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121.
Mantsis Damianos F. Sherwood Steven Dixit Vishal Morrison Hugh Thompson Greg 《Climate Dynamics》2020,54(7):3425-3439
Climate Dynamics - The simulation of Saharan mid tropospheric clouds is investigated with the weather research and forecasting (WRF) regional atmospheric model at convection permitting... 相似文献
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123.
The Total Irradiance Monitor (TIM) instrument is designed to measure total solar irradiance with an absolute accuracy of 100
parts per million. Four electrical substitution radiometers behind precision apertures measure input radiant power while providing
redundancy. Duty cycling the use of the radiometers tracks degradation of the nickel-phosphorous absorptive black radiometer
interiors caused by solar exposure. Phase sensitive detection at the shutter frequency reduces noise and simplifies the estimate
of the radiometer's equivalence ratio. An as-designed uncertainty budget estimates the instrument's accuracy goal. The TIM
measurement equation defines the conversion from measured signal to solar irradiance. 相似文献
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Many asteroids with a semimajor axis close to that of Mars have been discovered in the last several years. Potentially some of these could be in 1:1 resonance with Mars, much as are the classic Trojan asteroids with Jupiter, and its lesser-known horseshoe companions with Earth. In the 1990s, two Trojan companions of Mars, 5261 Eureka and 1998 VF31, were discovered, librating about the L5 Lagrange point, 60° behind Mars in its orbit. Although several other potential Mars Trojans have been identified, our orbital calculations show only one other known asteroid, 1999 UJ7, to be a Trojan, associated with the L4 Lagrange point, 60° ahead of Mars in its orbit. We further find that asteroid 36017 (1999 ND43) is a horseshoe librator, alternating with periods of Trojan motion. This asteroid makes repeated close approaches to Earth and has a chaotic orbit whose behavior can be confidently predicted for less than 3000 years. We identify two objects, 2001 HW15 and 2000 TG2, within the resonant region capable of undergoing what we designate “circulation transition”, in which objects can pass between circulation outside the orbit of Mars and circulation inside it, or vice versa. The eccentricity of the orbit of Mars appears to play an important role in circulation transition and in horseshoe motion. Based on the orbits and on spectroscopic data, the Trojan asteroids of Mars may be primordial bodies, while some co-orbital bodies may be in a temporary state of motion. 相似文献
126.
Greg Weirs Vikram Dwarkadas Tomek Plewa Chris Tomkins Mark Marr-Lyon 《Astrophysics and Space Science》2005,298(1-2):341-346
As a component of the Flash Center’s validation program, we compare FLASH simulation results with experimental results from
Los Alamos National Laboratory. The flow of interest involves the lateral interaction between a planar M
a
= 1.2 shock wave with a cylinder of gaseous sulfur hexafluoride (SF6) in air, and in particular the development of primary and secondary instabilities after the passage of the shock. While the
overall evolution of the flow is comparable in the simulations and experiments, small-scale features are difficult to match.
We focus on the sensitivity of numerical results to simulation parameters. 相似文献
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A colorimetric method for the determination of phosphorus in batches of geochemical survey samples is described. The powdered material is digested with a nitric-perchloric acid mixture, excess of acid is evaporated off and the residue is leached with water. Aliquots of the leachate are treated with vanadomolybdate reagent and the yellow phosphorus complex is extracted into isobutyl methyl ketone. The colour in the organic phase, which is stable for many days, is matched against a series of similarly prepared standards. Iron, other coloured ions, and titanium do not interfere. Standard deviations of ±0.02% about a mean value of 0.20% P2 O5 and ±0.4% about a mean of 11.6% P2 O5 were obtained. At least 40 powdered samples may be analysed per working day per person. 相似文献
129.
T. W. Thompson W. J. Roberts W. K. Hartmann R. W. Shorthill S. H. Zisk 《Earth, Moon, and Planets》1979,21(3):319-342
Radar, infrared, and photogeologic properties of lunar craters have been studied to determine whether there is a systematic difference in blocky craters between the maria and terrae and whether this difference may be due to a deep megaregolith of pulverized material forming the terra surface, as opposed to a layer of semi-coherent basalt flows forming the mare surface. Some 1310 craters from about 4 to 100 km diameter have been catalogued as radar and/or infrared anomalies. In addition, a study of Apollo Orbital Photography confirmed that the radar and infrared anomalies are correlated with blocky rubble around the crater.Analysis of the radar and infrared data indicated systematic terra—mare differences. Fresh terra craters smaller than 12 km were less likely to be infrared and radar anomalies than comparable mare craters: but terra and mare craters larger than 12 km had similar infrared and radar signatures. Also, there are many terra craters which are radar bright but not infrared anomalies.Our interpretation of these data is that while the maria are rock layers (basaltic flow units) where craters eject boulder fields, the terrae are covered by relatively pulverized megaregolith at least 2 km deep, where craters eject less rocky rubble. Blocky rubble, either in the form of actual rocks or partly consolidated blocks, contributes to the radar and infrared signatures of the crater. However, aging by impacts rapidly destroys these effects, possibly through burial by secondary debris or by disintegration of the blocks themselves, especially in terra regions.PSI Contribution No. 110. 相似文献
130.