Contributions of ineffective ice loads on sea-level and free-air gravity

2002 ◽  
pp. 177-185 ◽  
Author(s):  
Jun'ichi Okuno ◽  
Masao Nakada
Keyword(s):  
Sea Level ◽  
Free Air ◽  
Ice Loads ◽  
Free Air Gravity

Isostatic response to loading of the crust in Canada

1970 ◽  
Vol 7 (2) ◽  
pp. 716-727 ◽  
Author(s):  
R. I. Walcott
Keyword(s):  
Close Association ◽  
Ice Sheet ◽  
Ground Surface ◽  
Gravity Anomalies ◽  
A Value ◽  
Free Air ◽  
Ice Loads ◽  
Anomaly Map ◽  
Free Air Gravity ◽  
Free Air Anomaly

A smoothed free air anomaly map of Canada indicates that the central part of the region occupied by the Laurentide Ice Sheet is over-compensated. Due to the close association of the free air gravity, the apparent crustal warping, the time of deglaciation, and the congruence of the gravity anomalies and the Wisconsin Glaciation, it is concluded that the over-compensation is due to incomplete recovery of the lithosphere from the displacement caused by the Pleistocene ice loads. The amplitude of the anomalies, about –50 milligals, suggests that a substantial amount of uplift has yet to occur and that the relaxation time of crustal warping is of the order of 10 000 to 20 000 y.The profile of the ground surface at the edge of a continental ice sheet on an elastic lithosphere is assessed using a value of the flexural parameter of the lithosphere calculated from gravity and deformation studies in the Interior Plains. The conclusions are: (a) a purely elastic forebulge is not likely to reach an amplitude of more than a few tens of meters; (b) the crust will be depressed for a considerable distance beyond the edge of the ice sheet; and (c) for large ice sheets crustal failure will probably occur in a preferential zone several hundred kilometers inside the maximum ice limit.

scholarly journals Scattering of light by dust-free air, with artificial reproduction of the blue sky.—Preliminary note

1918 ◽  
Vol 94 (662) ◽  
pp. 453-459 ◽  
Keyword(s):  
Sea Level ◽  
Suspended Particles ◽  
Artificial Reproduction ◽  
Blue Colour ◽  
Foreign Matter ◽  
Preliminary Note ◽  
Scattering Of Light ◽  
Free Air

It is now well established that the luminosity and blue colour of the sky on very clear days and at considerable altitudes above the sea-level can almost be accounted for by the scattering of light by the molecules of air, without postulating suspended particles of foreign matter, such as were thought necessary by the earlier writers. This conclusion depends on the measured opacity of the atmosphere, deduced from observations such as those of Abbot and Fowle of the sun’s radiation at various zenith distances. The opacities measured at Mount Wilson for different wave-lengths are found to be nearly in agreement with what would be expected if scattering by the molecules were alone operative; leaving little room for the action of larger particles.

5. Gravity and the figure of the Earth

2018 ◽  
pp. 69-91
Author(s):  
William Lowrie
Keyword(s):  
Accurate Determination ◽  
Measurement Techniques ◽  
Gravity Anomalies ◽  
Dynamic Processes ◽  
The Core ◽  
The Earth ◽  
Free Air ◽  
Figure Of The Earth ◽  
Free Air Gravity

‘Gravity and the figure of the Earth’ discusses the measurement of gravity and its variation at the Earth’s surface and with depth. Gravity is about 0.5 per cent stronger at the poles than at the equator and it first increases with depth until the core–mantle boundary and then sinks to zero at the Earth’s centre. Using satellites to carry out geodetic and gravimetric observations has revolutionized geodesy, creating a powerful geophysical tool for observing and measuring dynamic processes on the Earth. The various measurement techniques employed fall in two categories: precise location of a position on the Earth (such as GPS) and accurate determination of the geoid and gravitational field. Bouguer and free-air gravity anomalies and isostasy are explained.

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