Bibliography

Extreme Ultraviolet Variability Experiment (EVE) on~the~Solar Dynamics Observatory (SDO): Overview~of~Science Objectives, Instrument Design, Data~Products, and Model Developments

The highly variable solar extreme ultraviolet (EUV) radiation is the major energy input to the Earth\textquoterights upper atmosphere, strongly impacting the geospace environment, affecting satellite operations, communications, and navigation. The Extreme ultraviolet Variability Experiment (EVE) onboard the NASA Solar Dynamics Observatory (SDO) will measure the solar EUV irradiance from 0.1 to 105\ nm with unprecedented spectral resolution (0.1\ nm), temporal cadence (ten seconds), and accuracy (20\%). EVE includes several irradiance instruments: The Multiple EUV Grating Spectrographs (MEGS)-A is a grazing-incidence spectrograph that measures the solar EUV irradiance in the 5 to 37\ nm range with 0.1-nm resolution, and the MEGS-B is a normal-incidence, dual-pass spectrograph that measures the solar EUV irradiance in the 35 to 105\ nm range with 0.1-nm resolution. To provide MEGS in-flight calibration, the EUV SpectroPhotometer (ESP) measures the solar EUV irradiance in broadbands between 0.1 and 39\ nm, and a MEGS-Photometer measures the Sun\textquoterights bright hydrogen emission at 121.6\ nm. The EVE data products include a near real-time space-weather product (Level\ 0C), which provides the solar EUV irradiance in specific bands and also spectra in 0.1-nm intervals with a cadence of one minute and with a time delay of less than 15\ minutes. The EVE higher-level products are Level\ 2 with the solar EUV irradiance at higher time cadence (0.25\ seconds for photometers and ten seconds for spectrographs) and Level\ 3 with averages of the solar irradiance over a day and over each one-hour period. The EVE team also plans to advance existing models of solar EUV irradiance and to operationally use the EVE measurements in models of Earth\textquoterights ionosphere and thermosphere. Improved understanding of the evolution of solar flares and extending the various models to incorporate solar flare events are high priorities for the EVE team.

Woods, T.; Eparvier, F.; Hock, R.; Jones, A.; Woodraska, D.; Judge, D.; Didkovsky, L.; Lean, J.; Mariska, J.; Warren, H.; McMullin, D.; Chamberlin, P.; Berthiaume, G.; Bailey, S.; Fuller-Rowell, T.; Sojka, J.; Tobiska, W.; Viereck, R.;

Published by: Solar Physics      Published on: 01/2012

YEAR: 2012     DOI: 10.1007/s11207-009-9487-6

EVE; SDO; Solar EUV irradiance; Space weather research

Solar EUV Experiment (SEE): Mission overview and first results

[1]\ The Solar EUV Experiment (SEE) is one of four scientific instruments on the NASA Thermosphere Ionosphere Mesosphere Energetics Dynamics (TIMED) spacecraft, which has been simultaneously observing the Sun and Earth\textquoterights upper atmosphere since January 2002. The SEE instrument measures the irradiance of the highly variable, solar extreme ultraviolet (EUV) radiation, one of the major energy sources for the upper atmosphere. The primary SEE data product is the solar spectral irradiances from 0.1 to 194 nm in 1 nm intervals that are fundamental for the TIMED mission\textquoterights investigation of the energetics in the tenuous, but highly variable, layers of the Earth\textquoterights atmosphere above 60 km. The TIMED mission began normal operations on 22 January 2002, a time when the Sun displayed maximum levels of activity for solar cycle 23, and has provided daily measurements as solar activity has declined to moderate levels. Solar irradiance variability observed by SEE during the 2 years of the TIMED prime mission includes a variety of moderate and large flares over periods of seconds to hours and dozens of solar rotational cycles over a typical period of 27 days. The SEE flare measurements provide important, new results because of the simultaneous spectral coverage from 0.1 to 194 nm, albeit limited temporal coverage due to its 3\% duty cycle. In addition, the SEE measurements reveal important, new results concerning phase shifts of 2\textendash7 days in the intermediate-term variations between different UV wavelengths that appear to be related to their different center-to-limb variations. The new solar EUV irradiance time series from SEE are also important in filling the \textquotedblleftEUV Hole,\textquotedblright which is the gap in irradiance measurements in the EUV spectrum since the 1980s. The solar irradiances measured by SEE (Version 7, released July 2004) are compared with other measurements and predictions from models of the solar EUV irradiance. While the measurement comparisons show reasonable agreement, there are significant differences between SEE and some of the models in the EUV range. The data processing algorithms and calibrations are also discussed.

Woods, Thomas; Eparvier, Francis; Bailey, Scott; Chamberlin, Phillip; Lean, Judith; Rottman, Gary; Solomon, Stanley; Tobiska, Kent; Woodraska, Donald;

Published by: Journal of Geophysical Research: Space Physics (1978\textendash2012)      Published on:

YEAR: 2005     DOI: 10.1029/2004JA010765

thermosphere; solar activity cycle; solar irradiance; ultraviolet emissions; solar effects