scholarly journals Enhancement of UV Radiation by Cloud Effect in NE of Brazil

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Chigueru Tiba ◽  
Sérgio da Silva Leal
Keyword(s):  
Solar Radiation ◽  
Uv Radiation ◽  
Extreme Values ◽  
Biological Effects ◽  
Global Solar Radiation ◽  
Seasonal Effect ◽  
Enhancement Effect ◽  
Monthly Basis ◽  
Uv Index ◽  
Clear Sky

This paper reports a detailed analysis of ground-based measurements of cloud-enhanced global solar and UV radiation in NE Brazil in the city of Recife. It was found that (a) the phenomenon of UV enhancement, above clear sky model, is not uncommon and that it occurs on at least eight months; (b) the cumulative duration can reach 13 minutes; (c) there is a clear seasonal effect, and the probability of occurrence on a monthly basis shows two peaks, one in March and another in October; and (d) the most extreme UV radiation was 70.4 W/m2, approximately 6 W/m2 higher than the clear sky UV radiation. The extreme values should be taken into account in the study of effects related to the UV index and biological effects. Two statistical models also were elaborated, to estimate the UV solar radiation, in which the first is for all sky conditions and the second exclusively for situations where the global solar radiation is equal to or higher than 1367 W/m2, resulting from the enhancement effect caused by a particular configuration of the clouds. The statistical indicatives for both models presented, respectively, MBE% of 3.09 and 0.48% and RMSE% of 15.80 and 3.90%.

scholarly journals Possible values of UV index in Serbia

2008 ◽  
Vol 136 (11-12) ◽  
pp. 640-643 ◽  
Author(s):  
Milorad Letic
Keyword(s):  
Uv Radiation ◽  
The Sun ◽  
Total Column Ozone ◽  
Uv Index ◽  
Clear Sky ◽  
Expected Values ◽  
June July ◽  
Column Ozone ◽  
Ozone Column

INTRODUCTION UV Index is an indicator of human exposure to solar ultraviolet (UV) rays. The numerical values of the UV Index range from 1-11 and above. There are three levels of protection against UV radiation; low values of the UV Index - protection is not required, medium values of the UV Index - protection is recommended and high values of the UV Index - protection is obligatory. The value of the UV Index primarily depends on the elevation of the sun and total ozone column. OBJECTIVE The aim of the study is to determine the intervals of possible maximal annual values of the UV Index in Serbia in order to determine the necessary level of protection in a simple manner. METHOD For maximal and minimal expected values of total column ozone and for maximal elevation of the sun, the value of the UV Index was determined for each month in the Northern and Southern parts of Serbia. These values were compared with the forecast of the UV Index. RESULTS Maximal clear sky values of the UV Index in Serbia for altitudes up to 500m in May, June, July and August can be 9 or even 10, and not less than 5 or 6. During November, December, January and February the UV Index can be 4 at most. During March, April, September and October the expected values of the UV Index are maximally 7 and not less than 3. The forecast of the UV Index is within these limits in 98% of comparisons. CONCLUSION The described method of determination of possible UV Index values showed a high agreement with forecasts. The obtained results can be used for general recommendations in the protection against UV radiation.

Estimation of global solar radiation under clear sky radiation in Turkey

2000 ◽  
Vol 21 (2) ◽  
pp. 271-287 ◽  
Author(s):  
Inci Turk Toğrul ◽  
Hasan Toğrul ◽  
Duygu Evin
Keyword(s):  
Solar Radiation ◽  
Global Solar Radiation ◽  
Clear Sky

scholarly journals UV Index Forecasting under the Influence of Desert Dust: Evaluation against Surface and Satellite-Retrieved Data

Atmosphere ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 96 ◽  
Author(s):  
Dillan Raymond Roshan ◽  
Muammer Koc ◽  
Amir Abdallah ◽  
Luis Martin-Pomares ◽  
Rima Isaifan ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Mesoscale Model ◽  
Dust Storms ◽  
Average Error ◽  
Accurate Estimation ◽  
Strong Impact ◽  
Uv Index ◽  
Desert Dust ◽  
Clear Sky ◽  
Uv Irradiance

Human exposure to healthy doses of UV radiation is required for vitamin D synthesis, but exposure to excessive UV irradiance leads to several harmful impacts ranging from premature wrinkles to dangerous skin cancer. However, for countries located in the global dust belt, accurate estimation of the UV irradiance is challenging due to a strong impact of desert dust on incoming solar radiation. In this work, a UV Index forecasting capability is presented, specifically developed for dust-rich environments, that combines the use of ground-based measurements of broadband irradiances UVA (320–400 nm) and UVB (280–315 nm), NASA OMI Aura satellite-retrieved data and the meteorology-chemistry mesoscale model WRF-Chem. The forecasting ability of the model is evaluated for clear sky days as well as during the influence of dust storms in Doha, Qatar. The contribution of UV radiation to the total incoming global horizontal irradiance (GHI) ranges between 5% and 7% for UVA and 0.1% and 0.22% for UVB. The UVI forecasting performance of the model is quite encouraging with an absolute average error of less than 6% and a correlation coefficient of 0.93. In agreement with observations, the model predicts that the UV Index at local noontime can drop from 10–11 on clear sky days to approximately 6–7 during typical dusty conditions in the Arabian Peninsula—an effect similar to the presence of extensive cloud cover.

scholarly journals SolarisNet : A deep regression network for solar radiation prediction

MAUSAM ◽  
2021 ◽  
Vol 71 (3) ◽  
pp. 443-450
Author(s):  
DEY SUBHADIP ◽  
PRATIHER SAWON ◽  
MUKHERJEE CHANCHAL KUMAR ◽  
BANERJEE SAON
Keyword(s):  
Solar Radiation ◽  
Global Solar Radiation ◽  
Parametric Models ◽  
High Tech ◽  
Short Term ◽  
Effective Utilization ◽  
Clear Sky ◽  
Past Data ◽  
Weather Stations ◽  
Short Term Forecasting

Effective utilization of photovoltaic (PV) plants requires weather variability robust global solar radiation (GSR) forecasting models. Random weather turbulence phenomena coupled with assumptions of clear sky model as suggested by Hottel pose significant challenges to parametric &non-parametric models in GSR conversion rate estimation. Also, a decent GSR estimate requires costly high-tech radiometer and expert dependent instrument handling and measurements, which are subjective. As such, a computer aided monitoring (CAM) system to evaluate PV plant operation feasibility by employing smart grid past data analytics and deep learning is developed. Our algorithm, SolarisNet is a 6-layer deep neural network trained on data collected at two weather stations located near Kalyani metrological site, West Bengal, India. The daily GSR prediction performance using SolarisNet outperforms the existing state of art and its efficacy in inferring past GSR data insights to comprehend daily and seasonal GSR variability along with its competence for short term forecasting is discussed.

scholarly journals UV Index and Total Ozone Column Climatology of Nepal Himalaya Using TOMS and OMI Data

2016 ◽  
Vol 9 (1) ◽  
pp. 45-59
Author(s):  
R.R. Sharma ◽  
B. Kjeldstad ◽  
P.J. Espy
Keyword(s):  
High Altitude ◽  
Total Ozone ◽  
Extreme Values ◽  
Nepal Himalaya ◽  
Uv Index ◽  
Total Ozone Column ◽  
Clear Sky ◽  
Ground Measurement ◽  
Filter Radiometer ◽  
Ozone Column

Ultraviolet index (UVI) and Total Ozone Column (TOC) climatology of six stations of Nepal Himalaya using ground measurement, and OMI / TOMS satellite data is presented. The positive bias found in the OMI UV index from previous study is corrected empirically using a ratio factor using the clear sky coincident data of OMI and ground measurement from NILU UV multi-band filter radiometer (MBFR). UV index >3 in the winter months (e.g. December) and more than 9 during the summer months (May-August) are common in most of the stations. High altitude stations even have more extreme values (>11) during the summer months. Under some meteorological conditions, UV index often found more than 16 at the high altitude station (latitude 28o, altitude 2850m) during a clear sky day in the monsoon season. Diurnal and altitudinal variability is also highlighted. Monthly average TOC climatology from November 1978 to March 2012 using TOMS (Nimbus 7, Meteor3 and Earth Probe) and OMI is also presented. The ozone column data follows the annual cycle, minimum in November/December and maximum in April/May. In addition, slight negative trend of TOC is found in the data from 1978 to 2012.Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.45-59

scholarly journals Reconstruction of global solar radiation time series from 1933 to 2013 at the Izaña Atmospheric Observatory

2014 ◽  
Vol 7 (9) ◽  
pp. 3139-3150 ◽  
Author(s):  
R. D. García ◽  
E. Cuevas ◽  
O. E. García ◽  
V. E. Cachorro ◽  
P. Pallé ◽  
...  
Keyword(s):  
Time Series ◽  
Solar Radiation ◽  
North Atlantic ◽  
Sunshine Duration ◽  
Global Solar Radiation ◽  
Global Scale ◽  
High Mountain ◽  
Atlantic Region ◽  
Clear Sky ◽  
Radiation Time

Abstract. This paper presents the reconstruction of the 80-year time series of daily global solar radiation (GSR) at the subtropical high-mountain Izaña Atmospheric Observatory (IZO) located in Tenerife (The Canary Islands, Spain). For this purpose, we combine GSR estimates from sunshine duration (SD) data using the Ångström–Prescott method over the 1933/1991 period, and GSR observations directly performed by pyranometers between 1992 and 2013. Since GSR measurements have been used as a reference, a strict quality control has been applied based on principles of physical limits and comparison with LibRadtran model. By comparing with high quality GSR measurements, the precision and consistency over time of GSR estimations from SD data have been successfully documented. We obtain an overall root mean square error (RMSE) of 9.2% and an agreement between the variances of GSR estimations and GSR measurements within 92%. Nonetheless, this agreement significantly increases when the GSR estimation is done considering different daily fractions of clear sky (FCS). In that case, RMSE is reduced by half, to about 4.5%, when considering percentages of FCS > 40% (~ 90% of days in the testing period). Furthermore, we prove that the GSR estimations can monitor the GSR anomalies in consistency with GSR measurements and, then, can be suitable for reconstructing solar radiation time series. The reconstructed IZO GSR time series between 1933 and 2013 confirms change points and periods of increases/decreases of solar radiation at Earth's surface observed at a global scale, such as the early brightening, dimming and brightening. This fact supports the consistency of the IZO GSR time series presented in this work, which may be a reference for solar radiation studies in the subtropical North Atlantic region.

ERITEMINĖS ULTRAVIOLETINĖS SPINDULIUOTĖS POKYČIŲ ANALIZĖ

2013 ◽  
Vol 23 (6) ◽  
pp. 25-28 ◽  
Author(s):  
Renata Chadyšienė ◽  
Aloyzas Girgždys
Keyword(s):  
Uv Radiation ◽  
Radiation Intensity ◽  
Total Ozone ◽  
Stratospheric Ozone ◽  
Downward Trend ◽  
Upward Trend ◽  
Uv Index ◽  
Clear Sky ◽  
Ozone Data ◽  
Very High

In this article the erythemally weighted UV radiation intensity variations during 2002-2011 were analysed. Also UV radiation intensity and total ozone data in this paper were analysed, because the UV index is directly dependent on the intensity of UV radiation, and most of the UV radiation is absorbed by stratospheric ozone. During 2002-2011 in the course of UV index - the upward trend was observed, and in the total ozone values - the downward trend was observed. During the investigated period in Lithuania the maximum UV index values (very high) on clear sky summer days were determined.

scholarly journals Optimizing UV index determination from broadband irradiances

2017 ◽  
Author(s):  
Keith A. Tereszchuk ◽  
Yves J. Rochon ◽  
Chris A. McLinden ◽  
Paul A. Vaillancourt
Keyword(s):  
Radiative Transfer ◽  
Root Mean Square ◽  
Uv Radiation ◽  
Relative Error ◽  
Spectral Resolution ◽  
High Spectral Resolution ◽  
Mean Square ◽  
Uv Index ◽  
Clear Sky ◽  
Sky Conditions

Abstract. Amidst mounting concerns about the depletion of stratospheric ozone (O3), and for subsequent increases in the surface irradiances of ultraviolet (UV) light and its effects on human health, a daily UV forecast program was launched by Environment Canada in 1993. The program serves to monitor harmful surface UV radiation and provide this information to the Canadian public through the UV index, a scale which reports the relative intensity of the Sun's UV radiation at the Earth's surface, and the corresponding protection actions to be taken. The UV index was accepted as a standard method of reporting surface UV irradiances by the World Meteorological Organization (WMO) and World Health Organization (WHO) in 1994. A study was undertaken to improve upon the prognosticative capability of Environment and Climate Change Canada's (ECCC) UV index forecast model. An aspect of that work, and the topic of this communication, was to investigate the use of the four UV broadband surface irradiance fields generated by ECCC's Global Environmental Multi-scale (GEM) numerical prediction model to determine the UV index. The basis of the investigation involves the creation of a suite of routines which employ high spectral resolution radiative transfer code developed to calculate UV index fields from GEM forecasts. These routines employ a modified version of the Cloud-J v7.4 radiative transfer model, which integrates GEM output to produce high spectral resolution surface irradiance fields. The output generated using the high-resolution radiative transfer code served to verify and calibrate GEM broadband surface irradiances under clear-sky conditions and their use in providing the UV index. A subsequent comparison of irradiances and UV index under cloudy conditions was also performed. Linear correlation agreement of surface irradiances from the two models for each of the two higher UV bands covering 310–330 nm and 330–400 nm is typically greater than 95 % for clear-sky conditions with associated root mean square relative errors of 5.5 % and 3.8 %. On the other hand, underestimations of clear-sky GEM irradiances were found on the order of ~30–50 % for the 294–310 nm band and by a factor of ~30 for the 280–294 nm band. This underestimation can be significant for UV index determination but would not impact weather forecasting. Corresponding empirical adjustments were applied to the broadband irradiances now giving a correlation coefficient of unity. From these, a least-squares fitting was derived for the calculation of the UV index. The resultant differences in UV indices from the high spectral resolution irradiances and the resultant GEM broadband irradiances are typically within 0.2 with a root mean square relative error in the scatter of ~5.5 % for clear-sky conditions. Similar results are reproduced under cloudy conditions with light to moderate clouds, having a relative error comparable to the clear-sky counterpart; under strong attenuation due to clouds, a substantial increase in the root mean square relative error of up to 30 % is observed due to differing cloud radiative transfer models.

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