Analysis of viticulture region climate structure and suitability in New Zealand

Abstract

Aims: This research analyzes four climate indices derived from gridded, interpolated data to assess New Zealand's climate structure and variation among wine regions. Methods and results:High resolution gridded data based on 1971-2000 climate normals was used to characterize climate indices depicting viticultural suitability in a geographic information system. The statistical properties of each index were assessed over 21 New Zealand viticulture regions. The results show predominately cool to moderately warm climate suitability in New Zealand, comparable to many European and United States regions. While many viticulture regions have one primary class of suitability, variability of climate within regions can be significant, with some regions containing two to four climate classes, making them suitable for a greater range of cultivars. Conclusion:While the indices depict broad patterns expected over New Zealand, both within and between region variations can be substantial among the indices. However, two indices, Growing Season Average Temperature (GST) and Growing Degree-Days (GDD), are functionally identical, but GST is easier to calculate and overcomes many methodological issues in GDD.Significance and impact of the study: This research provides the basis for evaluating general suitability for viticulture in New Zealand, assists comparisons between viticulture regions in New Zealand and worldwide, and offers growers measures of assessing appropriate cultivars and sites. AbstractRésumé

Climate trends in a non-traditional high quality wine producing region

“…These latter results are similar to those found by Back et al (2012;2013), Orlandini et al (2009), Ramos et al (2008 and Tomasi et al (2011), for several grapevine-producing regions of the world. Finally, after analyzing equations 1 and 2, one may correctly argue that the HI is less sensitive than the GDD to changes in Tmin series because it gives more weight to Tmax data (Anderson et al, 2012, Hall andJones, 2010;Tomasi et al, 2011). This latter feature and the different rate of changes shown by the Tmax and Tmin series (Table 4) explain the lower number of HI series showing significant increasing trends (Table 5).…”

“…These three temperaturebased indices were selected due to their previous use in studies that address the effect of regional climate conditions on the general wine style (Anderson et al, 2012;Back et al, 2012;2013;Tonietto and Carbonneau, 2004). Also, the use of these three temperature-based indices relies on the fact that the air temperature is one of the most important factors affecting the quality of vinegrapes production (Hall and Jones, 2010).…”

“…Thus, the trend analyses were carried out taking into account the grape phenological aspects for both summer (August to January) and winter (January to June) growing seasons. The GDD was calculated using equation 1 with a base temperature (Tb) equal to 10 °C (Anderson et al, 2012, among many others).…”

“…Initially proposed by Tonietto and Carbonneau (2004), the HI (Equation 2; Table 1) is largely used in viticulture studies (Anderson et al, 2012;Back 2012;2013;Orlandini et al, 2009). The HI and GDD equations are similar to each other (Anderson et al, 2012) but, the HI gives more emphasis to the effect of the Tmax on the crop development.…”

“…The HI and GDD equations are similar to each other (Anderson et al, 2012) but, the HI gives more emphasis to the effect of the Tmax on the crop development. Equation 2 also presents a k factor that take into account the length of the days at the analyzed site (latitude).…”