Fig. 4: Atmospheric circulation evolution in mid-troposphere.

ERA5 500 hPa geopotential height (gpm, shaded) and wind (m s−1, arrows) at 15 UTC on 2 (a), 4 (b), 6 (c) and 8 (d) February, 2020.

ERA5 500 hPa geopotential height (gpm, shaded) and wind (m s−1, arrows) at 15 UTC on 2 (a), 4 (b), 6 (c) and 8 (d) February, 2020.