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首页> 外文会议>Geoscience and Remote Sensing Symposium, 1995. IGARSS '95. 'Quantitative Remote Sensing for Science and Applications', International >SIR-C/X-SAR observations of convergent fronts in the Central Equatorial Pacific
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SIR-C/X-SAR observations of convergent fronts in the Central Equatorial Pacific

机译：SIR-C / X-SAR赤道中太平洋收敛锋面的观测

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The surface front separating cold equatorial water from warmer tropical water at 2-7/spl deg/N in the Central Pacific was studied twice for one week in April and October 1994 between 115/spl deg/W and 155/spl deg/W with the SIR-C/X-SAR synthetic aperture radar, with supporting NOAA satellites infrared images. During the October flight (the peak of the equatorial upwelling season), zonal linear features of enhanced backscatter intensity were observed at all wavelengths, and corresponded closely to the thermal front seen in the infrared images. A striking example of such feature is seen in an X-band real time image. On some data takes, several linear features were found at different latitudes, suggesting that the front may not have been unique. The motion of the front estimated from successive daily images was consistent with the westward propagation found by previous studies. In contrast, no fronts were observed in the images taken during the April flight, which were dominated by the surface signature of rain cells. The front was also visible as brightness changes in AVHRR images of the Sun glint, and photographs of the glint taken from the Space Shuttle show the equatorial front as a quasi-linear feature, often darker than surrounding water. These observations are consistent with in situ data collected during the Tropical Instability Wave Experiment in 1992 and 1995. Fine-structure was observed, suggesting northward subduction of cold, high salinity equatorial water, beneath warmer less saline ITCZ water. A 40 km drifter array deployed on the cold side of the front became aligned with the front in less than 3 days. The velocity averaged over five frontal crossing showed a 10 km-wide westward jet of 90 cm/s and a cross-frontal convergence of 15 cm/s, both confined above the thermocline. During these cruises, whitecapping was frequently enhanced over a band /spl sim/100 m wide near the front.
机译：1994年4月和1994年10月，在中太平洋地区以2-7 / spl deg / W将赤道冷水与热带暖水分离开来的地表锋进行了为期一周的两次研究，温度为115 / spl deg / W至155 / spl deg / W， SIR-C / X-SAR合成孔径雷达，带有支持NOAA卫星的红外图像。在十月的飞行中（赤道上升季节的高峰），在所有波长下都观察到增强的反向散射强度的纬向线性特征，并且与红外图像中的热锋非常接近。在X波段实时图像中可以看到此类功能的显着示例。在某些数据上，在不同的纬度上发现了几个线性特征，这表明前缘可能不是唯一的。从连续的每日图像估计的锋面运动与先前研究发现的向西传播一致。相比之下，在四月份的飞行中所拍摄的图像中未观察到任何前沿，而这些前沿主要是雨单元的表面特征。当太阳闪烁的AVHRR图像的亮度发生变化时，正面也可见，从航天飞机拍摄的闪烁照片将赤道面显示为准线性特征，通常比周围的水更暗。这些观察结果与在1992年和1995年的热带不稳定波浪实验中收集的原位数据一致。观察到的精细结构表明，北半球俯冲的冷，高盐度赤道水位于盐温较低的ITCZ水之下。在不到3天的时间内，部署在前部寒冷侧的40 km漂移器阵列与前部对齐。在五个额线交叉处的平均速度显示出向西喷射的10 km宽为90 cm / s，跨额线会聚为15 cm / s，都限制在温跃层以上。在这些航行中，经常在靠近前部的一个频带/ spl sim / 100 m处增强白光覆盖。

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