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Table 1 Table of variables used in regression model for yield data in southwest Michigan along with equations and accuracy of regressions for frost and GDD variables

From: Effects of a warming trend on cool climate viticulture in Michigan, USA

Variable Source Equation R2
GST Historical model runs Tavg of April–October months  
PPT Historical model runs Total precipitation of April–October months  
Frost Regression −10.410 + (1.389 × MayTmin) 0.52*
GDD Regression, base 10 °C −996.347 + (118.021 × JunTavg) + (237.501 × JulTavg) − (298.855 × AugTavg) + (67.267 × SepTavg) 0.61*
eGDD Historical model run, base 10 °C Tavg of April  
  1. * Significant at p < .001