Centre county Pennsylvania, USA | CCYM uses the crop year's trend yield, standard deviation of residuals from yield trend, and crop conditions to model yield for each week's condition reported by NASS in the crop year. Trend yield and standard deviation of residuals from yield trend are computed using NASS reported annual yield data back to 1986 ( 1986....2014). Conditions are for conditions reported by NASS for each week in the crop year.
CCYM is coded as a callable function, it must be called for each week's crop condition reported by NASS in the crop year. Trend yield for the crop year, standard deviation of residuals from yield trend for the crop year, and NASS reported conditions for each week in the crop year are call arguments. CCYM forecast yield is the CCYM yield prediction for a week in mid, or late, Jul (as shown on the charts). Below is copy/paste of help for that function, it should answer questions about what data are used for ccym yield predictions.
def ccym(condition,trendyield,sigma):
""" returns a yield forecast using crop conditions (percent[E,F,G,P,VP]), trend yield, and
sigma where sigma = std dev of trend residuals.
must be called for each week's crop condition reported by NASS in the crop year """ |
2015 corn and soybean CCYM yield prediction update
