| Resumo: |
The objective was to use the synoptic capability of NOAA-AVHRR images, and the physical variables inferred from them, in order to achieve spatial and temporal analysis that may allow correlating the satellite variables with oceanographic processes and biological or fishing data. Methodologies of image processing were developed to make possible the use of AVHRR information for the standardized and reliable generation of Sea Surface Temperature (SST) images (using bands 3 to 5 in the thermal infrared), and water reflectance images (using optic bands 1 and 2) as an index of surface turbidity in coastal zones. A methodology was also generated in order to obtain gradients images derived from SST images, which allows the identification of oceanographic fronts. Finally, different procedures were created in order to analyze the coherence and quality of a temporal series made up of 800 SST images for the period 1985-1995. The temporal 11 years series of SST data was utilized to describe the mean conditions of this variable in the SW Atlantic Ocean (SWAO), the thermal amplitude of the annual cycle, and the day of the year in which the maximal and minimal SST are expected to occur. These analysis complement and reinforce previous works carried out in the region. However, due to the improved spatial resolution when compared with available climatic maps, the satellite images of monthly and seasonal SST distributions could help to a better understanding of the annual pattern, significant for the interpretation of many biological events in this wide region. The temporal series also allowed the identification and characterization of several zones in the SWAO where oceanographic fronts take place, but considering in this case SST gradients images. The considerable extension of the area covered by each single image provided a synoptic perspective of the fronts impossible of getting by means of oceanographic campaigns. Turbidity images were utilized in the Rio de la Plata (Argentina-Uruguay) estuary for two purposes. A methodology involving an atmospheric correction of the AVHRR images was developed for correlating surface sediment concentrations and reflectance values. In addition, the significance of bottom salinity and surface turbidity fronts was analyzed in connection with the spatial distribution pattern of whitemouth croaker (Micropogonias furnieri) age-classes within the estuary. Satellite SST was associated with catches of mackerel (Scomber japonicus) in the coastal zone near Mar del Plata city (Buenos Aires prov., Argentina) (38 degree S), and with catches of long tail hake (Macruronus magellanicus) in the continental shelf break zone. The SST derived from AVHRR data showed to be useful in order to analyze the relationship between this variable and the catches, suggesting that methodologies involving the analysis of the sea surface temperature by means of AVHRR information could help in time saving and costs of sailing when fishing activities are considered.
Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales.
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