THE CLIMATE OF LAGO MAGGIORE AREA DURING THE LAST FIFTY YEARS

Data collected in over 50 years' activity at the C.N.R. meteorological station of Pallanza were analysed to see whether any changes have taken place in some climatic elements and to quantify the extent of such changes. A statistical analysis of the respective historical series was performed on nine meteorological parameters (solar radiation, insolation, air temperature, atmospheric pressure, humidity, cloud cover, precipitation, evaporation and wind), and on two other strictly limnological features: the level of Lago Maggiore and its water temperature at six different depths. In particular, we evaluated the means and the extremes (maxima and minima) on an annual, seasonal, monthly and daily level, with the results presented uniformly for all the parameters, also in graphic form. We especially highlighted the trend lines, even though they were not always statistically significant owing to the extreme variability of the meteorological data; in the absence of statistical validity, their significance is an approximate indication of their increasing or decreasing trend. Results showed that insolation, air temperature and atmospheric pressure had increased markedly over time, at least on an annual level, with the trends for solar radiation, humidity and cloud cover also showing an increase, though very slight. Evaporation and wind showed a steady, marked decrease, while precipitation and lake level were essentially stable. Water temperature showed a more varied picture, with the temperature of the topmost levels (to a depth of 10 m) continuing to increase.