Multiplication of Erwinia amylovora in fruit-trees. 2. A simulation study on sensitivity to weather

The sensitivity of an output variable of a model to changes of an input parameter value can be analyzed in various ways. Some methods of sensitivity analysis are described, and applied to a simulation model which has daily minimum and maximum temperatures (T _min andT _max, respectively), and daily global radiation as input parameters, and standardized relative multiplication rate ofErwinia amylovora in shoots in fruit-trees, averaged over a 24 hours' period, as output variable. Values of the input parameters were obtained from a weather station near Wageningen, the Netherlands, and refer to the second half of June, 1974–1988.According to the model, the output variable was twice as sensitive toT _max as toT _min. Because of this difference in sensitivity, and because the standard deviation ofT _max was larger than that ofT _min, the variation of the output variable due toT _max was three times larger than that due toT _min. The sensitivity to daily global radiation was negligible when the soil was moist.