Application of multi-window maximum cross-correlation to the mediterranean sea circulation by using MODIS data

Abstract

In a previous study an improved Maximum Cross-Correlation technique, called Multi-Window MaximumCross-Correlation (MW-MCC), was proposed, and applied to noise-free synthetic images in order to show its potentialand limits in oceanographic applications. In this work, instead, the application of MW-MCC to high resolution MODISimages, and its capability to provide useful and realistic results for ocean currents, is studied.When applied to real satellite images, the MW-MCC is subject to cloud cover and image quality problems. As a consequence the number of useful MODIS images is greatly reduced. However, for every MODIS image, multiple spectral bands are available, and it is possible to apply the MW-MCC algorithm to the same scene as many times as thenumber of these bands, increasing the possibility of finding valid current vectors.Moreover, the comparison among the results from different spectral bands allows to verify both the consistency ofthe computed current vectors and the validity of using a spectral band as a good tracer for the ocean circulation.Due to the lack of systematic current measurements in the area considered, it has been not possible to perform an extensive error analysis of the MW-MCC results, although a case study of a comparison between HF radar measurementsand MW-MCC data is shown. Moreover, some comparison between numerical ocean model simulations and MW-MCCresults are also shown. The coherence of the resulting circulation flow, the high number of current vectors found, theagreement among different spectral bands, and conformity with the currents measured by the HF radars or simulated byhydrodynamic models show the validity of the technique.