Death comes to us all. Life's but a walking shadow | I agree that it is likely that it is the transition from high to low ONI that correlates with a decline in yield. In fact you can see examples of that if you carefully inspect my chart. In some cases just the transition from an intermediate to a lower ONI seems to be accompanied by a subsequent yield decline. I just haven't figured out yet what analysis to apply in order to show this.
It is also apparent the good yields (high residuals) seem to follow lower ONI numbers and much better than average yields accompany negative ONI's. This is almost as important an observation as what happens following high ONI years.
Zenfarm, when you make your comparisons with 5 yr averages what years do you use. I could be wrong but I think if you use the previous five years you fail to account for the steady 1.9 bushel per acre yield increase due to the trend. In addition, by looking only at the strong El Nino years you may be missing some of the context.
Finally, I'm sure that meterologists have well developed theories as to the mechanism of how strong El Nino years weather works. That's way beyond me. I suspect that it's not necessarily the ONI itself that accounts for our crop weather but it's just the parameter we monitor.
What I think is helpful here is to have a way to just look at the pattern of ONI along side of the changes in crop yield. If you just take the time to scan the chart year by year I think you can convince yourself that there is some connection between changes in ONI and subsequent yields. Obviously there is error and uncertainty, that alone doesn't make it completely useless. |
JonSCKs, El Nino
