www.foralps.net [email protected] 2nd FORALPS CONFERENCE Salzburg, 28 November 2007

RECONSTRUCTION / ANALYSIS OF THE TEMPERATURE AND PRECIPITATION SERIES OF Michele Tarolli (1) , Roberto Rea (2) , Dino Zardi (3)

(1) PAT – Ufficio Previsioni e Organizzazione (2) of Campitello of Fassa (3) Dpt. Civil and Environmental Enigneering Trento - Trento – Italy Trento - Italy

The Fiemme Valley is one of the most remarkable valleys in the north-eastern part of , delimited northward by the Dolomities and furrowed by the River, a tributary of the Adige River. Studying its climate can be interesting for several reasons: mainly it allows to evaluate the climate of an area that has never been studied in the past. In addition, being the economy of the Valley strickly connected with the climate features (tourism), it is important to understand the climate evolution of the area, and to know possible trends assumed by the variables in the last century.

CAVALESE (1882-2006) (1896-2006) To perform this analysis four weather stations have been selected: , Predazzo, Paneveggio and Passo Rolle. This choice allows to evaluate the values of the variables not only at different points of the valley axis, but also at Satellite image of the north-east of Italy. Fiemme different altitudes. Valley is located in the pre-alpine area not far from The history of the stations was investigated and all the useful informations Trento and Bolzano. collected. The oldest station is Cavalese (first data go back to the 1882) and all the four weather stations are antecents the XX century. Unfortunately both Position of the weather station at the Dr. Agreiter collecting the data (left) series of Paneveggio (temperature and precipitation) display many gaps in the beginning of the century How appears the area today (right) measurements and it is not possible to make a significant analysis of them.

PANEVEGGIO (1895-2006) PASSO ROLLE (1895-2006) All the series, besides being incompletes, are also affected by inhomogeneties. To perform a correct analyis it is necessary to evaluate the quality of the data; this is done by comparing the values (monthly data) with reference series, evaluated on the basis of a weighted mean of correlation coefficients of the reference series with each single station. The series used as reference are from Trento, Bolzano/Bozen, Rovereto, Riva, Verona, Mantova, Belluno, Monte Maria/Marienberg. The test used is the Standard Normal Homogeneity Test The Fiemme Valley with the four stations analysed Paneveggio at the beginning of the century The weather station of Passo Rolle (red points) (only few houses) (today) close to the peak (Alexanderson and Moberg, 1997).

Temperature: Precipitation:

From the graph (on the left) it appears that on Meanly summer is characterized by the larger average July is the hottest month of the year, while amounts of rain while winter presents the lowest January is the coldest. The lapse rate is around 0.6 values (100 mm).The graph (on the right) shows °C/100 m (value usually referred to these latitudes), that the difference between the stations on the

Monthly mean temperature (°C) but its value is minimum in winter (around 0.4 valley floor (Cavalese and Predazzo) and the Monthly amount of rain (mm) °/100metres) and maximum in summer ( ~ 0.75 elevated one, Passo Rolle, is maximum in summer °/100metres) . (probably due to convective precipitations).

Finally the data are interpolated to evaluate possible Concerning the data of precipitation no clear trends. For the temperature, according to the trends can be inferred in the series. Some years indications of the IPCC (intergovernmental Panel on are characterized by larger amount of rains, while Cavalese mean temperature (°C) Climate Change ), the tendency is positive (around others are quite dry, but it does not seem that the Cavalese total precipitation (mm) 1°C/sec). This trend affects all the stations and total amount of rain has increased/decreased. increases analysing the last decades. Seasonaly, Similarly, the last winters (in the last two decades) summer and winter are characterized by the have been characterized by lower amounts of maximum values of the trend. precipitation, while intense precipitation events are increasing in number, particularly in autumn. Predazzo mean temperature (°C) Predazzo total precipitation (mm)

TREND (°C/ century) TREND (mm/ century)

Cavalese Predazzo Passo Rolle Cavalese Predazzo Passo Rolle (1882-2006) (1896 -2006) (1895-2006) (1882-2006) (1921 -2006) (1895-2006)

1.03 ± 0.47 1.06 ± 0.18 0.97 ± 0.21 -20 ± 35 -58 ± 78 6 ± 73

Passo Rolle mean temperature (°C) Passo Rolle total precipitation (mm)

Contacts

Eng. Michele Tarolli Eng. Roberto Rea Prof. Dino Zardi Provincia Autonoma of Trento- Meteotrentino Comune of Campitello of Fassa Atmospheric Physics Group Ufficio Previsioni e Organizzazione Trento - Italy Dpt. Civil and Environmental Engineering E-mail : Michele [email protected] E-mail: [email protected] University of Trento E-mail: [email protected]