A multi-year survey of dynamics near the surface in the northern hemisphere of Mars: Short-period baroclinic waves and dust storms

Icarus ◽  
2012 ◽  
Vol 219 (1) ◽  
pp. 307-320 ◽  
Author(s):  
David P. Hinson ◽  
Huiqun Wang ◽  
Michael D. Smith
2019 ◽  
Vol 89 (10) ◽  
pp. 1044-1051
Author(s):  
Aleksandr S. Rulev ◽  
Anna M. Pugacheva

From acceptance of the 1948 Plan of Field-Protective Afforestation to the present (2019), this article considers the new agroforestry paradigms protracted formation. Scientific achievements from the 1940s, introduced into practice, served as the basis for decisions on natures global transformation. Pilot facilities from the beginning of the 20th century (the Bogdinsky agroforestry stronghold, the Stone-steppe oasis) still serve as reference objects for agroforest reclamation of territories, with a scientific approach that allows them to function productively today. The plans main idea is to combat drought and desertification of steppe lands, erosion processes, and to prevent sand and dust storms. Creation of 5709 thousand hectares of protective forests, afforestation of 1106 thousand hectares of ravines, fixing and afforestation of sand on an area of 322 thousand hectares, and implementation of many planned activities during a short period locate this plan among other ambitious international projects. The authors draw attention to the time of creation and the volume of plantings of paramount importance, that is, state protective forest belts and protective forest plantations. Understanding the importance of agroforestry for modern agricultural landscapes led to formation of sustainable and durable agroforestry systems in subarid landscapes based on a combination of agricultural and landscape-ecological ideologies. Allegedly, considering terrain ecotopes, three-dimensional evaluation of the agrolandscape and a non-linear approach make it possible to create multifunctional, highly productive agroforestry systems in critical agriculture zones.


Author(s):  
J. Michael Battalio

AbstractThe ability of Martian reanalysis datasets to represent the growth and decay of short-period (1.5 < P < 8 sol) transient eddies is compared across the Mars Analysis Correction Data Assimilation (MACDA), Open access to Mars Assimilated Remote Soundings (OpenMARS), and Ensemble Mars Reanalysis System (EMARS). Short-period eddies are predominantly surface-based, have the largest amplitudes in the northern hemisphere, and are found, in order of decreasing eddy kinetic energy amplitude, in Utopia, Acidalia, and Arcadia Planitae in the northern hemisphere, and south of the Tharsis Plateau and between Argyre and Hellas Basins in the southern hemisphere. Short-period eddies grow on the upstream (western) sides of basins via baroclinic energy conversion and by extracting energy from the mean flow and long-period (P > 8 sol) eddies when interacting with high relief. Overall, the combined impact of barotropic energy conversion is a net loss of eddy kinetic energy, which rectifies previous conflicting results. When Thermal Emission Spectrometer observations are assimilated (Mars years 24–27), all three reanalyses agree on eddy amplitude and timing, but during the Mars Climate Sounder (MCS) observational era (Mars years 28–33), eddies are less constrained. The EMARS ensemble member has considerably higher eddy generation than the ensemble mean, and bulk eddy amplitudes in the deterministic OpenMARS reanalysis agree with the EMARS ensemble rather than the EMARS member. Thus, analysis of individual eddies during the MCS era should only be performed when eddy amplitudes are large and when there is agreement across reanalyses.


1957 ◽  
Vol 10 (1) ◽  
pp. 77 ◽  
Author(s):  
AA Weiss

The directions of the reflection points of sporadic meteor trails for March and September 1953, and the hourly echo rates of sporadic meteors obtained from the Adelaide radio survey of meteor activity over 1952?1956 are analysed. Diurnal and annual variations in the sporadic echo rate are predicted from contemporary theory on the reflection of radio waves from meteor trails for several model distributions. A sporadic distribution is derived which consists of a concentration of direct short-period orbits to the plane of the ecliptic superimposed upon a more uniform distribution of near-parabolic orbits. This distribution is consistent with the results of radar, visual, and telescopic surveys in the northern hemisphere. The density of sporadic meteors round the Earth's orbit is also derived.


1971 ◽  
Vol 13 ◽  
pp. 223-226
Author(s):  
Robert G. Roosen ◽  
Otto E. Berg ◽  
Neil H. Farlow

Silverberg (1970) has explained the “dust storms” observed by the early satellite-borne microphone detectors by postulating that the orbital planes of short-period, low-inclination comets are filled with micrometeoroids. We report here on three separate approaches to test the validity of this hypothesis. (1)Optical scans of the Gegenschein brightness can yield no useful information on the nearly isotropic sheets of dust predicted by Silverberg.(2)An attempt to directly collect dust particles during a predicted high flux period by means of a sounding rocket yielded negative results.(3)Over three years of particle impact data from extremely sensitive detectors flown aboard Pioneers 8 and 9 show no observable dust storms.Hence Silverberg’s hypothesis appears untenable.However, we should not rule out the possibility that observable showers of very small particles can be blown directly off the nuclei of some comets passing between the Earth and the Sun.


1962 ◽  
Vol 14 ◽  
pp. 133-148 ◽  
Author(s):  
Harold C. Urey

During the last 10 years, the writer has presented evidence indicating that the Moon was captured by the Earth and that the large collisions with its surface occurred within a surprisingly short period of time. These observations have been a continuous preoccupation during the past years and some explanation that seemed physically possible and reasonably probable has been sought.


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