东海对台风云娜的海洋响应

Many typhoons pass through the East China Sea(ECS) and the oceanic responses to typhoons on the ECS shelf are very energetic. However, these responses are not well studied because of the complicated background oceanic environment. The sea surface temperature(SST) response to a severe Typhoon Rananim in August 2004 on the ECS shelf was observed by the merged cloud-penetrating microwave and infrared SST data. The observed SST response shows an extensive SST cooling with a maximum cooling of 3°C on the ECS shelf and the SST cooling lags the typhoon by about one day. A numerical model is designed to simulate the oceanic responses to Rananim.The numerical model reasonably simulates the observed SST response and thereby provides a more comprehensive investigation on the oceanic temperature and current responses. The simulation shows that Rananim deepens the ocean mix layer by more than 10 m on the ECS shelf and causes a cooling in the whole mixed layer. Both upwelling and entrainment are responsible for the cooling. Rananim significantly deforms the background Taiwan Warm Current on the ECS shelf and generates strong Ekman current at the surface. After the typhoon disappears, the surface current rotates clockwise and vertically, the current is featured by near inertial oscillation with upward propagating phase.     

台风“布拉万”过境黄海时的异常增温事件研究

海洋对台风的响应通常表现为海表温度的降低,然而,出现在2012年8月的台风"布拉万"在经过黄海时却引起朝鲜半岛木浦沿岸海域海表的增温(而非降温),且增温幅度达4.2°C。本研究详细分析了此次异常事件的时空特征,并探讨了其可能的成因。结果发现,此次事件的产生和黄海表层冷水斑块(Surface Cold Patch,SCP)存在密切关系,并恰好出现在木浦SCP所在位置。上升流和潮混合是木浦SCP的两大形成机制,此次增温事件主要是台风"布拉万"通过抑制其生成机制之一的上升流而导致降温不足之故。具体而言,台风"布拉万"过境时位于木浦SCP的左侧,其上的北向风应力带来向岸的Ekman输运,造成外围暖水在木浦SCP地区堆积,从而抑制了该地区原本的上升流(甚至变为下降流)。     

东海南部海域夏秋季沿岸流特征

Current characteristics and vertical variations during summer and autumn in the southern East China Sea were investigated by measuring current profile, tide, wind, and wave data for 90 d from July 28 to October 25, 2015. Our results are:(1) The current was mainly a(clockwise) rotating flow, displaying reciprocating flow characteristics,and vertically the current directions were the same throughout the vertical profile.(2) The horizontal current speed was strongest during August(summer) with an average speed of 51.8 cm/s. The average current speeds during spring tides were highest in August and weakest in September, with speeds of 59.9 and 42.8 cm/s,respectively.(3) Considerable differences exist in average current speeds in different layers and seasons. The highest average current speeds were found in the middle–upper layers in August and in the middle–lower layers in September and October.(4) The residual current speed was highest in August, when the speed was 12.5–47.1 cm/s,whereas the vertical average current speed was 34.3 cm/s. The depth-averaged residual current speeds in September and October were only 50% of that in August, and the residual current direction gradually rotated in a counter-clockwise direction from the lower to surface layers.(5) Typhoon waves had a significant influence on the currents, and even affected the middle and lower water layers at depths of >70.0 m. Our results showed that the currents are controlled by the dynamic interplay of the Taiwan Warm Current, incursion of the Kuroshio Current onto the continental shelf, and monsoonal changes.     

台湾岛附近海洋对0908号台风“莫拉克”的响应特征

在模拟2009年登陆我国东部沿海的台风"莫拉克"的基础上,利用AVHRR/AMSR和SODA再分析数据和模拟结果,初步评估了GRAPES-ECOM海-气耦合模式(上海台风研究所基于GRAPES-TCM区域台风模式和ECOM海洋模式开发而成)模拟台风期间海洋响应的能力,并分析了台风期间台湾岛周围海域的海温、上升流、中尺度冷涡等的变化特点。分析结果表明,GRAPES-ECOM耦合模式较好地模拟了表层海温对台风的响应,与深水海洋响应比较,揭示了近海对台风响应的一些新特征:(1)在台湾以东海域,台风活动改变了黑潮海域海水的垂直运动,诱导黑潮南部沿岸上升流,而北部先于台风存在的上升流减弱,导致不同水深海温的最大降温位置都出现在路径左侧,与深海偏向路径右侧不同;(2)位于台湾岛东北面的彭佳屿冷涡因其形成与大陆架和黑潮有关,当台风在台湾以东洋面活动时,冷涡位于台风右前方,黑潮表层海水辐合流向大陆架,冷涡中心温度上升,强度减弱,当台风转折北上,冷涡位于台风东南侧,表层海水辐散,加强底层冷水上涌,从而增强了该冷涡的强度;(3)台风不仅加深了台湾海峡的混合层深度,还使得海水的垂直热力结构改变,并使整层海温趋于一致。     

南海东北部上层海洋对台风“莲花”的响应

台风过境会引起所经海域海洋环境要素场剧烈响应。本文通过分析南海东北部上层海域各要素对2015年第10号台风"莲花"的响应过程,发现以下规律:台风过境期间,海表温度(SST)影响台风的移动路径和强度,两次显著的台风移动方向偏转均发生在台风下垫面温度发生显著改变的条件下。台风吸收海表热量引起SST降低0～1.5℃,而这种热量(以短波辐射和潜热通量为主的海表净热通量)吸收引起的海表失热每秒可达60 W/m2,对台风移动过程产生影响。同时,台风过境时(7月6—9日)的SST降低与失热变化都存在一定的"左偏性"。台风引起的Ekman抽吸速率最高可达1.6×10-3m/s,引起台风过后(7月9日之后) SST的降低。通过对海面10 m风场、海表温度、降雨量进行EOF分析发现:风场在南海东北部海域呈东西反位相分布,风场增强持续时间约5天,具有显著"右偏性"且近岸的局部风场特征明显;降雨量在台风期间呈全域一致性的增加,持续时长约4天,具有显著"左偏性"且在吕宋岛北部局部降雨特征明显;SST在南海东北部绝大部分海域呈降温态势,时长超过8天,降温时间滞后风场约2～3天。整个降温过程(7月5—15日)受Ekman抽吸作用较海表失热作用更大,表现为在台风右侧降温更为显著。同时,台风移动速度越慢,降温效果越明显。台风过境时,粤东离岸流显著增强,上升流区的垂直温度降幅可达2.5℃且滞后流场响应约1～2天;垂直盐度降幅可达1.3 psu且滞后流场响应约2～3天。总体上看,温度在台风响应过程中起着重要的联结作用。     

厄尔尼诺和台风共同影响下的7月份黄、东海海温变化

基于历史海温数据和台风路径数据,研究了厄尔尼诺/拉尼娜（El Niño/La Niña）背景下7月份中国近海海温变化特征。结果表明:7月黄、东海海温异常与El Niño/La Niña有显著相关关系,OISST和GODAS海温数据与Niño3指数同步相关系数分别为-0.32和-0.45。El Niño年7月,黄、东海海表温度异常低于-0.5℃的概率超过60%;La Niña年7月,黄海海温异常高于0.5℃的概率约有60%;正常年7月,海温异常的空间分布与El Niño年相反,但量值偏低。El Niño年7月,中国近海及邻近区域大气异常能够给局地带来更多降水;同时,受El Niño背景场的影响,入侵黄、东海的台风强度更强、影响时间更长。大尺度的降水和台风活动的影响是导致黄、东海海温异常降低的重要原因。因此,分析和预测7月份中国近海海温异常,在充分考虑El Niño/La Niña背景场的基础上,需要结合局地的大尺度降水和台风的影响同时分析,这为特定背景下结合不同时间尺度上的因素共同分析中国近海海温变化提供了一种思路。     

渤海、黄海、东海冬季环流的数值模拟

在POM的基础上,建立一个σ坐标系下三维斜压预报模式,利用经过资料同化处理的周平均卫星遥感海面温度资料,考虑海底地形、外海出入流、海面风应力等因素的影响,较好的模拟了冬季渤、黄、东海环流的情况。     

海洋背景磁场模拟计算及东中国海表层磁场分布

海洋中海水的运动会切割地球磁场,生成微弱的电场,进而在海洋内部和周围空间激发感生电磁场,即约为地球磁场一万至十万分之一的微弱海洋背景磁场.文中针对海洋背景磁场的生成机制及近几十年来对海洋背景磁场的理论研究,结合世界磁场模型WMM2005,模拟计算了三种典型的海洋运动--海浪、海流、内波所产生的感应磁场,建立了海洋背景磁场的数值计算模型,并在此基础上设计开发了海洋背景磁场的模拟计算软件.最后用卫星多传感器资料驱动普林斯顿海洋动力学模式,得到的东中国海2005年海洋表层环流数据,模拟计算了东中国海海表层磁场分布,对其磁场变化与分布规律作了简要分析.     

台风“苏力”(2013)期间海洋上层温、盐及海平面异常变化特征

台风"苏力"是2013年最强的台风之一。本文利用再分析资料、卫星遥感资料及ARGO浮标数据等分析了台风过境所引起的海表面温度(SST)、海表面高度异常(SLA)以及海洋次表层温、盐的变化规律,给出了上层海洋对台风响应的基本特征。台风所经过的海域都存在着明显的降温,在冷涡区域引起了6~7℃的海表温度的冷却,降温区域集中在路径的右侧。台风造成SLA降低,最大为20cm左右。海表温度的变化滞后于海面高度的变化。ARGO浮标数据显示,台风引起了海面的显著降温,最大降温幅度为5℃,位于冷涡内,且位于路径的右侧。路径左侧的SST的降低相对较小,为1.5~2.5℃。台风的扰动导致次表层水涌升到表层,改变了表层的盐度和密度,引起混合层加深。     

吕宋海峡上层海洋对于台风南玛都响应的观测分析与数值模拟试验

利用海洋模式POM模拟了吕宋海峡上层海洋对历经其上的2011年8月1111号台风南玛都的响应过程。基于2个方面进行了模拟实验,其一是吕宋海峡上层海洋对固定大小及位置的台风风场响应;其二是吕宋海峡上层海洋对台风南玛都移动期间的响应。并分析了台风南玛都的风场和海洋响应南玛都的表层流场、SST及SSS。研究结果表明:(1)吕宋海峡上层海洋对台风风场结构不对称的响应表现出吕宋海峡上层海洋右侧的流速要远大于左侧,海流和台风一样具有右偏特征。海洋表面温度(SST)下降2~7℃,下降的空间范围直径在百公里,表现为右强左弱的不对称性。(2)上层海洋对驻台风的响应过程中,海洋流场及SST达到能量的极值后,会触发1个反气旋流场控制吕宋海峡,SST经过约10d时间恢复到初始态。(3)上层海洋对台风移动过程的响应表现为1个随台风移动的海洋流场,海流的强度和SST下降的幅度都较小,海流气旋式结构沿着路径有一定的拉伸,并且在路径后方出现尾流。     

山东半岛东部滨海沙滩对台风“米雷”的地貌响应

通过对台风“米雷”登陆前后山东半岛东部8个滨海沙滩地形地貌的现场调查以及一年后的重复调查对比分析了沙滩地貌形态的变化,并依据台风期间的风要素计算和评估了台风期间沙滩的沿岸输沙和横向输沙趋势,探讨了在热带风暴发生频次较低的地区沙滩的风暴响应模式和海岸恢复规律。研究结果表明,台风造成横向和纵向输沙量的增加和输沙方向的逆转是造成沙滩形态改变的主要因素,而在米雷登陆前的阶段横向和纵向输沙作用最为强烈。研究区内沙滩的风暴响应模式主要表现为侵蚀陡坎的形成和滩肩或滩面的侵蚀后退。与其他台风频发的区域不同,在研究区台风是一个偶然的强动力事件,因此台风特征对沙滩的风暴响应的作用更加明显。而沙滩剖面形态的作用,仅仅在耗散型沙滩上有所体现。此外,沙滩的走向是控制风暴作用强度的主要因素,并且与沙滩风后恢复密切相关。     

Upper Ocean Sensitivity to Wind Forcing in the South China Sea

The Naval Research Laboratory (NRL) Layered Ocean Model (NLOM) has been used to investigate the sensitivity of the upper South China Sea (SCS) circulation to various atmospheric wind forcing products. A 1/16° 6-layer, thermodynamic Pacific Ocean north of 20°S version of NLOM has been integrated using observed climatological monthly mean winds (Hellerman and Rosenstein, 1983) and climatologies based on two atmospheric prediction models: the European Centre for Medium-Range Weather Forecasts (ECMWF) and the National Centers for Environmental Prediction (NCEP). ECMWF products include the 10 meter winds (at both 1.125° and 2.5° resolution) and surface stresses (1.125°). The NCEP forcing (1.875°) is a surface stress product. Significant differences exist in the wind stress curl patterns and this is reflected in the upper ocean model response, which is compared to observational data. The model experiments suggest the generation of the West Luzon Eddy is controlled by positive wind stress curl. The degree of Kuroshio intrusion into the SCS, however, is not affected by wind stress curl but is governed by the coastline geometry of the island chain within Luzon Strait. The summertime offshore flow from the Vietnamese coast is present in all simulations but the dipole structure on either side of the jet is variable, even among experiments with similar wind stress curl patterns. The ECMWF surface stresses exhibit spurious coastal wind stress curl patterns, especially in locations with significant orographic features. This manifests itself in unrealistic small scale coastal gyres in NLOM. High resolution basin-scale and coastal models might be adversely affected by these stresses. This revised version was published online in July 2006 with corrections to the Cover Date.     

东海区台风模拟数值敏感性试验研究

采用分辨率为1(°)×1(°)的NCEP全球格点再分析资料,基于WRF模式结合典型台风个例,研究了不同积云对流参数化方案以及边界层方案的参数化方案组合对东海区14个台风的台风路径与强度模拟的敏感性,并比较分析了不同参数化方案组合对大尺度环流场以及潜热释放的影响。结果表明,虽然东海区台风路径模拟对于参数化方案组合的选择具有一定的"个例依赖性",即不同台风个例的最佳参数化方案组合有所变化,但综合来看,依然能够较为清晰地揭示KF积云对流方案与MYJ边界层方案的参数化方案组合模拟台风路径效果最佳。东海区台风强度模拟对于参数化方案组合的选择没有"个例依赖性"的特点。研究发现,KF积云对流方案与YSU边界层方案的参数化方案组合模拟台风强度效果最佳。通过对台风典型个例的研究发现,KF积云对流方案与MYJ边界层方案的参数化方案组合模拟大尺度环流场效果最佳。对于强度"迅速加强"的台风,KF积云对流方案与YSU边界层方案组合模拟更加准确,KF积云对流方案与MYJ边界层方案组合敏感性稍差;对于强度"逐渐加强"的台风,KF积云对流方案与YSU边界层方案组合则敏感性过强,致使台风强度偏低,误差增大。此时,KF积云对流方案与MYJ边界层方案组合模拟敏感性较好,强度模拟更加准确。     

Rogue waves during Typhoon Trami in the East China Sea

As concluded from physical theory and laboratory experiment,it is widely accepted that nonlinearities of sea state play an important role in the formation of rogue waves;however,the sea states and corresponding nonlinearities of real-world rogue wave events remain poorly understood.Three rogue waves were recorded by a directional buoy located in the East China Sea during Typhoon Trami in August 2013.This study used the WAVEWATCHⅢmodel to simulate the sea state conditions pertaining to when and where those rogue waves were observed,based on which a comprehensive and full-scale analysis was performed.From the perspectives of wind and wave fields,wave system tracking,High-Order Spectral method simulation,and some characteristic sea state parameters,we concluded that the rogue waves occurred in sea states dominated by second-order nonlinearities.Moreover,third-order modulational instabilities were suppressed in these events because of the developed or fully developed sea state determined by the typhoon wave system.The method adopted in this study can provide comprehensive and full-scale analysis of rogue waves in the real world.The case studied in this paper is not considered unique,and rules could be found and confirmed in relation to other typhoon sea states through the application of our proposed method.     

上层海洋对台风"凯萨娜"(2009)的响应特征

本文利用多源卫星遥感数据和Argo浮标数据对2009年台风"凯萨娜"过后,南海上层海洋的物理和生态响应特征进行了分析。结果表明,"凯萨娜"引起的上升流流速最大可以达到1.6×10~(–3)m/s,台风过后,海表面温度(SST)下降显著,最大降温幅度可以达到6℃,海表面高度降低,先前存在的中尺度冷涡进一步加强。台风过后,沿着台风路径,叶绿素浓度升高,最大值可以达到2 mg/m~3以上,初级生产力升高到台风过境前的5倍。SST的最大降温中心与海面高度下降区域以及叶绿素浓度升高的区域一致。Argo数据表明台风诱发了强烈的垂向混合和艾克曼泵吸,不同位置处,垂向混合和艾克曼泵吸的强度不一样。通过混合和泵吸过程,台风可以把海洋内部的营养盐输送到海洋表层,对整个南海的物理和生态过程有重要影响。     

Oceanic response to Typhoon Nari (2007) in the East China Sea

The oceanic response to a typhoon in the East China Sea (ECS) was examined using thermal and current structures obtained from ocean surface drifters and a bottom-moored current profiler installed on the right side of the typhoon’s track. Typhoon Nari (2007) had strong winds as it passed the central region of the ECS. The thermal structure in the ECS responded to Typhoon Nari (2007) very quickly: the seasonal thermocline abruptly collapsed and the sea surface temperature dropped immediately by about 4°C after the typhoon passed. The strong vertical mixing and surface cooling caused by the typhoon resulted in a change in the thermal structure. Strong near-inertial oscillation occurred immediately after the typhoon passed and lasted for at least 4–5 days, during which a strong vertical current existed in the lower layer. Characteristics of the near-inertial internal oscillation were observed in the middle layer. The clockwise component of the inertial frequency was enhanced in the surface layer and at 63 m depth after the typhoon passed, with these layers almost perfectly out of phase. The vertical shear current was intensified by the interaction of the wind-driven current in the upper layer and the background semi-diurnal tidal current during the arrival of the typhoon, and also by the near-inertial internal oscillation after the typhoon passage. The strong near-inertial internal oscillation persisted without significant interfacial structure after the mixing of the thermocline, which could enhance the vertical mixing over several days.     

海面温度变化影响台风"海棠"强度的数值研究

通过对台风"海棠"5 d的数值模拟,研究海表温度(SST)变化对台风强度的影响。与NCEP月平均海表温度相对比,在中尺度大气模式中引入热带测雨卫星(TRMM)微波成像仪(TMI)/先进微波扫描辐射计(AMSR-E)来考察SST对台风"海棠"路径和强度的影响。研究结果表明,每天变化SST的试验模拟的台风强度和路径整体效果不错;模拟的台风路径不敏感于SST的变化,而台风强度的变化不仅取决于由于台风移动引发的SST冷却的幅度大小,而且取决于SST冷却区域的相对位置。在台风"海棠"强烈发展过程中,台风中心右侧冷却区对台风中心气压影响很小;台风强烈发展过后,SST冷却区开始影响台风强度,但造成台风中心气压下降幅度不大,6 h内台风中心气压减弱约3.9 hPa。海面热量通量和海面风速与SST的分布都有良好的相关性:在SST变化为正值的暖水区,感热通量和潜热通量都是一个正的通量分布的极值区,并有风速极大值区域存在;在台风右侧相应的冷却区,则存在着负的通量异常和风速极小值区域。     

太平洋-印度洋暖池次表层水温与南海夏季风爆发

为探索太平洋—印度洋热带海域次表层水温对南海季风的影响,用Argo剖面浮标等实测资料,分析了太平洋—印度洋暖池次表层水温异常对南海夏季风爆发的影响。结果表明：冬季,太—印暖池次表层水温偏暖（冷）时,翌年南海夏季风爆发时间偏早（晚）是主要现象。太—印暖池次表层水温偏暖,可能引起Walker环流加强,西太平洋副热带高压偏弱,中心位置偏北偏东,南海和西太平洋上空对流层下层有气旋性距平环流出现,有利于低空西到西南气流的加强,导致南海夏季风爆发偏早;太—印暖池次表层水温偏冷,可能引起Walker环流东移并减弱,西太平洋副热带高压偏强,中心位置偏南偏西,南海和西太平洋上空对流层下层有反旋性距平环流出现,不利于低空西到西南气流的加强,导致南海夏季风爆发偏晚。结论：冬季,太—印暖池次表层水温偏暖（冷）,翌年南海夏季风爆发时间偏早（晚）是主要现象。     

黄海海洋对台风“灿鸿”外围过程响应的观测研究

2015年9月台风"灿鸿"经过黄海海域的QF111浮标,该浮标观测到黄海海洋的温度和流速响应。受台风影响,黄海海表温度有明显的下降,降温幅度在2～4°C,且在台风路径右侧形成了海表面温度低于20°C的低温斑块。流速的响应主要表现为台风过境期间流速增强,达1.2～1.5 m/s,呈现出全水深强化的特征。风一直对海洋有能量输入,且在台风过境期间风输入海洋的能量最大,旋转功率谱的分析结果表明台风输入海洋的能量向海洋内部传播。黄海海域由台风激发出的近惯性振荡衰减较快,近惯性振荡e折时间尺度约为2 d。     

Ocean temperature change around New Zealand over the last 36 years

Ocean temperature changes around New Zealand are estimated from satellite sea surface temperature (SST) products since 1981, two high resolution expendable bathythermograph transects (HRXBT) since 1986 and 1991, and Argo data since 2006. The datasets agree well where they overlap. Significant surface warming is found in subtropical waters. Greatest warming is east of Australia and in the central Pacific. All NZ coastal waters are warming, with strongest warming east of Wairarapa and weakest between East Cape and North Cape. Temperature changes are surface intensified, extending to ～200 m in the northeast and at least 850 m in the eastern Tasman. Significant interannual variability is coherent over a large area of ocean north of the Subtropical Front and modulates extreme events. NZ air temperatures are highly correlated at interannual timescales with SSTs over a broad region of ocean north of the Subtropical Front from the eastern Tasman to east of the dateline.