*2.2. Field Data*

In order to generate lodged crop per unit area, we used the 2018 CDL map because the 2020 CDL map is not yet available. Another reason for using the 2018 CDL map is that most farmers in Iowa and Illinois perform crop rotation. Fields where farmers consistently performed crop rotations for the last eight years were kept while fields where crop rotations were not consistent for the last eight years were removed. By doing this, we believe that corn and soybeans areas in 2018 should be similar to those of corn and soybean areas in 2020. The CDL data have a spatial resolution of 30 m, includes 132 detailed class labels, and was created from Landsat dataset using a decision tree algorithm trained on field samples [23]. The overall accuracy of the CDL dataset is about 95% for the United States Corn Belt. Apart from the CDL, we collected some ground truth data by field survey. Lodged fields were selected as samples for field observation. Mobile phone GPS was used for positioning the sampling points.

#### *2.3. Remote Sensing Data*

During 10 August 2020 and 11 August 2020, a derecho swept through Midwest that caused severe and widespread windstorms with some areas experiencing low-class tornadoes and heavy rain. As part of this, a windstorm was observed in Iowa and Illinois on 10 August 2020. The wind speed in both states ranged between 60 and 100 mph (Figure 2). Wind speed data for this study were acquired from the National Weather Service (NWS). NWS used several sources like Iowa DOT, personal weather station, Automated Surface Observing Systems (ASOS), and Automated Weather Observing Systems (AWOS) to estimate the wind speed data. Since corn and soybean are already in their reproductive stages at the time of the windstorm, high wind speed led to severe lodging.

In order to cover the agricultural areas damaged by the windstorm, we acquired six Sentinel-1A images in Interferometric Wideswath (IW) instrument mode. Our Sentinel-1A images were acquired between 29 July 2020, and 22 August 2020. Each Sentinel-1A image collection had a resolution of 10 m, a dual polarization (VH and VV; V = Vertical, H = Horizontal), and consisted of Level-1 Ground Range Detected (GRD) scenes. As shown in Table 1 and Figure 3, three images were acquired before the lodging event (pre-lodging event) and three images were acquired after the lodging event (post-lodging event).

**Figure 2.** Wind speed data acquired from the National Weather Service (NWS).



**Figure 3.** Pre-lodging images acquired on (**a**) 29 July 2020; (**b**) 3 August 2020; and (**c**) 4 August 2020. Post-lodging images acquired on (**d**) 22 August 2020; (**e**) 15 August 2020; and (**f**) 16 August 2020.
