M. Hulme et al., CONSTRUCTION OF A 1961-1990 EUROPEAN CLIMATOLOGY FOR CLIMATE-CHANGE MODELING AND IMPACT APPLICATIONS, International journal of climatology, 15(12), 1995, pp. 1333-1363
A 1961-1990 mean monthly climatology for a 'greater European' region e
xtending from 32 degrees W to 66 degrees E and from 25 degrees to 81 d
egrees N has been constructed at a resolution of 0.5 degrees latitude
by 0.5 degrees longitude for a suite of nine surface climate variables
: minimum, maximum, and mean air temperature; precipitation totals; su
nshine hours; vapour pressure; wind speed; and (ground) frost day and
rain day (>0.1 mm) frequencies. This climatology has been constructed
from observed station data distributed across the region. Station freq
uencies range from 936 (wind speed) to 3078 (precipitation). Over 95 p
er cent of these data are based on observations between 1961 and 1990
and over 90 per cent were supplied by individual national meteorologic
al agencies (NMAs) on specific request. For four variables, some stand
ardization of the data had to be performed because different countries
supplied data under different definitions. Thus cloud cover had to be
converted to sunshine hours, relative humidity to vapour pressure, ai
r frost days to ground frost days and rain days > 1 mm to rain days >0
.1 mm. The interpolation of the station data to the grid used elevatio
n as one of the predictor variables and thus enabled three climate sur
faces to be produced for each variable, reflecting the minimum, mean,
and maximum elevation within each 0.5 degrees by 0.5 degrees cell. Sub
sets of stations were used for the interpolation of each variable, the
selection being based on optimizing the spatial distribution, source
priority and length of record. The accuracy of the various interpolati
ons was assessed using validation sets of independent station data (i.
e. those not used in the interpolation). Estimated mean absolute error
s (MAE) ranged from under 4 per cent for vapour pressure to about 10 p
er cent for precipitation and up to 20 per cent for wind speed. The ac
curacy of the interpolated surfaces for minimum and maximum temperatur
e was between 0.5 degrees C and 0.8 degrees C. We believe these result
s constitute the first climatology that has been constructed for this
extensive European region at such a fine spatial resolution (0.5 degre
es by 0.5 degrees) from relatively dense station networks, for three d
ifferent elevation surfaces and for a wide range of surface climate va
riables, all expressed with respect to a standard 30-year period. The
climatology is already being used by researchers for applications in t
he areas of ecosystem modelling, climate change impact assessment and
climate model validation, and is available from the authors.