The North Polar Expeditions of Commander Peary and Dr. Cook

1909 ◽  
Vol 34 (4) ◽  
pp. 433
Keyword(s):  
The North ◽  
North Polar

scholarly journals Avalanches of the martian north polar cap

2020 ◽  
Author(s):  
Patricio Becerra ◽  
Susan Conway ◽  
Nicholas Thomas ◽  
Keyword(s):  
Polar Regions ◽  
Martian Surface ◽  
Polar Cap ◽  
Water Ice ◽  
The North ◽  
Imaging Science ◽  
Resolution Imaging ◽  
North Polar ◽  
Gas Expansion ◽  
Trigger Mechanisms

<p>In 2008, the High Resolution Imaging Science Experiment (HiRISE) on board NASA’s MRO fortuitously captured several discrete clouds of material in the process of cascading down a steep scarp of the water-ice-rich north polar layered deposits (NPLD). The events were only seen during a period of ~4 weeks, near the onset of martian northern spring in 2008, when the seasonal cover of CO2 is beginning to sublimate from the north polar regions. Russell et al. [1] analyzed the morphology of the clouds, inferring that the particles involved were mechanically analogous to terrestrial “dry, loose snow or dust”, so that the events were similar to terrestrial “powder avalanches” [2]. HiRISE confirmed the seasonality of avalanche occurrence the following spring, and continued to capture between 30 and 50 avalanches per season (fig. 1b,c) between 2008 and 2019, for a total of 7 Mars Years (MY29–MY35) of continuous scarp monitoring.</p><p>In this work we will present statistics on these events, in an attempt to quantify their effect on the mass balance of the NPLD, and with respect to competing processes such as viscous deformation and stress-induced block falls that do not trigger avalanches [3,4]. We also use a 1D thermal model [5] to investigate the sources and trigger mechanisms of these events. The model tracks the accumulation and ablation of seasonal CO2 frost on a martian surface. Russell et al. [1] support an initiation through gas-expansion related to the presence of CO2 frost on the scarp. Therefore the amount of frost that lingers on different sections of the model scarp at the observed time of the avalanches will provide evidence either for or against this particular mechanism. We will present preliminary results and discuss their implications.</p><p>References: [1] P. Russell et al. (2008) Geophys. Res. Lett. 35, L23204. [2] D. McClung, P.A. Schaerer (2006), Mountaineers, Seattle Wash. [3] Sori, M. M., et al., Geophys. Res. Lett., 43. [4] Byrne et al. (2016), 6th Int. Conf. Mars Polar Sci. Exploration [4] C. M. Dundas and S. Byrne (2010) Icarus 206, 716.</p>

scholarly journals Widespread Megaripple Activity Across the North Polar Ergs of Mars

2021 ◽  
Author(s):  
Matthew Chojnacki ◽  
David A. Vaz ◽  
Simone Silvestro ◽  
David C.A. Silva
Keyword(s):  
The North ◽  
North Polar

Sunspots, the QBO, and the Stratosphere in the North Polar Region: An Update

2008 ◽  
pp. 347-357 ◽  
Author(s):  
K. Labitzke ◽  
M. Kunze ◽  
S. Brönnimann ◽  
K. Labitzke ◽  
M. Kunze ◽  
...  
Keyword(s):  
Polar Region ◽  
The North ◽  
North Polar

Spectral Observation of the Soft X-Ray Background and of the North Polar Spur with Solid State Spectrometers

1983 ◽  
pp. 357-360 ◽  
Author(s):  
R. Rocchia ◽  
M. Arnaud ◽  
C. Blondel ◽  
C. Cheron ◽  
J. C. Christy ◽  
...  
Keyword(s):  
Solid State ◽  
Spectral Observation ◽  
X Ray ◽  
The North ◽  
North Polar ◽  
X Ray Background

scholarly journals Cloud activity on Mars near the equinox: Comparison of the 1937 and 1969 oppositions

1971 ◽  
Vol 40 ◽  
pp. 310-319
Author(s):  
G. de Vaucouleurs
Keyword(s):  
Northern Hemisphere ◽  
Cloud Systems ◽  
The North ◽  
North Polar

Four classes of manifestations of cloud activity observed in 1937 and 1969 near the autumn equinox of the northern hemisphere (165°< Ls < 192°) are discussed: (1) formation of the north polar haze cap, (2) unusual cloud systems on the disk, (3) recurrent or persistent cloud activity at the sunset limb, (4) clouds seen in projection above the sunrise terminator.

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