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The ability of the cosmic‐ray neutron albedo mechanism to account for geomagnetically trapped electrons is investigated quantitatively. Injection as a function of energy, pitch angle, and altitude is computed from a reasonable neutron albedo model. Loss mechanisms (slowing down and pitch‐angle diffusion) based on Coulomb interactions with the residual atmosphere are considered to act both independently and simultaneously. It is found that slowing down is generally dominant. The resulting electron belt has the following features: (a) an intensity whose energy spectrum shows a peak at ∼200 kev; (b) an angular distribution that is approximately ‘isotropic’ up to the loss cone; and (c) an omnidirectional, integral intensity in the geomagnetic equatorial plane that is approximately constant vs. altitude. The absolute intensities depend directly on the atmospheric model used in the calculation; namely, rv−2.7, where atmospheric density is taken as ρ0r−v. These results agree only poorly with spectrometer observations which show an energy spectrum with a peak at a much lower energy. However, the quantitative agreement as to intensity is good at energies ≳400 kev. It is concluded that only a small fraction of the trapped electrons can be accounted for in terms of neutron albedo, essentially all trapped electrons >400 kev. An ‘auroral’ component of low‐energy electrons is also present. The energy of this low‐energy component probably derives from local acceleration, and ultimately from the sun. The effect of the Capetown magnetic anomaly is investigated and shown to produce a ‘slot’ of only 2 per cent in the equatorial plane in the vicinity of 2.7 earth radii.
ABSTRACT:We examine tropospheric temperature trends of 67 runs from 22 'Climate of the 20th Century' model simulations and try to reconcile them with the best available updated observations (in the tropics during the satellite era). Model results and observed temperature trends are in disagreement in most of the tropical troposphere, being separated by more than twice the uncertainty of the model mean. In layers near 5 km, the modelled trend is 100 to 300% higher than observed, and, above 8 km, modelled and observed trends have opposite signs. These conclusions contrast strongly with those of recent publications based on essentially the same data.
The flow of plasma. in the earth's magnetotail has been measured with an electrostatic analyzer on Vela 4B at geocentric distances of ~18 Rr. The analyzer on the rotating (64-sec period) satellite measures proton energy spectra from 79 ev to 19 key, and the plasma. flow is detected and measured by the substantial spin modulation that it often causes in the measured proton fluxes. The satellite's spin axis is kept directed radially outward along a radius vector from the earth, and so the analyzer, whose aperture is in the satellite's equatorial plane, most effectively senses flows in the direction perpendicular to the radius vector. Some results of the measurements are that (1) plasma flow speeds of several hundred km/se.c are frequently measured in the plasma sheet, particularly during substorms, and these sometimes approach 1000 km/sec; however, evident flow in a given direction seldom persists for more thar• a few minutes; (2) these rapid substorm-related flows are usually directed generally sunward; (3) flow in the anti-sunward (tailward) direction is observed early in some substorms as the plasma sheet thins down; this may suggest the formation of a neutral line at geocentric distances •18 Rr; (4) the magnetotail is separated from the surrounding magnetosheath by a boundary layer a few thousand kilometers thick in which magnetosheath-like flow occurs but at reduced particle density and velocity; and (5) averaging of all flow measurements made in the plasma. •heet over' many months does not reveal any distinct pattern of flow either sunward or anti-sunward; an average of the flows observed during periods of a few minutes of clearly evident flow, however, does reveal a flow in the general direction of the sun. It appears that the plasma. sheet may often be in turbulent motion with turbulence-cell dimensions no greater than a few R r. • Permanent address, GeophysicalInstitute, University of Alaska, College, Alaska. 99701. Other recent evidence of this has been provided by observed penetration of magnetosheath-like plasma deep into the magnetosphere through the 'polar cusps' [Frank, 1971; Heikkila and Winningham, 1971]. However, acceptance of the belief that most of the magnetospheric plasma originates in the solar wind leaves unanswered, still, important questions regarding how and where it enters the magnetosphere and is distributed among the various regions, what fraction of the entering plasma leaves again, and how the plasma moves about within the magnetosphere during magnetically quiet and magnetically disturbed times. The subject of the plasma's motion or 'convection' within the magnetosphere has been investigated indirectly in the past, largely by deducing or measuring eiectric fields or plasma motions at ionospheric heights and extrapolating these into the outer ionosphere by use of the frozen-in field concept. Ax[ord and Hines [1961] postulated, on the basis of such investi-5503 5504 HowEs gations, that a raindrop-like convection pattern exists in the outer magnetosphere where magnetic field and plasma,...
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