Comparison of observed and simulated annual extreme minimum 10 cm soil temperatures.

<p>(a) Agro-IBIS average annual extreme minimum 10 cm soil temperature (based on 3-day running mean temperatures) compared with observations from 125 observation sites (SI, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068847#pone.0068847.s001" target="_blank">Table S1</a>) from the Midwest USA for original model values (open circles and dotted regression line), and statistically adjusted model values (filled circles and dashed regression line); (b) Agro-IBIS simulated frequency of occurrence of 10 cm soil temperatures (3-day running mean) reaching −3.5°C and (c) −6.0°C, respectively, compared with results from 125 observation sites in the Midwest USA. In these comparisons, Agro-IBIS was only simulated for a period from the beginning year that data was available for each observation station through 2007, which denotes the last year that gridded daily climate data was available.