<p>Fraction of total years during the 1978–2007 time period that simulated annual 10 cm soil temperatures were at or below a −3.5°C threshold (based on a 3-day running mean) for (a) MAIZE+TILL (bare soil), (b) MISCAN+R<sub>1 cm</sub>, (c) MISCAN+R<sub>2.5 cm</sub>, and (d) MISCAN+R<sub>5 cm</sub> simulations.</p