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Earth, Planets and Space
Fig. 3 | Earth, Planets and Space

Fig. 3

From: Temporal evolutions of \(\text {N}_2^+\) Meinel (1,2) band near \(1.5.\,\upmu \text {m}\) associated with aurora breakup and their effects on mesopause temperature estimations from OH Meinel (3,1) band

Fig. 3

NIRAS spectral measurements of OH Meinel (3,1) band at Syowa station in 2018 austral winter. Results obtained by measurements with the 600-lpmm grating are only shown. a Total exposure time for nightly mean intensities and temperature on each night. We only used good SNR data for the mean and a detail is described in a main text. A dashed curve indicates amount of time when SZA is greater than 100 ° on each night. Note that the time is multiplied by a factor of 5/6 because a cycle of measurement has one dark frame and five sky frames. b Nightly mean of \(\text {P}_1\)(2), \(\text {P}_1\)(3), and \(\text {P}_1\)(4) line intensities in OH (3,1) band. c Nightly mean of OH rotational temperatures estimated by a ratio between \(\text {P}_1\)(2), and \(\text {P}_1\)(4) line intensities. The nightly mean and 3-days smoothing are indicated by black diamonds and red lines, respectively. A blue curve is seasonal variations of 3-day smoothed temperature at 87-km altitude calculated by NRLMSISE-00 (Picone et al. 2002). Green triangles are 3-day smoothed temperature at geopotential height of 80 km obtained from Aura/MLS

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