Analog climates for Franconian viticulture – Using in depth principal component analysis and a multitude of indicators

For a practice oriented field study, a region with the climatic conditions expected in future in the viticultural region of Mainfranken located in Lower Franconia, Germany, is sought. The field study conducted by the Bavarian State Institute for Viticulture and Horticulture (Bayerische Landesanstalt für Weinbau und Gartenbau, LWG) aims to select and test scions of the typically Franconian grapevine variety Silvaner for cultivation under the more difficult conditions caused by climate crisis until the end of the 21st century.

To that end, climate analogs for four vineyards are calculated based on on-site station data as well as gridded observational data for the locations in comparison. The two data sources are each used for bias correction of a multi model ensemble of regional climate projections of CMIP5 based CORDEX runs. Standardized Euclidean distance calculated

For the combination of 30 climate indices selected in cooperation with the experts at LWG is used to derive the analogs. Alternatively, the scores of the major principal components of the indices are utilized for analog search in order to reduce the redundancy between the multitude of indices. The aim is to cover the aspects of the climate relevant to viticulture. The search for analog regions is conducted in the European domain based on E-OBS data.

The results for the indices themselves show three clusters independent of the choice of the vineyard and the data set for adjusting future data: Lot Valley and Lyon in France and Belgrade in Serbia.

Main analog regions for the vineyards’ mesoclimate expected at the end of the 21st century calculated using redundancy reduction with the principal component analysis are located in the region of Belgrade in Serbia, at the Romanian-Bulgarian border in the Region of Vratsa and Krasnodar Krai in the North Caucasus Region of Russia.

The study is part of the project BigData@Geo 2.0 co-funded by the European Regional Development Fund which aims to strengthen and support small and medium-sized enterprises in agriculture and silviculture in the face of the climate crisis.