engleski

Spatial and seasonal variability and trends of extreme soil temeprature in Croatia

Soil temperature analysis is becoming more important in the climate change issue. In this paper, the focus is on the trend analysis of extreme soil temperatures, which are very important for the management of crops in agriculture. Maximal and minimal soil temperatures were analyzed on annual and seasonal scale for depths 2, 5, 10 and 20 cm for the period 1961–2010. Monthly, seasonal, and annual data were extracted from daily measurements at a standard climatological time (7 h, 14 h, 21 h CET) at 18 meteorological stations. The variability of detrended data is represented by interquartile range. Trends were determined by Theil Sen's estimator, and statistical significance on 5 % level was determined using the Mann-Kendall test.In general, variability decreases with depth in all seasons, and is larger for maximal soil temperature of surface layer. The results of trend analysis show a general increase of maximal soil temperature at almost all stations in spring and summer seasons, whilst the number of significant trends of minimal soil temperature is much smaller in all seasons. Trends of annual maximal soil temperature are almost equal to summer trends, and ranges from 1.0–2.3 °C/decade. Significant trends of minimal soil temperature are smaller for an order of magnitude (-0.4–0.7°C/decade), with few exceptions in the surface layer of spring and summer season. The analysis shows a significant increase of the maximum soil temperature in spring and summer seasons in agricultural areas and the results may suggest the necessary adjustments to farmers when choosing seeding varieties.

soli temperature ; extreme meteorological events

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