Ground Surface Temperature (GST) is defined as the near-surface temperature of the ground (bedrock or surficial deposits), measured in the uppermost centimeters of the ground. GST is not a direct proof of permafrost existence but a proxy for estimating potential permafrost presence or absence in the subsurface and can be used for calibrating and validating numerical models. GST has to be distinguished from the Bottom Temperature of Snow cover (BTS), which is the temperature measured at the snow/ground interface in late winter. The APD does not collect raw GST data but the Mean Annual Ground Surface Temperature (MAGST) of a certain depth.

In this paper we present a study concerning the climatic behaviour of two principal observables, temperature and precipitation as obtained from the measurements carried out at 50 Italian meteorological stations, since 1961. Analyses of WMO Climate Normals (CliNo) from 1961 to 1990 have been performed dividing the 50 Italian stations in three different classes: mountain (11 stations), continental (17) and coastal areas (21). The comparison of the CliNo 1961-1990 with the trend of temperature and precipitation for the period 1991-2000 showed a sharp significant increase of summer temperatures over Italy starting from 1980. This phenomenon was particularly evident for mountain stations, where a significant temperature increase has been recorded also during the autumn. Moreover, the analysis of precipitation data permitted to point out that, starting from 1980, mountain stations have been affected by a significant increase of precipitation events during autumn and winter, while for the rest of the Italian territory a reduction of precipitations has been recorded during early spring.

Temperature measured in boreholes (BH) is the most reliable evidence of permafrost presence or absence. BH data provides min/max/mean subsurface temperature at differing depth, maximum active layer thickness (ALT) and (if available) the depth of zero annual amplitude (ZAA). The APD does not collects raw borehole data but yearly synthesis data.

I parametri meteorologici (temperatura dell’aria, pressione atmosferica, umidità relativa, precipitazione, velocità e direzione del vento) sono misurati con una stazione meteorologica automatica Vaisala WXT520. Meteorological parameters (air-temperature, atmospheric pressure, relative humidity, rain precipitation, wind speed and direction) are measured by an automatic weather station (Vaisala WXT520). Technical details: Wind Speed (range: 0 - 60 m/s, response time: 250 ms, accuracy (0 - 35 m/s): ±0.3 m/s or ±3%, accuracy (35 - 60 m/s): ±5%; output resolutions: 0.1 m/s) units 0.1 mph, 0.1 knots Wind Direction (response time: 250 ms; accuracy ±3°; output resolution and unit 1°) Rainfall (output resolutions and units 0.01 mm, accuracy: 5%, Due to the nature of the phenomenon, deviations caused by spatial variations may exist in precipitation readings, specially in a short time scale. The accuracy specification does not include possible wind induced errors) Relative Humidity (Range: 0 - 100 %RH; Accuracy (0-90%): ±3 %. accuracu (90-100%):±5, output resolution and unit 0.1 %R) Barometric Pressure (Range: 600 - 1100 hPa; Accuracy (0 - +30 °C): ±0.5 hPa, accuracy (-52 - +60 °C ): ±1 hPa, Output resolutions and units: 0.1 hPa) Air Temperature (Range: -52 - +60 °C; Accuracy for sensor at +20 °C: ±0.3 °C)

I parametri meteorologici (temperatura dell’aria, pressione atmosferica, umidità relativa, precipitazione, velocità e direzione del vento) sono misurati con una stazione meteorologica automatica Vaisala WXT520. Meteorological parameters (air-temperature, atmospheric pressure, relative humidity, rain precipitation, wind speed and direction) are measured by an automatic weather station (Vaisala WXT520). Technical details: Wind Speed (range: 0 - 60 m/s, response time: 250 ms, accuracy (0 - 35 m/s): ±0.3 m/s or ±3%, accuracy (35 - 60 m/s): ±5%; output resolutions: 0.1 m/s) units 0.1 mph, 0.1 knots Wind Direction (response time: 250 ms; accuracy ±3°; output resolution and unit 1°) Rainfall (output resolutions and units 0.01 mm, accuracy: 5%, Due to the nature of the phenomenon, deviations caused by spatial variations may exist in precipitation readings, specially in a short time scale. The accuracy specification does not include possible wind induced errors) Relative Humidity (Range: 0 - 100 %RH; Accuracy (0-90%): ±3 %. accuracu (90-100%):±5, output resolution and unit 0.1 %R) Barometric Pressure (Range: 600 - 1100 hPa; Accuracy (0 - +30 °C): ±0.5 hPa, accuracy (-52 - +60 °C ): ±1 hPa, Output resolutions and units: 0.1 hPa) Air Temperature (Range: -52 - +60 °C; Accuracy for sensor at +20 °C: ±0.3 °C)