Open Access

Observations of the lower thermospheric neutral temperature and density in the DELTA campaign

  • Junichi Kurihara14Email author,
  • Takumi Abe14,
  • Koh-Ichiro Oyama14,
  • Eoghan Griffin24,
  • Mike Kosch34,
  • Anasuya Aruliah24,
  • Kirsti Kauristie44,
  • Yasunobu Ogawa54,
  • Sayaka Komada64 and
  • Naomoto Iwagami64
Earth, Planets and Space200658:BF03352001

Received: 2 October 2005

Accepted: 3 June 2006

Published: 29 September 2006


The rotational temperature and number density of molecular nitrogen (N2) in the lower thermosphere were measured by the N2 temperature instrument onboard the S-310-35 sounding rocket, which was launched from Andøya at 0:33 UT on 13 December 2004, during the Dynamics and Energetics of the Lower Thermosphere in Aurora (DELTA) campaign. The rotational temperature measured at altitudes between 95 and 140 km, which is expected to be equal to neutral temperature, is much higher than neutral temperature from the Mass Spectrometer Incoherent Scatter (MSIS) model. Neutral temperatures in the lower thermosphere were observed using the auroral green line at 557.7 nm by two Fabry-Perot Interferometers (FPIs) at Skibotn and the Kiruna Esrange Optical Platform System site. The neutral temperatures derived from the look directions closest to the rocket correspond to the rotational temperature measured at an altitude of 120 km. In addition, a combination of the all-sky camera images at 557.7 nm observed at two stations, Kilpisjärvi and Muonio, suggests that the effective altitude of the auroral arcs at the time of the launch is about 120 km. The FPI temperature observations are consistent with the in situ rocket observations rather than the MSIS model.

Key words

The DELTA campaignthe lower thermospheretemperature and density