terclim by ICS banner
IVES 9 IVES Conference Series 9 Updating the Winkler index: An analysis of Cabernet sauvignon in Napa Valley’s varied and changing climate

Updating the Winkler index: An analysis of Cabernet sauvignon in Napa Valley’s varied and changing climate

Abstract

This study aims to create an updated, agile viticultural climate index (similar to the Winkler Index) by performing in-depth analyses of current and historical data from industry partners in several major winegrowing regions. The Winkler Index was developed in the early twentieth century based on analysis of various grape-growing regions in California. The index uses heat accumulation (i.e. Growing Degree Days) throughout the growing season to determine which grape varieties are best suited to each region. As viticultural regions are increasingly subject to the complexity and uncertainty of a changing climate, a more rigorous, agile model is needed to aid grape growers in determining which cultivars to plant where. For the first phase of this study, 21 industry partners throughout Napa Valley shared historical phenology, harvest, viticultural practice, and weather data related to their Cabernet sauvignon vineyard blocks. To complement this data, berry samples were collected throughout the 2021 growing season from 50 vineyard blocks located throughout 16 American Viticultural Areas that were then analyzed for basic berry chemistry and phenolics. These blocks have been mapped using a Geographic Information System (GIS), enabling analysis of altitude, vineyard row orientation, slope, and remotely sensed climate data. Sampling sites were also chosen based on their proximity to a weather station. By analyzing historical data from industry partners and data specifically collected for this study, it is possible to identify key parameters for further analysis. Initial results indicate extreme variability at a high spatial resolution not currently accounted for in modern viticultural climate indices and suggest that viticultural practices play a major role. Using the structure of data collection and analyses developed for the first phase, this project will soon be expanded to other wine regions globally, while continuing data collection in Napa Valley.

DOI:

Publication date: May 31, 2022

Issue: Terclim 2022

Type: Poster

Authors

Paige Breen, James Campbell, Kayla Elmendorf, Seth Frey and Elisabeth Forrestel 

Department of Viticulture and Enology, University of California, Davis, USA

Contact the author

Keywords

climate index, climate science, Growing Degree Days, Napa Valley, viticulture

Tags

IVES Conference Series | Terclim 2022

Citation

Related articles…

Vine phenology and climate in Bordeaux, since the beginning of the XIXth century

We analyze the effects of climate (temperature and pluviometry) on the phenologic stages of the vine (débourrement, flowering, ripening and grape harvest). We rebuilt time series starting from the beginning of the XIXth century for the Medoc and the area of Bordeaux, data very seldom mobilized by researchers.

Management of water status in vineyards: meta-analysis of its effects on yield and grape composition

Mediterranean vineyards have been traditionally grown under rainfed conditions, but in recent decades the irrigated area has increased significantly, seeking to minimize the adverse effects of severe water stress on grape quality and yield. Given the large area occupied by vineyards, and the increasing scarcity of water resources, it is necessary to develop strategies for the optimization and efficient use of water to reduce the risk of its overexploitation. The present study aims at valorizing previous knowledge generated in different research projects by means of a meta-analysis of the effects of water status management on vineyard performance.

Characterization of “territoires” throughout the production of wines obtained with withered grapes: the cases of “Terra della Valpolicella” (Verona) and “Terra della Valle del Piave” (Treviso) in Northern Italy

Dans la définition et la description d’un “territoire” (“terra” en italien), avec les facteurs du milieu et génétiques, un rôle important est joué par ceux agronomiques, techniques et de culture qui contribuent à caractériser le produit d’une zone spécifique.

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.

Relevance of the polyphenolic profile during oxidative aging in the accumulation and disappearance of oxidative and varietal aromas

The main objective of this work is to study and model the impact of the polyphenolic profile on the stability and quality of wine aroma during oxidative aging.