An information theory approach for evaluating Earth radiation budget (ERB) measurements: nonuniform sampling of diurnal longwave flux variations

Satellite measurements are subject to a wide range of uncertainties due to their temporal, spatial, and directional sampling characteristics. An information theory approach is suggested to examine the nonuniform temporal sampling of Earth radiation budget (ERB) measurements. The information (i.e. the entropy or uncertainty) before and after the measurements is determined, and the information gain is defined as a reduction in the uncertainties involved. A stochastic model for the diurnal outgoing flux variations that affect the ERB is developed. Using Gaussian distributions for the a priori and measured radiant exitance fields, the information gain is obtained by computing the a posteriori covariance. The information gain for the monthly outgoing flux measurements is examined for different orbital parameters and orbital tracks