Polar cap ionosphere and thermosphere during the solar minimum period: EISCAT Svalbard radar observations and GCM simulations

Hitoshi Fujiwara, Satonori Nozawa, Sawako Maeda, Yasunobu Ogawa, Yasunobu Miyoshi, Hidekatsu Jin, Hiroyuki Shinagawa, Kaori Terada

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The IPY long-run data were obtained from the European Incoherent Scatter Svalbard radar (ESR) observations during March 2007 and February 2008. Since the solar and geomagnetic activities were quite low during the period, this data set is extremely helpful for describing the basic states (ground states) of the thermosphere and ionosphere in the polar cap region. The monthly-averaged ion temperatures for 12 months show similar local time (or UT) variations to each other. The ion temperatures also show significant seasonal variations. The amplitudes of the local time and seasonal variations observed are much larger than the ones predicted by the IRI-2007 model. In addition, we performed numerical simulations with a general circulation model (GCM), which covers all the atmospheric regions, to investigate variations of the neutrals in the polar thermosphere. The GCM simulations show significant variations of the neutral temperature in the polar region in comparison with the NRLMSISE-00 empirical model. These results indicate that both the ions and neutrals would show larger variations than those described by the empirical models, suggesting significant heat sources in the polar cap region even under solar minimum and geomagnetically quiet conditions.

Original languageEnglish
Pages (from-to)459-465
Number of pages7
Journalearth, planets and space
Volume64
Issue number6
DOIs
Publication statusPublished - Jan 1 2012

Fingerprint

radar tracking
polar caps
thermosphere
ionospheres
general circulation model
ionosphere
radar
ion
seasonal variation
simulation
annual variations
ion temperature
temperature
electron spin resonance
heat source
polar region
EISCAT radar system (Europe)
heat sources
solar activity
polar regions

All Science Journal Classification (ASJC) codes

  • Geology
  • Space and Planetary Science

Cite this

Polar cap ionosphere and thermosphere during the solar minimum period : EISCAT Svalbard radar observations and GCM simulations. / Fujiwara, Hitoshi; Nozawa, Satonori; Maeda, Sawako; Ogawa, Yasunobu; Miyoshi, Yasunobu; Jin, Hidekatsu; Shinagawa, Hiroyuki; Terada, Kaori.

In: earth, planets and space, Vol. 64, No. 6, 01.01.2012, p. 459-465.

Research output: Contribution to journalArticle

Fujiwara, Hitoshi ; Nozawa, Satonori ; Maeda, Sawako ; Ogawa, Yasunobu ; Miyoshi, Yasunobu ; Jin, Hidekatsu ; Shinagawa, Hiroyuki ; Terada, Kaori. / Polar cap ionosphere and thermosphere during the solar minimum period : EISCAT Svalbard radar observations and GCM simulations. In: earth, planets and space. 2012 ; Vol. 64, No. 6. pp. 459-465.
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