Reassessment and update of long‐term trends in downward surface shortwave radiation over Europe (1939–2012)

Sánchez-Lorenzo, Arturo; Wild, Martin; Brunetti, Michele; Guijarro, José Antonio; Hakuba, Maria Z.; Calbó, Josep; Mystakidis, Stefanos; Bartók, Blanka

doi:10.1002/2015jd023321

Cited by 138 publications

(142 citation statements)

References 71 publications

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“…In particular, we compared the Italian trends with those obtained by Sanchez-Lorenzo et al (2015), using a new version of the GEBA (Global Energy Balance Archive) dataset updated to 2012, for southern Europe. This comparison shows similar trends in the dimming period, while in the brightening period the trends are significantly stronger for Italy than for southern Europe.…”

Section: Discussionmentioning

confidence: 99%

Detection of dimming/brightening in Italy from homogenized all-sky and clear-sky surface solar radiation records and underlying causes (1959–2013)

Manara

Brunetti

Celozzi³

et al. 2016

Atmos. Chem. Phys.

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Abstract. A dataset of 54 daily Italian downward surface solar radiation (SSR) records has been set up collecting data for the 1959-2013 period. Special emphasis is given to the quality control and the homogenization of the records in order to ensure the reliability of the resulting trends. This step has been shown as necessary due to the large differences obtained between the raw and homogenized dataset, especially during the first decades of the study period. In addition, SSR series under clear-sky conditions were obtained considering only the cloudless days from corresponding ground-based cloudiness observations. Subsequently, records were interpolated onto a regular grid and clustered into two regions, northern and southern Italy, which were averaged in order to get all-sky and clear-sky regional SSR records. Their temporal evolution is presented, and possible reasons for differences between all-sky and clear-sky conditions and between the two regions are discussed in order to determine to what extent SSR variability depends on aerosols or clouds. Specifically, the all-sky SSR records show a decrease until the mid1980s (dimming period), and a following increase until the end of the series (brightening period) even though strength and persistence of tendencies are not the same in all seasons. Clear-sky records present stronger tendencies than all-sky records during the dimming period in all seasons and during the brightening period in winter and autumn. This suggests that, under all-sky conditions, the variations caused by the increase/decrease in the aerosol content have been partially masked by cloud cover variations, especially during the dimming period. Under clear sky the observed dimming is stronger in the south than in the north. This peculiarity could be a consequence of a significant contribution of mineral dust variations to the SSR variability.

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Section: Discussionmentioning

confidence: 99%

Detection of dimming/brightening in Italy from homogenized all-sky and clear-sky surface solar radiation records and underlying causes (1959–2013)

Manara

Brunetti

Celozzi³

et al. 2016

Atmos. Chem. Phys.

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“…To our knowledge these calculations are the first of their kind and demonstrate the relative importance of the impacts of clear and cloudy skies on the all-sky radiation. Trend values for the all-sky radiation all fall within the bounds of Sanchez-Lorenzo et al (2015) given by their comprehensive summary of Europe's observations. For the clear-sky proxy radiation the trend is positive throughout the entire period and the absence of a curvature matching that of the all-sky radiation does not suggest a very strong causal link with it.…”

Section: Decomposing the All-sky Radiative Fluxesmentioning

confidence: 99%

Impact of aerosols and clouds on decadal trends in all-sky solar radiation over the Netherlands (1966–2015)

2017

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Abstract.A 50-year hourly data set of global shortwave radiation, cloudiness and visibility over the Netherlands was used to quantify the contribution of aerosols and clouds to the trend in yearly-averaged all-sky radiation (1.81 ± 1.07 W m −2 decade −1 ). Yearly-averaged clearsky and cloud-base radiation data show large year-to-year fluctuations caused by yearly changes in the occurrence of clear and cloudy periods and cannot be used for trend analysis. Therefore, proxy clear-sky and cloud-base radiations were computed. In a proxy analysis hourly radiation data falling within a fractional cloudiness value are fitted by monotonic increasing functions of solar zenith angle and summed over all zenith angles occurring in a single year to produce an average. Stable trends can then be computed from the proxy radiation data. A functional expression is derived whereby the trend in proxy all-sky radiation is a linear combination of trends in fractional cloudiness, proxy clearsky radiation and proxy cloud-base radiation. Trends (per decade) in fractional cloudiness, proxy clear-sky and proxy cloud-base radiation were, respectively, 0.0097 ± 0.0062, 2.78 ± 0.50 and 3.43 ± 1.17 W m −2 . To add up to the allsky radiation the three trends have weight factors, namely the difference between the mean cloud-base and clear-sky radiation, the clear-sky fraction and the fractional cloudiness, respectively. Our analysis clearly demonstrates that all three components contribute significantly to the observed trend in all-sky radiation. Radiative transfer calculations using the aerosol optical thickness derived from visibility observations indicate that aerosol-radiation interaction (ARI) is a strong candidate to explain the upward trend in the clear-sky radiation. Aerosol-cloud interaction (ACI) may have some impact on cloud-base radiation, but it is suggested that decadal changes in cloud thickness and synoptic-scale changes in cloud amount also play an important role.

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“…A comprehensive assessment of the trends in Europe using homogeneous GEBA records is reported in Sanchez-Lorenzo et al (2015). Figure 5 shows an updated composite mean series of the 56 European GEBA records used in SanchezLorenzo et al (2015) and illustrates the sequence of early brightening, dimming, and brightening over Europe.…”

Section: Detection Of Decadal Changes In the Surface Energy Fluxesmentioning

confidence: 99%

The Global Energy Balance Archive (GEBA) version 2017: a database for worldwide measured surface energy fluxes

Wild

Ohmura

Schär

et al. 2017

Earth Syst. Sci. Data

114

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Abstract. The Global Energy Balance Archive (GEBA) is a database for the central storage of the worldwide measured energy fluxes at the Earth's surface, maintained at ETH Zurich (Switzerland). This paper documents the status of the GEBA version 2017 dataset, presents the new web interface and user access, and reviews the scientific impact that GEBA data had in various applications. GEBA has continuously been expanded and updated and contains in its 2017 version around 500 000 monthly mean entries of various surface energy balance components measured at 2500 locations. The database contains observations from 15 surface energy flux components, with the most widely measured quantity available in GEBA being the shortwave radiation incident at the Earth's surface (global radiation). Many of the historic records extend over several decades. GEBA contains monthly data from a variety of sources, namely from the World Radiation Data Centre (WRDC) in St. Petersburg, from national weather services, from different research networks (BSRN, ARM, SURFRAD), from peer-reviewed publications, project and data reports, and from personal communications. Quality checks are applied to test for gross errors in the dataset. GEBA has played a key role in various research applications, such as in the quantification of the global energy balance, in the discussion of the anomalous atmospheric shortwave absorption, and in the detection of multi-decadal variations in global radiation, known as "global dimming" and "brightening". GEBA is further extensively used for the evaluation of climate models and satellite-derived surface flux products. On a more applied level, GEBA provides the basis for engineering applications in the context of solar power generation, water management, agricultural production and tourism. GEBA is publicly accessible through the internet via http://www.geba.ethz.ch. Supplementary data are available at https://doi.org/10.1594/PANGAEA.873078.

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Reassessment and update of long‐term trends in downward surface shortwave radiation over Europe (1939–2012)

Cited by 138 publications

References 71 publications

Detection of dimming/brightening in Italy from homogenized all-sky and clear-sky surface solar radiation records and underlying causes (1959–2013)

Detection of dimming/brightening in Italy from homogenized all-sky and clear-sky surface solar radiation records and underlying causes (1959–2013)

Impact of aerosols and clouds on decadal trends in all-sky solar radiation over the Netherlands (1966–2015)

The Global Energy Balance Archive (GEBA) version 2017: a database for worldwide measured surface energy fluxes

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