Mapping sea surface temperature from aircraft using a multi-angle technique: an experiment over the Orbetello lagoon
Abstract:Airborne scanner data collected in the thermal band over the Orbetello lagoon on 14 May 1993 were used to draw out a water surface temperature map. The geometric correction method was chosen after a quantitative comparison between the classic polynomial method and a technique based on matching Delaunay triangles. Sensor raw data were calibrated and striping noise was removed. Finally, a new atmospheric correction method was developed. The method consists of extracting, from the superimposed portion of two images, couples of measurements relative to the same resolution cell observed under two different angles. From these measurements we retrieved the atmospheric transmittance and integrated emitted radiance using an iterative algorithm capable of reducing the effects of measurement errors and taking into account the nonlinearity of the derived equations. The variation of surface emissivity with observation angle is also taken into account in the equations. In order to apply the method, the unknown covariance matrix of the parameters to be retrieved was valued. To this aim, we generated many statistical realizations of such atmospheric radiative quantities using the Lowtran 7 code applied to a large number of radiosoundings. The obtained atmospheric parameters were then used to correct the entire set of collected images and to produce a temperature map of the lagoon.
Document Type: Research Article
Publication date: 2000-11-10