A new method for estimating UV fluxes at ground level in cloud-free conditions

Nyamsi, William Wandji; Pitkänen, Mikko R. A.; Aoun, Youva; Blanc, Philippe; Heikkilä, Anu; Lakkala, Kaisa; Bernhard, Germar; Koskela, Tapani; Lindfors, Anders V.; Arola, Antti; Wald, Lucien

doi:10.5194/amt-10-4965-2017

Cited by 11 publications

(9 citation statements)

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“…Examples of such a combination are the clear-sky index and cloud modification factor, as discussed by Oumbe et al [19] or Huang et al [39] for total irradiance, or the UV range discussed by Calbo et al [40], den Outer et al [41] or Krotkov et al [42]. The approach suggested by Wandji Nyamsi et al [37] for the surface albedo in UV could be another means of improving PAR estimates in cloudless and all-sky conditions. Author Contributions: W.W.N.…”

Section: Discussionmentioning

confidence: 99%

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A New Clear-Sky Method for Assessing Photosynthetically Active Radiation at the Surface Level

et al. 2019

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A clear-sky method to estimate the photosynthetically active radiation (PAR) at the surface level in cloudless atmospheres is presented and validated. It uses a fast and accurate approximation adopted in several radiative transfer models, known as the k-distribution method and the correlated-k approximation, which gives a set of fluxes accumulated over 32 established wavelength intervals. A resampling technique, followed by a summation, are applied over the wavelength range [0.4, 0.7] µm in order to retrieve the PAR fluxes. The method uses as inputs the total column contents of ozone and water vapor, and optical properties of aerosols provided by the Copernicus Atmosphere Monitoring Service. To validate the method, its outcomes were compared to instantaneous global photosynthetic photon flux density (PPFD) measurements acquired at seven experimental sites of the Surface Radiation Budget Network (SURFRAD) located in various climates in the USA. The bias lies in the interval [−12, 61] µmol m −2 s −1 ([−1, 5] % in values relative to the means of the measurements at each station). The root mean square error ranges between 37 µmol m −2 s −1 (3%) and 82 µmol m −2 s −1 (6%). The squared correlation coefficient fluctuates from 0.97 to 0.99. This comparison demonstrates the high level of accuracy of the presented method, which offers an accurate estimate of PAR fluxes in cloudless atmospheres at high spatial and temporal resolutions useful for several bio geophysical models.

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Section: Discussionmentioning

confidence: 99%

“…The resampling technique has been presented in Wandji Nyamsi et al [30,37] for the PAR range and UV range, respectively. The technique is a pure modelling concept with radiative transfer simulations with libRadtran.…”

Section: Description Of the Spectral Resampling And The Proposed Methodsmentioning

confidence: 99%

A New Clear-Sky Method for Assessing Photosynthetically Active Radiation at the Surface Level

et al. 2019

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“…Kato bands are constructed with the idea that various atmospheric parameters tend to affect the irradiation spectra in different wavelength regions. This results in the construction of a spectrum having nonuniform wavelength bands, whose accuracy depends on the accuracy of the atmospheric parameters used for its construction [32], [36], [37]. Using Kato bands, the spectral data can also be split into direct and diffuse irradiance.…”

Section: A Irradiance Datamentioning

confidence: 99%

Impact of Irradiance Data on the Energy Yield Modeling of Dual-Junction Solar Module Stacks for One-Sun Applications

Höhn

Murthy

Steiner

et al. 2021

IEEE J. Photovoltaics

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With silicon-based tandem solar cells nearing commercialization, the significance of predicting the outdoor performance of tandem solar devices is growing. Although several models exist to calculate the outdoor performance, the availability of high-resolution irradiance data is limited. Therefore, we study the influence of the resolution of the irradiance data on the predicted energy yield of a 2-terminal III-V/Si tandem device. As an exemplary location, Golden, CO, USA, was chosen. We found that a wavelength resolution as low as 50 nm leads to a deviation of only 0.2% relative. We especially found that satellite-derived spectral data that are split into Kato bands lead to a deviation of 0.7% relative for Golden, CO, and, thus, are sufficient to model the energy yield of tandem devices. Confirming this finding for further locations has to be the scope of future work.

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“…These multisource satellite data are fused, and a downscaling model is applied to achieve a temporal resolution of 1 min, a spatial resolution in the range 1-12 km depending on latitude. Using more than one satellite source as an input for clouds, ozone and aerosols allows the expansion of existing models [26][27][28][29] to the PpIX action spectrum and all weather conditions which is particularly important for climates with highly variable weather such as the UK. This model is further development of a previously reported method for the near real-time monitoring of erythema effective ultraviolet radiation [25].…”

Section: Satellite Imagery Determination Of Ppix-effective Irradiancementioning

confidence: 99%

SmartPDT®: Smartphone enabled real-time dosimetry via satellite observation for daylight photodynamic therapy

McLellan

Morelli

Simeone

et al. 2020

Photodiagnosis and Photodynamic Therapy

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Background: Actinic keratosis (AK) affects one quarter of over 60 year olds in Europe with the risk of transforming into invasive squamous cell carcinoma. Daylight photodynamic therapy (dPDT) is an effective and patient preferred treatment that uses sunlight to clear AK. Currently, there is no standardised method for measuring the light received during treatment. Methods: SmartPDT® is a smartphone-based application and web-portal, developed by siHealth Ltd, enabling remote delivery of dPDT. It uses satellite imagery and computational algorithms to provide real-time determination of exposure to PpIX-effective solar radiation ("light dose"). The application also provides forecast of expected radiant exposures for 24-and 48-hs prior to the treatment period. Validation of the real-time and forecasted radiant exposure algorithms was performed against direct ground-based measurement under all weather conditions in Chilton, UK. Results: Agreement between direct ground measurements and satellite-determined radiant exposure for 2-h treatment was excellent at −0.1 % ± 5.1 % (mean ± standard deviation). There was also excellent agreement between weather forecasted radiant exposure and ground measurement, 1.8 % ± 17.7 % at 24-hs and 1.6 % ± 25.2 % at 48-hs. Relative Root Mean Square of the Error (RMSE r) demonstrated that agreement improved as time to treatment reduced (RMSE r = 22.5 % (48-hs), 11.2 % (24-hs), 5.2 % (real-time)). Conclusion: Agreement between satellite-determined, weather-forecasted and ground-measured radiant exposure was better than any existing published literature for dPDT. The SmartPDT® application and web-portal has excellent potential to assist with remote delivery of dPDT, an important factor in reducing risk in an elderly patient population during the Covid-19 pandemic.

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A new method for estimating UV fluxes at ground level in cloud-free conditions

Cited by 11 publications

References 48 publications

A New Clear-Sky Method for Assessing Photosynthetically Active Radiation at the Surface Level

A New Clear-Sky Method for Assessing Photosynthetically Active Radiation at the Surface Level

Impact of Irradiance Data on the Energy Yield Modeling of Dual-Junction Solar Module Stacks for One-Sun Applications

SmartPDT®: Smartphone enabled real-time dosimetry via satellite observation for daylight photodynamic therapy

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