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

2016 ◽  
Author(s):  
Veronica Manara ◽  
Michele Brunetti ◽  
Angela Celozzi ◽  
Maurizio Maugeri ◽  
Arturo Sanchez-Lorenzo ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Significant Contribution ◽  
Southern Italy ◽  
Temporal Evolution ◽  
Surface Solar Radiation ◽  
Clear Sky ◽  
The North ◽  
Underlying Causes ◽  
Set Up ◽  
Sky Conditions

Abstract. A dataset of 54 daily Italian downward surface solar radiation (SSR) records has been set up collecting data for the 1959–2013 period. Particular emphasis is placed upon 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, the records were interpolated onto a regular grid and clustered in 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 understand which part of the SSR variability depends on aerosols or clouds. Specifically, the all-sky SSR records show a decrease until the mid-1980s (dimming period) and a following increase until the end of the series (brightening period) even if the strength and the persistence of the tendencies are not the same in all seasons. The clear-sky records present stronger tendencies than the 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 the variations caused by the increase/decrease of 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.

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

2016 ◽  
Vol 16 (17) ◽  
pp. 11145-11161 ◽  
Author(s):  
Veronica Manara ◽  
Michele Brunetti ◽  
Angela Celozzi ◽  
Maurizio Maugeri ◽  
Arturo Sanchez-Lorenzo ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Significant Contribution ◽  
Southern Italy ◽  
Temporal Evolution ◽  
Surface Solar Radiation ◽  
Clear Sky ◽  
The North ◽  
Underlying Causes ◽  
Set Up ◽  
Sky Conditions

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 mid-1980s (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.

scholarly journals Analysis on the impact of aerosol optical depth on surface solar radiation in the Shanghai megacity, China

2011 ◽  
Vol 11 (7) ◽  
pp. 3281-3289 ◽  
Author(s):  
J. Xu ◽  
C. Li ◽  
H. Shi ◽  
Q. He ◽  
L. Pan
Keyword(s):  
Solar Radiation ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Decadal Variation ◽  
Surface Solar Radiation ◽  
Atmospheric Transparency ◽  
Clear Sky ◽  
Term Variation ◽  
Sky Conditions

Abstract. This study investigated the decadal variation of the direct surface solar radiation (DiSR) and the diffuse surface solar radiation (DfSR) during 1961–2008 in the Shanghai megacity as well as their relationships to Aerosol Optical Depth (AOD) under clear-sky conditions. Three successive periods with unique features of long term variation of DiSR were identified for both clear-sky and all-sky conditions: a "dimming" period from the late 1960s to the mid 1980s, a "stabilization"/"slight brightening" period from the mid 1980s to the mid 1990s, and a "renewed dimming" period thereafter. During the two dimming periods of DiSR, DfSR brightened significantly under clear-sky conditions, indicating that change in atmospheric transparency resulting from aerosol emission has an important role on decadal variation of surface solar radiation (SSR) over this area. The analysis on the relationship between the Moderate-resolution Imaging Spectroradiometer (MODIS) retrieved AOD and the corresponding hourly measurements of DiSR and DfSR under clear-sky conditions clearly revealed that AOD is significantly correlated and anti-correlated with DfSR and DiSR, respectively, both above 99% confidence in all seasons, indicating the great impact of aerosols on SSR through absorption and/or scattering in the atmosphere. In addition, both AOD and the corresponding DiSR and DfSR measured during the satellite passage over Shanghai show obvious weekly cycles. On weekends, AOD is lower than the weekly average, corresponding to higher DiSR and lower DfSR, while the opposite pattern was true for weekdays. Less AOD on weekends due to the reduction of transportation and industrial activities results in enhancement of atmospheric transparency under cloud free conditions so as to increase DiSR and decrease DfSR simultaneously. Results show that aerosol loading from the anthropogenic emissions is an important modulator for the long term variation of SSR in Shanghai.

scholarly journals Causes of Dimming and Brightening in China Inferred from Homogenized Daily Clear-Sky and All-Sky in situ Surface Solar Radiation Records (1958–2016)

2019 ◽  
Vol 32 (18) ◽  
pp. 5901-5913 ◽  
Author(s):  
Su Yang ◽  
Xiaolan L. Wang ◽  
Martin Wild
Keyword(s):  
Water Vapor ◽  
Solar Radiation ◽  
Water Vapor Pressure ◽  
Historical Records ◽  
Surface Solar Radiation ◽  
Clear Sky ◽  
The Past ◽  
Sky Conditions

AbstractThis paper presents a study on long-term surface solar radiation (SSR) changes over China under clear- and all-sky conditions and analyzes the causes of the “dimming” and “brightening.” To eliminate the nonclimatic signals in the historical records, the daily SSR dataset was first homogenized using quantile-matching (QM) adjustment. The results reveal rapid dimming before 2000 not only under all-sky conditions, but also under clear-sky conditions, at a decline rate of −9.7 ± 0.4 W m−2 decade−1 (1958–99). This is slightly stronger than that under all-sky conditions at −7.4 ± 0.4 W m−2 decade−1, since the clear-sky dimming stopped 15 years later. A rapid “wettening” of about 40-Pa surface water vapor pressure (SWVP) from 1985 to 2000 was found over China. It contributed 2.2% to the SSR decline under clear-sky conditions during the whole dimming period (1958–99). Therefore, water vapor cannot be the main cause of the long-term dimming in China. After a stable decade (1999–2008), an intensive brightening appeared under the clear-sky conditions at a rate of 10.6 ± 2.0 W m−2 decade−1, whereas a much weaker brightening (−0.8 ± 3.1 W m−2 decade−1) has been observed under all-sky conditions between 2008 and 2016. The remarkable divergence between clear- and all-sky trends in recent decades indicates that the clouds played two opposite roles in the SSR changes during the past 30 years, by compensating for the declining SSR under the cloud-free conditions in 1985–99 and by counteracting the increasing SSR under cloud-free conditions in 2008–16. Aerosols remain as the main cause of dimming and brightening over China in the last 60 years, although the clouds counteract the effects of aerosols after 2000.

scholarly journals Cloudiness Information Services for Solar Energy Management in West Africa

Atmosphere ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 857
Author(s):  
Derrick Kwadwo Danso ◽  
Sandrine Anquetin ◽  
Arona Diedhiou ◽  
Rabani Adamou
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
West Africa ◽  
Cloud Cover ◽  
Shortwave Radiation ◽  
Surface Solar Radiation ◽  
Clear Sky ◽  
Incoming Solar Radiation ◽  
Sahel Region ◽  
Sky Conditions

In West Africa (WA), interest in solar energy development has risen in recent years with many planned and ongoing projects currently in the region. However, a major drawback to this development in the region is the intense cloud cover that reduces the incoming solar radiation when present and causes fluctuations in solar power production. Therefore, understanding the occurrence of clouds and their link to the surface solar radiation in the region is important for making plans to manage future solar energy production. In this study, we use the state-of-the-art European Centre for Medium-range Weather Forecasts ReAnalysis (ERA5) dataset to examine the occurrence and persistence of cloudy and clear-sky conditions in the region. Then, we investigate the effects of cloud cover on the quantity and variability of the incoming solar radiation. The cloud shortwave radiation attenuation (CRASW↓) is used to quantify the amount of incoming solar radiation that is lost due to clouds. The results showed that the attenuation of incoming solar radiation is stronger in all months over the southern part of WA near the Guinea Coast. Across the whole region, the maximum attenuation occurs in August, with a mean CRASW↓ of about 55% over southern WA and between 20% and 35% in the Sahelian region. Southern WA is characterized by a higher occurrence of persistent cloudy conditions, while the Sahel region and northern WA are associated with frequent clear-sky conditions. Nonetheless, continuous periods with extremely low surface solar radiation were found to be few over the whole region. The analysis also showed that the surface solar radiation received from November to April only varies marginally from one year to the other. However, there is a higher uncertainty during the core of the monsoon season (June to October) with regard to the quantity of incoming solar radiation. The results obtained show the need for robust management plans to ensure the long-term success of solar energy projects in the region.

scholarly journals Analysis on the impact of aerosol optical depth on surface solar radiation in the Shanghai megacity, China

2011 ◽  
Vol 11 (1) ◽  
pp. 627-652
Author(s):  
J. Xu ◽  
C. Li ◽  
H. Shi ◽  
Q. He ◽  
L. Pan
Keyword(s):  
Solar Radiation ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Decadal Variation ◽  
Surface Solar Radiation ◽  
Atmospheric Transparency ◽  
Clear Sky ◽  
Term Variation ◽  
Sky Conditions

Abstract. This study investigated the decadal variation of the direct surface solar radiation (DiSR) and the diffuse surface solar radiation (DfSR) during 1961–2008 in the Shanghai megacity as well as their relationships to Aerosol Optical Depth (AOD) under clear-sky conditions. Three successive periods with unique features of long term variation of DiSR were identified for both clear-sky and all-sky conditions: a "dimming" period from the late 1960s to the mid 1980s, a "stabilization"/"slight brightening" period from the mid 1980s to the mid 1990s, and a "renewed dimming" period thereafter. During the two dimming periods of DiSR, DfSR brightened significantly under clear-sky conditions, indicating that change in atmospheric transparency resulting from aerosol emission has an important role on decadal variation of surface solar radiation (SSR) over this area. The analysis on the relationship between the Moderate-resolution Imaging Spectroradiometer (MODIS) retrieved AOD and the corresponding hourly measurements of DiSR and DfSR under clear-sky conditions clearly revealed that AOD is significantly correlated and anti-correlated with DfSR and DiSR, respectively, both above 99% confidence in all seasons, indicating the great impact of aerosols on SSR through absorption and/or scattering in the atmosphere. In addition, both AOD and the corresponding DiSR and DfSR measured during the satellite passage over Shanghai show obvious weekly cycles. On weekends, AOD is lower than the weekly average, corresponding to higher DiSR and lower DfSR, while the opposite pattern was true for weekdays. Less AOD on weekends due to the reduction of transportation and industrial activities results in enhancement of atmospheric transparency under cloud free conditions so as to increase DiSR and decrease DfSR simultaneously. Results show that aerosol loading from the anthropogenic emissions is an important modulator for the long term variation of SSR in Shanghai.

Surface solar radiation trends under all-sky and clear-sky conditions over Europe

2021 ◽  
Author(s):  
Lucas Ferreira Correa ◽  
Martin Wild ◽  
Doris Folini ◽  
Boriana Chtirkova
Keyword(s):  
Solar Radiation ◽  
Primary Source ◽  
Surface Solar Radiation ◽  
European Continent ◽  
Clear Sky ◽  
Radiative Processes ◽  
Diagnosis And Prognosis ◽  
In Situ Observations ◽  
Sky Conditions

<p>Solar radiation is the primary source of energy for the climate system and a variety of biological processes on the planet. In that sense, understanding the radiative processes in the atmosphere and identifying the governing factors of these processes is key for climate diagnosis and prognosis. In this work, we use daily in-situ observations from 528 stations over Europe from the World Radiation Data Centre (WRDC) database, to analyze Surface Solar Radiation (SSR) trends from 1964 until 2018 in all regions of the continent. Statistical methods were applied to quality-control the dataset: detecting and removing outliers, homogenization and gap-filling of the time series. Two different statistical approaches for identification of clear-sky conditions were applied and compared. Observations in most of the regions on the European continent agree with previously observed negative trends (diming) until the 80’s, followed by positive SSR trends (brightening) from then on, continuing until recent years. However, the regime shifts and the intensity of the trends are not homogeneous within the continent, indicating that regional aspects have non-negligible impacts on the SSR behavior. The comparison between all-sky and clear-sky SSR observations helps to identify to what extent the clouds were a relevant factor in the observed trends in every part of the continent. With this type of analysis we intend to not only present the SSR trends over Europe, but also to expand the comprehension of their spatial heterogeneity across the continent, as well as their causes.</p>

Daily Surface Solar Radiation Prediction Mapping Using Artificial Neural Network: The Case Study of Reunion Island

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Peng Li ◽  
Miloud Bessafi ◽  
Beatrice Morel ◽  
Jean-Pierre Chabriat ◽  
Mathieu Delsaut ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Wavelet Transform ◽  
Solar Radiation ◽  
Computational Time ◽  
Reunion Island ◽  
Surface Solar Radiation ◽  
Clear Sky ◽  
Réunion Island ◽  
Artificial Neural

Abstract This paper focuses on the prediction of daily surface solar radiation maps for Reunion Island by a hybrid approach that combines principal component analysis (PCA), wavelet transform analysis, and artificial neural network (ANN). The daily surface solar radiation over 18 years (1999–2016) from CM SAF (SARAH-E with 0.05 deg × 0.05 deg spatial resolution) is first detrended using the clear sky index. Dimensionality reduction of the detrended dataset is secondly performed through PCA, which results in saving computational time by a factor of eight in comparison to not using PCA. A wavelet transform is thirdly applied onto each of the first 28 principal components (PCs) explaining 95% of the variance. The decomposed nine-wavelet components for each PC are fourthly used as input to an ANN model to perform the prediction of day-ahead surface solar radiation. The predicted decomposed components are finally returned to PCs and clear sky indices, irradiation in the end for re-mapping the surface solar radiation's distribution. It is found that the prediction accuracy is quite satisfying: root mean square error (RMSE) is 30.98 W/m2 and the (1 − RMSE_prediction/RMSE_persistence) is 0.409.

scholarly journals Assessment and Day-Ahead Forecasting of Hourly Solar Radiation in Medellín, Colombia

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4402
Author(s):  
Julián Urrego-Ortiz ◽  
J. Alejandro Martínez ◽  
Paola A. Arias ◽  
Álvaro Jaramillo-Duque
Keyword(s):  
Solar Radiation ◽  
Markov Model ◽  
Power Plants ◽  
Wrf Model ◽  
Tropical Andes ◽  
Clear Sky ◽  
Proposed Model ◽  
Solar Power Plants ◽  
Solar Resource ◽  
Sky Conditions

The description and forecasting of hourly solar resource is fundamental for the operation of solar energy systems in the electric grid. In this work, we provide insights regarding the hourly variation of the global horizontal irradiance in Medellín, Colombia, a large urban area within the tropical Andes. We propose a model based on Markov chains for forecasting the hourly solar irradiance for one day ahead. The Markov model was compared against estimates produced by different configurations of the weather research forecasting model (WRF). Our assessment showed that for the period considered, the average availability of the solar resource was of 5 PSH (peak sun hours), corresponding to an average daily radiation of ~5 kWh/m2. This shows that Medellín, Colombia, has a substantial availability of the solar resource that can be a complementary source of energy during the dry season periods. In the case of the Markov model, the estimates exhibited typical root mean squared errors between ~80 W/m2 and ~170 W/m2 (~50%–~110%) under overcast conditions, and ~57 W/m2 to ~171 W/m2 (~16%–~38%) for clear sky conditions. In general, the proposed model had a performance comparable with the WRF model, while presenting a computationally inexpensive alternative to forecast hourly solar radiation one day in advance. The Markov model is presented as an alternative to estimate time series that can be used in energy markets by agents and power-system operators to deal with the uncertainty of solar power plants.

Coupling Groundwater, Vegetation, and Atmospheric Processes: A Comparison of Two Integrated Models

2017 ◽  
Vol 18 (5) ◽  
pp. 1489-1511 ◽  
Author(s):  
Mauro Sulis ◽  
John L. Williams ◽  
Prabhakar Shrestha ◽  
Malte Diederich ◽  
Clemens Simmer ◽  
...  
Keyword(s):  
Land Surface ◽  
Convective Precipitation ◽  
Atmospheric Processes ◽  
Clear Sky ◽  
The North ◽  
Western Germany ◽  
The Difference ◽  
Heat And Moisture ◽  
Sky Conditions ◽  
Diagram Approach

Abstract This study compares two modeling platforms, ParFlow.WRF (PF.WRF) and the Terrestrial Systems Modeling Platform (TerrSysMP), with a common 3D integrated surface–groundwater model to examine the variability in simulated soil–vegetation–atmosphere interactions. Idealized and hindcast simulations over the North Rhine–Westphalia region in western Germany for clear-sky conditions and strong convective precipitation using both modeling platforms are presented. Idealized simulations highlight the strong variability introduced by the difference in land surface parameterizations (e.g., ground evaporation and canopy transpiration) and atmospheric boundary layer (ABL) schemes on the simulated land–atmosphere interactions. Results of the idealized simulations also suggest a different range of sensitivity in the two models of land surface and atmospheric parameterizations to water-table depth fluctuations. For hindcast simulations, both modeling platforms simulate net radiation and cumulative precipitation close to observed station data, while larger differences emerge between spatial patterns of soil moisture and convective rainfall due to the difference in the physical parameterization of the land surface and atmospheric component. This produces a different feedback by the hydrological model in the two platforms in terms of discharge over different catchments in the study area. Finally, an analysis of land surface and ABL heat and moisture budgets using the mixing diagram approach reveals different sensitivities of diurnal atmospheric processes to the groundwater parameterizations in both modeling platforms.

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