Comments on: Retrieval of aerosol properties over the ocean using multispectral and multiangle photopolarimetric measurements from the research scanning polarimeter

Abstract

A recent paper [Chowdhary et al., 2001] (hereafter CCM&T) presents an aerosol retrieval case study using airborne RSP (Research Scanning Polarimeter) data over dark water to demonstrate the contribution polarization measurements can make to passive aerosol remote sensing. The paper also suggests that instruments such as MODIS (Moderate Resolution Imaging Spectroradiometer) [Barnes et al., 1998], MISR (Multi-angle Imaging SpectroRadiometer) [Diner et al., 1998], and POLDER (Polarization and Directionality of Earth Reflectances) [Deschamps et al., 1994], provide only a subset of the retrieval capabilities that would be available from EOSP (Earth Observing Scanning Polarimeter) [Travis, 1993], a satellite version of RSP. In this response, we argue that EOSP is not a replacement but a valuable complement to other measurement approaches. We also contend that MISR is significantly more capable than CCM&T imply. very tight constraints on this parameter Kahn et al. [2001]. The other metrics, which include spectral and angular ratios, provide additional sensitivity to particle microphysical properties because their accuracy over dark targets such as clear ocean (• 2%) is much better than the absolute radiometric accuracy (• 6%). Simulations show that MISR is sensitive to the difference between mono-modal and bimodal