Seasonal cycle of diurnal range of land surface temperature

"Diurnal range / average" of clear-sky upward LW radiation, Sept. - March

Calculated from NASA Langley SRB Rel. 2 LW data (Nov. 1985 -- Oct. 1995)
NH tropics + East Asia mid-lat.:SH tropics + N. Amer. mid-lat. + cold region(?)