Long baroclinic Rossby waves detected by TOPEX/POSEIDON
Long baroclinic Rossby waves detected by TOPEX/POSEIDON
复制标题
TOPEX/POSEIDON 检测到的长斜斜罗斯贝波
DOI：
--
复制
发表时间：
1997
期刊：
影响因子：
--
通讯作者：
P. Cornillon
中科院分区：
文献类型：
--
作者：
P. Polito;P. Cornillon
利用TOPEX/POSEIDON卫星高度计资料，得到了北大西洋海盆海面高度的剩余距平场。第一模态斜压Rossby波特征的向西向传播异常的证据。在5°×5°网格上，通过分析三维剩余高程异常的自相关矩阵，得到了相速度。周期是通过最小二乘拟合正弦函数的时间序列在每个网格点计算。纬向和纬向波长从相速度和周期获得，并且作为一致性检查对数据进行最小二乘拟合。纬向平均向西相速度在1至27 km/d之间变化，在50°至5°N之间，向南增加。相速度指向西南偏北约25°N和西北偏南该纬度。海平面高度信号分为两个谱带，第一个谱带的周期在280和450天之间，第二个谱带的周期在120和280天之间。对于第一个波段，整个流域的平均周期为370天。在第二个波段中，整个流域也明显存在6至7个月的周期信号。与第一波段有关的纬向平均波长在50°和5°N之间的400-4600 km范围内，与第二波段有关的纬向平均波长在45°和5°N之间的270-2500 km范围内。更长的波长被发现靠近南部边界。在盆地的北方部分发现了较短的波长。与数值模式结果的比较表明，在中纬度观测到的斜压波是由风应力旋度的波动在东边界产生的。在20°N以南观测到的波浪支持直接风强迫的假设。
Residual sea surface height anomaly fields are obtained over the North Atlantic Basin from TOPEX/POSEIDON altimeter data. Evidence of westward propagating anomalies characterized as first-mode baroclinic Rossby waves is presented. The phase speeds are obtained from the analysis of the autocorrelation matrices of the residual surface height anomaly in three dimensions, on a 5°×5° grid. Periods are calculated by least squares fitting a sinusoidal function to the time series at each grid point. Zonal and meridional wavelengths are obtained from the phase speed and period and are least squares fit to the data as a consistency check. Zonally averaged westward phase speeds vary between 1 and 27 km/d, between 50° and 5°N, increasing southward. Phase speeds are directed to the southwest north of approximately 25°N and to the northwest south of this latitude. The sea surface height signal is divided into two spectral bands, the first with periods between 280 and 450 days and the second with periods between 120 and 280 days. For the first band the average of the periods taken over the whole basin is 370 days. In the second band a signal of period between 6 and 7 months is evident also throughout the basin. The zonally averaged zonal wavelengths associated with the first band are in the range of 400–4600 km between 50° and 5°N and for the second band are in the range 270–2500 km between 45° and 5°N. Longer wavelengths are found close to the southern boundaries. Shorter wavelengths are found in the northern portion of the basin. Comparison with results from numerical models suggests that the baroclinic waves observed at midlatitudes are generated at the eastern boundary by fluctuations of the wind stress curl. Waves observed south of 20°N support the hypothesis of direct wind forcing.