Ionospheric response to the sustained high geomagnetic activity during the March 1989 great storm

Technical Report · Tue Nov 01 04:00:00 EST 1994

OSTI ID:137217

Sojka, J J; Schunk, R W; Denig, W F

A simulation was conducted to model the high-latitude ionospheric response to the sustained level of high geomagnetic activity for the great magnetic storm period of March, 13-14, 1989. The geomagnetic and solar activity indices and the DMSP F8 and F9 satellite data for particle precipitation and high-latitude convection were used as inputs to a time-dependent ionospheric model (TDIM). The results of the TDIM were compared to both DMSP plasma density data and ground-based total electron content (TEC) measurements for the great storm period as well as with earlier storm observations. The comparisons showed that the overall structure of the high-latitude ionosphere was dominated by an increased convection speed within the polar cap that led to increased ion temperatures. In turn, this enhanced the NO(+) density, raised the atomic-to-molecular ion transition height to over 300 km, decreased N{sub m}F{sub 2}, increased h{sub m}F{sub 2}, and in places either increased n{sub e} at 800 km or slightly decreased it. The morphology of the ionosphere under, these extreme conditions was considerably different than that modeled for less disturbed intervals. These differences included the character of the dayside tongue of ionization that no longer extended deep into the polar cap. Instead, as a result of the ion heating and consequent reduction in N{sub m}F{sub 2}, a large polar hole occupied much of the polar region. This polar hole extended beyond the auroral oval and merged with the night sector midlatitude trough. The limitations associated with the applicability of the TDIM to the geomagnetic conditions present on March 13 and 14 are discussed.

• Research Organization: Phillips Lab., Hanscom AFB, MA (United States)
• OSTI ID: 137217
• Report Number(s): AD-A--295067/3/XAB; PL-GP--95-46
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
COMPUTERIZED SIMULATION
CONVECTION
EARTH MAGNETOSPHERE
ELECTRON DENSITY
F REGION
IONOSPHERE
MAGNETIC STORMS
PLASMA DENSITY
POLAR REGIONS
T CODES
TIME DEPENDENCE