Preliminary Study of Oceanic Eddies Detected by Tiangong-2 Interferometric Imaging Radar Altimeter

摘要

Oceanic eddy, which plays an important role in ocean thermal cycling, is a significant branch of oceanic scientific research. Mesoscale eddies can be observed by multiple sensors. However, sub-mesoscale or small scale eddies cannot be detected by conventional radar altimeters. The Interferometric Imaging Radar Altimeter (InIRA) on Tiangong-2 provides a large amount of images for the observation and investigation of sub-mesoscale or small scale eddies. 100 InIRA images obtained during 2016-2018 are used to investigate possible mechanisms of the appearance of eddies in InIRA images. Result shows that under a moderate wind speed of 3-5 m/s, film mechanism is the main form of oceanic eddies and under a considerable near-water wind speed of 5-12 m/s, and the wave/current interaction mechanism comes into action. The interferometric data of InIRA are processed to detect eddies after a series of procedures. It is shown that the phase change is corresponding to ocean surface height anomaly induced by eddy. Moderate Resolution Imaging Spectrora-diometer (MODIS) sea surface temperature (SST) and chlorophyll-a (CHL) data are used to verify eddies identified from InIRA images. Result shows that the center of eddy with lowest SST corresponds to the highest CHL concentration.