Sea Ice Brightness Temperature as a Function of Ice Thickness: Computed curves for AMSR-E and SMOS (frequencies from 1.4 to 89 GHz)

TL;DR

This study models the relationship between sea ice thickness and microwave brightness temperature across various frequencies, highlighting the importance of scattering and complex permittivities, with implications for remote sensing of sea ice.

Contribution

It introduces a radiative transfer model incorporating variable scattering and permittivities to predict brightness temperature as a function of ice thickness.

Findings

Scattering significantly influences brightness temperature, especially in new ice.

Brightness temperature varies with weather conditions, requiring probabilistic modeling.

The model provides a range of brightness temperatures for different ice thicknesses.

Abstract

The relationship between sea ice thickness and microwave brightness temperature is explored. Parameterized ice profiles are fed to a radiative-transfer-based sea ice emissivity model (Microwave Emmission of Layered Snowpack, MEMLS). Complex permittivities, required as input for the simulation, are determined using a semi-empirical mixture model. Since the thickness-radiance relation is not fixed but can vary significantly depending upon past and current weather conditions, we determine a range of brightness temperature values for each thickness. This is done using a bootstrap model in which the salinities are varied based on variances supplied with the thickness-salinity curve and the complex permittivities are varied based on variance supplied by the mixture model. The results suggest that scattering is one of the most important parameters determining sea ice brightness temperature, especially for new and forming ice. Further work must be done to accurately model both scattering and complex permittivities in sea ice.