OMI Solar Proxy Index Data
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Matthew DeLand and Sergey Marchenko

Contact:  matthew.deland@ssaihq.com

Last revision:  11 January 2024


This file gives a basic description of the solar proxy index data that we have
produced from Aura OMI solar measurements. Detailed discussion can be found in
the paper "The solar chromospheric Ca and Mg indices from Aura OMI" by 
M. DeLand and S. Marchenko (2013), J. Geophys. Res. Atmos., 118, 3415-3423, 
doi:10.1002/jgrd.50310.

The most recent update of the OMI proxy index data are available in the text 
file 'solar_indices_OMI_alternative_20231231.txt'. The term '_alternative' in  
this file name indicates the use of data processing improvements that provide 
increased sampling compared to the standard L1B processing. These data were 
created using the Collection 4 reprocessing of OMI Level 1B data. Due to some 
anomalies in the calculated product, we have excluded the Mg I proxy index 
from this release of OMI data. The first measurement date is 1 October 2004, 
and the last date included in the current data file is 31 December 2023. Note 
that the measurement for 4 December 2023 has been removed because of anomalous 
results in all calculated index values. 

There are 8 columns with the following contents.

Column 1:  Year of measurement.

Column 2:  Month of measurement.

Column 3:  Day of measurement.

Column 4:  Hour of measurement [UT].

Column 5:  Minute of measurement [UT].

Column 6:  Daily average Mg II proxy index (280 nm).

Column 7:  Daily average Ca II K proxy index (393.4 nm).

Column 8:  Daily average Ca II H proxy index (396.8 nm).

Missing data are represented by -9.0 as a fill value.

NOTE: The Mg II index values are reported as derived from the OMI irradiance 
measurements. The Ca II K and Ca II H index values have been scaled to the 
scale of the National Solar Observatory ISS 1 A bandpass data sets.