## 4 Results and Discussion
### Temporal Features and Parameter Values
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Site** & & & & & & & \\
**ID** & & & & & & & \\ \hline
**1** & Cambodia, Takco & \(-18.0<-11.5\) & \(-6.0>-10.6\) & \(20.0>12.3\) & \(-11.0>-14.6\) & \(-13.0<-7.3\) & \(4.0<7.5\) \\ \hline
**2** & Philippines, Levie East & \(-14.0<-12.7\) & \(-7.5>-8.3\) & \(20.0>8.6\) & \(-11.0>-11.8\) & \(-10.5<-9.9\) & \(3.0<3.3\) \\ \hline
**3** & Philippines, & & & & & & \\  & Leyte West & \(-14.0<-11.1\) & \(-7.5>-7.4\) & \(20.0>12.3\) & \(-11.0>-12.8\) & \(-10.5<-9.1\) & \(3.0<3.7\) \\ \hline
**4** & Philippines, & & & & & & \\  & Agusan del Norte & \(-14.0<-10.6\) & \(-7.5>-7.9\) & \(20.0>12.5\) & \(-8.0>-11.4\) & \(-10.5<-9.1\) & \(3.0<4.2\) \\ \hline
**5** & Vietnam, Soc Trang & \(-15.5<-12.0\) & \(-7.5>-8.8\) & \(20.0>13.3\) & \(-10.5>-12.0\) & \(-10.0<-9.6\) & \(3.0<4.5\) \\ \hline
**6** & Vietnam, Nam Dinh & \(-15.5<-12.2\) & \(-7.5>-8.6\) & \(20.0>12.5\) & \(-10.5>-12.1\) & \(-11.0<-9.6\) & \(3.0<4.7\) \\ \hline
**7** & Indonesia, Subang & \(-17.5<-15.4\) & \(-6.0>-11.1\) & \(20.0>12.0\) & \(-12.0>15.6\) & \(-12.0<-11.1\) & \(4.0<6.3\) \\ \hline
**8** & India, Tamil Nadu, & & & & & & \\  & Cudalore & \(-14.0<-11.9\) & \(-8.0>-8.7\) & \(20.0>8.2\) & \(-12.0>-12.02\) & \(-11.0<-9.6\) & \(3.0<3.2\) \\ \hline
**9** & India, Tamil Nadu, & & & & & & \\  & Thanjavur & \(-14.0<-10.1\) & \(-8.0>-9.1\) & \(20.0>9.6\) & \(-11.0>-12.5\) & \(-11.0<-7.0\) & \(3.0<6.1\) \\ \hline
**10** & India, Tamil Nadu, & & & & & & \\  & Sivaganga & & & & & & \\ \hline
**11** & Thailand, Muang Yang & \(-14.0<-11.7\) & \(-4.0>-6.2\) & \(20.0>9.5\) & \(-8.0>-10.4\) & \(-10.5<-9.6\) & \(3.0<3.6\) \\ \hline
**12** & Thailand, Suphan Buri & \(-15.5<-13.1\) & \(-7.5>-8.6\) & \(20.0>11.8\) & \(-10.5>-12.0\) & \(-10.5<-11.1\) & \(3.0<2.11\) \\ \hline
**13** & Philippines, Nueva & & & & & & \\  & Ecija & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of the selected parameters (in dB) used for the rice classification at each site and the corresponding temporal feature values extracted from the field data. Shaded cells represent cases where the selected parameter did not follow the temporal feature criterion. temporally-stable backscatter over these durations. For X-band HH polarization, the highest variation in rice is typically observed between the agronomic flooding and the tillering stage. \(c\) was held constant at 20 dB across all sites as a conservative estimate of the maximum variation, which in practice never exceeded 14 dB. \(f\) was set to a conservative value of 3 or 4 dB, which is at the lower end of the variation expected from a rice crop. At only one site, Suphan Buri, was the temporal feature criterion not met. This site exhibited an extremely complex temporal pattern of rice cropping practices, often in very small fields at the limit of the spatial resolution of the filtered time series. \(d\), defined as the maximum value at SoS (_i.e._, at agronomic flooding), is typically expected at around \(-\)18 dB. However, the maximum was set at around \(-\)11 dB in order to not omit rice fields where the acquisition date was not synchronized with the agronomic flooding. Our observation here is that it is crucial that SAR data, in particular at higher frequencies, such as X-band, be acquired with a high repeat cycle. Moreover, wind conditions, vegetation over the water and field heterogeneity (_i.e._, part of the fields are not fully covered by water) can cause random scattering, thereby contributing to the backscattering coefficient increase. Finally, land practices or water scarcity also have an impact on the setting of this parameter; the two rainfed sites of Muang Yang and Agusan del Norte are examples where the temporal feature descriptor was correspondingly low. The temporal feature criterion was not met in Sivaganga, where rice is sown in a semi-dry practice and was marginally not met in Nueva Ecija. \(e\), the minimum value at maximum peak, corresponds to the tillering stage at this frequency and polarization (double bounce). \(d\) was often higher than \(e\).