Open AccessGlobal O/N 2 derived from DE 1 FUV dayglow data: Technique and examples from two storm periods
Author(s) -
Strickland D. J.,
Cox R. J.,
Meier R. R.,
Drob D. P.
Publication year - 1999
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/98ja02817
Subject(s) - physics , astrophysics , solar zenith angle , zenith , thermosphere , intensity (physics) , geomagnetic storm , flux (metallurgy) , middle latitudes , scaling , atmospheric sciences , earth's magnetic field , computational physics , optics , ionosphere , mathematics , geometry , astronomy , magnetic field , metallurgy , materials science , quantum mechanics
A technique is presented for deriving the column abundance of O relative to N 2 (designated as O/N 2 and referenced to an N 2 depth of 10 17 cm −2 ) from DE 1 imager dayglow data. For the band‐pass filter of interest, the data are dominated by O I 130.4 nm with minor contributions from O I 135.6 nm and N 2 Lyman‐Birge‐Hopfield. The technique relies on a first‐principles calculation of the intensity I 1P for the given band pass. Independent variables are solar zenith angle S , look angle D , and O/N 2 . There is a degree of nonuniqueness between I 1P and O/N 2 (∼10%), which is accounted for in our error analysis. A bias exists between I 1P and a given data set owing to errors in cross sections, the assumed solar EUV flux, and calibration. The bias is removed by scaling I 1P to agree with quiet time data as close in time as possible with the data set of interest. A comparison of the behavior of I 1P versus S and D is made with the empirical model of Craven and colleagues [ Craven et al. , 1994; Nicholas et al. , 1997; Immel et al. , 1997], which shows satisfactory agreement for S > 40° but some significant departures at smaller angles. Sequences of O/N 2 images over 2‐day periods are presented for geomagnetic storms commencing on days 267 and 295, 1981. Both storms produced major O depleted patches at midlatitudes to high latitudes, with extreme values of O/N 2 more than a factor of 2 smaller than undisturbed values. The results also show longitudinal motions of the patches over the reporting periods.