**2. Materials and Methods**

### *2.1. Test Sites and Field Measurements*

The field measurements used in this study were carried out during two seasons of winter wheat, three seasons of processing tomatoes, and two seasons of cotton in different locations in Israel (Table 2, Figure 1). LAI was measured by a SunScan Canopy Analysis System—SS1 developed by Delta-T Company (Cambridge, United Kingdom) during two wheat seasons and two processing tomato seasons. The SunScan is an accurate, nondestructive LAI measurement system successfully employed in many previous studies [25,67]. Each LAI value is an average of at least 30 consecutive field measurements taken at 20-cm intervals along a transect perpendicular to the row direction. Vegetation height was measured at a precision of 1 cm using a tape measure and represented by an average of at least 30 plants per measurement date. LAI and vegetation height in wheat and processing tomatoes were measured throughout the growing seasons; therefore, they represent the full range of these variables. Cotton height was measured during the middle and late stages of one growing season. The backscattering coefficient (σ0) and the radar brightness coefficient (β0) were used in linear scale. Sentinel-1 backscatter values were averaged for a polygon that represented the eddy covariance measurement footprint calculated based on a two-dimensional footprint model [68]. All the empirical regression models in this study utilized the average values of either σ0 or β0, and the local incidence angle (θ) within the areas of interest and same-date field measurements. In cases of gaps in the time series, linearly interpolated values of field measurements from adjacent dates (crop height and LAI) were used. The number of SAR images used for the derivation of the various models was not uniform because each model was based on the period for which field measurements were available, resulting in different numbers of corresponding satellite images. For example, LAI could not be measured using the SunScan system when the plants were very small, while vegetation height was easily measured at any time using a ruler. Accordingly, the LAI models were based on shorter time spans and fewer images than were plant height models. In-field paths and their surrounding area were masked out from analysis polygons of the processing tomato experiments which took place in 2019 to remove bare soil areas and avoid border effects. These excluded areas consisted of approximately 20% of the overall areas of interest. Therefore, the Gadash 2019 area of interest consisted of four vegetated regions separated by paths, and the Gadot 2019 area of interest consisted of two regions.

**Table 2.** Summary of seven field experiments conducted at six locations in Israel.


Note: \* Period indicates the starting and ending dates.
