进一步分析其海洋动力学和热力学过程。展开更多
文摘南海局地生成的台风简称土台风,西北太平洋生成进入南海的台风简称洋台风。土台风具有突发性强、路径复杂、预报难度大等特点,给区域防灾减灾带来挑战,亟须开展系统性统计研究以提升对其发生发展规律的认知。当前对南海土台风的研究相对零散,存在长期资料系统分析不足以及与洋台风对比不充分等问题,限制对其气候特征的深入理解。文章基于1949—2024年中国气象局热带气旋最佳路径数据集,系统分析了南海土台风的频数、强度、路径及源地分布特征,并与洋台风进行对比,揭示其时空变化模式。主要结论:1)土台风年均生成5.86个,年内分布呈单峰型,6—10月为高发期(78.9%),其中9月最多(21.7%),年频数存在显著下降线性趋势(-0.05个·年^(-1));2)土台风中心最低气压年均值位于965.0~999.5hPa,存在显著的下降线性趋势,路径以西/西北行为主,源地多位于南海中北部;3)与洋台风相比,土台风强度偏弱,仅13.7%的土台风为台风及以上等级,而洋台风可达61.7%,土台风累积气旋能量指数(accumulated cyclone energy index,ACE)和持续天数都更少,但变化迅速,登陆比例更高,更具突发性与局地性。
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFF0801400 and 2021YFF0704002)the Shandong Provincial Natural Science Foundation(Grant No.ZR2024LQX002)the National Science Foundation of China(Grant No.42176016).
文摘The Yellow Sea and Bohai Sea are among the global shelf seas susceptible to typhoons every year.Using observations and high-resolution numerical simulations,the current study investigates the dramatic changes in temperature and ocean heat content(OHC)of the Yellow Sea and Bohai Sea caused by Super Typhoon Maysak in early September 2020,which is representative of northward/northeastward-bypassing typhoons with centers just to the east of the study area.Temperature shows spatially coherent cooling in the upper mixed layer but warming in the subsurface layer in the majority of the offshore waters,due to wind-enhanced vertical mixing.In lower layers from the thermocline to sea bottom,temperature experiences significant warming in northeastern coastal waters of the Shandong Peninsula and in regions just off the Subei Shoal,but significant cooling in western coastal waters of the Korean Peninsula and southern coastal waters of the Shandong Peninsula.Significant temperature warming/cooling in lower layers is caused by coastal downwelling/upwelling.The total OHC of the study area decreases rapidly during Typhoon Maysak(2020)’s passage,which is generated comparably by latent heat loss at the sea surface and southward heat advection out of the study area at the southern boundary.Reduced shortwave radiation contributes positively but secondarily to the decreasing OHC during the first day.A numerical experiment suggests that Typhoon Maysak(2020)-induced OHC decline could have greatly affected the regional climate evolution in the following seasons.More studies are needed to fully understand the impacts of typhoons on regional climate changes in shelf seas at different time scales.
基金financially supported by the National Key R&D Program of China (No. 2022YFC3004204)the National Natural Science Foundation of China (No. 42275001)the Natural Science Foundation of Shandong Province (No. ZR2022MD038)。
文摘Explosive cyclones(ECs) are rapidly intensifying subtropical cyclones that can develop within a short time and pose considerable threats to coastal areas in middle and high latitudes.Gaining a comprehensive understanding of their formation,evolution,and mechanisms of explosive development is essential for improving forecasts of extreme weather events and mitigating associated impacts.Potential vorticity(PV),which is closely related to cyclone dynamics,serves as a valuable diagnostic tool in the study of ECs.In this study,two wintertime ECs of differing intensity over the Northwestern Pacific Ocean are analyzed to examine how different atmospheric processes influence PV generation and the rapid development of ECs.The maximum deepening rates of the two ECs are 2.81 Bergeron(called EC1) and 1.52 Bergeron(referred to as EC2).Results indicate that different stages of EC evolution are closely associated with PV tendency changes at different atmospheric levels.Using the PV tendency equation,during the explosive development of EC1,latent heat release may trigger the downward propagation of upper-level PV.For EC2,latent heat release notably enhances low-level PV,directly contributing to its rapid intensification.To validate these findings,sensitivity tests are conducted using the Weather Research and Forecasting model,with latent heat release turned off in the microphysical scheme for both cases.The results confirm the crucial role of latent heat release in generating low-level PV,further revealing that latent heat release contributes more to the explosive development of EC2 than that of EC1.
基金supported by the Key Research&Development Program of JianBing LingYan of Zhejiang Province(Project No.2025C02258)the National Center of Meteorology,Abu Dhabi,UAE,under the UAE Research Program for Rain Enhancement Science(UAEREP)+4 种基金the National Science Foundation under Cooperative Agreement no.1852977NCAR is a major facility sponsored by the National Science Foundation(NSF)under Cooperative Agreement 1852977supported by the National Natural Science Foundation of China(Grant No.42305038)the Joint Fund of Zhejiang Provincial NaturalScienceFoundationofChina(GrantNo.LZJMY25D050008)the Science Foundation of Donghai Laboratory(Grant Nos.L24QH002,L24QH007,and DH-2023QD0002)。
文摘This study describes a new bulk parameterization for sea salt aerosol(SSA)microphysics and investigates the impacts of SSA on an idealized tropical cyclone(TC)through numerical experiments.Results indicate that consideration of SSA microphysics enhances total precipitation and shifts its timing earlier,with opposite effects during the rapid intensification(RI)and mature(Mt)stages.During RI,SSA increases the maximum 10-m wind speed,strengthens eyewall updrafts,condensation,and cloud/rainwater content,while cooling mid-lower layers.In the Mt stage,SSA slightly reduces the wind speed,cools the warm core,elevates the latent heat release center to~500 m above the surface,and weakens the eyewall but enhances the outer rainband precipitation process.The findings reveal that SSA processes significantly strengthen TCs only during the RI stage,contrasting with previous studies showing continuous TC enhancement by SSA.
基金supported by the National Key R&D Plan Program of China [Grant number 2021YFC3101500]the National Natural Science Foundation of China [Grant number 42305014,42506024]。
文摘Energy transfers among internal waves in the northern South China Sea are not well characterized,particularly during typhoons,owing to the lack of in situ observations.Based on high-resolution mooring data collected during Typhoon Trami(2024),this study reveals the occurrence of robust vertical energy redistribution among diurnal internal tides(D1 ITs)and near-inertial waves(NIWs).Strikingly,the typhoon not only amplified the NIW energy but also triggered an unexpected surge in the D1 IT energy.The observed average net energy transfer rate of 1×10^(-7) W kg^(−1) from typhoon-forced NIWs to D1 ITs occurred at water depths of 120-170 m.Further bispectral analysis indicated that the energy transfer is driven by nonlinear wave—wave interaction.These results reveal the existence of a new energy transfer pathway—from atmospheric forcing to D1 ITs—and redefine the redistribution of the internal wave energy during extreme weather events.
文摘采用1958～2002年海洋同化资料SODA（Simple Ocean Data Assimilation）的海温场，定义了东印度洋。西太平洋永久性暖池（简称印．太暖池）指数，即不随季节变化的27．5℃等温面所包含的〉27．5℃的暖水体积或强度，并采用功率谱和小波分析的方法研究了其周期变化特征。结果表明，印度洋暖池和西太平洋暖池均具有显著的准10a的周期振荡和1976～1986年前后的年代际突变特征，暖池由1976年前的“冷”暖池转变为1986年后的“热”暖池；暖池指数的季节循环也存在显著的年代际突变特征，特别是西太平洋暖池在异常暖年代其季节变化还呈现出明显的增暖趋势；暖池三维结构的年代际变化主要表现为在暖年代热带南印度洋暖水的向西向南扩张和西太平洋暖池东边界的向东及北边界的向北扩张，暖异常主要分布在60m以浅的上混合层中暖池的东边界区域，而其下面的温跃层内则为更强的异常降温，垂向上表现出上暖下冷的斜压模态结构，而温跃层和混合层深度的变化在不同暖池区则有不同的特点，表明东印度洋暖池和西太平洋暖池的年代际变化可能由不同的机制引起，尚需进一步分析其海洋动力学和热力学过程。
