## 3 Results and Discussions
### Descriptive Statistics of Selected Input Variables  
Descriptive statistics of the selected variables are given in Table 2. The maximum air temperature ranged between \(-17\) and \(33.5\)\({}^{\circ}\)C for the period 2011-2017 for all sites. The highest maximum air temperature was recorded to be \(33.5\)\({}^{\circ}\)C for Summerside. The mean of maximum air temperature was in the range of \(9.2\)-\(10.7\)\({}^{\circ}\)C with high standard deviation; i.e., \(10.2\)-\(10.8\)\({}^{\circ}\)C for all sites. Because of seasonality, the maximum air temperature behaved as bimodal distribution for all sites (Figure 4). Exponential relation of maximum air temperature with ETo is evident in Figure 4.  
Figure 4: Pair plots of selected variables for year 2011–2017. Where \({}^{1}\)Max. Temp is Maximum air temperature; \({}^{2}\)ETo is reference evapotranspiration computed from the FAO-56 method.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Site**} & \multicolumn{2}{c}{**Variable**} & \multirow{2}{*}{**R\({}^{2}\)**} & \multirow{2}{*}{**1 HDD**} & \multicolumn{2}{c}{**2 Hourly Mean Air**} & \multicolumn{2}{c}{**3 Min. Air**} & \multicolumn{2}{c}{**4 Max. Air**} & \multicolumn{2}{c}{**Relative**} & \multicolumn{2}{c}{**5 Dew Point**} & \multicolumn{2}{c}{**6 Daily Mean**} \\  & **(Number)** & & & **Temp (\({}^{\circ}\)C)** & **Temp (\({}^{\circ}\)C)** & **Temp (\({}^{\circ}\)C)** & **Temp (\({}^{\circ}\)C)** & **Humidity (\%)** & **Temp (\({}^{\circ}\)C)** & **Temp (\({}^{\circ}\)C)** & **Air Temp (\({}^{\circ}\)C)** \\ \hline \multirow{9}{*}{Saint Peters} & 1 & 71.9 & & & & X & & & \\  & 2 & 83.0 & & & & X & X & & \\  & 3 & 83.9 & & & & X & & X & \\  & 4 & 84.6 & X & & & X & & X & \\  & 5 & 85.2 & X & \(\times\) & & X & & X & \\ \hline \multirow{9}{*}{Harrington} & 1 & 70.7 & & & & X & & & \\  & 2 & 83.9 & & & & X & & \\  & 3 & 84.4 & & & & X & & X & \\  & 4 & 84.8 & X & & & X & & X & \\  & 5 & 85.2 & X & \(\times\) & & X & & X & \\ \hline \multirow{9}{*}{North Cape} & 1 & 72.5 & & & & X & & & \\  & 2 & 87.0 & & & & X & & \\  & 3 & 88.0 & & & & X & & \\  & 4 & 88.8 & X & \(\times\) & & X & & \\  & 5 & 89.4 & X & \(\times\) & & X & & X & \\ \hline \multirow{9}{*}{Summerside} & 1 & 73.6 & & & & X & & & \\  & 2 & 83.6 & & & & X & & \\  & 3 & 84.2 & & & & X & & X & \\  & 4 & 84.7 & X & & & X & & \\  & 5 & 85.2 & X & & X & & & X \\ \hline \multirow{9}{*}{PEI} & 1 & 74.4 & & & & X & & & \\  & 2 & 86.2 & & & & X & & \\  & 3 & 87.2 & & & & X & & \\  & 4 & 87.7 & X & & & X & & \\  & 5 & 88.3 & X & \(\times\) & X & & & \\ \hline \hline \end{tabular}  
* Heat degree days\({}^{2}\) Hourly mean air temperature,\({}^{3}\) Minimum air temperature;\({}^{4}\) Maximum air temperature;\({}^{5}\) Drew point temperature; and\({}^{4}\) Daily mean air temperature.  
\end{table}
Table 2: Subset regression analysis regressed versus FAO-56 ETO.  
Relative humidity ranged from 37.6% to 100% for all sites. The average humidity was recorded to be 77.7-80.1% with higher standard deviation of 37.6-49.3% in year 2011 to 2017 for all sites (Table 2). Relative humidity represented with normal distribution and weaker inverse relation between ETo and relative humidity may be visualized in Figure 4.  
ETo computed from the FAO-56 method ranged between 0 and 9.3 mm/day for all sites and duration of 2011-2017. The maximum daily ETo was recorded to be 9.3 mm/day for Saint Peter site. The mean daily ETo ranged from 1.8 to 2.0 mm/day with slightly lower standard deviation of (i.e., 1.4-1.5 mm/day) for all sites. Distribution of daily ETo may be represented with right skewed distribution because of relatively low values in the winter season (Figure 4).  
The rainfall varying from 0 to 147.5 mm/day was recorded for all sites in the study period. The highest rainfall of 147.5 mm was recorded for the North Cape site. The average rainfall received by all sites was in the range of 2.4-3.2 mm/day with standard deviation of 6-7.7 mm/day. The Summerside station received relatively less rainfall in comparison with other sites (Table 3).