Engineering topics

Forbes, T. G.

Publications and source records attributed to Forbes, T. G..

39 records · Page 3

NASA NTRS1981

Evidence for the tailward retreat of a magnetic neutral line in the magnetotail during substorm recovery

Plasma sheet observations made during a substorm recovery at 0400 to 0430 UT on March 1, 1978 with the ISEE satellites strongly suggest that the observed field-aligned flow of plasma in the earthward direction has mirrored in the vicinity of the earth and returned to the position of the satellites to produce the tailward flow seen at this time. The correlation between the estimated speeds of the earthward and tailward moving distribution indicates that the observed changes in velocity are spatial rather than temporal. It is concluded that the movement of the plasma sheet surface results from the propagation of an energetic particle source on to new magnetic field lines which progressively map deeper into the tail and also to higher polar latitudes at the earth. The movement of the source onto new magnetic field lines is clearly consistent with the tailward retreat of a magnetic neutral line in the plasma sheet during substorm recovery.

Forbes, T. G.↗

NASA NTRS1980

Structure of the low latitude boundary layer

Observations at high temporal resolution of the frontside magnetopause and plasma boundary layer, made with the LASL/MPE fast plasma analyzer onboard the ISEE 1 and 2 spacecraft, revealed a complex quasiperiodic structure of some of the observed boundary layers. A cool tailward streaming boundary layer plasma was seen intermittently, with intervening periods of hot tenuous plasma which has properties similar to the magnetospheric population. While individual encounters with the boundary layer plasma last only a few minutes, the total observation time may extend over one hour or more.

Sckopke, N.↗

NASA NTRS1971

Mathematical models of the open magnetosphere - Application to dayside auroras.

Two static mathematical models of the open or Dungey model of the magnetosphere are constructed. The process of construction is similar to that for early closed magnetosphere models, such as the Taylor-Hones model. The first model in fact is simply an addition of an interplanetary field in arbitrary direction to a Taylor-Hones image dipole model. In order to preserve the shape of the magnetosphere at high latitudes, and to partially exclude the exterior field, another model is constructed with the magnetopause approximated by a diamagnetic sphere. We find that there are some interplanetary field lines connected to the earth for all orientations of the interplanetary field other than strictly northward, and that the maximum number of connected field lines occurs with a due southward field. For an average spiral hose angle of the interplanetary field, the dayside neutral point occurs on the magnetopause at about 10 o'clock local time. Dayside auroras, convection patterns, and other phenomena may exhibit symmetry about this local time. For a positive (negative) interplanetary field sector, energetic, anisotropic particle fluxes should have direct access to the northern (southern) polar caps, as is supported by many recent observations.

Forbes, T. G.↗