Multispectral data from Sentinel-2 as a tool for monitoring late frost events on vineyards

Aim: Climate change is altering some aspects of winegrape production with an advancement of phenological stages which may endanger viticultural areas in the event of a late frost. This study aims to evaluate the potential of satellite-based remote sensing to assess the damage and the recovery time after late frost events.

Methods and Results: Multispectral images derived from the Copernicus Sentinel-2 mission were used to monitor an area in north-eastern Italy affected by late frost in 2017. The study focused on Vitis vinifera cv. Garganega, a white variety mainly cultivated in the provinces of Vicenza and Verona. The reflectance values obtained from satellite imagery of the frost affected area (F) and control area (NF) were used to compute several vegetation indices (VIs). The reflectance of the spectral bands and VIs were compared using an unpaired two-sample t-test. Frost damage was detected by Chlorophyll Absorption Ratio Index (CARI), Enhanced Vegetation Index (EVI) and Modified Triangular Vegetation Index 1 (MTVI1) (P ≤ 0.0001, 0.0001, 0.05, respectively). The spectral bands more sensitive to assess the frost damage were Near-Infrared (NIR) and Red Edge (P ≤ 0.0001). The previous VIs/spectral bands, the Normalised Difference Vegetation Index (NDVI) and the Modified Simple Ratio (MSR) provided information on the full recovery time (P ≤ 0.0001) approximately 40 days after the frost event. 

Conclusions: 

The results suggest that multispectral data from Sentinel-2 have the potential to assess the damage and the recovery time of late frost in vineyards. Moreover, the analysis highlighted the spectral regions and the VIs more related to frost damage and recovery time detection. These findings suggest that Sentinel-2 data may represent a tool for prompt assessment and quantification of the damage, supporting reactive and effective decision-making.

Significance and Impact of the Study: The findings suggest that Sentinel-2 data may represent a cost-effective tool for prompt assessment and quantification of the damage, supporting reactive and effective decision-making. The insurance industry, which usually manage farmers’ risk, may benefit from a timely and near real-time overview of crop conditions.

Moreover, achieving valuable information from open-access imagery would represent the tool to extend the frost management from local to global scale.