The Character of Soil Temperature Regime over Turkey

Abstract

This paper presents the spatial and temporal characteristics of Turkish soil temperature regimes. Basic data consists of the monthly soil temperature averages from 153 stations at depths of 5, 10, 20, 50 and 100 cm for 44 years (1975-2018) record length. The soil temperature regime of Turkey has been analyzed based on both classical climatic regime approach (monthly average soil temperature change) and Soil Taxonomy. As expected, The annual course of soil temperatures differs between the coastal and inland areas of Turkey and in the western and eastern half. Latitude and continentality shapes the soil temperature regime in the eastern half of Turkey while elevation shapes the soil temperature regime in the western half of Turkey. The frost is seen in the eastern half of Turkey in January and February, except for coastal areas. Morever, the frost period goes up to 4 months (November-February) in northeastern Anatolia. Frost reaches up to 90 cm in this area. The high soil temperatures adversely affecting plant life (35 °C and above) is seen in the South-East Anatolia Region and Çukurova region in Turkey in July and August. These high temperatures are effective up to 80 cm in the region. The majority of Turkey has thermic soil or mesic soil. Considering long-term averages (1975-2018), there are four main soil temperature regimes in Turkey as frigid, thermic, mesic, hyperthermic. The eastern Mediterranean coastline and the southwestern Anatolian coastline are hyperthermic soil temperature regime character and the northeast Anatolia (Ardahan surroundings) show a frigid temperature regime character. Percentages of thermic and hyperthermic soil temperature regime have been increasing in the last 10 years. The increase is probably due to the above normal average air temperatures from July to December and the breaking of air temperature records in the last 10 years.