mef: forrecast bias, mean of the errors between forecast F and the verifying reference O:

\[ \text{mef}=\overline{F-O} \]

sdef: standard deviation of the forecast error:

\[ \text{sdef}=\sqrt{\overline{\left[(F-O)-\overline{F-O}\right]^2}} \]

rmsef: square root of the mean square error of the forecast:

\[ \text{rmsef}=\sqrt{\overline{(F-O)^2}} \]



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