Title: A multicriteria climatic classification system for grape-growing regions worldwide
Abstract: This study concerns firstly the methodology to describe the climate of vineyards, on a macroclimate scale of viticultural regions worldwide. Three synthetic and complementary viticultural climatic indices (potential water balance of the soil over the growing cycle, heliothermal conditions over the growing cycle and night temperature during maturation), validated as descriptors, are used: (1) dryness index (DI) which corresponds to the potential water balance of the soil of Riou’s index, here adapted using precise conditions to calculate it, as an indicator of the level of presence-absence of dryness; (2) heliothermal index (HI) which corresponds to Huglin’s heliothermal index; (3) cool night index (CI) an index developed as an indicator of night temperature conditions during maturation. These indices are representative of the variability of the viticultural climate worldwide, related to the requirements of varieties, vintage quality (sugar, colour, aroma), and typeness of the wines. A Multicriteria Climatic Classification System (Géoviticulture MCC System) for the grape-growing regions worldwide is formulated based on classes for each of the three climate indices, with elements to explain the results. Three formulated concepts provide the system base: viticultural climate, climatic group and viticultural climate with intra-annual variability (for warm regions with more than one harvest a year in natural climate conditions). The application of the Géoviticulture Multicriteria Climatic Classification System is presented for 97 grape-growing regions in 29 countries. The system is a research tool for grape-growing and wine-making zoning. It also enables work at different levels on the scale, on a world-wide scale or larger – the large grape-growing region, the small grape-growing region, as shown by the studies performed. It allows relating the viticultural climate to the elements of grape quality and the typeness of the wines considering the climatic zone.