Extreme ultraviolet solar irradiance during the rising phase of solar cycle 24 observed by PROBA2/LYRA

Abstract

The Large-Yield Radiometer (LYRA) is a radiometer that has monitored the solar irradiance at high cadence and in four pass bands since January 2010. Both the instrument and its spacecraft, PROBA2 (Project for OnBoard Autonomy), have several innovative features for space instrumentation, which makes the data reduction necessary to retrieve the long-term variations of solar irradiance more complex than for a fully optimized solar physics mission. In this paper, we describe how we compute the long-term time series of the two extreme ultraviolet irradiance channels of LYRA and compare the results with those of SDO/EVE. We find that the solar EUV irradiance has increased by a factor of 2 since the last solar minimum (between solar cycles 23 and 24), which agrees reasonably well with the EVE observations. © Owned by the authors, Published by EDP Sciences 2012.