HiRISE observations of Recurring Slope Lineae (RSL) during southern summer on Mars

•HiRISE image survey to understand geologic context and characteristics of RSL.•Discovered new RSL sites and confirmed sites from previous studies.•In depth study of RSL seasonality, surface temperature and other surface properties.•Strong seasonality, geographical distribution and formation temperature observed.•Brine hypothesis best explains the observed correlation and morphology.