scostep 2010 (stp12) - Leibniz-Institut für Atmosphärenphysik an der ...

STP12 Abstracts
Berlin, 12 - 16 July 2010
SCOSTEP Symposium 2010
Morphology of 557.7 nm dayglow emission under varying solar activity conditions
Sunil Krishna MV , Singh Vir
Indian Institute of Technology Roorkee
The atomic oxygen emission at 557.7 nm is the most widely observed airglow feature in the
upper mesosphere and lower thermospheric regions. The approximation of solar irradiance
fluxes is very crucial in the modeling of this emission. The recently introduced Solar2000
EUV flux model is a suitable candidate to provide the solar EUV flux for any level of solar
activity on any given day. The Solar2000 EUV flux model has not been tested for its
applicability in the airglow modeling studies. In the present study a comprehensive model has
been developed to study the 557.7 nm dayglow emission using Solar2000 EUV flux model.
This study presents the model results of diurnal and yearly variations of 557.7 nm dayglow
emission under equinox conditions. The effect of varying solar activity on this emission is
studied for a period of five years (2001-2005) at a fixed date of April 3. This date is chosen
due to the fact of large variations in the solar activity during the period of five years. The
volume emission rates obtained from the model in the upper mesospheric region are found
higher than the observed results. This discrepancy is due to the extremely high values of solar
EUV flux generated by the Solar2000 EUV flux model at 102.5 and 103.7 nm wavelengths.
The model is found in good agreement with the measurements in the thermospheric region.
The morphology is presented as a function of F10.7 solar index for five years (2001 – 2005)
equator and 45◦ N at a fixed longitude.