engleski

Climatological basis for prediction of temperature regime on ground

In the lack of the data on air and road surface temperatures, the climatological data from the site of the meteorological station have been used to determine temperature relations needed for predicting of road slipperiness. The analysis is deduced for the cold period of the year (September to May) for the 10-year period (1971-1980) at station Zagreb-Maksimir, located in the Sava river valley at the foot of mount Medvednica. The analysis involves the relations in minimum air temperatures at two levels, 2m and 5cm as well as minimum air temperatures at 2m height and soil temperatures at 5cm depth at 7am during various weather situations, defined by means of average cloudiness and wind conditions as well as situations with fog and frozen ground during the night preceding the occurrence of minimum temperatures. In weather situations with prevailing radiation processes (clear/calm and partly cloudy/calm) minimum surface air temperatures are always lower than at 2m height. On the contrary, after cloudy nights, without regard to the wind velocity, minimum surface temperatures are lower than those at 2m only over determined temperature levels. Minimum air temperatures at 5cm height are lower than 0oC when the minimum temperatures at 2m height are lower than 3oC during clear/calm, clear/windy and partly cloudy/calm situations. During partly cloudy/windy, cloudy/calm and cloudy/windy situations differences between the minimum temperatures at two levels are lower, and consequently, negative minimum surface temperatures appear if the minimum temperatures at 2m are about 0oC. Relations between minimum air temperatures and soil temperatures do not differ significantly for different weather types. However, they are pronounced between months. According to these conclusions, soil temperatures should be predicted particularly by means of regression equations deduced for each month.

temperature; soil temperature; weather types; correlation

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