Typhoon Hinnamnor(2022)was the only tropical cyclone(TC)during 1982-2023 that maintained strong or higher intensity north of 25°N while undergoing two rapid intensification(RI)events under marine heatwave(MHW)con...Typhoon Hinnamnor(2022)was the only tropical cyclone(TC)during 1982-2023 that maintained strong or higher intensity north of 25°N while undergoing two rapid intensification(RI)events under marine heatwave(MHW)conditions.These RI events differed significantly in both duration and intensification rates.This study investigated the role of MHWs in modulating these events,with a focus on variations in ocean stratification and atmospheric circulation.The results revealed that the first RI lasted 18 h,during which typhoon Hinnamnor intensified from a strong tropical storm to a super typhoon,which was driven primarily by oceanic thermal conditions.The anomalous MHW deepened the warm subsurface waters,leading to sustained accumulation of upper ocean heat content(UOHC),which fueled the RI.The cyclone’s rapid movement and moderate intensity helped preserve the abnormally thick barrier layer(BL),which maintained the UOHC via a subsurface“heat pump”effect,thus supporting continued intensification.In contrast,the second RI lasted only 6 h and involved a one-category intensification from a strong typhoon to a super typhoon,influenced by both oceanic and atmospheric factors.The prolonged and intensified MHW maintained a high UOHC,while strong upper-level divergence,increased mid-level moisture and low-level convergence enhanced deep convection,triggering the RI.However,a shallow mixed layer confined warm anomalies to the surface,whereas the cyclone’s slower movement,stronger winds,and thinner BL induced cold water upwelling.This“cold suction”effect depleted the UOHC,prematurely terminating the RI.These findings highlight the complex interplay between oceanic and atmospheric factors in shaping TC intensification under MHW conditions,emphasizing the critical role of upper ocean stratification in improving TC intensity forecasts.展开更多
This study examined the impact of the preceding boreal summer(June–August) North Atlantic Oscillation(NAO) on early autumn(September) rainfall over Central China(RCC). The results show that a significant positive cor...This study examined the impact of the preceding boreal summer(June–August) North Atlantic Oscillation(NAO) on early autumn(September) rainfall over Central China(RCC). The results show that a significant positive correlation exists between the preceding summer NAO and the early autumn RCC on the interannual timescale. In order to understand the physical mechanism between them, the role of ocean was investigated. It was found that the strong summer NAO can induce a tripole sea surface temperature anomaly(SSTA) in the North Atlantic; this SSTA pattern can persist until early autumn. The diagnostic analysis showed that the tripole SSTA pattern excites a downstream Atlantic-Eurasian(AEA) teleconnection, which contributes to an increase in RCC. The circulation anomalies related to SSTA caused by the weak NAO are opposite, so the RCC is less than normal. The results imply that the preceding summer NAO may be regarded as a forecast factor for the early autumn RCC.展开更多
This study aims to evaluate the significance of the Earth＇ s triaxiality to the polar motion theory. First of all, we compare the polar motion theories for both the triaxial and rotationally-symmetric Earth models, w...This study aims to evaluate the significance of the Earth＇ s triaxiality to the polar motion theory. First of all, we compare the polar motion theories for both the triaxial and rotationally-symmetric Earth models, which is established on the basis of the EGM2008 global gravity model and the MHB2000 Earth model. Then, we use the atmospheric and oceanic data （the NCEP/NCAR reanalyses and the ECCO assimulation products） to quantify the triaxiality effect on polar motion excitations. Numerical results imply that triaxiality only cause a small correction （ about 0. 1 - 0. 2 mas） to the geophysical excitations for the rotationally-symmetric case. The triaxiality correction is much smaller than the errors in the atmospheric and oceanic data, and thus can be neglected for recent studies on polar motion excitations.展开更多
基金The National Natural Science Foundation of China under contract Nos 42275024,42405063,42575023,W2441014,and 42176001the Guangdong Basic and Applied Basic Research Foundation under contract Nos 2023B1515020009 and 2024B1515040024+1 种基金the Special Fund of the South China Sea Institute of Oceanology,Chinese Academy of Sciences,under contract Nos SCSIO2023QY01 and SCSIO2023HC07the Science and Technology Planning Project of Guangzhou under contract No.2024A04J6275.
文摘Typhoon Hinnamnor(2022)was the only tropical cyclone(TC)during 1982-2023 that maintained strong or higher intensity north of 25°N while undergoing two rapid intensification(RI)events under marine heatwave(MHW)conditions.These RI events differed significantly in both duration and intensification rates.This study investigated the role of MHWs in modulating these events,with a focus on variations in ocean stratification and atmospheric circulation.The results revealed that the first RI lasted 18 h,during which typhoon Hinnamnor intensified from a strong tropical storm to a super typhoon,which was driven primarily by oceanic thermal conditions.The anomalous MHW deepened the warm subsurface waters,leading to sustained accumulation of upper ocean heat content(UOHC),which fueled the RI.The cyclone’s rapid movement and moderate intensity helped preserve the abnormally thick barrier layer(BL),which maintained the UOHC via a subsurface“heat pump”effect,thus supporting continued intensification.In contrast,the second RI lasted only 6 h and involved a one-category intensification from a strong typhoon to a super typhoon,influenced by both oceanic and atmospheric factors.The prolonged and intensified MHW maintained a high UOHC,while strong upper-level divergence,increased mid-level moisture and low-level convergence enhanced deep convection,triggering the RI.However,a shallow mixed layer confined warm anomalies to the surface,whereas the cyclone’s slower movement,stronger winds,and thinner BL induced cold water upwelling.This“cold suction”effect depleted the UOHC,prematurely terminating the RI.These findings highlight the complex interplay between oceanic and atmospheric factors in shaping TC intensification under MHW conditions,emphasizing the critical role of upper ocean stratification in improving TC intensity forecasts.
基金supported jointly by the National Basic Research Program of China(973 program,Grant No.2013CB340203)the National Natural Science Foundation of China(NSFC)(Grant Nos.41290255 and 41205046)
文摘This study examined the impact of the preceding boreal summer(June–August) North Atlantic Oscillation(NAO) on early autumn(September) rainfall over Central China(RCC). The results show that a significant positive correlation exists between the preceding summer NAO and the early autumn RCC on the interannual timescale. In order to understand the physical mechanism between them, the role of ocean was investigated. It was found that the strong summer NAO can induce a tripole sea surface temperature anomaly(SSTA) in the North Atlantic; this SSTA pattern can persist until early autumn. The diagnostic analysis showed that the tripole SSTA pattern excites a downstream Atlantic-Eurasian(AEA) teleconnection, which contributes to an increase in RCC. The circulation anomalies related to SSTA caused by the weak NAO are opposite, so the RCC is less than normal. The results imply that the preceding summer NAO may be regarded as a forecast factor for the early autumn RCC.
基金supported by the National Natural Science Foundation of China (41174011)
文摘This study aims to evaluate the significance of the Earth＇ s triaxiality to the polar motion theory. First of all, we compare the polar motion theories for both the triaxial and rotationally-symmetric Earth models, which is established on the basis of the EGM2008 global gravity model and the MHB2000 Earth model. Then, we use the atmospheric and oceanic data （the NCEP/NCAR reanalyses and the ECCO assimulation products） to quantify the triaxiality effect on polar motion excitations. Numerical results imply that triaxiality only cause a small correction （ about 0. 1 - 0. 2 mas） to the geophysical excitations for the rotationally-symmetric case. The triaxiality correction is much smaller than the errors in the atmospheric and oceanic data, and thus can be neglected for recent studies on polar motion excitations.
