Estimated upper limits to the abundances of hydrated Cl-bearing salts in our observations. The observed regions on Europa are shown in the middle inset. (a) Estimated absorption depth of hydrated Cl-bearing salts as a function of abundance compared with the noise levels of our observations. (b) Absorption of hydrated Cl-bearing salts for the estimated upper limits to the abundances at 111° ± 25°W, 38° ± 16°S compared with the residuals of the reflectance spectra fitted by the polynomial regression line at 1.150–1.255 μm (Figure 9(b)). Offsets have been added to the spectra of hydrated Cl-bearing salts and residuals for clarification.