Laguna Watershed Knowledgebase

Climate change will challenge continued production of quality wine grapes in Sonoma County. In order to effectively consider climate change in vineyard design and management, a multi-scale approach to climate is required. Macroclimate refers to broad-scale atmospheric circulation over scales of 100+ kilometers, such as the rainfall –temperature gradient along the entire Pacific Coast. Mesoclimate operates over scales of 1-100 km, such as the coastal-inland gradient in temperature and rainshadows across mountain ranges. Topoclimate refers to phenomena across local topography, down to scales of 10 meters, where solar exposure (i.e. N- versus S-facing slopes), wind exposure, and cold-air drainage operate. At the finest scale, microclimate encompasses the effects of vegetation canopies on solar radiation, humidity, and temperature, such as the effects of trellis design on berry temperature on either side of the trellis.
In this presentation, I describe the various tools available for understanding climate and climate change at these multiple scales. Climate stations, and interpolated surfaces such as PRISM (www.prism.oregonstate.edu/), account for macroclimatic and mesoclimatic gradients down to a scale of 800 m. Historical interpolations from WESTMAP (www.cefa.dri.edu/Westmap/) at 4 km provide monthly mean, maximum, and minimum temperatures and precipitation from 1895 to the present and form a basis for examining climate changes to date. Topoclimatic gradients are derived from digital elevation models (DEMs) using solar radiation models (Solar Tools in ArcGIS), and topographic position and slope. At the finest microclimatic scales, hemispherical photography quantifies trellises from a “grapes’ eye view,” allowing estimation of solar radiation on grape clusters at half hourly intervals for each month of the growing season. By combining all of these methods, the temperatures of grape clusters can be tracked through growing seasons using local weather station data, with numerous key insights into vineyard design and management in a variable and changing climate.