Complementing Optical Remote Sensing with Synthetic Aperture Radar Observations of Hail Damage Swaths to Agricultural Crops in the Central United States

Abstract

The normalized difference vegetation index (NDVI) has been frequently used to map hail damage to vegetation, especially in agricultural areas, but observations can be blocked by cloud cover during the growing season. Here, the European Space Agency’s Sentinel-1A/ 1B C-band synthetic aperture radar (SAR) imagery in co- and cross polarization is used to identify changes in backscatter of corn and soybeans damaged by hail during intense thunderstorm events in the early and late growing season. Following a June event, hail-damaged areas produced a lower mean backscatter when compared with surrounding, unaffected pixels [vertical–vertical (VV): −1.1 dB; vertical–horizontal (VH): −1.5 dB]. Later, another event in August produced an increase in co- and cross-polarized backscatter (VV: 0.7 dB; VH: 1.7 dB) that is hypothesized to result from the combined effects of crop growth, change in structure of damaged crops, and soil moisture conditions. Hail damage regions inferred from changes in backscatter were further assessed through coherence change detections to support changes in the structure of crops damaged within the hail swath. While studies using NDVI have routinely concluded a decrease in NDVI is associated with damage, the cause of change with respect to the damaged areas in SAR backscatter values is more complex. Influences of environmental variables, such as vegetation structure, vegetation maturity, and soil moisture conditions, need to be considered when interpreting SAR backscatter and will vary throughout the growing season.

Satellite-Based Assessment of Hailstorm Affected Potato Crop for Insurance Purpose

“…The guiding principle for remote sensing-based hailstorm damage is based on the fact that the hailstorm induced changes in the biophysical properties of the crop can be detected by one or more vegetation indices. The hailstorm induces stress/damage on potato crop can be addressed using ΔNDVI as shown in the present study (Table 3) and also corroborated by the previous studies (Ray et al 2016;Prabhakar et al 2019;Bell et al 2020).…”

Limitations of Remote Sensing in Assessing Vegetation Damage Due to the 2019–2021 Desert Locust Upsurge

“…SAR provides information about the texture of the Earth's surface and is not limited by cloud cover. Specifically, Sentinel-1 C-band vertical-vertical (VV) and vertical-horizontal (VH) backscatter are known to be sensitive to changes in vegetation conditions, such as damage caused by hail (Bell et al, 2020) and above ground biomass (AGB) (Pereira et al, 2018). Areas that have been damaged by DL are expected to have lower backscatter power due to a reduction in vegetation cover.…”

Global Open Data Remote Sensing Satellite Missions for Land Monitoring and Conservation: A Review

“…Open data satellite missions for specialized applications are in constant development, such as the visible infrared imaging radiometer suite (VIIRS) mission owned by NASA to automatically report new wildfires globally in near-real-time. Ecological and natural disasters monitored by global satellite missions consist of oil spills in the seas and oceans [96], glacier melting in the Arctic [97], forest wildfires [98], floods [32], and damage to agricultural crops affected by hailstorms [99]. Monitoring of the spatial coverage of ecological and natural disasters based on the mentioned studies represents the basis for remediating the resulting damage.…”