13th Conference on Applied Climatology and the 10th Conference on Aviation, Range, and Aerospace Meteorology

Tuesday, 14 May 2002: 4:15 PM
Mapping varietal potential for quality wines in Oregon using PRISM spatial climate data
Gregory V. Jones, Southern Oregon University, Ashland, OR; and P. Hille and H. E. Jones
Oregon currently ranks as the fourth largest wine producer in the United States, growing grapes in 6 appellations (Federally designated grape growing and wine making regions, called American Viticultural Areas): the Applegate Valley, the Columbia Valley, the Rogue Valley, the Umpqua Valley, the Walla Walla Valley, and the Willamette Valley. In the state, there are currently 491 vineyards and 145 wineries growing over 20 different varieties on over 7500 harvestable acres with an economic benefit of over 200 million dollars.

Deciding to grow grapes in Oregon is complex issue due to our diverse geography and climate. For any potential grape grower, vineyard site selection is the single most important decision they will face. Combined with matching the site to a grape variety, this decision will ultimately affect the vineyard's yield, the quality of the wine produced, and the vineyard's long-term profitability. Overall, the quality of wine produced in any viticultural region comes primarily from the high quality of the grapes, which are carefully vinified. The quality of the grape, however, is the result of the combination of four main factors: the climate, the site or local topography, the nature of the soil, and the choice of the grape variety.

Today, Oregon viticulture is an ever-growing agribusiness. While the state has over 40 years of grape growing experience, it is still in the trial and error phase of finding the ideal varieties to grow in its diverse climate and landscape. To facilitate this growth and better ensure economic viability, this body of research defines regions by their suitability of growing different grape varieties. Using GIS and PRISM spatial climate data, the research establishes where in the state varietal groupings (e.g., cool versus warm climate varieties, white versus red varieties, etc.) should be planted to achieve the highest potential quality. The model uses growing season length and degree-days, along with spring and fall median frost dates, harvest rainfall and humidity levels, and extreme winter minimum temperatures to create a composite ranking of potential grape growing regions.

For most potential growers, site selection will involve compromises, in that few sites will possess ideal characteristics in every respect. While compromises have been the rule, this research provides one of the best tools yet to help growers select the right varietal for a respective region with the ultimate goal of increasing the stature of Oregon's wine industry.

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