Imaging date (as day-of-year 2017) vs. the median-averaged global ME expansion from the UVS reference oval for those northern-hemisphere HST image series with known magnetospheric (MS) compression states, after Yao et al. (2022). An uncompressed magnetosphere is denoted by a red triangle and a compressed magnetosphere by a green square. The average ME expansion in the uncompressed-magnetosphere case (−600 km) is denoted by a red dot-dashed line, and that in the compressed-magnetosphere case (−1600 km) by a green dashed line. The shaded regions around each average-value line denote the 1σ range.