Different time stamping procedure

[BaptisteVandecrux]

"the time stamp of GC-Net [...] is half an hour
after the interval mid-point (i.e., data stamped as 8 a.m. represent
the average from 7 to 8 a.m.); the one of PROMICE is
half an hour before the interval mid-point (i.e., data stamped
as 8 am represent the average from 8 to 9 a.m.)."

Wang, W., Zender, C. S., van As, D., Smeets, P. C. J. P., and van den Broeke, M. R.: A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: application to Greenland, The Cryosphere, 10, 727–741, https://doi.org/10.5194/tc-10-727-2016, 2016.