scholarly journals Inactivation times from 290 to 315 nm UVB in sunlight for SARS coronaviruses CoV and CoV-2 using OMI satellite data for the sunlit Earth

2020 ◽  
Author(s):  
Jay Herman ◽  
Bryan Biegel ◽  
Liang Huang
Keyword(s):  
Solar Zenith Angle ◽  
Action Spectrum ◽  
Geographic Area ◽  
Direct Sunlight ◽  
Clear Sky ◽  
Direct Measurements ◽  
Atmospheric Data ◽  
Subsolar Point ◽  
Ultraviolet Irradiance ◽  
Laboratory Exposure

Abstract UVB in sunlight, 290–315 nm, can inactivate SARS CoV and SARS CoV-2 viruses on surfaces and in the air. Laboratory exposure to ultraviolet irradiance in the UVC range inactivates many viruses and bacteria in times less than 30 min. Estimated UVB inactivation doses from sunlight in J/m2 are obtained from UVC measurements and radiative transfer calculations, weighted by a virus inactivation action spectrum, using OMI satellite atmospheric data for ozone, clouds, and aerosols. For SARS CoV, using an assumed UVC dose near the mid-range of measured values, D90 = 40 J/m2, 90% inactivation times T90 are estimated for exposure to midday 10:00–14:00 direct plus diffuse sunlight and for nearby locations in the shade (diffuse UVB only). For the assumed D90 = 40 J/m2 model applicable to SARS CoV viruses, calculated estimates show that near noon 11:00–13:00 clear-sky direct sunlight gives values of T90 < 90 min for mid-latitude sites between March and September and less than 60 min for many equatorial sites for 12 months of the year. Recent direct measurements of UVB sunlight inactivation of the SARS CoV-2 virus that causes COVID-19 show shorter T90 inactivation times less than 10 min depending on latitude, season, and hour. The equivalent UVC 254 nm D90 dose for SARS CoV-2 is estimated as 3.2 ± 0.7 J/m2 for viruses on a steel mesh surface and 6.5 ± 1.4 J/m2 for viruses in a growth medium. For SARS CoV-2 clear-sky T90 on a surface ranges from 4 min in the equatorial zone to less than 30 min in a geographic area forming a near circle with solar zenith angle < 60O centered on the subsolar point for local solar times from 09:00 to 15:00 h.

Evaluation of Illuminance of Rooms Oriented to Different Cardinal Points

2014 ◽  
Vol 1041 ◽  
pp. 390-394
Author(s):  
Stanislav Darula ◽  
Jitka Mohelníková
Keyword(s):  
Working Time ◽  
Direct Sunlight ◽  
Central European ◽  
Clear Sky ◽  
The Common ◽  
Sky Conditions ◽  
Overcast Sky

Daylighting levels in interiors are changed every day since sunrise to sunset in dependence on luminous exterior conditions. Indoors are illuminated by diffuse skylight prevailing time of the year in Central European counties while a lot of sunny situations occur mainly during transitional and summer periods. The later can produce overheating as well as glare or disturbing luminance due to excessive sunlight in the space close to windows. If interiors are designed with screened work places the influence of direct sunlight during working time has to be evaluated.The article will present results of computer daylight simulations in a side-lit office room oriented to cardinal points. The study is focused on daylighting evaluation of the room orientation influence on levels under clear sky conditions and compared with results achieved for the CIE overcast sky model. The calculations were run in software Daylight Visualizer 2.6.7. The daylight simulation show that applying the clear sky model for illumination of oriented rooms, the substantial different illuminances can be resulted compared to outputs from the common overcast sky daylight metrics.

Could Vikings have navigated under foggy and cloudy conditions by skylight polarization? On the atmospheric optical prerequisites of polarimetric Viking navigation under foggy and cloudy skies

2007 ◽  
Vol 463 (2080) ◽  
pp. 1081-1095 ◽  
Author(s):  
Ramón Hegedüs ◽  
Susanne Åkesson ◽  
Rüdiger Wehner ◽  
Gábor Horváth
Keyword(s):  
Linear Polarization ◽  
The Sun ◽  
Direct Sunlight ◽  
Birefringent Crystal ◽  
Clear Sky ◽  
Open Sea ◽  
Skylight Polarization ◽  
Imaging Polarimetry

In sunshine, the Vikings navigated on the open sea using sundials. According to a widespread hypothesis, when the Sun was occluded by fog or clouds the Vikings might have navigated by skylight polarization detected with an enigmatic birefringent crystal (sunstone). There are two atmospheric optical prerequisites for this alleged polarimetric Viking navigation under foggy/cloudy skies: (1) the degree of linear polarization p of skylight should be high enough and (2) at a given Sun position, the pattern of the angle of polarization α of the foggy/cloudy sky should be similar to that of the clear sky. Until now, these prerequisites have not been investigated. Using full-sky imaging polarimetry, we measured the p - and α -patterns of Arctic foggy and cloudy skies when the Sun was invisible. These patterns were compared with the polarization patterns of clear Arctic skies. We show here that although prerequisite (2) is always fulfilled under both foggy and cloudy conditions, if the fog layer is illuminated by direct sunlight, prerequisite (1) is usually satisfied only for cloudy skies. In sunlit fog, the Vikings could have navigated by polarization only, if p of light from the foggy sky was sufficiently high.

scholarly journals Blue Skies: A Methodology for Data-Driven Clear Sky Modelling

2017 ◽  
Author(s):  
Kartik Palani ◽  
Ramachandra Kota ◽  
Amar Prakash Azad ◽  
Vijay Arya
Keyword(s):  
Machine Learning ◽  
State Of The Art ◽  
Weather Conditions ◽  
Data Driven ◽  
Machine Learning Techniques ◽  
Clear Sky ◽  
Learning Techniques ◽  
Atmospheric Data ◽  
Average Irradiance ◽  
Photo Voltaic

One of the major challenges confronting the widespread adoption of solar energy is the uncertainty of production. The energy generated by photo-voltaic systems is a function of the received solar irradiance which varies due to atmospheric and weather conditions. A key component required for forecasting irradiance accurately is the clear sky model which estimates the average irradiance at a location at a given time in the absence of clouds. Current methods for modelling clear sky irradiance are either inaccurate or require extensive atmospheric data, which tends to vary with location and is often unavailable. In this paper, we present a data-driven methodology, Blue Skies, for modelling clear sky irradiance solely based on historical irradiance measurements. Using machine learning techniques, Blue Skies is able to generate clear sky models that are more accurate spatio-temporally compared to the state of the art, reducing errors by almost 50%.

scholarly journals A Simple Method for the Assessment of the Cloud Cover State in High-Latitude Regions by a Ground-Based Digital Camera

2006 ◽  
Vol 23 (3) ◽  
pp. 437-447 ◽  
Author(s):  
M. P. Souza-Echer ◽  
E. B. Pereira ◽  
L. S. Bins ◽  
M. A. R. Andrade
Keyword(s):  
A Priori ◽  
Digital Camera ◽  
Correlation Coefficients ◽  
Visible Range ◽  
Direct Sunlight ◽  
Simple Method ◽  
Charge Coupled Device ◽  
Clear Sky ◽  
Sky Conditions ◽  
Overcast Sky

Abstract This work describes the development of a simple method of field estimating the sky cloud coverage percentage for several applications at the Brazilian Antarctic Station, Ferraz (62°05′S, 58°23.5′W). The database of this method was acquired by a digital color camera in the visible range of the spectrum. A new algorithm was developed to classify each pixel according to a criteria decision process. The information on the pixel contamination by clouds was obtained from the saturation component of the intensity, hue, and saturation space (IHS). For simplicity, the images were acquired with a limited field of view of 36° pointing to the camera’s zenith to prevent direct sunlight from reaching the internal charge-coupled device (CCD) on the camera. For a priori–classified clear-sky images, the accuracy of the method was superior to 94%. For overcast-sky conditions, the corresponding accuracy was larger than 99%. A comparison test was performed with two human observers and our method. The results for the 29 images collected for several time of days during 50 days in 1999 summer were compared to visual observations of these same digital images by two trained field meteorologists. Correlation coefficients between human observers and the automatic method ranged from 0.84 for clear-sky conditions, and the lowest was 0.09 for undefined-sky conditions.

Observations of Radio Emission of the Moon at 2.3 cm by the Pulkovo Large Radio Telescope

1962 ◽  
Vol 14 ◽  
pp. 527-532
Author(s):  
N. L. Kaydanovsky ◽  
V. N. Ihsanova ◽  
G. P. Apushkinsky ◽  
O. N. Shivris
Keyword(s):  
Brightness Temperature ◽  
Resolving Power ◽  
Variable Component ◽  
Central Meridian ◽  
Lunar Crust ◽  
Maximum Brightness ◽  
Area Efficiency ◽  
Direct Measurements ◽  
Subsolar Point ◽  
And Shifts

The measurement of the amplitude of variation of the brightness temperatureTaat the centre of the lunar disk enables, as is shown in [1], to evaluate the magnitude of the equivalent conductivity σ of the material of the lunar crust. The amplitude of variation of brightness temperatureTacan be determined with the aid of radio telescopes with high resolving power by direct measurements of the brightness temperatureTein the course of a lunation. Such measurements require that the area efficiency σ of the antenna and conditions of calibration of the receiving apparatus over the period of observations to be constant, and this is hard to ensure.Tacan also be determined by measuring the shift of the centre of gravity of radiationxu[2]†, resulting from the fact that the variable component of brightness temperature, in superimposing itself on the constant component, distorts the symmetry of the curves of equal light intensity (isophotes) relative to the central meridian, and shifts the point of maximum brightness away from the centre of the disk in the direction of the subsolar point, asTais a functionxu.

scholarly journals Monitoring of UV spectral irradiance at Thessaloniki (1990–2005): data re-evaluation and quality control

2006 ◽  
Vol 24 (12) ◽  
pp. 3215-3228 ◽  
Author(s):  
K. Garane ◽  
A. F. Bais ◽  
S. Kazadzis ◽  
A. Kazantzidis ◽  
C. Meleti
Keyword(s):  
Quality Control ◽  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Spectral Irradiance ◽  
Internal Temperature ◽  
Ancillary Data ◽  
Response Error ◽  
Temperature Coefficients ◽  
History Of ◽  
Ultraviolet Irradiance

Abstract. We present a re-evaluation and quality control of spectral ultraviolet irradiance measurements from two Brewer spectroradiometers operating regularly at Thessaloniki, Greece. The calibration history of the two instruments was re-examined and data flaws were identified by comparing quasi synchronous measurements. Analysis of the sensitivity of both instruments to variations of their internal temperature revealed that they have temperature coefficients of different sign. These coefficients exhibit small variability during the 15-year period. Using averaged temperature coefficients, we corrected both datasets. Corrections were applied for the angular response error using two different approaches depending on the availability of required ancillary data. The uncertainties associated with the measurements have been estimated and presented. Finally, the two datasets are compared using ratios of irradiance integrals at various bands in the UV, in order to assess any dependencies on the internal instrument temperature, solar zenith angle and wavelength.

scholarly journals The impact of parameterising light penetration into snow on the photochemical production of NO<sub>x</sub> and OH radicals in snow

2015 ◽  
Vol 15 (6) ◽  
pp. 8609-8646
Author(s):  
H. G. Chan ◽  
M. D. King ◽  
M. M. Frey
Keyword(s):  
Radiative Transfer ◽  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Action Spectrum ◽  
Transfer Model ◽  
Oh Radicals ◽  
Nitrate Anion ◽  
Photolysis Rate ◽  
Polar Snow ◽  
The Impact

Abstract. Snow photochemical processes drive production of chemical trace gases, including nitrogen oxides (NO and NO2), and HOx radicals in snowpacks which are then released to the lower atmosphere. Coupled atmosphere–snow modelling on global scales requires simple parameterisations of actinic flux in snow to reduce computational cost. The disagreement between a physical radiative transfer method and a method based upon the e-folding depth of light-in snow is evaluated. In particular for the photolysis of the nitrate anion (NO3-), the nitrite anion (NO2-) and hydrogen peroxide (H2O2) within snow and photolysis of gas-phase nitrogen dioxide (NO2) within the snowpack interstitial air are considered. The emission flux from the snowpack is estimated as the depth-integrated photolysis rate, v, calculated (a) explicitly with a physical radiative transfer model (TUV), vTUV and (b) with a simple parameterisation based on e-folding depth, vze. The evaluation is based upon the deviation of the ratio of depth-integrated photolysis rate determined by the two methods,vTUV/vze, from unity. The disagreement in depth-integrated photolysis rate between the RT model and e-folding depth parameterisation depends primarily on the photolysis action spectrum of chemical species, solar zenith angle and optical properties of the snowpack, (scattering cross-section and a weak dependence on light absorbing impurity (black carbon) and density). For photolysis of NO2, the NO2- anion, the NO3- anion and H2O2 the ratio vTUV/vze varies within the range of 0.82–1.35, 0.88–1.28 and 0.92–1.27 respectively. The e-folding depth parameterisation underestimates for small solar zenith angles and overestimates at solar zenith angles around 60°. A simple algorithm has been developed to improve the parameterisation which reduced the ratio vTUV/vze to 0.97–1.02, 0.99–1.02 and 0.99–1.03 for photolysis of NO2, the NO2- anion, the NO3- anion and H2O2 respectively. The e-folding depth parameterisation may give acceptable results for the photolysis of the NO3- anion and H2O2 in cold polar snow with large solar zenith angles, but can be improved by a correction based on solar zenith angle.

scholarly journals Hourly resolved cloud modification factors in the ultraviolet

2008 ◽  
Vol 8 (9) ◽  
pp. 2493-2508 ◽  
Author(s):  
H. Staiger ◽  
P. N. den Outer ◽  
A. F. Bais ◽  
U. Feister ◽  
B. Johnsen ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Uv Radiation ◽  
Weather Prediction ◽  
Action Spectrum ◽  
Monitoring Program ◽  
Daily Basis ◽  
Solar Irradiation ◽  
Cloud Optical Depth ◽  
Clear Sky ◽  
The Cost

Abstract. Cloud impacts on the transfer of ultraviolet (UV) radiation through the atmosphere can be assessed by using a cloud modification factor (CMF). CMF, which is based on total global solar irradiation (SOLCMF), has proved to be a solid basis to derive CMFs for the UV radiation (UVCMF). This is an advantage, because total global irradiance, the basis for SOLCMF, is frequently measured and forecasted by numerical weather prediction systems and includes all relevant effects for radiation transmission, such as cloud optical depth, different cloud layers, multiple reflection, as well as the distinct difference as to whether the solar disc is obscured by clouds or not. In the UV range clouds decrease the irradiance to a lesser extent than in the visible and infrared spectral range. Thus the relationship between CMFs for solar radiation and for UV-radiation is not straight forward, but will depend on whether, for example, the solar zenith angle (SZA) and wavelength band or action spectrum in the UV have been taken into consideration. Den Outer et al. provide a UVCMF algorithm on a daily basis, which accounts for these influences. It requires as input a daily SOLCMF and the SZA at noon. The calculation of SOLCMF uses the clear-sky algorithm of the European Solar Radiation Atlas to account for varying turbidity impacts. The algorithm's capability to derive hourly UVCMFs based on the SZA at the corresponding hour and its worldwide applicability is validated for erythemal UV using observational data retrieved from the databases of the COST-Action 726 on "Long-term changes and climatology of UV radiation over Europe" and the USDA UV-B Monitoring Program. The clear-sky part of the models has proved to be of good quality. Accumulated to daily doses it forms a tight cluster of points to the highest measured daily sums. All sky model performances for hourly resolution are shown to be comparable in accuracy with the well performing daily models of the COST-726 model intercomparison.

Sign in / Sign up

Export Citation Format

Share Document