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Upper ocean response to typhoon Bolaven analyzed with Argo profiling floats
利用Argo资料分析海洋上层对Bolaven台风的响应
Received:October 29, 2012  Revised:July 29, 2014
DOI:
Key words:Typhoon Bolaven  Argo profiling floats  Response in the Mixed Layer  Ocean heat content
中文关键词:  Bolaven台风  Argo剖面浮标  混合层响应  海洋热含量
基金项目:国家重点基础研究发展计划(973计划);国家自然科学基金项目(面上项目,重点项目,重大项目);科技部基础性工作专项重点项目
Author NameAffiliationAddress
liu zeng hong The Second Institute of Oceanography, SOA 浙江省杭州市保俶北路36号
Xu jian ping The Second Institute of Oceanography, SOA 
Sun chao hui The Second Institute of Oceanography, SOA 
Wu xiao fen The Second Institute of Oceanography, SOA 
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Abstract:
      In situ observations from Argo profiling floats combined with satellite retrieved SST and rain rate are used to investigate the upper ocean response to typhoon Bolaven from 20 through 29 August 2012. After the passage of typhoon Bolaven, deepening of Mixed Layer Depth (MLD), and cooling of Mixed Layer Temperature (MLT) were observed. The changes of Mixed Layer Salinity (MLS) showed an equivalent number of increasing and decreasing because typhoon-induced salinity changes in the mixed layer were influenced by precipitation, evaporation, turbulent mixing and upwelling of thermocline water. The deepening of MLD and cooling of MLT indicated a significant rightward bias, whereas MLS was freshened to the left side of the typhoon track and increased on the other side. Intensive temperature and salinity profiles observed by Iridium floats make it possible to view response processes in the upper ocean after the passage of a typhoon. In our case study, the cooling in the near-surface and warming in the subsurface were observed by two Iridium floats located to the left side of the cyclonic track during the development stage of the storm, beyond the radius of maximum winds relative to the typhoon center. Water salinity increases at the base of the ML and the top of the thermocline were the most obvious change observed by those two floats. On the right side of the track and near the typhoon center when the typhoon was intensified, the significant cooling from sea surface to the depth of 200 dbar except the water at the top of the thermocline was observed by the other Iridium float. Due to the enhanced upwelling near the typhoon center, water salinity in the near-surface increased obviously. The heat pumping from the ML into the thermocline induced by downwelling and the upwelling induce by the positive wind stress curl are the main cause for the different temperature and salinity variations on the different sides of the track. It seems that more time are required for the anomalies in the subsurface to restore to the pre-typhoon conditions than the anomalies in the ML.
中文摘要:
      本文利用2012年8月20-28日期间BOLAVEN台风经过海区的Argo浮标观测资料,并结合卫星遥感SST和降水资料,分析了海洋上层对该台风的响应及响应过程,并对台风路径两侧的海水热含量变化进行了探讨。台风过后混合层内的响应主要包括混合层深度(MLD)的加深、混合层温度(MLT)下降,但混合层盐度(MLS)的变化受降水、蒸发、混合和跃层抬升等过程的影响,其变化没有倾向性。MLD和MLT的变化具有明显的右偏特征,而MLS的变化在台风左侧下降、右侧增加。台风左侧的浮标观测到混合层加深约26.6-33.7 dbar,并可持续4-6 d时间;位于台风右侧的MLD增加及MLT下降比左侧更为显著,MLS的变化相对复杂,取决于混合、蒸发和降水等过程的竞争结果,而混合层内溶解氧浓度在台风经过后呈微弱的上升趋势,并能持续至少一周时间。 台风路径左右两侧温、盐度断面变化则完全不同,位于左侧的浮标观测到近表层海水降温,并能持续一周或更长的时间;而次表层(40 dbar以下)出现大范围的增温现象, 30-100 dbar范围内海水盐度下降最为明显;台风右侧观测到0-200 dbar内海水大范围的降温,以40 dbar以浅和60-170 dbar降温最明显,同时近表层盐度明显增加(最大可以达到0.49),而在40 dbar以下盐度平均下降约0.10,以上过程均能维持一周以上时间。热含量的变化在左右两侧也不相同,左侧在台风过后3-4 d内热含量并没有下降的趋势,随后出现的热含量下降也很短暂;台风右侧上层海洋热含量呈明显的下降趋势,至少能维持一周时间,与风速增强所导致的海面向大气输送热量相应增加有关。研究表明,新颖的Argo剖面浮标有望为人们进一步了解上层海洋对台风过程的响应,甚至揭示上层海洋是如何影响台风生成及其移动路径等预测、预报台风的关键科学问题提供鲜为人知的第一手现场观测资料。
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