Solarzenith angle (SZA) dependence of (a) crossing numbers, (b) median plasma beta (β, the ratio of thermal pressure to magnetic pressure), (c) median proton number density (), and (d) median proton temperature in PDR upstream of TD at every 10° of SZA. The error bars stand for the median absolute deviation (MAD, ΔX = median(|X_i −median(X_i)|); Hampel & Frank 1974). The values of and β in each bin roughly satisfy a power law and exponential distributions, respectively, which is completely different from a normal distribution (not shown). Thus, the median and MAD of the parameters are adopted here. The parameters of the proton in this figure are all from SWIA.