scholarly journals Relations between erythemal UV dose, global solar radiation, total ozone column and aerosol optical depth at Uccle, Belgium

2014 ◽  
Vol 14 (11) ◽  
pp. 16529-16589
Author(s):  
V. De Bock ◽  
H. De Backer ◽  
R. Van Malderen ◽  
A. Mangold ◽  
A. Delcloo
Keyword(s):  
Time Series ◽  
Solar Radiation ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Change Point ◽  
Total Ozone ◽  
Global Solar Radiation ◽  
Uv Dose ◽  
The Individual ◽  
Ozone Column

Abstract. At Uccle, a long time series (1991–2013) of simultaneous measurements of erythemal ultraviolet (UV) dose, global solar radiation, total ozone column (TOC) and Aerosol Optical Depth (AOD) (at 320.1 nm) is available which allows for an extensive study of the changes in the variables over time. A change-point analysis, which determines whether there is a significant change in the mean of the time series, is applied to the monthly anomalies time series of the variables. Only for erythemal UV dose and TOC, a significant change point (without any known instrumental cause) was present in the time series around February 1998 and March 1998 respectively. The change point in TOC corresponds with results found in literature, where the change in ozone levels (around 1997) is attributed to the recovery of ozone. Linear trends were determined for the different (monthly anomalies) time series. Erythemal UV dose, global solar radiation and TOC all increase with respectively 7, 4 and 3% per decade. AOD shows an (insignificant) negative trend of −8% per decade. These trends agree with results found in literature for sites with comparable latitudes. A multiple linear regression (MLR) analysis is applied to the data in order to study the influence of global solar radiation, TOC and AOD on the erythemal UV dose. Together these parameters are able to explain 94% of the variation in erythemal UV dose. Most of the variation (56%) in erythemal UV dose is explained by global solar radiation. The regression model performs well with a slight tendency to underestimate the measured erythemal UV doses and with a Mean Absolute Bias Error (MABE) of 18%. However, in winter, negative erythemal UV dose values are modeled. Applying the MLR to the individual seasons solves this issue. The seasonal models have an adjusted R2 value higher than 0.8 and the correlation between modeled and measured erythemal UV dose values is higher than 0.9 for each season. The summer model gives the best performance, with an absolute mean error of only 6%. Again, global solar radiation is the factor that contributes the most to the variation in erythemal UV dose, so there is no doubt about the necessity to include this factor in the regression models. A large part of the influence of AOD is already represented by the global solar radiation parameter. Therefore the individual contribution of AOD to erythemal UV dose is so low. For this reason, it seems unnecessary to include AOD in the MLR analysis. Including TOC however, is justified as the adjusted R2 increases and the MABE of the model decreases compared to a model where only global solar radiation is used as explanatory variable.

scholarly journals Relations between erythemal UV dose, global solar radiation, total ozone column and aerosol optical depth at Uccle, Belgium

2014 ◽  
Vol 14 (22) ◽  
pp. 12251-12270 ◽  
Author(s):  
V. De Bock ◽  
H. De Backer ◽  
R. Van Malderen ◽  
A. Mangold ◽  
A. Delcloo
Keyword(s):  
Time Series ◽  
Solar Radiation ◽  
Aerosol Optical Depth ◽  
Change Point ◽  
Regression Models ◽  
Total Ozone ◽  
Global Solar Radiation ◽  
Uv Dose ◽  
The Individual ◽  
Ozone Column

Abstract. At Uccle, Belgium, a long time series (1991–2013) of simultaneous measurements of erythemal ultraviolet (UV) dose (Sery), global solar radiation (Sg), total ozone column (Q_{O3}$) and aerosol optical depth (τaer) (at 320.1 nm) is available, which allows for an extensive study of the changes in the variables over time. Linear trends were determined for the different monthly anomalies time series. Sery, Sg and QO3 all increase by respectively 7, 4 and 3% per decade. τaer shows an insignificant negative trend of −8% per decade. These trends agree with results found in the literature for sites with comparable latitudes. A change-point analysis, which determines whether there is a significant change in the mean of the time series, is applied to the monthly anomalies time series of the variables. Only for Sery and QO3, was a significant change point present in the time series around February 1998 and March 1998, respectively. The change point in QO3 corresponds with results found in the literature, where the change in ozone levels around 1997 is attributed to the recovery of ozone. A multiple linear regression (MLR) analysis is applied to the data in order to study the influence of Sg, QO3 and τaer on Sery. Together these parameters are able to explain 94% of the variation in Sery. Most of the variation (56%) in Sery is explained by Sg. The regression model performs well, with a slight tendency to underestimate the measured Sery values and with a mean absolute bias error (MABE) of 18%. However, in winter, negative Sery are modeled. Applying the MLR to the individual seasons solves this issue. The seasonal models have an adjusted R2 value higher than 0.8 and the correlation between modeled and measured Sery values is higher than 0.9 for each season. The summer model gives the best performance, with an absolute mean error of only 6%. However, the seasonal regression models do not always represent reality, where an increase in Sery is accompanied with an increase in QO3 and a decrease in τaer. In all seasonal models, Sg is the factor that contributes the most to the variation in Sery, so there is no doubt about the necessity to include this factor in the regression models. The individual contribution of τaer to Sery is very low, and for this reason it seems unnecessary to include τaer in the MLR analysis. Including QO3, however, is justified to increase the adjusted R2 and to decrease the MABE of the model.

scholarly journals Comparative Study of the Influence of Air Pollution on UVI at Maitri in Antarctica and New Delhi in India

2012 ◽  
Vol 2012 ◽  
pp. 1-5
Author(s):  
Nandita D. Ganguly
Keyword(s):  
Air Pollution ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Negative Correlation ◽  
Total Ozone ◽  
Surface Ozone ◽  
New Delhi ◽  
Increasing Trend ◽  
Ultraviolet Irradiance ◽  
Ozone Column

The influence of air pollution on the erythemal ultraviolet irradiance (UVI) reaching the earth's surface has been investigated at the Indian Antarctic station Maitri and compared with that at New Delhi, the capital of India, over a period of three years from 2005 to 2007. Total ozone column (TOC), surface ozone, NO2 column, middle tropospheric SO2 column, and BrO column are observed to exhibit a deceasing trend at Maitri, having a clean and pristine environment, while UVI and aerosol optical depth at 500 nm exhibit an increasing trend. This negative correlation suggests that O3, NO2, SO2, and BrO act as filters against erythemal ultraviolet irradiance reaching the earth's surface, while the aerosols, which are present in the atmosphere of Maitri, may not be either very effective in filtering out the UVI reaching the earth's surface or may not be large enough to produce measurable effects on UVI. TOC and BrO column are observed to exhibit a deceasing trend at New Delhi, having comparatively higher levels of pollution, while UVI, NO2 column, middle tropospheric SO2 column, surface ozone, and aerosol optical depth at 500 nm exhibit an increasing trend. This suggests that TOC and BrO act as filters against UVI, while NO2, surface ozone, SO2, and aerosols in the atmosphere of New Delhi may not be large enough to produce measurable effects on UVI.

scholarly journals Ultraviolet Radiation modelling using output from the Chemistry Climate Model Initiative

2018 ◽  
Author(s):  
Kévin Lamy ◽  
Thierry Portafaix ◽  
Béatrice Josse ◽  
Colette Brogniez ◽  
Sophie Godin-Beekmann ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Northern Hemisphere ◽  
Total Ozone ◽  
Climate Model ◽  
Sudden Increase ◽  
Total Ozone Column ◽  
Rcp 8.5 ◽  
Ozone Column

Abstract. We have derived values of the Ultraviolet Index (UVI) at solar noon from the Tropospheric Ultraviolet Model (TUV) driven by ozone, temperature and aerosol fields from 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 clear-sky UVI. We compared the UVI climatologies obtained from CCMI and TUV against present-day climatological values of UVI derived from 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 and TUV and ground-based measurements ranged between −4 % and 11 %. We 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 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 RCP 2.6, 4.5 and 6.0, and found a 2.3 % decrease in RCP 8.5. Higher UV indices 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 RCP 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, the same signal is 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 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 UVI as total column does.

scholarly journals Comparison of the optical depth of total ozone and atmospheric aerosols in Poprad-Gánovce, Slovakia

2018 ◽  
Vol 18 (10) ◽  
pp. 7739-7755
Author(s):  
Peter Hrabčák
Keyword(s):  
Solar Radiation ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Atmospheric Aerosol ◽  
Total Ozone ◽  
Diffuse Radiation ◽  
Stray Light ◽  
Atmospheric Ozone ◽  
Solar Ultraviolet Radiation ◽  
Ultraviolet Solar Radiation

Abstract. The amount of ultraviolet solar radiation reaching the Earth's surface is significantly affected by atmospheric ozone along with aerosols. The present paper is focused on a comparison of the total ozone and atmospheric aerosol optical depth in the area of Poprad-Gánovce, which is situated at the altitude of 706 m a. s. l.  in the vicinity of the highest mountain in the Carpathian mountains. The direct solar ultraviolet radiation has been measured here continuously since August 1993 using a Brewer MKIV ozone spectrophotometer. These measurements have been used to calculate the total amount of atmospheric ozone and, subsequently, its optical depth. They have also been used to determine the atmospheric aerosol optical depth (AOD) using the Langley plot method. Results obtained by this method were verified by means of comparison with a method that is part of the Brewer operating software, as well as with measurements made by a Cimel sun photometer. Diffuse radiation, the stray-light effect and polarization corrections were applied to calculate the AOD using the Langley plot method. In this paper, two factors that substantially attenuate the flow of direct ultraviolet solar radiation to the Earth's surface are compared. The paper presents results for 23 years of measurements, namely from 1994 to 2016. Values of optical depth were determined for the wavelengths of 306.3, 310, 313.5, 316.8 and 320 nm. A statistically significant decrease in the total optical depth of the atmosphere was observed with all examined wavelengths. Its root cause is the statistically significant decline in the optical depth of aerosols.

scholarly journals A Simple Semi-Empirical Model for the Estimation of Photosynthetically Active Radiation from Satellite Data in the Tropics

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
S. Janjai ◽  
A. Sripradit ◽  
R. Wattan ◽  
S. Buntoung ◽  
S. Pattarapanitchai ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Empirical Model ◽  
Photosynthetically Active Radiation ◽  
Total Ozone ◽  
Data Set ◽  
Active Radiation ◽  
Total Ozone Column ◽  
Semi Empirical ◽  
Ozone Column

This paper presents a simple semi-empirical model for estimating global photosynthetically active radiation (PAR) under all sky conditions. The model expresses PAR as a function of cloud index, aerosol optical depth, total ozone column, solar zenith angle, and air mass. The formulation of the model was based on a four-year period (2008–2011) of PAR data obtained from the measurements at four solar monitoring stations in a tropical environment of Thailand. These are Chiang Mai (18.78°N, 98.98°E), Ubon Ratchathani (15.25°N, 104.87°E), Nakhon Pathom (13.82°N, 100.04°E), and Songkhla (7.20°N, 100.60°E). The cloud index was derived from MTSAT-1R satellite, whereas the aerosol optical depth was obtained from MODIS/Terra satellite. For the total ozone column, it was retrieved from OMI/Aura satellite. The model was validated against independent data set from the four stations. It was found that hourly PAR estimated from the proposed model and that obtained from the measurements were in reasonable agreement, with the root mean square difference (RMSD) and mean bias difference (MBD) of 14.3% and −5.8%, respectively. In addition, for the case of monthly average hourly PAR, RMSD and MBD were reduced to 11.1% and −5.1%, respectively.

scholarly journals Comparative measurements of total ozone amount and aerosol optical depth during a campaign at El Arenosillo, Huelva, Spain

2005 ◽  
Vol 23 (11) ◽  
pp. 3399-3406 ◽  
Author(s):  
A. de La Casinière ◽  
V. Cachorro ◽  
I. Smolskaia ◽  
J. Lenoble ◽  
M. Sorribas ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Total Ozone ◽  
Near Infrared ◽  
Relative Difference ◽  
Diurnal Variations ◽  
Near Ultraviolet ◽  
Ozone Amount ◽  
The Difference ◽  
Ozone Column

Abstract. A one week field campaign took place in September 2002 at El Arenosillo, Spain. The objective was to compare total ozone column (TOC) and aerosol optical depth (AOD) from near ultraviolet to near infrared, measured by several Spanish and French instruments. Three spectroradiometers, Brewer, SPUV02, and LICOR, and a CIMEL photometer, have been used simultaneously and the results are presented for four clear days. TOC values are given by the Brewer instrument, and by SPUV02, using two different methods. The ground instruments compare satisfactorily (within 5 DU) and the values are consistent with TOMS data (within 10 DU). AOD from the various instruments are compared at seven different wavelengths between 320 nm and 1020 nm: the agreement is very good at 350, 380, and 870 nm; at the four other wavelengths the difference is smaller than 0.03, which can be explained by a relative difference of 4% only between the calibrations of the various instruments. Larger AOD diurnal variations were observed at short wavelengths than in the visible and near infrared; this is most likely due to changes in aerosol size along the day, during the campaign.

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

2019 ◽  
Vol 19 (15) ◽  
pp. 10087-10110 ◽  
Author(s):  
Kévin Lamy ◽  
Thierry Portafaix ◽  
Béatrice Josse ◽  
Colette Brogniez ◽  
Sophie Godin-Beekmann ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Northern Hemisphere ◽  
Total Ozone ◽  
Climate Model ◽  
Total Ozone Column ◽  
Clear Sky ◽  
Rcp 8.5 ◽  
Ozone Column

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.

scholarly journals Influence of Atmospheric Aerosols on Evapotranspiration over a Semiarid Region in Northeast Brazil

2018 ◽  
Vol 33 (4) ◽  
pp. 677-683
Author(s):  
Antonio José Steidle Neto ◽  
Daniela de Carvalho Lopes
Keyword(s):  
Solar Radiation ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Atmospheric Aerosols ◽  
Reference Evapotranspiration ◽  
Irrigation Management ◽  
Global Solar Radiation ◽  
Radiative Energy ◽  
Semiarid Region ◽  
Northeast Brazil

Abstract The knowledge of atmospheric aerosol characteristics at regional and local scales, their temporal changes and interrelations with meteorological variables are of great importance because can modify the global radiative energy balance. This study was carried out to evaluate the influence of aerosols on evapotranspiration over a semiarid region in Northeast Brazil. Aerosol optical depth, global solar radiation, air temperature, air relative humidity, and wind speed were measured in the Research National Center of Semiarid, located at Petrolina, Pernambuco State, Brazil, along two consecutive years. A multivariate model was calibrated and validated for estimating the global solar radiation (Rglobal) based on the aerosol optical depths (AOD) and extraterrestrial solar radiation (R0). Estimates of the reference evapotranspiration (ET0) were obtained by using the FAO standard Penman-Monteith method. Results confirmed that larger aerosol optical depth tends to decrease both Rglobal and ET0. Otherwise, ticker aerosol optical depth tends to absorb less radiation, increasing the ET0. For the semiarid region in Northeast Brazil, most of ET0 deviations were smaller than ±4%. However, higher deviations were also observed, contributing jointly to around 30%, which may result in relevant consequences on the irrigation management, water balance, agroclimatic zoning, among other activities based on the ET0 estimates.

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