Volume 141, June 2016, Pages 39–53
Highlights
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- A grape harvest dates series was built after 34,200 newspapers and recent annuals.
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- A reconstruction of growing season maxima temperatures back to 1856 was achieved.
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- Relations between maxima temperatures and teleconnection patterns were analysed.
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- A solar forcing signal (TSI) in maxima temperatures was highlighted via SCA index.
Abstract
This
paper reports a climatic reconstruction approach for the Minho region
(NW of Portugal) using grape harvest dates (GHD) as proxy of surface air
temperature. This new GHD series was built based on the records from a
set of local and regional newspapers (1854–1978) and the annuals of a
Wine Producers Cooperative (1978–2010). The strong inverse correlation
between Minho GHD and the mean maxima temperatures of the preceding
March to August months (GSTmax), registered at the Braga weather station
for the overlap period 1941–2009, allowed a reconstruction, with
associated statistical uncertainties, of the regional GSTmax back to
1856. These were then used to characterize the main climatic episodes in
the region during the last 154 years. The most noticeable feature that
emerges from the comparison of the Minho GSTmax with the global annual
average temperatures of Jones et al. (2013)
is that these regional temperatures, in clear contrast with the global
warming observed from around 1990 onwards, show no noteworthy increasing
trend. The influence of climatic variability was examined also in terms
of the relations between GSTmax (1950–2009) and the main meteorological
teleconnection patterns affecting the North Atlantic European sector
where the Minho region is included. Data support the hypothesis that
persistent positive modes of spring-summer Scandinavian (SCA) and summer
East Atlantic/Western Russia patterns triggered lower GSTmax,
especially in the 60s–80s. The search for solar imprints in the Minho
region climate identified the SCA mode as a promising connection between
the two, since it is significantly inversely correlated with both, the
TSI and the GSTmax.
Like in other traditional European
viticultural regions, the Minho GHD have shown to be a valuable tool
for understanding the interactions between large-scale circulation modes
and regional/local climatic conditions. Besides it will deliver a
reliable assessment of climatic proxies from geological record, like
tidal marsh benthic foraminifera assemblages.
Keywords
- Newspapers;
- Grape harvest dates;
- Growing season;
- Maxima temperatures;
- Teleconnection modes;
- TSI
© 2016 Elsevier B.V. All rights reserved.
