GUVI Level 3 Data Products
Thermospheric O/N_{2}
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What am I looking at?
The thermospheric column number density ratio of O and N_{2} referenced at N_{2} column number density level of 10^{17} cm^{2}
How were they produced?
There are a few steps of processing to produce the O/N2 ratios.

Select a number of neutral density profiles from MSIS86 model during a big magnetic storm and calculate the model O/N2 ratio from the profiles. Run AURIC for the selected density profiles at different look angles (070 degrees) and solar zenith angles (SZA) (089 degrees) to get simulated GUVI 135.6nm and LBHS intensities. The simulated LBHS intensities are increased by 60% due to adjustment in the N_{2 } LBH cross section [Strickland et al., 2004]. Two lookup tables are created, table 1 for the simulated 135.6nm and LBHS intensity versus look angle and SZA and table 2 for model O/N2 versus the 135.6nm/LBHS ratio at nadir (look angle =0) and SZA=0. A linearfit line between O/N_{2} and the 135.6nm/LBHS ratios is obtained from values in table 2. The fitting line is used to estimate the O/N_{2} ratios [Zhang et al., 2004]

Grid the GUVI 135.6nm and LBHS dayglow data (SZA < 90), SZA and look angle with a grid size of 1.757ºx1.757º in geographic latitude and longitude or 200x200km at equator. Use table 2 to normalize the GUVI 135.6nm and LBHS data to SZA=0 and look angle=0. Calculate the ratio of the normalized 135.6nm and LBHS intensities. Use the ratio and the fitting line obtained in step 1 to find O/N_{2} ratio.
Summary Images – Available in both GIF and PostScript files (each for one day). Online access for download.
Data Files – Available in NetCDF and IDLsave files. Online access for download.
Sample Images
Page Last Modified: February 26, 2014