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Sunshine duration variability and trends in Italy from homogenized instrumental time series (1936-2013)

A data set of quality checked daily sunshine duration measurements was collected from 104 Italian sites over the 1936 to 2013 period. Monthly mean values were homogenized, projected onto a grid, and subjected to principle component analysis, which identified two significantly different regions: North and South. Sunshine duration temporal evolution is presented, and possible reasons for differences between the two regions are discussed in the light of a comparison with the trends found in observations of total cloud cover and with results from two neighboring regions: the Alps and Spain. In addition, trends for irradiance records, estimated from sunshine duration records using the angstrom ngstrom-Prescott formula, are presented too. The major feature of the trends, an increase in sunshine duration from the mid-1980s, was common to both northern and southern Italy; the decrease in the preceding 30 year period was not, as northern Italy had a lower rate of decrease than southern Italy. The few records available during the earliest period of the data set indicate that sunshine duration in Italy increased from the mid-1930s to the mid-1950s. The further steps needed to identify and quantify the mechanisms giving rise to the observed trends and to the reported regional differences in dimming and brightening are outlined

A. Sanchez-Lorenzo was supported by the Postdoctoral Fellowships 2011-BP-B-00078 and JCI-2012-12508, and the Spanish Ministry of Science and Innovation Projects CGL2010-18546 and CGL2011-27574-C02-02

© Journal of Geophysical Research: Atmospheres, 2015, vol. 120. núm. 9, p. 3622-3641

American Geophysical Union (AGU)

Author: Sánchez Lorenzo, Arturo
Date: 2015
Abstract: A data set of quality checked daily sunshine duration measurements was collected from 104 Italian sites over the 1936 to 2013 period. Monthly mean values were homogenized, projected onto a grid, and subjected to principle component analysis, which identified two significantly different regions: North and South. Sunshine duration temporal evolution is presented, and possible reasons for differences between the two regions are discussed in the light of a comparison with the trends found in observations of total cloud cover and with results from two neighboring regions: the Alps and Spain. In addition, trends for irradiance records, estimated from sunshine duration records using the angstrom ngstrom-Prescott formula, are presented too. The major feature of the trends, an increase in sunshine duration from the mid-1980s, was common to both northern and southern Italy; the decrease in the preceding 30 year period was not, as northern Italy had a lower rate of decrease than southern Italy. The few records available during the earliest period of the data set indicate that sunshine duration in Italy increased from the mid-1930s to the mid-1950s. The further steps needed to identify and quantify the mechanisms giving rise to the observed trends and to the reported regional differences in dimming and brightening are outlined
A. Sanchez-Lorenzo was supported by the Postdoctoral Fellowships 2011-BP-B-00078 and JCI-2012-12508, and the Spanish Ministry of Science and Innovation Projects CGL2010-18546 and CGL2011-27574-C02-02
Format: application/pdf
ISSN: 2169-897X (versió paper)
2169-8996 (versió electrònica)
Document access: http://hdl.handle.net/10256/11841
Language: eng
Publisher: American Geophysical Union (AGU)
Collection: MICINN/PN 2011-2014/CGL2010-18546
SUR/2011 BP-B 00078
Reproducció digital del document publicat a: http://dx.doi.org/10.1016/j.bspc.2012.12.00310.1002/2014JD022560
Articles publicats (D-F)
Is part of: © Journal of Geophysical Research: Atmospheres, 2015, vol. 120. núm. 9, p. 3622-3641
Rights: Tots els drets reservats
Subject: Radiació solar -- Itàlia
Solar radiation -- Italy
Title: Sunshine duration variability and trends in Italy from homogenized instrumental time series (1936-2013)
Type: info:eu-repo/semantics/article
Repository: DUGiDocs

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