water.
Since, in this study, the focus is on large-scale storm systems, persisting for at least one day,
variability on shorter time-scales (mainly the diurnal cycle and atmospheric tides) is eliminated
by calculating averages from the four 6-hourly reanalysis fields of each day (6-hourly precip-
8
Figure 1.
Top: Average fields of 500 hPa geopotential height in winter (DJF 1989-90)
and summer (JJA
/media/vedurstofan/utgafa/skyrslur/2015/VI_2015_005.pdf