Effective cloud optical depth and enhancement effects for broken liquid water clouds in Valencia (Spain)

Marı́n, Marı́a José; Serrano, D.; Utrillas, M. P.; Núñez, M.; Martínez‐Lozano, J. A.

doi:10.1016/j.atmosres.2017.05.008

Cited by 7 publications

(5 citation statements)

References 41 publications

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“…In most cases, clouds attenuate the UV signal at the surface by about 15 % to 45 % (Calbó et al, 2005). Broken cloud cover can also enhance the surface UV radiation (Lovengreen et al, 2005;Marín et al, 2017). Krzyścin and Puchalski (1998) found a 1.5 % increase in erythemal UV for a 10 % decrease in aerosol optical depth (AOD) and up to a 30 % decreases in UV erythemal can be observed due to biomass burning emissions (Lamy et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Clear-sky ultraviolet radiation modelling using output from the Chemistry Climate Model Initiative

et al. 2019

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Abstract. We have derived values of the ultraviolet index (UVI) at solar noon using the Tropospheric Ultraviolet Model (TUV) driven by ozone, temperature and aerosol fields from climate simulations of the first phase of the Chemistry-Climate Model Initiative (CCMI-1). Since clouds remain one of the largest uncertainties in climate projections, we simulated only the clear-sky UVI. We compared the modelled UVI climatologies against present-day climatological values of UVI derived from both satellite data (the OMI-Aura OMUVBd product) and ground-based measurements (from the NDACC network). Depending on the region, relative differences between the UVI obtained from CCMI/TUV calculations and the ground-based measurements ranged between −5.9 % and 10.6 %. We then calculated the UVI evolution throughout the 21st century for the four Representative Concentration Pathways (RCPs 2.6, 4.5, 6.0 and 8.5). Compared to 1960s values, we found an average increase in the UVI in 2100 (of 2 %–4 %) in the tropical belt (30∘ N–30∘ S). For the mid-latitudes, we observed a 1.8 % to 3.4 % increase in the Southern Hemisphere for RCPs 2.6, 4.5 and 6.0 and found a 2.3 % decrease in RCP 8.5. Higher increases in UVI are projected in the Northern Hemisphere except for RCP 8.5. At high latitudes, ozone recovery is well identified and induces a complete return of mean UVI levels to 1960 values for RCP 8.5 in the Southern Hemisphere. In the Northern Hemisphere, UVI levels in 2100 are higher by 0.5 % to 5.5 % for RCPs 2.6, 4.5 and 6.0 and they are lower by 7.9 % for RCP 8.5. We analysed the impacts of greenhouse gases (GHGs) and ozone-depleting substances (ODSs) on UVI from 1960 by comparing CCMI sensitivity simulations (1960–2100) with fixed GHGs or ODSs at their respective 1960 levels. As expected with ODS fixed at their 1960 levels, there is no large decrease in ozone levels and consequently no sudden increase in UVI levels. With fixed GHG, we observed a delayed return of ozone to 1960 values, with a corresponding pattern of change observed on UVI, and looking at the UVI difference between 2090s values and 1960s values, we found an 8 % increase in the tropical belt during the summer of each hemisphere. Finally we show that, while in the Southern Hemisphere the UVI is mainly driven by total ozone column, in the Northern Hemisphere both total ozone column and aerosol optical depth drive UVI levels, with aerosol optical depth having twice as much influence on the UVI as total ozone column does.

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Section: Introductionmentioning

confidence: 99%

Clear-sky ultraviolet radiation modelling using output from the Chemistry Climate Model Initiative

et al. 2019

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“…Near CSZA 0.3, the majority of cases were observed, with 28 % of total of cases. As Marín et al (2017) reported, the enhancement effect does not depend on CSZA and the maximum of cases were observed between 40-50 % of cloud cover. They reported a median of NCRE of 0.18 and percentile 75 of 0.3.…”

Section: Shortwave Cloud Radiative Effectssupporting

confidence: 68%

“…The position of the solar disk relative to the clouds is a crucial condition for strong enhancement: solar disk near clouds or low CSZA with clouds present near zenith (Tzoumanikas et al, 2016). Marín et al (2017) showed that the enhancement can be observed at any time of the day CSZA and the maximum is observed between 40-50 % of cloud cover. They reported a median of NCRE of 0.18 and percentile 75 of 0.3 at Valencia, Spain.…”

Section: The Enhancement Effect Of Clouds On the Solar Radiationmentioning

confidence: 99%

Clouds and their effects on solar radiation in São Paulo

Santana¹

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Queria agradecer primeiramente aos meus pais por me incentivar e motivar no mundo da meteorologia. Ao sistema de educação de Cuba (público e para todos) por contribuir com minha formação como meteorologista. Agradecimento especial à minha estimada orientadora Dra Marcia Akemi Yamasoe, por todo apoio e profissionalismo durante a pesquisa, em ensinar novos conhecimentos que enriqueceram esta pesquisa e minha formação. A CAPES pela concessão da bolsa de mestrado. Aos doutores Eduardo Landulfo, Fabio Lopes por fornecer os dados do Lidar e sky câmera.

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“…On the other hand, the 3D radiative effects on the transmitted radiance observed on the ground are not well understood, and their influence on the retrieval of the cloud physical properties from ground-based observation is not clear. For transmitted radiance, radiation enhancement frequently occurs [21]. Several algorithms have been proposed to estimate the 3D cloud field by iterative 3D radiative transfer calculations, using the variational and ensemble Kalman filter methods [22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Retrieval of Cloud Optical Thickness from Sky-View Camera Images using a Deep Convolutional Neural Network based on Three-Dimensional Radiative Transfer

et al. 2019

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Observation of the spatial distribution of cloud optical thickness (COT) is useful for the prediction and diagnosis of photovoltaic power generation. However, there is not a one-to-one relationship between transmitted radiance and COT (so-called COT ambiguity), and it is difficult to estimate COT because of three-dimensional (3D) radiative transfer effects. We propose a method to train a convolutional neural network (CNN) based on a 3D radiative transfer model, which enables the quick estimation of the slant-column COT (SCOT) distribution from the image of a ground-mounted radiometrically calibrated digital camera. The CNN retrieves the SCOT spatial distribution using spectral features and spatial contexts. An evaluation of the method using synthetic data shows a high accuracy with a mean absolute percentage error of 18% in the SCOT range of 1–100, greatly reducing the influence of the 3D radiative effect. As an initial analysis result, COT is estimated from a sky image taken by a digital camera, and a high correlation is shown with the effective COT estimated using a pyranometer. The discrepancy between the two is reasonable, considering the difference in the size of the field of view, the space–time averaging method, and the 3D radiative effect.

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Effective cloud optical depth and enhancement effects for broken liquid water clouds in Valencia (Spain)

Cited by 7 publications

References 41 publications

Clear-sky ultraviolet radiation modelling using output from the Chemistry Climate Model Initiative

Clear-sky ultraviolet radiation modelling using output from the Chemistry Climate Model Initiative

Clouds and their effects on solar radiation in São Paulo

Retrieval of Cloud Optical Thickness from Sky-View Camera Images using a Deep Convolutional Neural Network based on Three-Dimensional Radiative Transfer

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