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| Titel |
Increasing cloud cover in the 20th century: review and new findings in Spain |
| VerfasserIn |
A. Sanchez-Lorenzo, J. Calbó, M. Wild |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 8, no. 4 ; Nr. 8, no. 4 (2012-07-20), S.1199-1212 |
| Datensatznummer |
250005707
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| Publikation (Nr.) |
 copernicus.org/cp-8-1199-2012.pdf |
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| Zusammenfassung |
| Visual observations of clouds have been performed since the establishment of
meteorological observatories during the early instrumental period, and have
become more systematic and reliable after the mid-19th century due to
the establishment of the first national weather services. During the last
decades a large number of studies have documented the trends of the total
cloud cover (TCC) and cloudy types; most of these studies focus on the
trends since the second half of the 20th century. Due to the lower
reliability of former observations, and the fact that most of this data is
not accessible in digital format, there is a lack of studies focusing on the
trends of cloudiness since the mid-19th century. In the first part,
this work attempts to review previous studies analyzing TCC changes with
information covering at least the first half of the 20th century. Then,
the study analyses a database of cloudiness observations in Southern Europe
(Spain) since the second half of the 19th century. Specifically, monthly TCC
series were reconstructed since 1866 by means of a so-called parameter of
cloudiness, calculated from the number of cloudless and overcast days. These
estimated TCC series show a high interannual and decadal correlation with
the observed TCC series originally measured in oktas. After assessing the
temporal homogeneity of the estimated TCC series, the mean annual and
seasonal series for the whole of Spain and several subregions were
calculated. The mean annual TCC shows a general tendency to increase from
the beginning of the series until the 1960s; at this point, the trend
becomes negative. The linear trend for the annual mean series, estimated
over the 1866–2010 period, is a highly remarkable (and statistically
significant) increase of +0.44% per decade, which implies an overall
increase of more than +6% during the analyzed period. These results are
in line with the majority of the trends observed in many areas of the world
in previous studies, especially for the records before the 1950s when a
widespread increase of TCC can been considered as a common feature. |
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