Understanding uncertainties in the retrieval of polar mesospheric clouds from the cloud imaging and particle size experiment in the presence of a bright Rayleigh background

摘要

This paper presents a framework for understanding and quantifying the leverage available for inverting the radiance signal in order to retrieve particle size distribution mode radius and albedo from polar mesospheric clouds (PMC) observations using the cloud imaging and particle size (CIPS) instrument on board the aeronomy of ice in the mesosphere (AIM) satellite. The observed signal is a superposition of the scattering angle dependence of the cloud albedo and the Rayleigh scattered albedo controlled by ozone at the stratopause. The leverage as is defined in the paper is a way to quantify how much the net scattering angle dependence changes as a function of mode radius. The leverage is determined by decomposing the observed signal into orthogonal components which isolate the parts of the signal that are unique to changes in mode radius from those that could be due to changes in the background. This leverage is considered along with instrument noise performance to determine retrieval uncertainties and to understand minimum thresholds in the cloud retrieval parameters.