Determination of marine wind fields in the Campos basin from ENVISAT/ASAR images / Extração do campo de vento na Bacia de Campos, RJ, a partir de imagens ENVISAT/ASAR

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The knowledge of ocean surface winds is very important for oceanographic and meteorological studies as well as for practical applications. Considering the great difficulty of installation, operation and maintenance of instrumentation for the in situ measurement of marine winds, it is of high interest the development of methodologies for obtaining this variable by remote sensors. Although the wind field can be derived by the scatterometers, the spatial resolution of such data (25 km) is not adequate for applications over the coastal ocean. High-resolution wind data (500 1500 m) can be extracted from SAR images. This is possible because radar backscatter signal, after calibration into sigma-naught values, can be related to wind speed. In this context, the objective of this study was to determine the potential of the ASAR sensor, flying onboard the ENVISAT satellite, to extract high spatial resolution (~1 km) wind field (10 m above the sea surface). Wind speeds fields were determined using C-Band geophysical models and the wind direction data from the atmospheric model BRAMS and QuikSCAT scatterometer. Three geophysical models were used: CMOD4, CMOD5 and CMOD-IFR2. The final accuracy of this procedure was evaluated by comparing the ASAR winds speeds with wind speeds measurements from the QuickSCAT scatterometer and the BRAMS data. The results here presented show wind speeds with a mean correlation coefficient against QuikSCAT data of 0,75 and a RMS= 2 m/s when QuikSCAT wind directions were used as input to the model. The use of BRAMS wind directions yielded a mean RMS of 2,23 m/s and r=0,37 against BRAMS wind speed data. More accurate results were found with CMOD4 and CMOD-IFR2 models.

ASSUNTO(S)

wind direction quikscat wind velocity radar de abertura sintética velocidade do vento direção do vento retroespalhamento radar sensoriamento remoto backscatter remote sensing synthetic aperture radar quikscat

ACESSO AO ARTIGO

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