Response of dayside thermosphere to an intense geomagnetic storm

Journal Article · Tue Jan 01 04:00:00 EST 1974 · Nature (London), v. 247, no. 5435, pp. 23-25

DOI:https://doi.org/10.1038/247023a0· OSTI ID:4329015

Allan, R R

Increases in the density of the neutral thermosphere associated with geomagnetic activity have been noted. Although the thermosphere will not be in equilibrium, and acceleration by electrodynamic forces may be involved, the increased density must reflect additional heating. The heating appears to be greater at high latitudes and, for larger disturbances, sometimes much greater. It also seems to be slightly greater on the night side, but possibly showing an opposite trend for larger disturbances. The low g accelerometer calibration system (LOGACS) experiment carried on an attitude -controlled Agena vehicle launched by the US Air Force on May 22nd 1967 provided a unique opportunity to determine the response to an intense storm and ob servations are discussed. The accelerometer provided values of atmospheric density with an estimated accuracy better than 10% and a time resolution of 1 sec. It was found that the density in the northern night side auroral regions increased with the onset of geomagnetic activity, whereas the density in the northern day side auroral regions initially decreased. An independent analysis was made of the LOGACS data, concentrating on the day side, for which the data were more complete and contained the most clearly defined structures. Although the gross structure of the response has a wave-like pattern, it is not a propagating wave. It seems possible that the heating is due to particle precipitation rather than Joule heating. The most interesting feature of the response is the pronounced peak on the magnetic equator, apparently related to the growth and decay of the storm-time ring current, An important loss process discussed for ring current protons is the charge-exchange collision with nautral Hatoms. (UK)

• Research Organization: Royal Aircraft Establishment, Farnborough, Eng.
• NSA Number: NSA-29-025082
• OSTI ID: 4329015
• Journal Information: Nature (London), v. 247, no. 5435, pp. 23-25, Journal Name: Nature (London), v. 247, no. 5435, pp. 23-25; ISSN NATUA
• Country of Publication: United Kingdom
• Language: English

Related Subjects

*MAGNETIC STORMS-- AURORAL ZONES
*THERMOSPHERE-- MAGNETIC STORMS
ATOMS
CHARGE-EXCHANGE INTERACTIONS
DAILY VARIATIONS
DENSITY
HYDROGEN
N58100* --Physics (Atmospheric)--Auroral & Ionospheric Phenomena
PROTONS
RING CURRENTS