Solar extreme ultraviolet irradiance observations from GOES: design characteristics and initial performance

Abstract

Solar EUV irradiance plays a critical role in the variability of the upper atmosphere and ionosphere of Earth. Many systems are impacted by these terrestrial changes including radio communication, GPS navigation, and satellite orbits. Monitoring the solar EUV irradiance in the past has been left to research satellites and there have been long periods where gaps in the observational record make it difficult to study and understand the long-term trends and impacts on Earth. The National Oceanic and Atmospheric Administration (NOAA) has, for the first time, included an EUV Sensor (EUVS) on the Geostationary Environmental Operational Satellite (GOES). This EUV Sensor (EUVS), launched in May 2006, is design to provide the solar EUV irradiance information most critical to understanding and modeling Earth's upper atmosphere. The EUVS has five broad EUV channels between 5 and 125 nm. It uses transmission gratings and thin-film filters for wavelength discrimination and silicon diodes for detectors. The EUVS was extensively calibrated at the Brookhaven National Labs Synchrotron Light Source with calibration standards traceable to NIST. It samples the solar irradiance every ten seconds on a continuous basis from geosynchronous orbit. This paper will provide an overview of the EUVS design, calibration, and performance results.