## Materials and Methods  
### Study Site and Dataset  
The study site is located in an agricultural area near the city of London in southwestern Ontario, Canada. The geographical location of this study area, and the Pauli RGB image corresponding to 12 April 2015 over the overlapping area of all RADARSAT-2 images, is presented in Figure 1. This site is very suitable for planting crops, attributed to abundant precipitation, mild weather and fertile soil, with relatively flat topography [39; 41]. The main crop types over this site are winter wheat, corn, soybean and forage consisting of alfalfa, hay and grass. A few fields of tobacco and watermelon are also planted in this site. Almost all crops are rain-fed without irrigation. In addition to field crops, there are a few buildings and forest patches in the study area. The planting and harvest time for major crops in the study area are basically the same year by year. Corn and soybean are routinely seeded in May, ripened in September and harvested in October. In contrast, winter wheat is usually seeded in October of the previous fall, matured in July, and harvested from late July to early August the following year. Due to the long-time (November to March) of heavy snow in this region, farmers don't start field operations until early April, and the winter wheat fields follow the same calendar to start regrowth around the same time. As crop rotations are commonly practiced in this region, crop residuals left from previous year's harvest are mostly different from the crops seeded in the current year. For instance, the winter wheat fields are likely to have residues of corn or soybean prior to seeding at field preparation. As shown in Table 1, seven fully polarimetric C-band RADARSAT-2 images in FQ10W (Fine-Quad Wide) covering the entire growing season from April to September in 2015 were employed. The uniform image acquisition beam mode offers the advantage of reduced complexity caused by varying SAR incidence angles for multitemporal stud  
Figure 1: Location and Pauli RGB image acquired on 12 April 2015 over the overlapping area of all RADARSAT-2 images. (RADARSAT-2 Data and Products © MacDonald, Dettwiler and Associates Ltd. (2015)—All Rights Reserved. RADARSAT is an official traemark of the Canadian Space Agency). ies [35; 36; 37]. In particular, except for the date on 30 May, when the satellite did not overpass our study area to acquire imagery due to user conflicts, the time interval between data acquisitions was 24 days. From April to September 2015, field surveys were conducted every month by the Geographic Information Technology and Application (GITA) laboratory at the University of Western Ontario (UWO). Agricultural information, including crop type, crop height, soil moisture, crop phenological stage and field photos was recorded. Figure 2 shows field photos of three main crops (winter wheat, corn and soybean) on RADARSAT-2 acquisition dates. Since the corn and soybean were not emerging yet on 12 April and 6 May, there were no ground photos for corn and soybean taken on both dates. Field surveys of corn and soybean started on 23 May. Fields photos of three main crops on this date are presented in Figure 3. The heights of winter wheat were significantly taller than those of corn and soybean on 23 May. The winter wheat field was harvested from the end of July to early August and standing residuals were left; hence, field photos over winter wheat in harvested state were only taken once in August, as shown in Figure 1. From these field photos, we observed that the collected PolSAR time-series imagery covered the crops' growth changes throughout almost the full growing season of the main crops over the study site. The dataset is very suitable for crop monitoring by analyzing the temporal evolution of the polarimetric parameters. The ground truth labels of crop types were collected in a field survey, and then we manually digitized the boundary of each field based on satellite imagery in a Geographic Information System (GIS).