Validação de dados de altímetro com base em dados de marégrafos na costa de Moçambique

Abstract

Satellite altimetry has revolutionized human understanding of ocean dynamics thanks to frequent sampling and global coverage. Even so it was difficult in the past, recovering useful data of altimetric satellites close to the coast, due to ground contamination from the form of return waves, and so the UK Oceanographic Center (NOC) developed the retroconverter algorithm of ALES altimeter for coastal regions, in order to reprocess altimeter data from past missions to provide a continuous time series of sea level. The total water level and the sea ​​surface height estimated by ALES is validated for the Jason-1 and Jason-2 missions for the years 2002 to 2016, the validation of ALES data is performed by comparison with data from tide gauges from each sea level measurement station selected for the present study through a specific software in the Python environment, which is potentially dedicated to this type of comparison. The results indicate that there is good agreement between the two observations (satellite altimetry and tide gauge) although the stations of Inhambane and Beira do not show, as it is due to insufficiency of data since probably, to have good estimates of the sea level it is necessary to have data from at least 2 years of measurement. At Maputo station the correlation coefficient is lower with 0.29, however the similarity between the observations is greater, however it is possible to notice the agreement between the altimeter and tide gauge observations at Pemba station with a maximum correlation of 0.71, which demonstrates reliability of coastal satellite data reprocessed by the NOC for level analysis of the sea in Mozambique.