engleski

Estimation of air temperature at 5 cm above grassland at the Zagreb-Maksimir Observatory

The possibility to estimate air temperature at 5 cm above grassland is examined using an empirical as well as a theoretical approach. For this purpose, hourly data (air temperature, cloudiness, air pressure and wind speed) at the Zagreb-Maksimir Observatory (Croatia) for the period June-August 1975 have been used. A clustering procedure has been applied to form groups of days having similar diurnal variations of the air temperature difference between 5 cm and 2 m. In this way, three groups of similar days (types) have been found. The air temperature at 5 cm above grassland has been estimated using the multiple regression method and a method which is based on the Monin-Obukhov similarity theory. The results obtained are more accurate for near-neutral stability conditions, i.e. during cloudy weather (Type 1), and the least accurate in the case of clear sky (Type 3). Through clustering, systematic errors have been discovered in these approaches and shortly discussed.

Air temperature at 5 cm; Clustering; Multiple regression; Monin-Obukhov similarity theory.

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