Historical daily weather data, including daily mean tempera-ture (Tmean), maximum temperature (Tmax), minimum temperature(Tmin), solar radiation (SRD), precipitation, and sunshine duration at the agricultural meteorological stations from 1980 to 2009 were also obtained from CMA. At the stations without SRD observations,SRD was estimated using sunshine duration observation and theÅngström–Prescott (A-P) equation (Prescott, 1940):