scholarly journals Estimating solar ultraviolet irradiance (290-385 nm) by means of the spectral parametric models: SPCTRAL2 and SMARTS2

2000 ◽  
Vol 18 (11) ◽  
pp. 1382-1389 ◽  
Author(s):  
I. Foyo-Moreno ◽  
J. Vida ◽  
F. J. Olmo ◽  
L. Alados-Arboledas
Keyword(s):  
Solar Irradiance ◽  
Biological Effects ◽  
Stratospheric Ozone ◽  
Radiant Energy ◽  
Parametric Models ◽  
Spectral Irradiance ◽  
Atmospheric Composition ◽  
Relevant Variables ◽  
Ultraviolet Irradiance ◽  
Solar Ultraviolet

Abstract. Since the discovery of the ozone depletion in Antarctic and the globally declining trend of stratospheric ozone concentration, public and scientific concern has been raised in the last decades. A very important consequence of this fact is the increased broadband and spectral UV radiation in the environment and the biological effects and heath risks that may take place in the near future. The absence of widespread measurements of this radiometric flux has lead to the development and use of alternative estimation procedures such as the parametric approaches. Parametric models compute the radiant energy using available atmospheric parameters. Some parametric models compute the global solar irradiance at surface level by addition of its direct beam and diffuse components. In the present work, we have developed a comparison between two cloudless sky parametrization schemes. Both methods provide an estimation of the solar spectral irradiance that can be integrated spectrally within the limits of interest. For this test we have used data recorded in a radiometric station located at Granada (37.180°N, 3.580°W, 660 m a.m.s.l.), an inland location. The database includes hourly values of the relevant variables covering the years 1994-95. The performance of the models has been tested in relation to their predictive capability of global solar irradiance in the UV range (290–385 nm). After our study, it appears that information concerning the aerosol radiative effects is fundamental in order to obtain a good estimation. The original version of SPCTRAL2 provides estimates of the experimental values with negligible mean bias deviation. This suggests not only the appropriateness of the model but also the convenience of the aerosol features fixed in it to Granada conditions. SMARTS2 model offers increased flexibility concerning the selection of different aerosol models included in the code and provides the best results when the selected models are those considered as urban. Although SMARTS2 provide slightly worse results, both models give estimates of solar ultraviolet irradiance with mean bias deviation below 5%, and root mean square deviation close to experimental errors.Key words: Atmospheric composition and structure (transmission and scattering of radiation) - Meteorology and atmospheric dynamics (radiative process)

Photokeratitis and Other Phototoxic Effects on the Cornea and Conjunctiva

2002 ◽  
Vol 21 (6) ◽  
pp. 455-464 ◽  
Author(s):  
Anthony P. Cullen
Keyword(s):  
Clinical Signs ◽  
Radiant Energy ◽  
Damage Threshold ◽  
Primary Response ◽  
Human Cornea ◽  
Ultraviolet Irradiance ◽  
By Products ◽  
Solar Ultraviolet

Except when sleeping, the cornea and interpalpebral conjunctiva are exposed to the ambient environment, both natural and man-made. Levels of solar ultraviolet irradiance reaching the eye may exceed the damage threshold under a number of circumstances. The consequences of overexposure may be acute after a latent period, sequelae to an acute exposure, or long-term chronic effects. Previously derived action spectra for photokeratitis and photoconjunctivitis due to incoherent ultraviolet are presented. These reveal interspecies similarities for the levels of radiant energy reaching each tissue. The initial in vivo (clinical) signs of photokeratitis are due to lost or damaged epithelial cells with other signs produced by this primary response. The conjunctival signs include injection and chemosis. Chronic exposure to solar ultraviolet is a factor in climatic droplet keratopathy and pterygium. Phototoxic compounds or their by-products potentially can reach the cornea from the air, via the tears or aqueous humor, or from the limbal capillaries. However, the human cornea appears to be much less susceptible to the influence of phototoxic agents than the skin.

scholarly journals Estimating solar ultraviolet irradiance (290–385 nm) by means of the spectral parametric models: SPCTRAL2 and SMARTS2

2000 ◽  
Vol 18 (11) ◽  
pp. 1382-1389
Author(s):  
I. Foyo-Moreno ◽  
J. Vida ◽  
F. J. Olmo ◽  
L. Alados-Arboledas
Keyword(s):  
Parametric Models ◽  
Ultraviolet Irradiance ◽  
Solar Ultraviolet

Limitations in our knowledge of the Sun’s variability and impact on stratospheric ozone

2016 ◽  
Author(s):  
William Thomas Ball
Keyword(s):  
Solar Cycle ◽  
Solar Irradiance ◽  
Stratospheric Ozone ◽  
Standard Solar Model ◽  
Solar Observations ◽  
Surface Climate ◽  
The Standard Model ◽  
The Tropics ◽  
Climate Studies ◽  
Solar Ultraviolet

Changes in the Sun over the 11-year solar cycle modify the amount of ozone in the atmosphere over the tropics above 20 km. It is thought that the temperature change resulting from the induced variations of ozone may lead to an impact on the surface climate. Knowing by how much the solar ultraviolet light changes over the cycle is key to understanding the size of that influence. We provide a new model dataset of solar irradiance variability and compare it to the standard model used in climate studies, and to solar observations. We have shown that our model agrees better with an older instrument observing solar irradiance than the standard solar model for climate, though the two solar models and the older observations display much lower solar cycle variability than more recent observations. We discuss the differences and the uncertainties in the measurements. We also demonstrate that the true effect of solar ultraviolet changes on ozone is highly uncertain. This is important to be aware of since our understanding of the Sun’s impact on climate depends, in part, on getting the solar cycle changes in the ultraviolet correct.

scholarly journals Variability and trends in surface solar spectral ultraviolet irradiance in Italy: on the influence of geopotential height and lower-stratospheric ozone

2021 ◽  
Vol 21 (24) ◽  
pp. 18689-18705
Author(s):  
Ilias Fountoulakis ◽  
Henri Diémoz ◽  
Anna Maria Siani ◽  
Alcide di Sarra ◽  
Daniela Meloni ◽  
...  
Keyword(s):  
Geopotential Height ◽  
Total Ozone ◽  
Stratospheric Ozone ◽  
Extended Period ◽  
Spectral Irradiance ◽  
Positive Trend ◽  
Uv Irradiance ◽  
Ultraviolet Irradiance ◽  
Solar Uv Irradiance

Abstract. The short- and long-term variability of the surface spectral solar ultraviolet (UV) irradiance is investigated across Italy using high-quality ground-based measurements from three locations: Aosta (45.7∘ N, 7.4∘ E, 570 m a.s.l.), Rome (41.9∘ N, 12.5∘ E, 15 75 m a.s.l.), and Lampedusa (35.5∘ N, 12.6∘ E, 50 m a.s.l.). The three sites are characterized by different environmental conditions and represent almost the full latitudinal extent of the Italian territory. Data of two periods were analysed: 2006–2020 (all sites) and 1996–2020 (Rome only). The main objective of this study is to quantify the effect of the geopotential height (GPH) at 250 hPa on total ozone, and spectral irradiance at 307.5 and 324 nm. We first show that monthly anomalies in GPH, total ozone, and spectral irradiances are correlated amongst the three sites, suggesting that Italy is often affected by the same synoptical weather systems. We further find statistically significant anticorrelations between GPH and monthly anomalies in total ozone for all stations and months. Conversely, we identify positive correlations between GPH and monthly anomalies in spectral irradiance at 307.5 nm for most months. The influence of GPH on short-term variability also hold for long-term trends. For example, long-term changes in total ozone over the period 2006–2020 were associated with changes in GPH for all stations. This suggests that observed negative trends in total ozone were mainly driven by changes in lower-stratospheric ozone as upper-stratospheric ozone was increasing over this period. For several months of the year, positive trends in UV irradiance were observed, and we found that these trends were predominantly caused by changes in clouds and/or aerosols instead of total ozone. For the longer period of 1996–2020, a statistically significant annualized decrease in total ozone of ∼ 0.1 % per year was identified for Rome and could subsequently be attributed to decreasing lower-stratospheric ozone. While positive trends in spectral irradiance at 307.5 nm were observed for several months of this extended period, the negative trend in total ozone did not lead to a positive trend in the spectral irradiance at 307.5 nm in the deseasonalized data. Our study provides evidence that dynamical processes taking place in the troposphere lead to significant variability in total ozone and surface solar UV irradiance.

scholarly journals How Does the Sun’s Spectrum Vary?

2012 ◽  
Vol 25 (7) ◽  
pp. 2555-2560 ◽  
Author(s):  
Judith L. Lean ◽  
Matthew T. DeLand
Keyword(s):  
Solar Activity ◽  
Solar Irradiance ◽  
Solar Spectrum ◽  
Total Solar Irradiance ◽  
Spectral Irradiance ◽  
Model Calculations ◽  
Uv Irradiance ◽  
Infrared Spectral ◽  
Total Irradiance ◽  
Solar Ultraviolet

Abstract Recent observations made by the Spectral Irradiance Monitor (SIM) on the Solar Radiation and Climate Experiment (SORCE) spacecraft suggest that the Sun’s visible and infrared spectral irradiance increased from 2004 to 2008, even as the total solar irradiance measured simultaneously by SORCE’s Total Irradiance Monitor (TIM) decreased. At the same time, solar ultraviolet (UV) irradiance decreased 3–10 times more than expected from prior observations and model calculations of the known effects of sunspot and facular solar features. Analysis of the SIM spectral irradiance observations during the solar minimum epoch of 2008, when solar activity was essentially invariant, exposes trends in the SIM observations relative to both total solar irradiance and solar activity that are unlikely to be solar in origin. The authors suggest that the SIM’s radically different solar variability characterization is a consequence of undetected instrument sensitivity drifts, not true solar spectrum changes. It is thus doubtful that simulations of climate and atmospheric change using SIM measurements are indicative of real terrestrial behavior.

scholarly journals A simple framework for modelling the photochemical response to solar spectral irradiance variability in the stratosphere

2012 ◽  
Vol 12 (16) ◽  
pp. 7707-7724 ◽  
Author(s):  
R. Muncaster ◽  
M. S. Bourqui ◽  
S. Chabrillat ◽  
S. Viscardy ◽  
S. M. L. Melo ◽  
...  
Keyword(s):  
Solar Irradiance ◽  
Regression Models ◽  
Linear Models ◽  
Initial Conditions ◽  
Stratospheric Ozone ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Spectral Irradiance ◽  
Coefficient Of Determination ◽  
Column Model

Abstract. The stratosphere is thought to play a central role in the atmospheric response to solar irradiance variability. Recent observations suggest that the spectral solar irradiance (SSI) variability involves significant time-dependent spectral variations, with variable degrees of correlation between wavelengths, and new reconstructions are being developed. In this paper, we propose a simplified modelling framework to characterise the effect of short term SSI variability on stratospheric ozone. We focus on the pure photochemical effect, for it is the best constrained one. The photochemical effect is characterised using an ensemble simulation approach with multiple linear regression analysis. A photochemical column model is used with interactive photolysis for this purpose. Regression models and their coefficients provide a characterisation of the stratospheric ozone response to SSI variability and will allow future inter-comparisons between different SSI reconstructions. As a first step in this study, and to allow comparison with past studies, we take the representation of SSI variability from the Lean (1997) solar minimum and maximum spectra. First, solar maximum-minimum response is analysed for all chemical families and partitioning ratios, and is compared with past studies. The ozone response peaks at 0.18 ppmv (approximately 3%) at 37 km altitude. Second, ensemble simulations are regressed following two linear models. In the simplest case, an adjusted coefficient of determination R2 larger than 0.97 is found throughout the stratosphere using two predictors, namely the previous day's ozone perturbation and the current day's solar irradiance perturbation. A better accuracy (R2 larger than 0.9992) is achieved with an additional predictor, the previous day's solar irradiance perturbation. The regression models also provide simple parameterisations of the ozone perturbation due to SSI variability. Their skills as proxy models are evaluated independently against the photochemistry column model. The bias and RMS error of the best regression model are found smaller than 1% and 15% of the ozone response, respectively. Sensitivities to initial conditions and to magnitude of the SSI variability are also discussed.

scholarly journals A New SATIRE-S Spectral Solar Irradiance Reconstruction for Solar Cycles 21–23 and Its Implications for Stratospheric Ozone*

2014 ◽  
Vol 71 (11) ◽  
pp. 4086-4101 ◽  
Author(s):  
William T. Ball ◽  
Natalie A. Krivova ◽  
Yvonne C. Unruh ◽  
Joanna D. Haigh ◽  
Sami K. Solanki
Keyword(s):  
Solar Irradiance ◽  
Current Knowledge ◽  
Stratospheric Ozone ◽  
Spectral Irradiance ◽  
High Solar Activity ◽  
Naval Research ◽  
Solar Cycles ◽  
Mesospheric Ozone ◽  
Spectral Solar Irradiance ◽  
The Impact

Abstract The authors present a revised and extended total and spectral solar irradiance (SSI) reconstruction, which includes a wavelength-dependent uncertainty estimate, spanning the last three solar cycles using the Spectral and Total Irradiance Reconstruction—Satellite era (SATIRE-S) model. The SSI reconstruction covers wavelengths between 115 and 160 000 nm and all dates between August 1974 and October 2009. This represents the first full-wavelength SATIRE-S reconstruction to cover the last three solar cycles without data gaps and with an uncertainty estimate. SATIRE-S is compared with the Naval Research Laboratory Spectral Solar Irradiance (NRLSSI) model and ultraviolet (UV) observations from the Solar Radiation and Climate Experiment (SORCE) Solar Stellar Irradiance Comparison Experiment (SOLSTICE). SATIRE-S displays similar cycle behavior to NRLSSI for wavelengths below 242 nm and almost twice the variability between 242 and 310 nm. During the decline of the last solar cycle, between 2003 and 2008, the SSI from SORCE SOLSTICE versions 12 and 10 typically displays more than 3 times the variability of SATIRE-S between 200 and 300 nm. All three datasets are used to model changes in stratospheric ozone within a 2D atmospheric model for a decline from high solar activity to solar minimum. The different flux changes result in different modeled ozone trends. Using NRLSSI leads to a decline in mesospheric ozone, while SATIRE-S and SORCE SOLSTICE result in an increase. Recent publications have highlighted increases in mesospheric ozone when considering version 10 SORCE SOLSTICE irradiances. The recalibrated SORCE SOLSTICE version 12 irradiances result in a much smaller mesospheric ozone response than that of version 10, and this smaller mesospheric ozone response is similar in magnitude to that of SATIRE-S. This shows that current knowledge of variations in spectral irradiance is not sufficient to warrant robust conclusions concerning the impact of solar variability on the atmosphere and climate.

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