Abstract:
This study used climatic and topographic data to characterize the sub-appellations that have been recently delineated in the Niagara Peninsula viticulture area and assessed their potential for ripening early to late season Vitis vinifera varieties. To determine whether each sub-appellation possesses a unique set of climatic characteristics that are likely to influence grape quality, the study analysed such factors as the length of the growing season with a threshold temperature >10oC, the mean daily temperature distribution, the diurnal temperature range and fluctuation, distribution of heat units, and frequency of occurrences of maximum temperature <25oC. Also analyzed are the mean ripening temperatures in the months of August and September.
The data base comprised daily heat units, mean, maximum and minimum temperatures and the diurnal temperature range for each sub-appellation. The length of the record extends from 1995 to 2005. Each sub-appellation has at least one monitoring site that is considered representative of the mesoclimate of that sub-appellation. The temperature sensors are located in the vine canopy and in a few cases about two metres from the nearest vine row. The data are archived on an hourly basis from which the statistics for various climatic parameters are compiled. The viticulture area has one monitoring site with daily values extending over thirty years.
The analysis indicates only minor differences observed in the mean ripening-period temperatures and heat units between the sub-appellations. However, distance from Lake Ontario and elevation appears to have a significant influence on the diurnal temperature range observed for each sub-appellation.
