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Long‐term temperature trends in the ionosphere above Millstone Hill
Author(s) -
Holt J. M.,
Zhang S. R.
Publication year - 2008
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl031148
Subject(s) - ionosphere , millstone hill , term (time) , geology , environmental science , climatology , atmospheric sciences , geophysics , f region , physics , astronomy
Increasing concentrations of greenhouse gases are expected on theoretical grounds to lead to a cooling of the upper atmosphere. Due to the close thermal coupling of the neutral and ionized components of the upper atmosphere the effects of this cooling are also expected to be seen in the ionospheric ion temperature. Long‐term satellite observations of neutral density show a trend consistent with the expected cooling. Temperature data from the Millstone Hill incoherent scatter radar (46.2°N, 288.5°E) from 1978 to 2007 have been analyzed to provide a direct estimate of the temperature trend above the radar. The long‐term trend in the directly measured ion temperature T i at 375 km is found to be −4.7 K/year with a 95% confidence interval of −3.6 to −5.8 K. The estimated trend in the neutral temperature T n is −5.0 K/year. These are significantly larger than predicted by theory.