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…

Contribution of grape seeds to evolution of acetaldehyde, pigments and tannins reactive towards salivary proteins of red wine over time

This study investigated the impact of the gsk/gse ratio on the evolution of acetaldehyde and of major phenolic compounds of aglianico wine in wine like solution and real wine. Four model solutions and the correspondant control wines were prepared. The natural weight ratio between grape skins and seeds was determined on the real grapes, and a control wine was obtained from those.

Read More

New ways of grape pomaces valorization: production of functional beverages or nutraceuticals

The wine industry generates each year 20 million tons of by-products. Among them grape pomaces represent a big part that can be considered as a source of potentially bioactive molecules such as polyphenols. Kombucha fermentation is an ancestral process which allow to increase the biological properties of tea by the action of a microbial consortium formed by yeasts and bacteria called scoby.

Read More

A geologic numeric mapping, with geophysic transects, of Marsannay’s vineyard (Burgundy, France)

Marsannay est l’appellation la plus septentrionale de la Côte de Nuits, à la limite Sud de Dijon. Elle regroupe trois villages, Chenôve, Marsannay-la-Côte et Couchey, et constitue l’appellation la plus vaste de la Côte de Nuits avec 315 hectares en A.O.C. Elle possède uniquement des niveaux d’appellations régionales et communales depuis 1987.

Read More

Influence of processing parameters on aroma profile of conventional and ecological Cabernet-Sauvignon red wine during concentration by reverse osmosis

Wine aroma represents one of the most important quality parameter and it is influenced by various factors (viticulture and vinification techniques, climate or storage conditions etc.). Wines produced from conventionally and ecologically grown grapes of same variety have different chemical composition and aroma profile [1]. Aroma profile of wine can be also influenced by additional treatment of wine, such as concentration of wine by reverse osmosis (RO). Reverse osmosis represents a pressure-driven membrane separation technique that separates the initial wine on the retentate or concentrate that is retained on the membrane, and permeate that passes through it [2]. Wine permeate usually containes water, ethanol, acetic acid and several low molecular weight compounds that can pass through the membrane. This property enables the use of reverse osmosis membranes for wine concentration, partial dealcoholization, acetic acid or aroma correction [3,4].

Read More

Unveiling Metschnikowia spp.: mechanisms and impacts of bioprotection in winemaking

Bioprotection, leveraging beneficial microorganisms, has emerged as a sustainable approach to modern winemaking, minimizing reliance on chemical preservatives like as sulfur dioxide (SO₂).

Read More