Observations of Solar Activity (Mg II Index) by GOME, SCIAMACHY, and GOME-2

Mg II index data

The Mg II data are derived from GOME starting in June 1995 and ending in June 2011. SCIAMACHY did measurements between 2002 and 2012; GOME-2 started in 2007 and continues operation. All three data sets as well as the composite data are available (see links below). In recent years the GOME solar irradiance has degraded to about 20% of its value near 280 nm in 1995, so that the GOME data have become noisier.

Additional information

The emission core of the Mg II doublet (280 nm) exhibits the largest natural solar irradiance variability above 240 nm. It is frequently used as a proxy for spectral solar irradiance variability from the UV to EUV associated with the 11-yr solar cycle (22-yr magnetic cycle) and solar rotation (27d). Figure 1 shows the Mg II index derived from GOME (1996-2011), SCIAMACHY (2002-2012), and GOME-2 (2007-present).


By combining data from different satellites, a composite Mg II index can be derived that covers more than three solar cycles as shown in Figure 2.


Figure 1. Mg II core-to-wing ratio from GOME, SCIAMACHY, and GOME-2.




Figure 2. Composite Mg II index. Values indicated are the numbers of days for each satellite contributing to the composite index. Missing values were filled using scaled F10.7 cm radio flux data.




References

Cebula, R.P., and M.T. DeLand, 1998: Comparisons of the NOAA11 SBUV/2, UARS SOLSTICE, and UARS SUSIM MgII solar activity proxy indices, Sol. Phys. 177, 117-132

DeLand, M.T., and R. P. Cebula, 1998: Solar UV activity at solar cycle 21 and 22 minimum from NOAA 9 SBUV2 data, Sol. Phys. 177, 105-116.

DeLand, M.T., and R. P. Cebula, 1993: Composite MgII solar activity index for solar cycles 21 and 22, J. Geophys. Res. 98, 12809-12823.

de Toma, G., et al., 1997: Mg II core-to-wing index: Comparison of SBUV and SOLSTICE time series, J. Geophys. Res. 102, 2597-2610.

Floyd, L.E., et al., 1998: Solar cycle 22 UV spectral irradiance variability, Sol. Phys. 177, 79-87.

Snow, M., McClintock, W., Woods, T., White, O., Harder, J., and Rottman, G., The Mg II Index from SORCE, Solar Physics, 230, 325-344, 2005.

Snow, M., M. Weber, J. Machol, R. Viereck, and E. Richard, Comparison of Magnesium II core-to-wing ratio observations during solar minimum 23/24, J. Space Weather Space Clim., 4, A04, doi:10.1051/swsc/2014001, 2014.

Viereck, R.A., and L.C. Puga, 1999: The NOAA Mg II core-to-wing solar index: Construction of a 20-year time series of chromospheric variability from multiple satellites, J. Geophys. Res. 104, 9995-10005.

Viereck, R., L. Puga, D. McMullin, D. Judge, M. Weber, W.K. Tobiska, The Mg II Index: A Proxy for Solar EUV, Geophys. Res. Lett. 28, 1343-1346, 2001.

Viereck, R. A., L. E. Floyd, P. C. Crane, T. N. Woods, B. G. Knapp, G. Rottman, M. Weber, L. C. Puga, and M. T. DeLand, A composite Mg II index spanning from 1978 to 2003, Space Weather, 2, S10005, doi:10.1029/2004SW000084, 2004.

Weber, M., J.P. Burrows, and R.P. Cebula, 1998: GOME Solar UV/VIS Irradiance Measurements between 1995 and 1997 - First Results on Proxy Solar Activity Studies, Sol. Phys. 177, 63-77.

Weber, M., 1999: Solar activity during solar cycle 23 monitored by GOME, Proc. European Symposium on Atmospheric Measurements from Space (ESAMS'99), ESTEC, Noordwijk, The Netherlands, 18-22 January 1999, WPP-161, European Space Agency, p. 611-616 (PDF 431kbytes, PS gzipped 186kbytes).


written by Mark Weber
last change: 2014/04/16
Institute of Environmental Physics, University of Bremen