Fig. 1.

Mean (geometric weighted average; for details see Materials and Methods) of hourly CH₄ fluxes over the full diel cycle (black dots) in the lakes LJE (A) and VEN (B) during stratified period, and in VEN (C), ERS (D), and PRS (E) during the mixing period (n = 4,580). Colored areas indicate day (yellow) or night (blue) during the time of the measurements, depending on the time of the year at a given location. Gray indicates times that during the sampling period was classified either as day or night.