Thermal and albedo mapping of the north and south polar regions of Mars

The first maps of the thermal properties of the north and south polar region of Mars are presented. The maps complete the mapping of the entire planet. The maps for the north polar region were derived from Viking Infrared Thermal Mapper (IRTM) observations obtained from 10 Jun. to 30 Sep. 1978. This period corresponds to the early summer season in the north, when the north residual water ice cap was exposed, and the polar surface temperatures were near their maximum. The maps in the south were derived from observations obtained between 24 Aug. to 23 Sep. 1977. This period corresponds to the late summer season in the south, when the seasonal polar cap had retreated to close to its residual configuration, and the second global dust storm of 1977 had largely subsided. The major results concerning the following topics are summarized: (1) surface water ice; (2) polar dune material; and (3) dust deposits

Modeling interannual variability in the Martian seasonal CO2 cycle

One aspect of the seasonal pressure variations measured at the Viking Lander sites is their nearly perfect interannual repeatability. This presents a problem because it implies that the behavior of the seasonal polar caps should be highly repeatable from year to year as well. There are a number of observations and theories suggesting that the presence of dust and water ice clouds in the Martian atmosphere should have significant direct and indirect effects on the rates of CO2 condensation and sublimation in the north and south polar regions. These effects include (1) reduced rates of CO2 frost condensation during polar night seasons due to the radiative effects of dust and water ice clouds and associated CO2 clouds or elevated atmospheric temperatures and (2) reduced or elevated rates of frost sublimation due to the radiative effects of atmospheric dust or to changes in frost emissivities and albedos due to contamination by water ice and dust. The Viking Landing pressure observations are examined to determine the range and character of the interannual variations present. Then a diurnal and seasonal thermal model is used to examine the effects of interannual variations in the polar heat balance on seasonal pressure variations

Drill/borescope System for the Mars Polar Pathfinder

The primary goals of the Mars Polar Pathfinder (MPP) Discovery Mission are to characterize the composition and structure of Mars' north polar ice cap, and to determine whether a climate record may be preserved in layers of ice and dust. The MPP would land as close as possible to the geographic north pole of Mars and use a set of instruments similar to those used by glaciologists to study polar ice caps on Earth: a radar sounder, a drill/borescope system, and a thermal probe. The drill/borescope system will drill approximately 50 cm into the surface and image the sides of the hole at 10 micron resolution for compositional and stratigraphic analysis. Several uncertainties have guided the development of this instrument, and they are discussed

The influence of thermal inertia on Mars' seasonal pressure variation and the effect of the weather component

Using a Leighton-Murray type diurnal and seasonal Mars thermal model, we found that it is possible to reproduce the seasonal variation in daily-averaged pressures (approximately 680-890 Pa) measured by Viking Lander 1 (VL1), during years without global dust storms, with a standard deviation of less than 5 Pa. In this simple model, surface CO2, frost condensation, and sublimation rates at each latitude are determined by the net effects of radiation, latent heat, and heat conduction in subsurface soil layers. An inherent assumption of our model is that the seasonal pressure variation is due entirely to the exchange of mass between the atmosphere and polar caps. However, the results of recent Mars GCM modeling have made it clear that there is a significant dynamical contribution to the seasonal pressure variation. This 'weather' component is primarily due to large-scale changes in atmospheric circulation, and its magnitude depends somewhat on the dust content of the atmosphere. The overall form of the theoretical weather component at the location of VL1, as calculated by the AMES GCM, remains the same over the typical range of Mars dust opacities

A Pluto thermal model

The recent discovery of nitrogen on Pluto suggests that Pluto's volatile cycles may be similar to those on Neptune's moon Triton. Here, we report the first results of our efforts to apply a thermal model that we developed to study the seasonal nitrogen cycle on Triton to the case of Pluto. The model predicts volatile behavior as a function of time to calculate frost deposit depth, polar cap boundaries, temperature of the frost and substrate, and atmospheric pressure, assuming nitrogen frost deposits in solid-vapor equilibrium with nitrogen in the atmosphere

Coupling the Biophysical and Social Dimensions of Wildfire Risk to Improve Wildfire Mitigation Planning

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113114/1/risa12373.pd

Quantifying Timing Leaks and Cost Optimisation

We develop a new notion of security against timing attacks where the attacker is able to simultaneously observe the execution time of a program and the probability of the values of low variables. We then show how to measure the security of a program with respect to this notion via a computable estimate of the timing leakage and use this estimate for cost optimisation.Comment: 16 pages, 2 figures, 4 tables. A shorter version is included in the proceedings of ICICS'08 - 10th International Conference on Information and Communications Security, 20-22 October, 2008 Birmingham, U

IRTM brightness temperature maps of the Martian south polar region during the polar night: The cold spots don't move

A series of infrared thermal mapper (IRTM) south polar brightness temperature maps obtained by Viking Orbiter 2 during a 35-day period during the southern fall season in 1978 was examined. The maps show a number of phenomena that have been identified in previous studies, including day to day brightness temperature variations in individual low temperature regions and the tendency for IRTM 11-micron channel brightness temperatures to also decrease in regions where low 20-micron channel brightness temperatures are observed. The maps also show new phenomena, the most striking of which is a clear tendency for the low brightness temperature regions to occur at fixed geographic regions. During this season, the coldest low brightness temperatures appear to be concentrated in distinct regions, with spatial scales ranging from 50 to 300 km. There are approximately a dozen of these concentrations, with the largest centered near the location of the south residual polar cap. Other concentrations are located at Cavi Angusti and close to the craters Main, South, Lau, and Dana. Broader, less intense regions appear to be well correlated with the boundaries of the south polar layered deposits and the Mountains of Mitchell. No evidence for horizontal motion of any of these regions has been detected

Precision SUSY Measurements at LHC

If supersymmetry exists at the electroweak scale, then it should be discovered at the LHC. Determining masses, of supersymmetric particles however, is more difficult. In this paper, methods are discussed to determine combinations of masses and of branching ratios precisely from experimentally observable distributions. In many cases such measurements alone can greatly constrain the particular supersymmetric model and determine its parameters with an accuracy of a few percent. Most of the results shown correspond to one year of running at LHC at ``low luminosity'.Comment: 52 pages, Latex with 42 postscript figures. Postscript version also at http://www-physics.lbl.gov/www/theorygroup/papers/39412.p

Habitat assessment and ecological restoration design for an unnamed tributary of Stone Dam Creek, Conway, Arkansas

Urbanization can lead to increased sedimentation, erosion, pollution, and runoff into streams. The United States Environmental Protection Agency’s (USEPA) Rapid Bioassessment Protocols (RBPs) are sets of guidelines that can be used to assess a habitat’s sedimentology, hydrology, vegetation, and geomorphology to determine impairment. An unnamed tributary of Stone Dam Creek on the University of Central Arkansas (UCA) campus in Conway, Arkansas runs partially underground and through the urbanized UCA campus watershed. The stream was assessed using the USEPA’s RBPs to determine impairment of the stream, and received a RBP score of 71.2 out of 200 compared to 153.5 in a reference stream. An ecological restoration design was then prepared for a 2-year, 1-hour rainfall event to address areas of impairment. The goal was to increase the RBP score by increasing cross-sectional area of the stream as well as by improving stream morphology where possible. With the proposed design, modeled stream velocity was reduced throughout the stream by an average of 19.6%. It was assessed that as a result of the reduction in velocity and changes to morphology, RPB scores would increase throughout the stream reach