Heavy rainfall, floods, and flash floods in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere system

Abstract

Abstract. Heavy rainfall events causing floods and flash floods are examined in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere system. The superposed epoch (SPE) analyses of solar wind variables have shown a tendency of severe weather to follow arrivals of high-speed streams from solar coronal holes (Prikryl et al., 2018). Precipitation datasets based on rain-gauge and satellite sensor measurements are used to examine the relationship between the solar wind high-speed streams and daily precipitation rates over several mid-latitude regions. The SPE analysis results show an increase in occurrence of high precipitation rates following arrivals of high-speed streams, including recurrence with a periodicity of 27 days. The cross-correlation analysis applied to the SPE averages of the green (Fe XIV, 530.3 nm) corona intensity observed by ground-based coronagraphs, solar wind parameters and daily precipitation rates show correlation peaks at lags spaced by solar rotation period. When the SPE analysis is limited to years around the solar minimum (2008–2009), which was dominated by recurrent coronal holes separated by ~120˚ in heliographic longitude, significant cross-correlation peaks are found at lags spaced by 9 days. These results are further demonstrated by cases of heavy rainfall, floods and flash floods in Europe, Japan, and the U.S., highlighting the role of solar wind coupling to the magnetosphere-ionosphere-atmosphere system in severe weather, mediated by aurorally excited atmospheric gravity waves.

Occurrence of heavy precipitation influenced by solar wind high-speed streams through vertical atmospheric coupling

“…The superposed epoch analysis (SPE) method (Ambrož, 1979) is applied on the time series of green corona intensity, solar wind parameters and high-rate precipitation keyed to heavy rainfall events, arrivals of major HSSs/CIRs (Prikryl et al, 2021a;Prikryl et al, 2021b), or the maximum growth rate of extratropical cyclones (Prikryl et al, 2016(Prikryl et al, ). 10.3389/fspas.2023 3 The SPE analysis of high precipitation occurrences in the context of solar wind HSSs Following the approach taken in previous studies ( Prikryl et al, 2021a;Prikryl et al, 2021b), the SPE analysis (Figures 1A, B) of the time series of the green corona intensity and solar wind variables is keyed to the initial days of heavy rainfall events that lead to floods in Canada. For each epoch day, Figure 1C shows, for the IMERG data that are available since 2000, the cumulative number of IMERG grid cells over Canada up to 60°N of latitude where daily precipitation rates exceeded thresholds of 60, 80, 100, and 120 mm.…”

“…A tendency of significant weather conditions, including explosive extratropical cyclones (Prikryl et al, 2016;Prikryl et al, 2018), rapid intensification of tropical cyclones (Prikryl et al, 2019), and heavy rainfall causing floods (Prikryl et al, 2021a;Prikryl et al, 2021b), to follow arrivals of solar wind high-speed streams from coronal holes has been observed. A possible physical mechanism that could explain these results was proposed (Prikryl et al, 2003;Prikryl et al, 2007;Prikryl et al, 2009a;Prikryl et al, 2009b).…”