Variability in horizontal current velocities in the central and eastern equatorial Atlantic in 2002
Variability in horizontal current velocities in the central and eastern equatorial Atlantic in 2002
复制标题
2002年赤道大西洋中东部水平流速变化
DOI：
--
复制
发表时间：
2007
期刊：
影响因子：
--
通讯作者：
A. Kartavtseff
中科院分区：
文献类型：
--
作者：
L. Bunge;C. Provost;A. Kartavtseff
[1]对2002年热带大西洋23°W的Pilot Research系泊阵列的近地表流速数据进行了重新检查，并与同期未公布的10°W的近地表流速数据进行了比较。在23°W的纬向速度分量和温度记录中观察到了强烈的7天周期波动，温跃层深度附近的温度波动很大，表明在相同的7天周期内存在垂直速度分量。7天周期信号出现在6/7月，与季节性上升流同时出现。经向速度分量在23°W和10°W处具有相似的谱含量，在两个位置都观察到两个明显的准周期信号：第一个信号出现在春季，周期约为14天，次表层增强，具有Rossby-重力混合波的特征。第二次信号在一年中发生了3次(一次在2001-2002年冬季，一次在夏季，另一次在2002年秋季)，周期约为20d，在靠近地面的地方最强，是热带不稳定波(TIW)通过的结果。卫星海表温度(SST)资料与经向速度记录具有相同的周期性，并呈现出与TIW-SST特征相一致的空间结构。2002年夏季不同地区的TIW-SST模式不同，表明存在不同类型的TIW。总体而言，2002年海流计数据的变化主要是由于海流不稳定造成的，除了北方春季附近，那里的地面风的季节内变化最强。
[1] Near-surface current velocity data from the Pilot Research Moored Array in the Tropical Atlantic at 23°W in the year 2002 were re-examined and compared to simultaneous unpublished velocity data at 10°W, near the surface. Strong 7-day-period fluctuations were observed in the zonal velocity component and in temperature records at 23°W. The large temperature fluctuations near the thermocline depth suggest a vertical velocity component at the same 7-day period. The 7-day-period signals occurred in June/July simultaneously with the seasonal upwelling. The meridional velocity component presented similar spectral contents at 23°W and at 10°W. Two distinguishable quasiperiodic signals were observed in the meridional component at both locations: The first signal occurred in the spring, had a periodicity of about 14 days, was subsurface intensified, and had the characteristics of a mixed Rossby-gravity wave. The second signal occurred three times in the year (once in winter 2001–2002, another in summer, and another during fall 2002), had a periodicity of about 20 days, was strongest close to the surface, and was the result of the passage of tropical instability waves (TIWs). Satellite sea surface temperature (SST) data show the same periodicities as the meridional velocity records, and present a spatial structure in accordance with the TIW-SST signature. The summer of 2002 showed different TIW-SST patterns depending upon location, suggesting the existence of different types of TIWs. Overall, variability in the current meter data for the year 2002 was mainly due to current instabilities, except around boreal spring, where intraseasonal variability in surface winds was strongest.