Hysteresis and Longitudinal Variation in Air–Water Temperature Relationships in the Han River Basin

We examined changes in water temperature in relation to air temperature in the two upper, two middle and lower reaches of the Han River basin, Republic of Korea. Air and water temperatures were monitored from 2020 to 2025, with analyses restricted to the May–October period of each year. TW exhibited pronounced spatial variability, whereas TA exhibited relatively low spatial variability. Hysteresis loops were analyzed separately for the warming (May–July) and cooling (August–October) phases using