Soft X-ray irradiances during solar flares observed by TIMED-SEE

Abstract

Observations from the Thermosphere Ionosphere Mesosphere Energetics Dynamics-Solar Extreme Ultraviolet Experiment (TIMED-SEE) are analyzed to determine the solar soft X-ray energy emission during a solar flare. The TIMED-SEE X-ray ultraviolet Photometer System (XPS) detectors utilize broadband photodiodes that observe from 0.1 to 27 nm. The XPS observed 29 flares of various strengths over a 6-month period in 2002. We describe an emission measure technique to interpret the broadband observations and determine a best fit flare spectrum. This technique is applied to the 29 flares observed by the XPS. Our results show that most of the enhancement in the solar spectrum during a flare comes from the 0-2 nm wavelength range. We also show that the XPS calculated 0.1-0.8 nm irradiance for brighter M-class and X-class flares is in good agreement with the Geostationary Operational Environmental Satellites (GOES) observed 0.1-0.8 nm irradiance. Also, the XPS 0-7 nm flare irradiance is well correlated with the 0.1-0.8 nm irradiance observed by GOES. We show that the total 0-7 nm irradiance of smaller X-class flares (X1-X5) calculated at the time of the XPS observation provides 2-3 times the energy of the quiet Sun 0-7 nm irradiance. Copyright 2006 by the American Geophysical Union.