Review of the Tropical Gyre in the Indian Ocean with Its Impact on Heat and Salt Transport and Regional Climate Modes     

Yan Du  Lianyi Zhang  Yuhong Zhang 《地球科学进展》2019,34(3):243-254

Due to the IO monsoon impact, the tropical IO circulation has significant seasonal variation, especially in the northern IO. However, in mean-state, a relatively closed current loop is established by eastward current along the equator and westward current south of equator, which is regarded as Tropical Gyre in the Indian Ocean. Based on this circulation system, relevant studies were reviewed. Its impact on heat and salt transports and regional climate changes were discussed.  相似文献   

不同强度热带气旋对中国降水变化的影响     

杨慧  任福民  杨明仁 《地球科学进展》2019,(7):747-756

基于1960—2017年2 000多个气象台站逐日降水数据和中国气象局热带气旋(TC)最佳路径资料集,采用客观天气图分析法(OSAT)识别得到TC降水。研究表明,中国TC降水总体呈显著下降趋势,较12年前的研究结果下降趋势变缓;TC盛期(7~9月)降水占到TC总降水的78.5%,TC盛期降水和TC非盛期降水均呈显著下降趋势。TC降水气候趋势在空间分布上以减少为主要特征,并表现出明显的地域差异,自南向北呈"减少—增多—减少"的分布型,减少趋势中心位于广东和海南。按TC影响期最大强度分级(弱TC、中等强度TC和强TC)研究不同强度TC降水的变化,结果显示,强TC降水表现出显著减少趋势,主要决定着TC总降水的影响范围和趋势等主要特征。进一步分析发现,影响TC频数在1960—2017年呈显著减少趋势,并在1995年发生突变;对1995年前后2个时期的对比研究显示,与前一时期(1960—1994年)相比,后一时期(1995—2017年)影响TC活动频次在20°N以南的海域呈现出显著的减少趋势,减少大值中心位于南海北部,而且这一特征也主要由影响TC中的强TC所决定;强TC的这一变化趋势导致了华南地区尤其是广东和海南TC降水日数的减少,进而使得TC降水减少。  相似文献   

基于神经网络的印度洋长鳍金枪鱼(Thunnus alalunga)时空分布与海洋环境关系研究     

程懿麒  张俊波  汪金涛  雷林 《海洋与湖沼》2021,52(4):960-970

长鳍金枪鱼(Thunnusalalunga)是主要的经济性金枪鱼鱼种之一,其空间分布与环境因子存在着密切联系。利用2012—2019年印度洋长鳍金枪鱼生产数据和海洋环境数据,包括海表面温度(sea surface temperature, SST)、叶绿素浓度(chlorophyll a, chl a)和海表面盐度(sea surface salinity, SSS)构建印度洋长鳍金枪鱼时空分布神经网络模型。以空间(经度,纬度)、环境因子(SST, chl a, SSS)为解释变量,局部渔获量为因变量,变化隐含层节点数,构建了18个BP空间分布模型,并采用10×10交叉验证模型稳定性,以均方误差(meansquareerror,MSE)、平均相对方差(averagerelativevariance,ARV)以及拟合优度(R~2)作为不同模型精度与稳定性的评判标准,最终选取5-18-1(隐含层节点18)模型为最佳模型,其平均MSE值为0.02232,平均ARV值为0.511。利用最优模型预测结果与同期实际捕捞产量进行叠加对比发现两者具有一致性。环境因子敏感性分析表明海表温度显著影响印度洋长鳍金枪鱼渔场分布,其贡献率达到0.2。印度洋长鳍金枪鱼高精度BP神经网络时空分布模型为其资源的可持续开发与动态管理提供了一种新思路。  相似文献   

利用区域气候模式预估未来登陆中国热带气旋活动     

聂心宇  谭红建  蔡榕硕  高学杰 《气候变化研究进展》2023,19(1):23-37

鉴于热带气旋（TC）对我国沿海地区的影响,研究全球变暖背景下未来登陆我国TC活动的变化,对于我国沿海地区的防灾减灾具有重要意义。基于CMIP5中全球气候模式HadGEM2-ES数据,文中利用区域气候模式RegCM4开展了历史时期和3种情景（RCP2.6、RCP4.5和RCP8.5）下未来东亚区域气候的动力降尺度模拟,检验了模式对历史登陆我国TC活动及其相关大尺度环境场的模拟能力,并预估了3种情景下2030—2039年、2050—2059年和2089—2098年,登陆我国TC的路径、强度和频率的变化特征。结果表明：模式能合理地再现东亚区域历史时期（1986—2005年）大气环流场的空间结构以及登陆我国TC的特征;在3种情景下未来登陆我国TC的平均强度和数量均有不同程度的增加,尤其是台风及以上级别TC的总数明显增加,其中RCP8.5情景最突出,到21世纪末期（2089—2098年）登陆我国TC的平均强度、台风及以上级别TC总数的年平均值较历史时期将分别增加7.56%和1.05个;不同情景下未来登陆我国TC的路径均有不同程度的北移趋势,且全球升温的幅度越大,北移趋势越明显,这可能与未来中国近海显著变暖和垂直风切变减弱有关。未来我国沿海地区尤其是中高纬度很可能将面临日益严峻的TC灾害风险,亟需尽快开展防灾减灾及对策研究。  相似文献   

Possible relationship between NAO and tropical cyclone genesis frequency in the western North Pacific     

《Dynamics of Atmospheres and Oceans》2017

This study examined a strong positive correlation between the North Atlantic Oscillation (NAO) index during June and the total tropical cyclone (TC) genesis frequency in the western North Pacific during July and August. To investigate a possible cause for this relation, the mean difference between highest positive NAO years and lowest negative NAO years was analyzed by dividing into when the El Niño and La Niña years were included and when the El Niño and La Niña years were not included.When the El Niño and La Niña years were included, for positive NAO years, the TCs mostly occurred in the northwestern region of tropical and subtropical western Pacific, and showed a pattern that migrate from the sea northeast of the Philippines, pass the East China Sea, and move toward the mid-latitudes of East Asia. In contrast, for negative NAO years, the TCs mostly occurred in the southeastern region of tropical and subtropical western Pacific, and showed a pattern that migrate westward from the sea southeast of the Philippines, pass the South China Sea, and move toward the southern coast of China and Indochinese peninsula. These two different TC migration patterns affect the recurving location of TC, and for positive NAO years, the recurving of TC was averagely found to take place in the further northeast. In addition, the migration patterns also affect the TC intensity, and the TCs of positive NAO years had stronger intensity than the TCs of negative NAO years as sufficient energy can be absorbed from the ocean while moving north in the mid-latitudes of East Asia. The TCs of negative NAO years showed weak intensity as they weaken or disappear shortly while landing on the southern coast of China and Indochinese peninsula. On the other hand, the above result of analysis is also similarly observed when the El Niño and La Niña years were not included.  相似文献   

Simulated sensitivity of tropical cyclone track to the moisture in an idealized monsoon gyre     

《Dynamics of Atmospheres and Oceans》2017

In this study, the sensitivity of tropical cyclone (TC) track to the moisture condition in a nearby monsoon gyre (MG) is investigated. Numerical simulations reveal that TC track is highly sensitive to the spatial distribution of relative humidity (RH). In an experiment conducted with higher (lower) RH in the eastern (western) semicircle of an MG, the TC experiences a sharp northward turning. In contrast, when the RH pattern is reversed, the simulated TC does not show a sharp northward turning. The RH distribution modulates the intensity and structure of both the TC and MG, so that when the TC is initially embedded in a moister environment, convection is enhanced in the outer core, which favors an expansion of the outer core size. A TC with a larger outer size has greater beta-effect propagation, favoring a faster westward translational speed. Meanwhile, higher RH enhances the vorticity gradient within the MG and promotes a quicker attraction between the TC and MG centers through vorticity segregation process. These cumulative effects cause the TC to collocate with the MG center. Once the coalescence process takes place, the energy dispersion associated with the TC and MG is enhanced, which rapidly strengthens southwesterly flows on the eastern flanks. The resulting steering flow leads the TC to take a sharp northward track.  相似文献   

CFSv2模式产品在汛期海南热带气旋频数预测模型中的应用   总被引：1，自引：1，他引：0  

邢彩盈  吴慧  胡德强  吴胜安 《气象科学》2017,37(5):666-672

利用1982—2014年汛期影响海南的热带气旋频数、NCEP/NCAR逐月再分析资料和CFSv2模式历史回报数据,分析了热带气旋频数特征及同期环流特征,并利用逐步回归构建基于模式有效预测信息的热带气旋频数预测模型。结果表明:汛期影响海南热带气旋频数的异常与同期大尺度环流变化密切相关,且CFSv2模式对其环流影响关键区具有较好的预测技巧,包括南海到热带太平洋的海平面气压、500 h Pa位势高度场、低层风及热带太平洋纬向风切变。据此,利用逐步回归构建热带气旋频数预测模型,其26 a交叉检验中实况与预测相关为0.88,距平同号率达88%;6 a预测试验仅2 a预测与观测反号,可见模型具有良好的稳定性和预测技巧,可为汛期热带气旋频数预测提供依据。  相似文献   

西太平洋暖池对西北太平洋季风槽和台风活动影响过程及其机理的最近研究进展   总被引：4，自引：1，他引：3  

黄荣辉  皇甫静亮  刘永  冯涛  武亮  陈际龙  王磊 《大气科学》2016,40(5):877-896

本文回顾和综述了近年来关于西太平洋暖池对西北太平洋热带气旋和台风（TCs）活动影响过程及其机理的研究进展。文中首先简单回顾了近年来关于西太平洋暖池热状态和菲律宾周围对流活动变化特征及其对与TCs活动有关的南海夏季风爆发和西太平洋副热带高压的季节内、年际变异的影响过程和机理的研究;然后,本文系统地回顾了近年来关于西太平洋暖池热状态通过西北太平洋季风槽影响TCs活动年际和年代际变化的影响过程及其机理的研究。此外,文中还指出了关于西太平洋暖池对西北太平洋上空季风槽和TCs活动变异的热力和动力作用需进一步深入研究的科学问题。  相似文献   

A spatiotemporal analysis of tropical cyclone tracks in the Atlantic Basin and their relationship to El Niño-Southern Oscillation     

Cody Frick 《自然地理学》2016,37(1):26-37

There has been an enhanced focus on Atlantic tropical cyclone climatologies with the significant cyclones of the past decade and the associated loss of life and property. This study examines the geographic location of cyclone tracks and their relationship to El Niño-Southern Oscillation (ENSO). The average annual cyclone track latitude and longitude correlate positively with hurricane-season El Niño indices, indicating that during El Niño conditions, tropical cyclone tracks are shifted northward and eastward. June–November indices explain 11–22% and 3–11% of the variance in cyclone track latitude and longitude, respectively. Examination of the strongest and weakest El Niño years yields similar results. Higher sea level pressure over North America, a slight contraction of the Bermuda High, and a slight decrease in 500 mb heights during El Niño years helps to explain the observed northward and eastward movement of tropical cyclone tracks during El Niño years. Additionally, weaker easterly and stronger southerly winds on the western side of the North Atlantic Basin exist during El Niño years. Although future tropical cyclone track projection is beyond the scope of this research, these results may provide insight into forecast improvement and ultimately better responses for coastal communities.  相似文献   

中国南海东部海域气候特征及风浪流极值参数的研究——LAGFD数值模式群的应用     

陈顺楠  乔方利  潘增弟  赵伟  万振文 《海洋科学进展》1998,(2)

本文采用先进的ＬＡＧＦＤ风、浪数值模式和ＰＯＭ（ＰｒｉｎｃｅｔｏｎＯｃｅａｎＭｏｄｅｌ）三维海流模式对自１９４５～１９９５年间发生并影响南海东部海域的２９９个历史最强热带气旋过程进行数值后报,给出了南海东部部分海域（１９°～２３°Ｎ,１１３°～１１８°Ｅ）中１０００ｍ等深线内６０个点的多年一遇风、浪、流和水位极值,并简要分析了南海东部（１５°～２７°Ｎ,１０８°～１２２°Ｅ）的气候特征,为该海域区域性海洋环境研究与工程开发提供了基础参考数据。  相似文献