Identification and replacement of proton‐contaminated real‐time ACE solar wind measurements

Abstract

[1] Real-time solar wind speed measurements derived from measurements by the Solar Wind Electron, Proton, and Alpha Monitor (SWEPAM) aboard the Advanced Composition Explorer (ACE) satellite are critical to specifying and forecasting current space weather and its impacts. When solar energetic protons produce high background levels in SWEPAM, the real-time solar wind speed measurements can be corrupted due to errors in the onboard algorithm. We analyzed 14 years of ACE real-time solar wind data for the years 1998 through 2011 to determine how to identify the contaminated measurements and what proxy might be substituted for these corrupt data. We find that good criteria for flagging contaminated data are that (1) the measured solar wind speeds are below 305 km s , and (2) the >10 MeV ion fluxes measured by the ACE Solar Isotope Spectrometer (SIS) are above 180 pfu. We also compare several potential proxies for the contaminated solar wind and determine that the best proxy depends on the last valid measured wind speed, v initial , and the duration of the contamination period. For the first 25 h, the best proxy is simply v initial . At later times, if v initial < 400 km s

On the Considerations of Using Near Real Time Data for Space Weather Hazard Forecasting

“…Haines et al., 2021). Meanwhile, longer time‐scale reconstruction of solar wind data has also been performed using ground based indices (Kataoka & Nakano, 2021; Machol et al., 2013) and magnetosheath data (Nabert et al., 2015). However, while ground magnetometer data may be available in NRT, filling NRT data gaps with such reconstructions may be challenging in an operational forecast.…”

“…However, given limited telemetry and processing the NRT data are an approximation of the full scientific data that will later be available. This may lead to differences in the value that the data take, and also whether data are available for some intervals (e.g., Machol et al., 2013). Nonetheless, the NRT data must be used in order to provide actionable forecasts of upcoming hazardous space weather.…”

Reconstruction of gaps in the past history of solar wind parameters

“…As a future line of research, SSA gap‐filling technique can be extended for filling the gaps in solar wind parameters that result in ACE measurements that are contaminated by solar proton events [ Machol et al , ]. Another promising extension of the presented results would be to predict solar wind data in real‐time setting and with 1 min resolution, where it can be potentially useful to include other geomagnetic indices (such as polar cap PC index) into SSA gap‐filling procedure.…”