Figure 11.

Time series of data recorded by a multi-channel sensor (f at 20 MHz) in sand with low clay content during summer 2015. Fluctuations of medium permittivity and conductivity of each channel are correlated to diurnal cycles of soil temperature at the same level. Data at depth 5–10 cm (red), at depth 10–15 cm (dark) and at depth 15–20 cm (green).