Most of the statistical studies correlate crop yields at a province or county scale from census data with seasonal climate computed during a coarse and fixed crop growth period. In fact, cropping systems have shifted in the past few decades under the combined effects of climate change, cultivars turnover and agronomic management (Welchet al., 2010; Tao et al., 2012a,b; Tao and Zhang, 2013). There is a clearand present need to synthesize crop yield and climate data from