Units of similar optical properties have been defined for a large part of the surface of Mars using primarily Viking 2 approach maps of red (0.59 •m) and violet (0.45 •m) normal albedo. Of available global data sets, spectral albedo most closely relates to surface mineralogy. The resultant unit map represents Mars at the time the Viking images were acquired (L s = 103 ø-105 ø, morning, northern...

The formal expression of pro positional attitudes, especially when nested (iterated), is an important problem for A I . An interesting first-order extensional logical system for such expression has been proposed by Creary. In this system concepts (and concepts of concepts, etc.) are made explicit. The system includes "concept functions", which are special functions which act on and deliver conc...

Changes in agricultural practices are considered a possible option to mitigate climate change. In particular, reducing or suppressing tillage (no-till) may have the potential to sequester carbon in soils, which could help slow global warming. On the other hand, such practices also have a direct effect on regional climate by altering the physical properties of the land surface. These biogeophysi...

A method is presented for determining the single scattering albedo of clouds at selected wavelengths in the visible and near-infrared wavelength regions. The procedure compares measurements of the ratio of the zenith to nadir propagating intensities deep within a cloud layer with radiative transfer computations of the same. Analytic formulas are derived which explicitly show the dependence of t...

[1] This study analyzes diurnal and seasonal variations of snow albedo at four Baseline Surface Radiation Network stations in the Arctic and Antarctica from 2003 to 2008 to elucidate similarities and differences in snow albedo diurnal cycles across geographic zones and to assess how diurnal changes in snow albedo affect the surface energy budget. At the seasonal scale, the daily albedo for the ...

Soil surface temperature, an important driver of terrestrial biogeochemical processes, depends strongly on soil albedo, which can be significantly modified by factors such as plant cover. In sparsely vegetated lands, the soil surface can be colonized by photosynthetic microbes that build biocrust communities. Here we use concurrent physical, biochemical and microbiological analyses to show that...

We use the GEANT4 Monte Carlo framework to calculate the γ-ray albedo of the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our calculation of the albedo spectrum agrees with the EGRET data. We show that the spectrum of γ-rays from the Moon is very steep with an effective cutoff around 3–4 GeV (600 MeV for the inner part of the Moon disk) and exhibits a narrow pion-decay lin...