Title | Attribution of interminima changes in the global thermosphere and ionosphere |
Publication Type | Journal Article |
Year of Publication | 2014 |
Authors | Emmert, JT, McDonald, SE, Drob, DP, Meier, RR, Lean, JL, Picone, JM |
Journal | Journal of Geophysical Research: Space Physics |
Volume | 119 |
Issue | 8 |
Pagination | 6657 - 6688 |
Date Published | 08/2014 |
Keywords | ionosphere total electron content; solar minimum; thermosphere mass density |
Abstract | We present a statistical attribution analysis of the changes in global annual average thermospheric mass density and ionospheric total electron content (TEC) between the cycle 22/23 solar minimum (which occurred at epoch 1996.4) and the prolonged cycle 23/24 minimum (2008.8). The mass density data are derived from orbital drag, and the TEC data are derived from ground-based GPS receivers. The interminima change in mass density was −36% relative to the 1996.4 yearly average. Considering each multiplicative forcing independently, lower average geomagnetic activity during the cycle 23/24 minimum produced an interminima density change of at least −14%, solar extreme ultraviolet (EUV) irradiance forcing produced a density change of −1% to −13%, and changes in thermospheric CO2concentration produced a density change of −5%. There was essentially no interminima change in global TEC derived from ground-based GPS receivers or space-based altimeters, even though past behavior suggests that it should have changed −3% (0.2 TEC units (1 TECU = 1016 el m−2)) in response to lower geomagnetic activity and −1% to −9% (0.1–0.8 TECU) in response to lower EUV irradiance. There is large uncertainty in the interminima change of solar EUV irradiance; the mass density and TEC data suggest a plausible range of 0% to −6%. |
URL | http://doi.wiley.com/10.1002/2013JA019484 |
DOI | 10.1002/2013JA019484 |
Short Title | J. Geophys. Res. Space Physics |
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