## 2 Establishing the Aircraft Bay Humidity Model  
Based on the above analysis on the measured humidity values and the relationship between local temperature and humidity in the bay, it can be concluded that humidity does not vary much during the nighttime. The nighttime local humidity can be determined using the ambient humidity (measured in the thermometer shelter) and the structure coefficient \(m_{i}\) (previously defined in reference [23] and reflects the responsiveness of the local temperature of the bay to the ambient temperature, which is only related to the type of bay). According to this, humidity values during the daytime can be obtained \begin{table}
\begin{tabular}{c c c} \hline \hline
**Bay** & \(\overline{p_{i}}\) & **Variance/\(\sigma^{2}\)** \\ \hline
1 & 0.946 & 0.00469 \\
2 & 0.409 & 0.01476 \\
3 & 0.594 & 0.00831 \\
4 & 0.913 & 0.00458 \\
5 & 0.813 & 0.01116 \\
6 & 0.858 & 0.00318 \\
7 & 0.994 & 0.00823 \\
8 & 0.619 & 0.00931 \\
9 & 0.943 & 0.00861 \\
10 & 0.694 & 0.01050 \\
11 & 0.890 & 0.00753 \\
12 & 0.946 & 0.01085 \\
13 & 0.772 & 0.00985 \\
14 & 0.947 & 0.00200 \\
15 & 1.000 & 0.00000 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Humidity characteristic coefficient of each bay. using local temperature values of the bay and the slope of the relational expression describing the rate of change of temperature and humidity \(q_{i}\). Assuming that the humidity value of the \(i\)-th bay at the \(j\)-th moment of the day is \(h_{ij}\), then the temperature value is \(T_{ij}\), and the temperature and humidity values measured at the thermometer shelter are \(T_{0j}\) and \(h_{0j}\), respectively; the bay structure coefficient is \(m_{i}\); the illumination coefficient is \(s_{i}\) (provided in reference [23] and reflects the responsiveness of the bay to sunlight); and the bay HCC is \(p_{i}\). Since the nighttime temperature model of the bay is \(T_{ij}=T_{0j}+m_{i}\)[23], and the temperature differences between the different bays at night is only related to the bay structure coefficient \(m_{i}\) (that is, \(m_{i}\) can be regarded as a coefficient reflecting the temperature difference between bays at night), the first measured humidity value \(h_{i0}\) at time 0:00 every day can be approximated by the following formula:  
\[h_{i0}=h_{00}+q_{i}m_{i}=h_{00}+p_{i}q_{0}m_{i} \tag{3}\]  
where \(h_{00}\) is the first humidity value measured at the thermometer shelter at 0:00. According to Equations (1) and (2),  
\[q_{i}=\left(h_{ij}-h_{i0}\right)/\left(T_{ij}-T_{i0}\right) \tag{4}\]  
Therefore, if the first humidity value \(h_{i0}\) of the bay can obtained, the bay humidity value can be calculated based on the bay temperature value, as follows:  
\[h_{ij}=h_{i0}+q_{i}\left(T_{ij}-T_{i0}\right) \tag{5}\]  
According to reference [23], the mathematical expression of the local temperature model of the aircraft bay is  
\[T_{ij}=s_{i}T_{0j}+m_{i}+(1-s_{i})T_{t} \tag{6}\]  
where \(T_{ij}\) is the local temperature of the \(i\)-th bay, \(s_{i}\) and \(m_{i}\) are the illumination coefficient and structural coefficient of the bay, respectively, \(T_{0j}\) is the ambient temperature (measured at the thermometer shelter), \(T_{t}\) is the ambient temperature when the sunshine starts to take effect (normally the ambient temperature measured 2 h after sunrise). According to Equations (3) and (6), Equation (5) can be rewritten as  
\[h_{ij}=\left(h_{00}+p_{i}q_{0}m_{i}\right)+p_{i}q_{0}s_{i}\left(T_{0j}-T_{00}\right) \tag{7}\]  
where h\({}_{00}\), \(h_{00}\), \(T_{0j}\), and \(T_{00}\) are values measured at the thermometer shelter; \(m_{i}\), \(s_{i}\) and \(p_{i}\) are parameters of the bay (which are known quantities based on real-world scenarios); \(q_{0}\) is the amount of fitting obtained by applying the temperature and humidity values measured at the thermometer shelter to Equations (1) and (2).