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 Maximum
Cross-Correlation (MW-MCC), was proposed, and applied to noise-free synthetic images in order to show its potential
and limits in oceanographic applications. In this work, instead, the application of MW-MCC to high resolution MODIS
images, 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 the
number 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 of
the 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 measurements
and MW-MCC data is shown. Moreover, some comparison between numerical ocean model simulations and MW-MCC
results are also shown. The coherence of the resulting circulation flow, the high number of current vectors found, the
agreement among different spectral bands, and conformity with the currents measured by the HF radars or simulated by
hydrodynamic models show the validity of the technique.