The variability of sea surface temperature in the Patagonian Shelf Argentina, from 35 years of satellite information

ALLEGA, LUCRECIA; PISONI, JUAN PABLO; COZZOLINO, EZEQUIEL; MAENZA, REINALDO AGUSTÍN; PICCOLO, MARÍA CINTIA

INTERNATIONAL JOURNAL OF REMOTE SENSING

TAYLOR & FRANCIS LTD

Año: 2021 vol. 42 p. 6092 - 6108

0143-1161

The aim of the present work is to analyse the variations of Sea SurfaceTemperature (SST) and Anomaly of Sea Surface Temperature (ASST)using more than thirty years of satellite data. We studied if thesevariations have possible ocean-atmosphere connections with theSouthern Annular Mode (SAM), the Southern Oscillation Index (SOI),and the Oceanic Niño Index (ONI) in a crucial region for fisheries off thePatagonian Shelf. For the analysis, we used SST data collected from1985 to 2019 with Advanced Very High Resolution Radiometer(AVHRR) and Moderate Resolution Imaging Spectroradiometer(MODIS) instruments. The two databases were merged to obtain35 years of continuous SST data. The study area was divided intothree zones to present different oceanographic and bathymetric characteristics.These zones are located in the gulf, in the middle of thecontinental shelf, and at the shelf break. For each of the zones, themonthly SST climatology and the ASST series are shown. To definetheir periodicity, monthly ASST data were analysed spectrally by FastFourier Transform (FFT) and Wavelet Transform. Cross-WaveletTransform (XWT) was applied to analyse the co-variance of ASST withrespect to climate indices. Our results show that the isotherm distributionseems to be separated by the 64º W meridian. To the east of 64ºW, it follows an oblique direction from southwest to northeast; to thewest of 64º W, a more complex behaviour of the SST field seems to beassociated with the coastal dynamics. The ASST series shows that thevalues of negative anomalies are higher than those of the positiveones. Nevertheless, positive ASSTs are more extreme and persistent intime than the negative ones. The ASST wavelet diagrams denotea common and non-stationary periodicity in the three zones, withstatistically significant power spectra in the intra-seasonal (9-month)and inter-annual (24-month and 4-year) time scales. There are clearlycommon features in the wavelet power of the time series related toASST and climate forcing. The SAM exhibited the closest relationshipwith ASST in the three zones. The SAM and ASST indices denotesignificant power peaks in the 2-year and 4- to 6-year bands.