Search results for "Gram"
showing 10 items of 9069 documents
Evidence for montmorillonite or its compositional equivalent in Columbia Hills, Mars
2007
During its exploration of the Columbia Hills, the Mars Exploration Rover ‘‘Spirit’’ encountered several similar samples that are distinctly different from Martian meteorites and known Gusev crater soils, rocks, and sediments. Occurring in a variety of contexts and locations, these ‘‘Independence class’’ samples are rough-textured, iron-poor (equivalent FeO 4 wt%), have high Al/Si ratios, and often contain unexpectedly high concentrations of one or more minor or trace elements (including Cr, Ni, Cu, Sr, and Y). Apart from accessory minerals, the major component common to these samples has a compositional profile of major and minor elements whic…
Obtaining the three-dimensional structure of tree orchards from remote 2D terrestrial LIDAR scanning
2009
In recent years, LIDAR (light detection and ranging) sensors have been widely used to measure environmental parameters such as the structural characteristics of trees, crops and forests. Knowledge of the structural characteristics of plants has a high scientific value due to their influence in many biophysical processes including, photosynthesis, growth, CO2-sequestration and evapotranspiration, playing a key role in the exchange of matter and energy between plants and the atmosphere, and affecting terrestrial, above-ground, carbon storage. In this work, we report the use of a 2D LIDAR scanner in agriculture to obtain three-dimensional (3D) structural characteristics of plants. LIDAR allows…
SAL—A Novel Quality Measure for the Verification of Quantitative Precipitation Forecasts
2008
Abstract A novel object-based quality measure, which contains three distinct components that consider aspects of the structure (S), amplitude (A), and location (L) of the precipitation field in a prespecified domain (e.g., a river catchment) is introduced for the verification of quantitative precipitation forecasts (QPF). This quality measure is referred to as SAL. The amplitude component A measures the relative deviation of the domain-averaged QPF from observations. Positive values of A indicate an overestimation of total precipitation; negative values indicate an underestimation. For the components S and L, coherent precipitation objects are separately identified in the forecast and obser…
A laboratory study on the uptake of HCl, HNO3, and SO2 gas by ice crystals and the effect of these gases on the evaporation rate of the crystals
1998
The results of our new and earlier laboratory studies on the uptake of gases by ice crystals are summarized in terms of (1) the equilibrium phase diagram for a system gas/H2O, (2) the effect of these gases on the evaporation rate of ice crystals, and (3) in terms of the uptake of the gases by water drops. It is shown that the intrinsic quasi-liquid layer significantly affects the uptake of a gas by an ice surface in that, depending on the gas phase concentration, the layer thickness may be considerably increased by depressing the equilibrium freezing point causing additional surface melting. It is further shown that the evaporation rate of ice particles previously exposed to a gas may becom…
Depth selective Mössbauer spectroscopy: Analysis and simulation of 6.4 keV and 14.4 keV spectra obtained from rocks at Gusev Crater, Mars, and layere…
2008
[1] The miniaturized Mossbauer spectrometer (MIMOS) II Mossbauer spectrometers on the Mars Exploration Rovers (MER) simultaneously obtained 6.4 keV and 14.4 keV Mossbauer spectra from rock and soil targets. Because photons with lower energy have a shallower penetration depth, 6.4 keV spectra contain more mineralogical information about the near-surface region of a sample than do 14.4 keV spectra. The influence of surface layers of varying composition and thickness on Mossbauer spectra was investigated by Monte Carlo simulation and by measurement using a copy of the MER MIMOS II instrument and samples with one or two layers of known thicknesses. Thin sections of minerals or metallic Fe foil …
Data flow of spectral UV measurements at Sodankylä and Jokioinen
2016
Abstract. The data flow involved in a long-term continuous solar spectral UV irradiance monitoring program is investigated and structured to provide an overall view on the multiphase process from data acquisition to the final products. The program employing Brewer spectrophotometers as measuring instruments is maintained by the Finnish Meteorological Institute (FMI) ever since the 1990s at two sites in Finland: Sodankylä (67° N) and Jokioinen (61° N). It is built upon rigorous operation routines, processing procedures, and tools for quality control (QC) and quality analysis (QA) under continuous development and evaluation. Three distinct levels of data emerge, each after certain phase in th…
REGEOTOP: New climatic data fields for East Asia based on localized relief information and geostatistical methods
2004
Climate data fields represent essential tools for climate, biogeographical and agricultural research to run models and to provide observational data for the verification of global climate models (GCM). Climate data fields are generated through interpolation of observations taken at meteorological stations. Most current interpolation procedures try to describe the influence of topography on spatial climatic variations by relating them directly to absolute elevation or by introducing simple relief variables such as exposure. In both cases this may not properly describe spatial climatic variations, particularly not those of precipitation. This paper describes a regionalization procedure (REGEO…
Overview of the magnetic properties experiments on the Mars Explorations Rovers
2009
[1] The Mars Exploration Rovers have accumulated airborne dust on different types of permanent magnets. Images of these magnets document the dynamics of dust capture and removal over time. The strongly magnetic subset of airborne dust appears dark brown to black in Panoramic Camera (Pancam) images, while the weakly magnetic one is bright red. Images returned by the Microscopic Imager reveal the formation of magnetic chains diagnostic of magnetite-rich grains with substantial magnetization (>8 Am2 kg−1). On the basis of Mossbauer spectra the dust contains magnetite, olivine, pyroxene, and nanophase oxides in varying proportions, depending on wind regime and landing site. The dust contains a …
Current and emerging developments in subseasonal to decadal prediction
2020
Weather and climate variations on subseasonal to decadal time scales can have enormous social, economic, and environmental impacts, making skillful predictions on these time scales a valuable tool for decision-makers. As such, there is a growing interest in the scientific, operational, and applications communities in developing forecasts to improve our foreknowledge of extreme events. On subseasonal to seasonal (S2S) time scales, these include high-impact meteorological events such as tropical cyclones, extratropical storms, floods, droughts, and heat and cold waves. On seasonal to decadal (S2D) time scales, while the focus broadly remains similar (e.g., on precipitation, surface and upper-…
Spirit Mars Rover Mission to the Columbia Hills, Gusev Crater: Mission overview and selected results from the Cumberland Ridge to Home Plate
2008
This paper summarizes the Spirit rover operations in the Columbia Hills of Gusev Crater from sols 513 to 1476 and provides an overview of selected findings that focus on synergistic use of the Athena Payload and comparisons to orbital data. Results include discovery of outcrops (Voltaire) on Husband Hill that are interpreted to be altered impact melt deposits that incorporated local materials during emplacement. Evidence for extensive volcanic activity and aqueous alteration in the Inner Basin is also detailed, including discovery and characterization of accretionary lapilli and formation of sulfate, silica, and hematite-rich deposits. Use of Spirit's data to understand the range of spectra…