The Impact of Surface Scattering on Ocean Atmospheric Boundary Layer (ABL) Wind Profile Estimates from an Airborne Doppler Radar

Abstract

IWRAP, the Imaging Wind and Rain Airborne Profiler is a conically scanning dual-band (C and Ku), dual-polarized pencil-beam airborne Doppler radar that profiles the volume reflectivity and Doppler velocity from precipitation. It also measures the ocean backscatter response especially during tropical and extra tropical cyclones. IWRAP is designed to measure troposphere winds and surface winds. Of particular importance to the storm forecasting and research community are the winds in the lower part of the hurricane boundary layer near the sea surface (lower ABL). The covariance data processing technique IWRAP traditionally employed assumes a uni-modal and symmetric Doppler spectrum and therefore, it alone is unable to account properly for the influence of the surface scattering on wind profiles in the lower ABL region. In this paper we compare covariance-based approaches and full-spectral approaches utilized to derive the true wind speed for atmospheric vertical profiles. Techniques for removal of the surface contamination and example of wind profiles retrieved from Hurricane Rita are presented.