Abstract Conventional nadir looking altimeters make along track measurements on a line and mapped sea level anomaly (SLA) information is obtained using a combination of several such altimeters (Jason, SARAL, Cryosat etc.). Mapping techniques, in general, introduce a lot of uncertainties in sea level representation and sub-mesoscale variability. Surface Water and Ocean Topography (SWOT) mission, based on radar interferometry, will measure SLA along wide swath thus providing detailed ocean information. This study aims to evaluate the advantages of SWOT measurements over nadir looking altimeters by making use of SWOT-simulator tool in the Bay of Bengal (BoB) region. Although, BoB is a small basin but interestingly it is full of mesoscale and sub-mesoscale features. The study performs several sensitivity experiments to allow a comparison of gridded SLA product from SWOT with the product from a constellation of nadir altimeters. Space-time scales for mapping the SLA from SWOT were obtained by performing a series of sensitivity experiments involving different spatial resolutions and temporal sampling. Sensitivity to different type of errors on the quality of mapped SLA fields from nadir-altimeters and SWOT is also carried out. In case of SWOT, mapped SLA fields generated using correlated noise were better as compared to the maps that were generated by making an assumption that the noise is uncorrelated. It is found that gridded SLA from SWOT have less error in the eddy dominant (high variability) regions as compared to the mapped SLA field from nadir altimeters, which perform better in the regions of low SLA variability. Apart from this, the position and strength of mesoscale eddies is well resolved by SWOT-mapped SLA fields as compared to nadir-altimeter mapped fields.

中文翻译：

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最低点高度测量 Vis-à-Vis 条带高度测量：孟加拉湾 SWOT 任务背景下的一项研究

摘要 传统的天底高度计沿线进行轨道测量，并使用多个此类高度计（Jason、SARAL、Cryosat 等）的组合获得映射的海平面异常 (SLA) 信息。一般来说，制图技术在海平面表示和亚中尺度变化方面引入了很多不确定性。基于雷达干涉测量法的地表水和海洋地形 (SWOT) 任务将沿宽幅测量 SLA，从而提供详细的海洋信息。本研究旨在通过使用孟加拉湾 (BoB) 地区的 SWOT 模拟器工具来评估 SWOT 测量相对于最低点高度计的优势。虽然 BoB 是一个小盆地，但有趣的是它充满了中尺度和亚中尺度特征。该研究进行了多项灵敏度实验，以比较来自 SWOT 的网格 SLA 产品与来自一组最低点高度表的产品。用于从 SWOT 映射 SLA 的时空尺度是通过执行一系列涉及不同空间分辨率和时间采样的灵敏度实验获得的。还进行了对来自天底高度计和 SWOT 的映射 SLA 字段质量的不同类型错误的敏感性。在 SWOT 的情况下，与通过假设噪声不相关而生成的地图相比，使用相关噪声生成的映射 SLA 字段更好。发现与来自最低点高度计的映射 SLA 场相比，来自 SWOT 的网格 SLA 在涡流主导（高可变性）区域具有较小的误差，在低 SLA 可变性的区域中表现更好。除此之外，与最低点高度计映射场相比，SWOT 映射的 SLA 场可以很好地解决中尺度涡流的位置和强度。