Title: Is F10.7 a Good Proxy for Solar EUV Flux?
Author: K. K. Mahajan
Affil: National Physical Laboratory, New Delhi
Email: mahajan@csnpl.ren.nic.in
Authors: N.K.Sethi
Abstract: The Langmuir probe acted as a photo-diode on Pioneer Venus Orbiter and measured the integrated solar EUV flux (ipe) over a 13-year period from March 1979 to April 1992. Since F10.7, the solar radio flux, has often been used as a proxy for the EUV flux, we examine the relationship between ipe and F10.7 during the PVO measurements. We observe that daily F10.7 is a poor proxy for the EUV flux on day on day to day basis. However, the 81-day averaged F10.7 shows a linear relationship with the 81-day averaged ipe up to about 160 flux units, above which ipe rises sharply. We also study the relationship of ipe with solar Lyman alpha and solar magnetic field and conclude that these are better proxies for the EUV flux, than F10.7, at all levels of solar activity.