The effects of aerosol scattering on remote pressure measurement via oxygen A-band absorption

Abstract

The technique recently proposed by Barton and Scott to monitor surface pressure using absorption of reflected sunlight in the oxygen A-band is subject to errors due to aerosol scattering. Errors arising from specified uncertainties in the aerosol optical depth are evaluated. It is shown that, for a sea surface over which the optical depth is 0.1 ± 20 per cent, measurements accurate to better than a few millibars can be obtained only by observing towards the maximum of the sunglint region. The method is not feasible under hazy conditions where the optical depth is 0.3 + 20 per cent. Zones of feasibility are presented for typical surface conditions and aerosol parameters. This shows that the region within which an accuracy of 2 mbar is obtained is so small as to render the technique operationally unviable, even if monitoring of the aerosol optical depth to ±0.02 was available. Measurements over land would be feasible where surface albedo is above ∼ 10 per cent provided that the aerosol optical depth uncertainty is below ±0.02. However, obtaining this accuracy over land may be problematic.