TY - JOUR

T1 - A solar cycle of upper thermosphere density observations from the EISCAT Svalbard Radar

T2 - thermospheric density over Svalbard

AU - Vickers, H.

AU - Kosch, M. J.

AU - Sutton, E.

AU - Bjoland, L.

AU - Ogawa, Y.

AU - La Hoz, C.

N1 - ©2014. American Geophysical Union. All Rights Reserved.

PY - 2014

Y1 - 2014

N2 - We exploit a recently developed technique, based on ion-neutral coupling, which allows estimations of the upper thermospheric neutral density using measurements of ionospheric plasma parameters made by the European Incoherent Scatter (EISCAT) Svalbard Radar (ESR). The technique is applied to a 13 year long data set of measurements for the purpose of studying and quantifying the effect of solar activity on the upper thermospheric density inside the polar cap. We concentrate on the effect of solar activity at 350 km altitude and find a strong linear correlation between the ESR estimates for the atomic oxygen density and the solar irradiance proxy F10.7 index. We use the relationship to isolate variations in the thermospheric density that are present after solar activity influences are removed. Our results show a decrease in the density of a few percent over the 13 year period, which is nevertheless smaller than the uncertainty associated with the decline. We anticipate that the statistical significance of this result will only increase by studying a longer data set. Conjunctions with the CHAMP satellite that show very good agreement is achieved at 350 km especially during low solar activity.

AB - We exploit a recently developed technique, based on ion-neutral coupling, which allows estimations of the upper thermospheric neutral density using measurements of ionospheric plasma parameters made by the European Incoherent Scatter (EISCAT) Svalbard Radar (ESR). The technique is applied to a 13 year long data set of measurements for the purpose of studying and quantifying the effect of solar activity on the upper thermospheric density inside the polar cap. We concentrate on the effect of solar activity at 350 km altitude and find a strong linear correlation between the ESR estimates for the atomic oxygen density and the solar irradiance proxy F10.7 index. We use the relationship to isolate variations in the thermospheric density that are present after solar activity influences are removed. Our results show a decrease in the density of a few percent over the 13 year period, which is nevertheless smaller than the uncertainty associated with the decline. We anticipate that the statistical significance of this result will only increase by studying a longer data set. Conjunctions with the CHAMP satellite that show very good agreement is achieved at 350 km especially during low solar activity.

KW - thermosphere

KW - solar cycle

KW - polar cap

U2 - 10.1002/2014JA019885

DO - 10.1002/2014JA019885

M3 - Journal article

VL - 119

JO - Journal of Geophysical Research: Space Physics

JF - Journal of Geophysical Research: Space Physics

SN - 2169-9380

ER -