国际Argo计划执行现状剖析

国际Argo计划自2000年实施以来,世界上25个国家和团体已经在全球海洋中布放了5000余个Argo浮标,其中在海上正常工作的浮标已经超过3000个。这标志着全球Argo实时海洋观测网已经全面建成。文中将系统介绍国际Argo计划主要成员国在浮标布放、回收和Argo资料管理等方面所作出的贡献,以帮助读者对这21世纪的重大国际海洋观测计划有一较全面、深入的了解。     

Argo floats revealing bimodality of large-scale mid-depth circulation in the North Atlantic

Analysis of Argo float trajectories at 1 000 m and temperature at 950 m in the North Atlantic between November 2003 and January 2005 demonstrates the existence of two different circulation modes with fast transition between them. Each mode has a pair of cyclonic - anticyclonic gyres. The difference is the location of the cyclonic gyre. The cyclonic gyre stretches from southeast to northwest in the first mode and from the southwest to the northeast in the second mode. The observed modes strongly affect the heat and salt transport in the North Atlantic. In particular, the second mode slows down the westward transport of the warm and saline water from the Mediterranean Sea.     

应用Argo资料分析西北太平洋冬、夏季水团

应用Argo剖面浮标观测的温、盐度资料,分析了西北太平洋海域冬、夏季的温、盐度分布、水团结构及其分布。首先采用T-S点聚图法分析了该海域水团分布的基本情况,由点聚分析结果可知,该海域至少存在6种以上水团;再用模糊聚类软化法对水团作进一步划分,分别计算了该海域6至11类水团的F和△F值,结果表明,冬、夏季的△F值都以划分为8类时为最大,这与大洋水团的稳定性是一致的,因此,该海域冬、夏季水团以划分为8类最佳,它们分别是北太平洋热带表层水、北太平洋次表层水、北太平洋中层水、北太平洋副热带模态水、北太平洋深层水和赤道表层水,以及南太平洋次表层水和南太平洋中层水。     

An assessment of TropFlux and NCEP air-sea fluxes on ROMS simulations over the Bay of Bengal region

This study presents an assessment of the TropFlux and the National Centers for Environmental Prediction (NCEP) reanalysis air-sea fluxes in simulating the surface and subsurface oceanic parameters over the Bay of Bengal (BoB) region during 2002–2014 using the Regional Ocean Modelling System (ROMS). The assessment has been made by comparing the simulated fields with in-situ and satellite observations. The simulated surface and subsurface temperatures in the TropFlux forced experiment (TropFlux-E) show better agreement with the Research Moored Array for African-Asian-Australian Monsoon Analysis (RAMA) and Argo observations than the NCEP forced experiment (NCEP-E). The BoB domain averaged sea surface temperature (SST) simulated in the NCEP-E is consistently cooler than the satellite SST, with a root mean square error (RMSE) of 0.79 °C. Moreover, NCEP-E shows a limitation in simulating the observed seasonal cycle of the SST due to substantial underestimation of the pre-monsoon SST peak. These limitations are mostly due to the lower values of the NCEP net heat flux. The seasonal and interannual variations of SST in the TropFlux-E are better comparable to the observations with correlations and skills more than 0.80 and 0.90 respectively. However, SST is overestimated during summer monsoon periods mainly due to higher net heat flux. The superiority of TropFlux forcing over the NCEP reanalysis can also be seen when simulating the interannual variabilities of the magnitude and vertical extent of Wyrtki jets at two equatorial RAMA buoy locations. The jet is weaker in the NCEP-E relative to the TropFlux-E and observations. The simulated sea surface height anomalies (SSHA) from both the experiments are able to capture the regions of positive and negative SSHA with respect to satellite-derived altimeter data with better performance in the TropFlux-E. The speed of the westward propagating Rossby wave along 18°N in the TropFlux-E is found to be about 4.7 cm/s, which is close to the theoretical phase speed of Rossby waves.     

基于Argo浮标数据的星载微波辐射计Aquarius数据产品质量评估

Aquarius是专门用于海洋盐度监测的L波段辐射计,于2011年6月发射入轨,目前已进入业务化运行阶段。本文以太平洋为研究区域,利用Argo盐度现场数据对星载微波辐射计Aquarius的2012年2级数据产品质量进行了分析与讨论,结果表明:与Argo数据比较,Aquarius数据盐度存在0.1的负偏差,标准差约为0.7,升轨和降轨数据差异不明显;受亮温陆地污染和无线电射频干扰的影响,近岸海域反演误差较大;海面温度较高的低纬海域反演结果优于中纬度海域;受亮温敏感性及粗糙海面发射率模型的影响,Aquarius在低温水域以及高风速条件下盐度反演误差较大,标准差可达1以上。     

IMPROVEMENT OF OCEAN DATA ASSIMILATION SYSTEM AND CLIMATE PREDICTION BY ASSIMILATING ARGO DATA

The Argo(Array for Real-time Geostrophic Oceanography) data from 1998 to 2003 were used in the Beijing Climate Center-Global Ocean Data Assimilation System(BCC-GODAS). The results show that the utilization of Argo global ocean data in BCC-GODAS brings about remarkable improvements in assimilation effects. The assimilated sea surface temperature(SST) of BCC-GODAS can well represent the climatological states of observational data. Comparison experiments based on a global coupled atmosphere-ocean general circulation model(AOCGM) were conducted for exploring the roles of ocean data assimilation system with or without Argo data in improving the climate predictability of rainfall in boreal summer. Firstly, the global ocean data assimilation system BCC-GODAS was used to obtain ocean assimilation data under the conditions with or without Argo data. Then, the global coupled atmosphere-ocean general circulation model(AOCGM) was utilized to do hindcast experiments with the two sets of the assimilation data as initial oceanic fields. The simulated results demonstrate that the seasonal predictability of rainfall in boreal summer, particularly in China, increases greatly when initial oceanic conditions with Argo data are utilized. The distribution of summer rainfall in China hindcast by the AOGCM under the condition when Argo data are used is more in accordance with observation than that when no Agro data are used. The area of positive correlation between hindcast and observation enlarges and the hindcast skill of rainfall over China in summer improves significantly when Argo data are used.     

利用Argo浮标定位信息估算分析赤道太平洋中层流场状况

本文利用Argo浮标的定位信息,经过较为严格的质量控制与误差估算,得到2003～2005年赤道太平洋区域中层流场信息,并对其进行较为详细的诊断与分析,得到以下几个结论:(1)棉兰老涡、赤道逆流和南赤道流在中层流场中多数时间清晰可辨,北赤道流较弱,有时不易分辨。(2)棉兰老涡、赤道逆流和南赤道流都存在明显的季节变化。一般在2、3月间最弱,8、9月间最强。(3)棉兰老涡、赤道逆流和南赤道流存在较明显的年际变化。(4)赤道逆流通常表现为两支,分别位于东赤道太平洋和西赤道太平洋,东太平洋支主轴位置大约在7～8°N附近,西太平洋支主轴位置大约在3°N附近。     

Argo数据的网络可视化集成平台开发及其应用

为了方便广大用户实时获取和使用A rgo资料,研制开发了“A rgo网络数据库可视化平台”。该平台以数据库管理的形式,使用W eb-G IS技术,并采取可视化方式向用户提供查询和获取全球海洋中的A rgo资料。文中就该平台的设计、组成与功能和应用等作一系统介绍,以帮助广大A rgo资料用户熟悉和了解该平台,推动A rgo资料的应用研究进程。     

全球海洋中Argo剖面浮标运行状况分析

A rgo剖面浮标是A rgo全球海洋实时观测网建设中的主要观测设备。自2001年国际A rgo计划组织实施以来,世界上已经有22个国家和团体在全球海洋中陆续布放了3 000多个A rgo剖面浮标,它们的寿命和运行状况一直是人们重视和关心的问题,因为这关系到何时能够实现国际A rgo计划的最终目标,更重要的是,涉及到浮标的性能、资料的可靠性。文中就这些问题进行了探讨,希望能有助于关注者对A rgo全球海洋实时观测网的建设及运行情况有一比较全面的了解。     

巴西暖流和马尔维纳斯寒流交汇点的变动及其影响机制的探讨

西南大西洋的马尔维纳斯寒流(Malvinas Current,MC)和巴西暖流(Brazil Current,BC)交汇点(the Brazil-Malvinas Confluence,BMC)的南移是很多影响因子共同作用的结果。本文从海流流量的变化和风场的变化来分析交汇点变动的原因。利用1993年1月至2016年12月的月平均流场计算截面流量,分析得到MC流量呈现递减趋势,而BC流量则出现递增趋势。2014–2016年的Argo浮标的轨迹线表明MC的水体主要来自于南极绕极流(Antarctic Circumpolar Current,ACC)经过德雷克海峡的3个极锋中的其中之一—亚南极锋(the Subantarctic Front,SAF)。计算SAF的流量,得到其也表现出递减的趋势,这是MC流量减少的重要原因。而和SAF相邻位于其南边的极锋(the Polar Front,PF)的流量出现递增趋势。利用1993–2016年月平均风场数据分析得到南半球盛行西风风应力增加且有向南极偏移的趋势,这会使得ACC也有向南极收缩的趋势,这解释了SAF流量减少而PF的流量增加的原因,故得到南半球盛行西风的南移和BC流量的增加是BMC南移的原因。