HOW TO ASSESS IMPACT OF CLIMATE CHANGE ON SOIL CLIMATE BY NEWHALL MODEL – CENTRAL EUROPE AS A CASE STUDY AREA

The original version of Newhall Simulation Model (NSM 1.0) that is based on monthly water balance calculation shows significant bias towards drier soil climate regimes. This error is magnified in some areas when model is used for climate change impact studies. The underlying cause of the bias is thought to be an overestimation of evapotranspiration by Thornthwaitexs method. In order to correct this bias we developed a new version of Newhal Simulation Model (NSM 2.0) which is built around the daily water balance model and daily soil temperature model. This study compares results of NSM 1.0 and NSM 2.0 both under present and expected climate. In order to objectively evaluate the model results we used high quality soil moisture observations from three most productive agricultural soil types of Central Europe. To demonstrate the benefit of NSM 2.0 use over its predecessor the spatial analysis of the soil climate of Czech Republic was also carried out using both versions of NSM. This comparison included the present climate (1961-2000) as well as conditions expected during 21st century. In latter case we took into account combinations of three Global Circulation Models (ECHAM, HadCM and NCARPCM) and two emission scenarios (SRES-A2 and SRES-B2) for time slices of 2025, 2050 and 2100. As there is a notable tendency of NSM 1.0 to predict drier soil climates than is the reality (at least in case of Central Europe) the estimates based on this model should be treated with care. The newly proposed method seems to yield more reliable results in case of the temperate climate of Central Europe. More widespread evaluation of the model concept is anticipated in near future.

Acknowledgement: This study was conducted with support of the project AMVIS-KONTAKT (ME 844) and National Agency for the Agricultural Research (project 1G46055 – “Mitigation of the drought impact on the selected crops...”) .