The
role of orography was found to be crucial in determining the precipitation dis-
tribution and amount.
Atmospheric flow over Iceland was simulated for the period January 1961
through June 2006 using version 3–7–3 of the PSU/NCAR MM5 mesoscale
model (Grell et al., 1995). The domain used is 123× 95 points, centered at
64◦ N and 19.5◦ W, with a horizontal resolution of 8 km. There are 23 vertical
/media/ces/Paper-Olafur-Rognvaldsson_91.pdf
hydrological model. J. Hydrol., 267, 40–52.
Jasper, K., and Kaufmann P. 2003. Coupled runoff simulations as validation
tools for atmospheric models at the regional scale. Q. J. R. Meteorol. Soc., 129,
673–692.
Jóhannesson, T., Aðalgeirsdóttir G., Björnsson H., Crochette P., Elíasson E.
B., Guðmundsson S., Jónsdóttir J. F., Ólafsson H., Pálsson F., Rögnvaldsson
Ó., Sigurðsson O., Snorrason Á
/media/ces/Paper-Olafur-Rognvaldsson_92.pdf
properly even if the
sample size is increased and systematic biases may be expected.
2.2.3 Predictors
Mean sea level pressure (MSLP), geopotential height (Z), specific humidity (q) and tempera-
ture (T) at different pressure levels are considered in this study to describe the meteorological
situations at the synoptic scale and to identify weather analogues. The MSLP and geopotential
height (Z) describe
/media/vedurstofan/utgafa/skyrslur/2014/VI_2014_006.pdf
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
the maximum discharge of jökulhlaup water at the glacier
terminus is estimated as 97 m3 s 1. This jökulhlaup was a fast-rising jökulhlaup as
other jökulhlaups in Skaftá and cannot be described by the traditional Nye-theory of
jökulhlaups. The total volume of flood water was estimated as 53 Gl. The average
propagation speed of the subglacial jökulhlaup flood front was found to be in the range
0.2–0.4 m s 1
/media/vedurstofan/utgafa/skyrslur/2009/VI_2009_006_tt.pdf
absolute errors (MAEs) are listed in Table 1. For
temperature, the overall bias in January is reduced by 86%, with a reduction in overall MAE of
17%. For wind speed, the overall January bias is reduced by 74%, with a reduction in overall
MAE of 9%. Both, for temperature and wind speed, the main benefit of the correction procedure
is a reduction of differences between monthly mean values. Mean absolute
/media/vedurstofan/utgafa/skyrslur/2014/VI_2014_005.pdf
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/media/loftslag/Outline_for_the_case_Road_maintenance_in_a_changing_climate.pdf
contours). Bottom panel: manned and automated surface
observations over Iceland.
13
Figure 4. Hourly rainfall during 3 September 2012, based on HARMONIE model simula-
tions. Times are in UTC (local time).
14
Figure 5. Distribution of low- (red crosses), medium- (green vertical lines), and high-
level (blue horizontal lines) cloud cover of at least 90%, based on HARMONIE model
simulations. Terrain
/media/vedurstofan/utgafa/skyrslur/2015/VI_2015_006.pdf
approximately centred around Iceland: the outer domain with
43 42 grid points spaced at 27 km (1134 1107 km), the intermediate domain with 9590 grid
points spaced at 9 km, and the inner domain with 196 148 grid points spaced at 3 km. The
northwest corner of the outer domain covers a part of the southeast coastal region of Greenland.
Otherwise, the only landmass included in the model domain
/media/vedurstofan/utgafa/skyrslur/2013/2013_001_Nawri_et_al.pdf