Data & Methods - European Trend Atlas of Extreme Temperature and Precipitation Records - page 8

Fig. 2.1 Overview map showing the meteorological Tmin and Tmax
observations used for each period and the regional division used for the
period 1901-2000

Fig. 2.2 Overview map showing the meteorological Tmean observa-
tions used for each period and the regional division used for the period
1901-2000

2.1 Climate Indices Calculated

quality controlled and homogenized within the HISTALP
project (Auer et al. 2007). There is an obvious need for in-
creased resources and efforts going into further developing
homogenization methods in order to improve data quality
especially for observations with temporal resolution higher
than monthly, last but not least with respect to climatology
beyond mean conditions. Brunet and Jones (2011) estimate
that about 80 % of past climate data is still unavailable to the
research community hampering a more robust assessment of
climate parameters.

All the selected indices have been computed for each of
the three periods described above. Typically there was one
value per season per index comprising the index timeseries
(100, 150 or 200 years) which was then used for the trend
estimation. The indices are listed and explained in Table 2.2 .
Most indices are either percentiles or percentile-based.
With percentiles the most extreme values in both tails of