Laboratory for
Climatology and Remote Sensing

Abstract:

We propose simple analytical equations for the modeling of clean and dusty flat glacier ice surfaces, which can be used to inversely derive the parameters of microstructure of flat bare glacier ice and snow using both ground – based and spaceborne observations of the hyperspectral solar reflectance. The retrievals are based on the asymptotic radiative transfer equations valid for the case of weak light absorption in the semi-infinite turbid medium. The light reflection at the air - ice and ice - air interfaces is fully accounted for. To demonstrate the validity of the approach, the derived equations are exemplarily applied to both ground – based and EnMAP satellite measurements over the Hardangerjøkulen glacier (Norway). A number of important parameters controlling spectral signatures of the snow and glacier ice surfaces have been derived. The ground-based measurements confirm that the theoretical formulation presented in this work can be used to represent the solar light spectral reflectivity of glaciers. The application to satellite hyperspectral imagery shows that this novel technique allows for the determination of the glacier ice albedo (spectral, broadband) based on spaceborne glacier ice reflectance measurement. Additionally, the results demonstrate that not spectrally neutral soot but rather deposited atmospheric dust which enhances the absorption towards UV is responsible for the light absorption by snow for the case studied. Spatial distribution maps of ice grain diameter and dust concentration are derived over the glacier. These findings show that the analytical theory presented in this work can support further research on the characterization and monitoring of glaciers based on current and upcoming hyperspectral remote sensing satellite missions.

Abstract:

In Analytical Methods in Radiative Transfer, a team of distinguished researchers delivers a comprehensive exploration of solutions to practical problems of modern atmospheric optics related to solar light interaction with the terrestrial atmosphere and the remote sensing of clouds, aerosols, and gases. The authors describe analytic methods in radiative transfer that help explain atmospheric phenomena. The book includes discussions on the interaction of solar light with the atmosphere. Readers will also benefit from thorough reviews of various analytical radiative transfer techniques, for various turbid media, including media with phase functions extended in the forward direction, and also semi-infinite, non-absorbing, weakly absorbing, and strongly absorbing light scattering media. Analytical Methods in Radiative Transfer also includes: A thorough introduction to exact solutions of the radiative transfer equation, including situations of single scattering, as well as isotropic and Rayleigh scattering A comprehensive exploration of approximate solutions for scalar radiative transfer, including single and multiple light scattering separation and the case of semi-infinite media such as snow In-depth examinations of the applications of analytical methods in atmospheric radiative transfer, including aerosol remote sensing, cloud remote sensing, and the remote sensing of trace gases Perfect for meteorologists, climatologists and graduate students studying physics, Analytical Methods in Radiative Transfer is also an indispensable resource for geophysicists seeking a practical exploration of modern atmospheric optics.