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[SOL] Solar Radiation Spectrum

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#21 Andrea B.

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Posted 14 May 2018 - 19:21

Solar Light Penetration into Sea Water

Institute for Environment and Sustainability of the European Commission
Here is the original but no longer working link:
http://ies.jrc.ec.europa.eu/uploads/fileadmin/Documentation/Reports/Global_Vegetation_Monitoring/EUR_2006-2007/EUR_22217_EN.pdf]

Read the following carefully:
The vertical axis is depth, in meters, at which the intensity of that wavelength is equal to one percent of the intensity at the surface.
Attached Image: PenetrationLightInotSeawater.jpg
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#22 Andrea B.

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Posted 14 May 2018 - 19:29

Solar Energy in Fiji in July

The chart has been obtained from the solar spectrum at the boundary of the earth atmosphere using the SMARTS 2.9.5 scientific simulation software. This simulator takes into account light absorption by various components of the atmosphere as well as scattered light from the sky.

If this does not convince you of the scarcity of UV light around 300 nm in the solar spectrum, then nothing will! (I do grant that Fiji in July is a rather rare location for most of us. I would suspect that the situation is much worse UV-wise where I live.)

Attached Image: SolarSpectrumFijiJuly.jpg
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#23 Cadmium

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Posted 14 May 2018 - 22:55

Actinic lighting is often used as supplemental lighting for aquariums because it peaks at 420nm and penetrates water deeper than other lighting, good for corals, etc..
Also sometimes used in phototherapy of infant jaundice.

#24 Mark

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Posted 15 May 2018 - 09:24

I find it interesting that there is an inflection point at ~330 nm where UV irradiance finally drops off to practically nothing (in JMC's charts). Interesting because, this is also at about the peak absorbance wavelength of the melanin in our skin. Its almost as if nature made a judgement call and said, "This is as far down (in nm) as I need to go with pigment protection... anything below that is too weak to worry about". Or something like that ;).

#25 Andrea B.

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Posted 15 May 2018 - 15:09

Interesting to learn, Mark. Thanks. :D

If the atmosphere is preventing UVC and much below 330 nm from ever reaching earth, then it certainly makes evolutionary sense that melanin is like that.
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#26 Bill De Jager

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Posted 16 May 2018 - 03:49

View PostAndrea B., on 14 May 2018 - 19:21, said:

Solar Light Penetration into Sea Water

Institute for Environment and Sustainability of the European Commission
Here is the original but no longer working link:
http://ies.jrc.ec.europa.eu/uploads/fileadmin/Documentation/Rceports/Global_Vegetation_Monitoring/EUR_2006-2007/EUR_22217_EN.pdf]

Read the following carefully:
The vertical axis is depth, in meters, at which the intensity of that wavelength is equal to one percent of the intensity at the surface.
Attachment PenetrationLightInotSeawater.jpg

I was surprised to read a while back about UV getting down to the bottom of 594m-deep Crater Lake in the state of Oregon in the U.S., an unusually clear freshwater lake. This paper, to which I don't have full access, provides some information on UV (including UV-B ) in Crater Lake and how it affects life in that lake: https://pubs.er.usgs.gov/publication/70031744.

There's also an in-depth and rather technical discussion here: http://www.craterlak...cs/complete.htm

Edited by Bill De Jager, 16 May 2018 - 03:50.


#27 Dmitry

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Posted 16 May 2018 - 13:47

I made photos of solar spectrum as it seen by camera sensor thru lens and jewelry spectroscope. Final image is some kind of function of sensor sensitivity and lens+spectroscope transparency. Thanks to Fraunhofer lines, I can confirm ability to work with at least 350-800nm range

#28 Pedro J. Aphalo

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Posted 21 May 2018 - 15:47

Does anybody reading this site use R? I have developed a set of packages for doing photobiological and UV and VIS radiation calculations. One of the most recently accepted at CRAN (Comprehensive R Archive Network) is 'photobiologySun'. This is a data-only package with example spectral data for sunlight and shade light. If interested, there is more information at https://www.r4photobiology.info/. Just let me know if you have any questions.

#29 Andrea B.

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Posted 21 May 2018 - 16:54

I don't myself, but thank you for this link, Pedro. That is a really nice program you have written !!

What I would like are some nice display charts if they are better than what I've found so far.

Perhaps a colourful chart of sunlight at sea level at the equator in summer at high noon.

And maybe sunlight at 3000 feet at a northern or southern latitude halfway between the equator and the north pole.

Are those possible with your program?
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#30 Pedro J. Aphalo

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Posted 21 May 2018 - 21:06

Not directly spectra at those locations, but the nice plotting is possible... my packages just have some example data and functions for plotting and calculating various summaries, and for easily combining light source emission and filter transmittance spectra. However, the simulations of the solar spectrum can be done rather easily, either on-line at http://cprm.acom.uca...nteractive_TUV/ (the page has been updated and now accepts 780 nm as upper limit for wavelength) or using libRadtran which is a free download at http://www.libradtra...u.php?id=start. I could really use those spectra that you want in my own teaching so I will put this in my to do list! Both of these radiation transfer models start from the extraterrestrial solar spectrum and compute the attenuation by the atmosphere taking into account composition and solar elevation angle. TUV has more detail on atmospheric chemistry, while libRadtran can be used to simulate the whole solar spectrum at ground level, from UVB to IR.

#31 Andrea B.

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Posted 22 May 2018 - 18:13

Pedro, if you get the time to make such charts they would be welcome addition on UVP.

My purpose is simply to illustrate to members and readers how little UV light there is available for our photography - small amounts of UVA and even smaller amounts of UVB. It would be nice to see the range of the chart in finer intervals than are commonly shown in the charts I have posted.

I was thinking that having an "ideal" chart -- equator at high noon at sea level in summer -- would be the way to go because any other location, altitude, time-of-year and time-of-day would offer less UV light. Unless perhaps one is underneath a ozone hole in the atmosphere! (Is that big ozone hole still there? I need to look that up.)
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#32 JCDowdy

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Posted 23 May 2018 - 23:53

The QUICK TUV CALCULATOR has been my favorite for years.

Pedro, it will let you input wavelength values >1000 but the output table does not display >999 in the WVL columns only ****** but it reports irradiance values in the other columns, but they don't appear to model atmospherics beyond ~1000nm.

For example, here is a plot of 280-1200nm with 920 increments (nm x1) with all other inputs left at default except that output option 2 is selected and all boxes but IRRADIANCE, SPECTRAL (W m-2 nm-1) are unchecked.

Andrea, one can input any location and time or simply solar altitude zenith angle to generate spectral tables.


Attached Image: TUV_Default.JPG


Edited by JCDowdy, 23 May 2018 - 23:57.


#33 Pedro J. Aphalo

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Posted 24 May 2018 - 13:35

Very odd, it stops at 779 when I set small steps for wavelength, but outputs longer wavelengths when I set fewer steps... but the limit at about 779 nm stays at the same wavelength for both 1 nm and 2 nm steps. It seems to be behaving differently for the two of us... oh, now I see, I was trying 280-1280 and 1000 and other number of steps among other things. I think there must be something "hanging around" from the old limit somewhere in the code of the program that triggers the limit at 780 nm with some specific input.
The ability to go past 780 nm was not there in earlier versions of TUV, even a couple of years ago (not even in the FORTRAN version).
I will ask from Sasha Madronich, the author of TUV.

#34 JCDowdy

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Posted 24 May 2018 - 14:29

Pedro,
I tried some input variations and found it gives an error message when increments are >999.
When I tried 280-1279, 999 it generated a spectral data table but the values >1247 are all zero.
I have never run the TUV model out into the NIR before as my interests are primarily UV photobiology.

#35 Andrea B.

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Posted 24 May 2018 - 15:27

John, I think you've mentioned this before? But thanks again. I'm going to go add both your link and Pedo's link to the top of this Solar Spectrum pinned topic.

oh la! Nevermind. I already have John's link in the first post and it was given to us by Pedro. You two are def on top of all things solar !!
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#36 JCDowdy

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Posted 24 May 2018 - 21:23

I don't recall if I have talked about the TUV model before, perhaps in the UV part of the old NG site before the rift.

Here is another perhaps useful tool, nice geographical interface, the NOAA Solar Calculator, which gives solar positions and times.

#37 Reed F. Curry

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Posted 20 June 2018 - 14:57

The image below is from https://agupubs.onli...1002/jgrc.20308

Posted Image
Best regards,
Reed
http://www.uvroptics.com

#38 Pedro J. Aphalo

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Posted 13 August 2018 - 19:23

Hi Andrea and others,

I finally made some progress with the spectra. I posted in my web site a video showing how to use the Quick TUV calculator and a document based on simulations done with it. In the document I included examples of spectra for different solar elevation angles and some plots of the elevation of the sun through the day at different latitudes and times of the year. Just let me know if you want to some specific plots to post here or repost any of this material. This is usable, but I may revise both the video and the document still in the next weeks and months.

https://www.r4photob...tuv-calculator/

In case anybody is curious, I made the video with a program called Flashback.

#39 Andrea B.

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Posted 17 August 2018 - 14:42

Pedro, thank you for the update on this. Greatly appreciated.

There is a lot of really great info in the Solar Spectrum user guide: https://docs.r4photo...article.nb.html

I particularly enjoyed the charts in Section 5 showing the effects of the solar elevation.
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#40 Andrea B.

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Posted 28 October 2018 - 16:42

Sources and measurement of ultraviolet radiation
Brian L. Diffey*

Regional Medical Physics Department,
Newcastle General Hospital, Newcastle upon Tyne NE4 6BE, UK
Accepted 19 June 2002

On a summer’s day, UVB (when taken as 290–320 nm)
constitutes approximately 6% of terrestrial UV,
and UVA (when taken as 320–400 nm), the remaining 94%.

6.1. Xenon arc lamps
For many experimental studies in photobiology it is simply not practicable to use natural sunlight
and so artificial sources of UV radiation designed to simulate the UV component of sunlight are employed.
No such source will match exactly the spectral power distribution of sunlight and as the shorter UV wavelengths
(less than around 340 nm) are generally more photobiologically active than longer UV wavelengths,
the usual goal is to match as closely as possible the UVB and UVAII regions.
The classic so-called solar simulator consists of an optically filtered xenon arc lamp.
This lamp has a smooth continuous spectrum in the UV region and various models of solar simulators
are available with input power in the range 75 W to 6 kW and above, from companies that include Oriel Corporation,
Solar Light, Spectral Energy Corporation, and Schoeffel Optical
[8]. Optical filters and dichroic mirrors
are used to shape the spectrum. In most cases a 1-mm-thick Schott Type WG320 filter is used to control
the short wavelength end
of the spectrum. By varying the thickness of the filter from 1 to 1.5 or 2mm,
spectra are obtained that approximate varying solar altitudes. The simulator normally also incorporates an UV-transmitting,
visible light absorbing filter (e.g., Schott UG5 or UG11) or other filters or multiple dichroic mirrors to remove
visible and infrared wavelengths. The spectrum of a solar simulator is compared with natural sunlight in Fig. 4.
A comprehensive review of solar simulators, with specific refer- ence to sunscreen testing, is given by Wilkinson [8].
F. Wilkinson, in: R. Matthes, D. Sliney (Eds.), Measurements of Optical Radiation Hazards, International Commission on
Non-ionizing Radiation Protection, 1998, pp. 653–684.



References in this paper include the following:

[1] I. Newton, Philos. Trans. R. Soc. London 6 (1672) 3075–3087.

Gotta love authors who take the time to look up Newton.....
Andrea G. Blum
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