From: fmims@aol.com (FMims)
Newsgroups: sci.environment
Subject: Re: Record low ozone over Hawaii, winter 1994-5
Date: 27 Jun 1996 14:04:50 -0400

Jim Scanlon has raised interesting questions about the
paper on record low ozone at Mauna Loa Observatory
(MLO) by Dave Hofmann et al. in Geophysical Research
Letters (23, 1533-1536, 1 June 1996). Scanlon is
correct to raise questions about this paper's lack of
data about UV-B.

At least one respondent takes issue with Scanlon and
states that the paper does indeed show data about UV-B
during the low ozone episode. This is misleading since
Figure 1 in this paper shows scatterplots of ozone and
the ratios, not absolute amounts, of the irradiances at
295, 300 and 305 nm (wavelengths strongly absorbed by
ozone) to the irradiance at 325 nm (a wavelength not
absorbed significantly by ozone).

I assume that Scanlon would like to see data about the
irradiance levels of biologically-active UV-B during
the low ozone episode, especially since the paper's
abstract states that, "Total ozone values this low have
not previously occurred over populated areas except on
rare occasions when the edges of the springtime
Antarctic ozone hole temporarily pass over the southern
tip of Argentina." These data are available. During the
event in question at least one broadband UV-B
radiometer was at MLO. (Up to two others may have also
been present.) However, two of these instruments were
removed from MLO shortly before my annual calibration
visit last month.

The paper by Hofmann et al. has 21 authors. It is
puzzling why not a single author included in his/her
section of the paper results from the broadband UV-B
measurements. For those who question or criticize such
measurements, for 62 days last summer I compared
several broadband UV-B radiometers with an EPA Brewer
spectrophotometer. The correlation of the UV-B measured
by these instruments was excellent (paper in
preparation). Indeed, the broadband instruments
performed better when clouds were present as the Brewer
requires 8 minutes to do a complete UV-B scan.

In closing, this paper illustrates a serious deficiency
in current ozone-UV-B research: There is great interest
in ozone but little in the UV-B that actually reaches
populated areas. On the Big Island of Hawaii, for
example, NOAA does not operate a UV-B instrument near
sea level. For the past 5 summers I have made
measurements of UV-B at sea level and MLO (3.4 km MSL),
sometimes using automatic data loggers. There can be
very significant differences in the UV-B at these
locations. Volcanic haze and clouds at the Sun can
significantly reduce UV-B. Clouds near the sun can
cause significant increases in UV-B (Mims, Nature, 22
Sep 1994). I cannot understand why NOAA doesn't itself
make such measurements. (Should someone suggest they
lack the instruments, I will be glad to donate two
calibrated instruments, one for MLO and one for sea
level, at no cost. If lack of time is suggested as the
reason, I will explain in detail why it isn't.)

There has been considerable criticism by government and
university scientists of the lack of interest in
serious UV-B monitoring by those who control the tax
dollars available for such research. Jim Scanlon is
well aware of this serious deficiency, and I hope his
comments on the matter can be taken seriously.

Forrest M. Mims III
Sun Photometer Atmospheric Network (SPAN)

From: fmims@aol.com (FMims)
Newsgroups: sci.environment
Subject: Re: Record low ozone over Hawaii, winter 1994-5
Date: 27 Jun 1996 18:05:40 -0400

James Acker responded to my note on the recent
paper in GRL on record low ozone at MLO:

>Thanks for your comments.  I understand from the
>other respondent's comments that 295 nm radiation is
>in the UV-B range.  If the irradiance at 325 nm is not
>strongly absorbed by ozone, is it relatively constant, or
>are there any other aerosols or factors that will affect it?
>f it is relatively constant, then it should be a simple
>matter to convert the ratios to actual irradiance values.
[cut...]

The 325 nm radiation is attenuated by Rayleigh scattering
(although less than lower wavelengths) and Mie scattering
caused by aerosols. It is an excellent reference.

But why convert the ratios to actual irradiance values when
NOAA and the Smithsonian already have that data? They
also have the broadband data. Why they did not include it
goes back to Jim Scanlon's original questions. I am
completely puzzled by this major lapse.

Forrest M. Mims III
Sun Photometer Atmospheric Network (SPAN)

From: fmims@aol.com (FMims)
Newsgroups: sci.environment
Subject: Re: Record low ozone over Hawaii, winter 1994-5
Date: 30 Jun 1996 17:03:32 -0400

James G. Acker wrote (in part) in response to
my question about why the paper we are discussing
failed to include a time series of absolute UV-B:

>Since the focus of the paper was
>on the causes of the decrease in ozone over Hawaii, would
>the paper have been enhanced by including the radiance data?
>Not by much, IMO.  If it was not included I presume it is due
>to the brevity of the GRL format.

This response nicely illustrates what some of us discussed in this
forum last year, viz. there is lots of interest in ozone but very little
in how much UV-B gets through the ozone layer. As many UV-B
scientists have pointed out since 1978, this is inexplicable. The
data are available from MLO and could easily have been included.

Should the broadband data be somehow criticized, then I note
that some of the Smithsonian UV-B filters have in the past
exhibited significant leakage in the UV-A. I know this personally since I
have measured some of these filters.

Forrest M. Mims III

Newsgroups: sci.environment
From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Subject: UV-B in New Zealand 1988-95
Date: Wed, 03 Jul 1996 08:31:44 GMT

Well, this paper is fairly topical, given the ongoing discussion on
ground-level UV monitoring. This paper summarises some results of the
New Zealand ground-level UV programme that has been underway since
1988, and which I posted earlier results a year or so ago.

According to one of the authors, their funding proposal for the
continuation of this work has been rejected by the NZ Government
"public good" science funding agency because it is not "research",
despite having excellent reviews from all the referees. It seems
that the pot of gold for such monitoring was small, and that
several unusual factors came into play, including boys with bigger,
more expensive toys. The fact that this programme monitored the UV
at actual population centres rather than some remove sheep-filled
plateau seems to me to have been considered a negative factor by
some scientists.

Anyway..onwards...Jargon ( as defined by me )
Broadband radiometers can have spectral responses similar to the
wavelength sensitivities of skin that cause reddening ( erythemal
action spectrum ) or non-melanomona skin cancers ( carcinogenic
action spectrum ). Both action spectra show a rapid decrease in
response of several orders of magnitude from 295nm to 340nm.
Converting the measured irradiances to a hypothetical quantity of
of a monochromatic wavelength that requires the same exposure time
to result in erythema, involves some rather boring integral and
normalisation steps, which ultimately create the " Erythemally
effective irradiance at wavelength...".

I've previously commented how amazingly diligent and meticulous
these researchers have been about the calibration of their
instruments, and the same applies to this paper. There is some
well presented data for each year.

"Erthemal Ultraviolet Insolation in New Zealand at Solar Zenith
Angles of 30 or 45 degrees"
K.G.Ryan, G.J.Smith, D.A.Roades, and R.B.Coppell
Photochemistry and Photobiology v.63 p628-632 (1996).

Actinic UV radiometers from International Light Inc were installed
at three NZ population centres in 1988/89, as they have reasonably
close spectral match to to the erythemal and carcinogenic action
spectra of skin. Measurement of solar erythemal radion is difficult
for several reasons. Errors can arise if the rapid change of
sensitivity with wavelength is not accurately duplicated by the
instrument response. Solar UV irradiances are highly variable,
being susceptible to variations in atmospheric ozone levels,
solar angle, cloud and atmospheric turbidity, and in some cases
ground reflectivity. They discuss in detail the methodology used.

Because the focus of the work was to mimic the impact of radiation
on human skin, the authors have foregone the traditional integration
over daily (or longer) periods, and have selected data at solar
zenith angles of 30 and 45 degrees.  This will introduce a strong
seasonal bias in the data by excluding winter, however at these
latitudes (37S, 41S, 43.5S) the erythemally effective UVB insolation
is low in winter. They have selected 310nm as the reference
wavelength for the erythemally effective UV irradiances reported.
They also screened the data to remove the effects of highly variable
cloud cover, and thus really only play with the upper portion of the
full data set, although one full set is provided to illustrate the
effect of the screening.

Results

Spring to autumn yearly erythemally effective irradiances
( uW cm^-2 at 310nm ) up to March 1995.
                Auckland         Wellington      Christchurch
Degrees        30      45        30      45       30      45
1988/89        -       -       111.8    51.6    104.1    47.1
1989/90      106.0    51.0     124.2    62.5    112.4    51.1
1990/91      121.6    58.6     122.9    59.9    103.3    45.2
1991/92      107.5    54.4      97.6    47.5     90.9    41.2
1992/93      110.0    55.7     112.5    53.3     95.5    44.2
1993/94      121.1    66.2     127.5    62.9     94.2    41.1
1994/95      120.0    61.4     132.4    66.7     86.9    40.1

From the above they arrived at the folowing conclusions
1. No monotonic trend for cloudless skies at solar zenith angles
   of 30 or 45 degrees was observed. This is consistent with the
   absence of any monotonic change in total ozone column during the
   period.
2. There were some statistically-significant differences, especially
   the 1991/92 period - which may be a consequence of increased
   aerosols from Mt Pinatubo.
3. There was an increase in erythemally effective UV irradiance from
   spring to autumn each year in all three sites and this was
   attributed to the natural annual cycle of levels of ozone at
   midlatitudes [I haven't shown that data].

Subsequent discussions with an author indicated that a very brief
review of the 1995/96 data indicated the irradiance was probably
higher than 94/95. He also noted that the huge natural variability
of the Ozone layer would preclude identification of any effects
from the breakup of the infamous "Ozone Hole" in the data - even
looking at the unsreened data. He was also concerned that some
published literature indicated there are some poorly-calibrated,
and poorly-designed UV measuring instruments in use that give numbers
more appropriate for the the Wellington telephone directory than
scientific publications. He also noted that there was a significant
vested financial interest by some well-known researchers in the
selection of equipment,  and that some researchers in the field
have unfortunately not been able to refrain from publically and
privately attacking the users of different instruments. Such
attacks don't help researchers seeking funds from funders covering
a wide range of science - they will move new or additional funds
to less controversial areas.

All in all, a nice piece of research that lays the foundation
for future work, hopefully the authors will finding some funding,
as baseline data is essential for all science.

                       Bruce Hamilton

From: fmims@aol.com (FMims)
Newsgroups: sci.environment
Subject: Re: Record low ozone over Hawaii, winter 1994-5
Date: 3 Jul 1996 12:21:38 -0400

James G. Acker wrote (in part):

>What do you think the chances would be of getting
>funding for a few UV-B monitoring sites from a public health
>agency?  Has it been attempted?

The EPA has 7 Brewer spectrophotometers that measure
UV-B and total ozone. They placed one at my site for
62 days last summer. Unfortunately, these very expensive
instruments are primarily deployed along the East Coast.
There's one in Boston but none in any of the States along
the Gulf Coast or in New Mexico and Arizona where
some of the the highest UV-B levels occur.

The Department of Agriculture has a much bigger network
of broadband UV-B instruments. These data are available
on the net but are not now widely publicized.

That's about it. The US simply has no national UV-B network.
The NWS issues UV-B forecasts based on satellite
ozone data, but these forecasts do not account for effects
of haze and local conditions.

Forrest M. Mims III
Sun Photometer Atmospheric Network (SPAN)

From: fmims@aol.com (FMims)
Newsgroups: sci.environment
Subject: Re: Record low ozone over Hawaii, winter 1994-5
Date: 3 Jul 1996 18:53:10 -0400

James Acker wrote (in part):

[Mims wrote:]

>: The Department of Agriculture has a much bigger network
>: of broadband UV-B instruments. These data are available
>: on the net but are not now widely publicized.

>	Is the data potentially useful, in your opinion?
>Seems like there should be an enterprising graduate student
>out there SOMEWHERE...

The DOA data are definitely useful, especially since each instrument is
paired with a multi-wavelength radiometer that gives absolute irradiance
of the full and diffuse sky radiation. Perhaps nearby radio and TV
stations
could begin using these data.

Forrest M. Mims III
Sun Photometer Atmospheric Network (SPAN)

Newsgroups: sci.environment
From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Subject: Re: Record low ozone over Hawaii, winter 1994-5
Date: Sun, 7 Jul 1996 13:56:52 LOCAL

In article <4rm3da$scq@newsbf02.news.aol.com>
 fmims@aol.com (FMims) writes:
>This was discussed at some length last year in this news group.
>The Happer firing was written up in PHYSICS TODAY and various other
>science magazines and journals. I will try to find some of my
>posts on this. The objection to UV-B monitoring is well known within the
>atmospheric sciences community. The latest WMO ozone assessment
>is more than 500 pages long; the UV-B section is, as I recall, only
>21 pages long. It appears that the major reason for the lack of
>funding for and interest in UV-B monitoring is the difficulty of
>correlating falling UV trends with any trend in UV-B because
>changing air pollution and cloudiness significant affect UV-B trends.

My discussions with one of the scientists monitoring UV-B
in New Zealand reveals some dismal aspects. As indicated
last week, when I posted my summary of their latest paper
under the title " UV-B in New Zealand 1988-95 ", their
programme did not receive NZ Government funding from the
"public good science fund" this year, and is likely to be
much diminished or killed next year, even though they had
excellent referees and reviewers reports.

There appears to me to be several reasons why a 7 year old
monitoring programme is facing extinction.

1. It was not seen as "research", even though the scientists
    had been working with their Australian counterparts improving
    and validating calibrations and data, and formally reporting in
    appropriate peer-reviewed journals.
2. It wasn't perceived as "sophisticated enough", when
    compared to the high resolution spectrophotometers used
    in atmospheric research - which were also seeking funds from
    the same funding body.
3. It was perceived as wrongly located - in the population
    centres, where man-made interferences are more likely,
    rather than remote sites.
4. It was perceived as unnecessary duplications, with some
    subtle insinuations by other researchers that ground-level UV
    monitoring was effectively duplicating other work, as it
    allegedly could be calculated from the high-resolution data.
5. It appeared to be contentious and fragmented, with no cohesive
    scientific approach including both the ground level and atmospheric
    researchers, thus the funders decide to give the money to a less
    controversial programme.
6. The researchers were effectively building a database of ground-level
    UV, but there appeared to be no obvious utility in the information,
    it was just data that might have some utility as background
    information... sometime. NZers were considered to be already
    sufficiently aware of UV.

Rather sad, really - I've been impressed by the data they have
measured, and their diligence. It's a pity there wasn't a unified
voice talking to the funders about how complementary much of
the differing research was.

             Bruce Hamilton

From: fmims@aol.com (FMims)
Newsgroups: sci.environment
Subject: Re: Record low ozone over Hawaii, winter 1994-5
Date: 10 Jul 1996 00:56:53 -0400

Josh Halpern discusses my remarks about UV-B.
What is needed on the net is a good UV-B faq.
Robert Parson has made an excellent start in
this direction. Perhaps I can supplement his
faq with additional information. Meanwhile,
this is a very busy season for measuring UV-B,
which means I have less free time to write about it
than those who don't actually spend their days in the
Sun. But I'll try to respond to Halpern's points in this post.

I am hopeful that future comments about the
lack of a global UV-B network can also be sent to the various
scientific agencies which long ago should have agreed on a
viable global UV-B network, particularly since they have yet
to do so.

jbh@ILP.Physik.Uni-Essen.DEF writes:

>Mims (fmims@aol.com) wrote:
>: jbh@ILP.Physik.Uni-Essen.DE wrote (in part):
>:
>: >Just for calibration purposes, how many Dobson/Brewer
>: >systems are operating in the US to measure ozone
>:
>: The EPA has 7 Brewers in a new network primarily along
>: the East Coast  ( 1 in Bozeman, Montanna). NOAA has Dobsons
>: at Fesno (CA), Boulder (CO), Nashville (TN), Tallahassee (FL),
>: Wallops Island (VA) and in ND and ME (I think). Dobsons do
>: not measure full sky UV-B. They measure ratios of direct Sun
>: UV-B, from which the ozone column is estimated. NOAA data are
>: made available by the World Ozone data Center in Toronto
>: and on the web.
>:
>I am aware of this, however, my point was that your posts leave
>the impression that there are a large number of sites measuring
>ozone concentrations, supported by government funds, while total
>UV measurements are (purposely) not supported because they
>(would) contradict some perceived political, scientific orthrodoxy.

The fact there is no global UV-B network speaks for itself far better than

I can. Measuring UV-B is difficult, and any trends can be distorted by
many variables other than ozone. The difficulty of the task is
one reason that there is no global UV-B network.

> Comparing the number of sites in the Dobson/Brewer system to
>the number of sites measuring UV (DoAg etc.) is therefore a
>useful exercise.

>Moreover, IMHO simple total UV-B measurements would not be a very
>useful exercise.

Then you must endorse the very unfortunate closing of the New Zealand
program.

>There are several reasons for this
>
>1.  The biological activity of UV-B increases exponentially with
>increasing frequency (decreasing wavelength).  Therefore a simple
>total measurement of UV-B does not provide the needed information
>for evaluation of any possible damage to plants and animals.

The action spectra for erythema in human skin and for DNA are both
broadband in nature. The former peaks at about 308-310 nm. Broadband
detectors such as those developed by Solar Light and Yankee and my
filter radiometers closely simulate the erythema action spectrum.
Thus your assumption is invalid.

>2.  The absorption of ozone increases exponentially from about
>330 to 290 nm.  Note that because of this a small loss in ozone
>concentration can have a major biological effect all other things
>being equal.  Total UV B measurements will not reflect this.

Again, your assumption is invalid. Broadband UV-B instruments
definitely show the effects of variations in colum ozone. I observe this
daily. Keep in mind that by "broadband" I refer to instruments that
simulate one of the relevant action spectra (e.g. erythema).

>Thus, if one is interested in biological effects, either a properly
>weighted filter meter should be used (the correct word is
>epythermally?? anyhow, Bruce Hamilton recently posted about
>a project in NZ which used such a system and has been defunded) or
>a complete spectrum should be measured (Brewers).

(The term is erythemal. It simply means the reddening of skin.)  What
Bruce Hamilton wrote about is exactly what
I wrote about: The need for measuring UV-B. The fact the NZ program
is being cancelled says far more about the dismal state of UV-B
measurement
programs than I could ever say. It's reminiscent of the U.S. closure of
the NOAA
Berger network in 1988 when the results showed a downward trend in UV-B
instead of the expected upward trend. Only later were papers published
showing
the effects of air pollution on UV-B and the fact the network instruments
may have had calibration problems. (A recent request for a nominal grant
by a NOAA scientist who wants to reconstruct these data was not approved.)


>3.  The other two molecules which will absorb in the UV-B region
>are NO2 and SO2, which are pollution products.  Simple total UV-B
>measurements cannot distinguish between the effects due to SO2, NO2
>and O3.  This is without even getting into the question of haze
>and clouds

NO2 is insignificant compared to SO2. But why does this even matter?
The bottom line is UV-B at the surface, and UV-B has many modulators
beyond ozone. In the summer when ozone is rather steady, haze has a much
more dramatic effect on UV-B than ozone. When one wants to know how
much UV-B people are receiving, it matters little that SO2 might play a
role in
reducing that UV-B, as do tropospheric ozone and haze. Clouds: Keep in
mind that cumulus clouds in a very clear sky (as at my site on 8 July)
can cause very significant increases in UV-B.

>4.  It has been shown that on clear days, in unpolluted atmospheres,
>ozone measurements can be used to predict UV-B.

Of course. I use the Canadian AES empirical model to do just this.

>: The Sun Photometer Atmospheric Network has ozone instruments
>: in Togo, Falkland Islands, 5 Pacific Islands (from Hawaii to Near New
>: Guinea), South Africa, Paraguay, Colorado, California, and Texas.
>: Data will eventually be on the web. SPAN is a totally volunteer
>: operation with good science as its only agenda.
>:
>iSeems quite dour to me.  Most of the "amature" astronomers, and even
>the pros that I know do it mostly for the delight of discovery.

I wrote that good science is the only agenda. Would that be true of all
measurement programs. What I did not write is that SPAN observers do
indeed volunteer because they very much love to do science.

>Josh Halpern


: Forrest M. Mims III
: Sun Photometer Atmospheric Network (SPAN)

From: fmims@aol.com (FMims)
Newsgroups: sci.environment
Subject: Re: Record low ozone over Hawaii, winter 1994-5
Date: 11 Jul 1996 16:45:56 -0400

Josh Halpern again writes about UV-B.
As I stated in a prior post, most of the points he
makes could be easily clarified in a comprehensive
UV-B faq. Perhaps I can help put one together after this
very busy year closes.

Meanwhile, I'll try to respond to some of his key points.
Sorry, but I just don't have the free time to answer them all.

Halpern write (in part):

[deletions...]

[F. Mims wrote:]

>: The fact there is no global UV-B network speaks for itself far better
than
>: I can. Measuring UV-B is difficult, and any trends can be distorted by
>: many variables other than ozone. The difficulty of the task is
>: one reason that there is no global UV-B network.

>We had a discussion on this point before, basically that it is easier
>to measure a ratio of intensities than an absolute intensity.  My
>point then was that one of the reasons UV-B measurements were
>lagging was that there was not sufficient confidence that the
>instruments could be kept in calibration.

Here you suggest that the instruments are not yet perfected.
Then at the end of your post you state that:

>Frankly, I think your beating the wrong horse, trying to get science
>agencies to set up UVB monitoring networks.  It looks to me like
>this falls muhch closer to the remit of weather forcasting agencies.

Broadband instruments are well established and work quite
well. They are already being used by weather services in several
countries. But not my country (USA).

[deletions...]

[F. Mims wrote:]

>: The action spectra for erythema in human skin and for DNA are both
>: broadband in nature. The former peaks at about 308-310 nm. Broadband
>: detectors such as those developed by Solar Light and Yankee and my
>: filter radiometers closely simulate the erythema action spectrum.
>: Thus your assumption is invalid.

>This again is arguing past each other.  My argument is that a simple,
>evenly weighted UVB broadband measurement is not very (OK as) useful
>as a filter system weighted to reflect the action spectrum you are
>trying to measure.  (erythemal)

I am unaware of any measurement program that uses the instrument
you describe. The only widely used, commercial broadband instruments
of which I am aware have an erythemally weighted action spectrum. As I
mentioned in the prior post, all this could be explained in a complete UV
faq so non-specialists can better understand what measuring UV-B is all
about.

>: >2.  The absorption of ozone increases exponentially from about
>: >330 to 290 nm.  Note that because of this a small loss in ozone
>: >concentration can have a major biological effect all other things
>: >being equal.  Total UV B measurements will not reflect this.
>:
>: Again, your assumption is invalid. Broadband UV-B instruments
>: definitely show the effects of variations in colum ozone. I observe
this
>: daily. Keep in mind that by "broadband" I refer to instruments that
>: simulate one of the relevant action spectra (e.g. erythema).

>To say they show 'effects' is not the same as to say that one can
>invert the measurement, and with no additional data accurately
>predict the ozone variation.

I am mystified by your concern about ozone when when the botom line
is as I stated: UV-B. Yes, a broadband instrument does reflect changes
caused
by ozone, sulfur dioxide, haze and clouds. All four of these modulators
are
very important during the summer months, the latter playing a bigger role
than
ozone changes in many regions.

[deletions...]

>My impression from reading the literature is different.  I have read
>reports from many groups operating observation sites about their
>calibration and operation over what is now a few years of filter
>UV-B instruments.  My impression is that they are gaining confidence
>in their skill with these instruments and that within the next
>few years they will be confident enough to publish.

I am unaware of "a few years of filter UV-B instruments" unless you
are referring to some of my papers. If you meant broadband instruments,
then they have been in continuious use since 1978. (Another reason for
a thorough faq...)

>IMHO total UV-B measurements are now about where O3 measurements were
>in the 60s and 70s, as far as technique, interpretation of results
>and calibration.  There are, again, IMHO two  important differences:

I would add that the UV-B database now is somewhat like the ozone database

was in the 1960's.

>First, on the scientific side, while there would be some use for
>medical survey studies, it is not clear how the iUVB data could be used
>to support atmospheric science in a direct way.  There are better
>ways of measuring atmospheric O3, etc. and more useful parameters
>to test atmospheric models against.

Halpern overlooks the bottom line: Ozone in the stratosphere does not
cause
problems for the environment. Those problems are caused by excessive
UV-B leaking through the ozone layer. Ozone is measured by hundreds of
instruments and by several satellites. There is nothing close to this for
measuring
UV-B.

>Second, there is a public health argument for these measurements,
>and I would expect that UVB measurements would become part of the
>weather forcast (already so in some newpapers).

>Frankly, I think your beating the wrong horse, trying to get science
>agencies to set up UVB monitoring networks.  It looks to me like
>this falls muhch closer to the remit of weather forcasting agencies.

The science of understanding UV-B is woefully incomplete. It is a
wide open field which aspiring grad students should look into--if they
can find any support. As of today, the vast majority of funding in this
field goes for ozone, not UV-B.

[deletions...]

Forrest M. Mims III
Sun Photometer Atmospheric Network (SPAN)

From: fmims@aol.com (FMims)
Newsgroups: sci.environment
Subject: Re: Record low ozone over Hawaii, winter 1994-5
Date: 16 Jul 1996 10:19:47 -0400

Josh Halpern's latest response again contains errors.
I have time to correct only the most important:

>: [F. Mims wrote:]
>: >: The action spectra for erythema in human skin and for DNA are both
>: >: broadband in nature. The former peaks at about 308-310 nm. Broadband

>: >: detectors such as those developed by Solar Light and Yankee and my
>: >: filter radiometers closely simulate the erythema action spectrum.
>: >: Thus your assumption is invalid.
>: i

>Nuts, the McKinley and Diffey erythermal action spectrum increases
>smoothly and non-linearly from 324 nm to slightly below 300 nm,
>where it cuts off.  308 nm light is roughly 1/10th as efficient
>at redening skin at 300 nm light.  (In Human exposure to UV
>Radiation: Risks and Regulation, Elsevier, 1987, pp83).

Your assumption would be correct if the irradiance at 300 and 308 nm
was equal. However, it is not, and 300 nm radiation is absorbed much
 more by ozone than is 308 nm radiation. Therefore, as discussed in
various published papers, the effective peak for the erythemal action
spectrum is about 308 nm.

Halpern made various other incorrect or misleading comments. For example,
his statement about models applies only to a clear or relatively clear
sky. Canada's AES model works very well outside the tropics (where it
underestimates) on clear days. But it overestimates when haze is present.
Haze is a much more important modulator of UV-B than generally
known.

Forrest M. Mims III
Sun Photometer Atmospheric Network (SPAN)

From: fmims@aol.com (FMims)
Newsgroups: sci.environment
Subject: UV-B Measurements in New Zealand: Open Letter
Date: 16 Jul 1996 22:01:15 -0400

k.ryan@irl.cri.nz previously noted that a particular
broadband UV-B measurements program in New Zealand
may be cancelled. What follows is a letter I have sent to
him which he is forwarding to the appropriate officials.
Perhaps others who have knowledge of the measurement
of solar UV-B may also wish to consider sending a letter.


To whom it may concern:

New Zealand is admired within the scientific community for
its outstanding research into the to measurement of total
ozone and UV-B. I am particularly indebted to New Zealand's
work in these areas, for the development of the various
hand-held ozonometers I have designed was
stimulated in large part by the work of Mathews and others
who demonstrated that interference filter instruments could
indeed measure ozone with a reasonable degree of accuracy.

However, I am very troubled to learn that New Zealand may cancel
an important program to measure trends in broadband UV-B. Having
conducted a 62-day comparison of several broadband UV-B
radiometers against a much more costly Brewer spectrphotometer
during the summer of 1995, I can assure those who may have
doubts about broadband instruments that my test showed a very high
correlation between inexpensive broadband instruments and the
much more costly scanning instrument (paper in preparation).
Moreover, broadband instruments have significant advantages
over much more expensive scanning spectral radiometers:

1. Very few maintenance problems.

2. Ease of calibration.

3. Rapid response time.

4. Simplified data acquisition and processing.

5. Real time measurement of erythemally-effective
radiation without the need to integrate over a scanned
spactrum of wavelengths.

The rapid response time is especially important in regions where
clouds occur in a clear blue sky as scattering from such clouds
can cause a very significant increase in UV-B. (See F. M. Mims,
Cumulus clouds and UV-B, NATURE 371, 291, 1994.)

New Zealand is a very important region for measuring UV-B.
Besides the well known seasonal Antarctic ozone minimum,
New Zealand receives some 7% more solar radiation in summer
than Northern Hemisphere sites since the Earth is closer to
the Sun during December than in July. New Zealand has much cleaner
skies than many Northern Hemisphere sites. This is an important
reason why New Zealand's Richard McKenzie found higher UV-B
levels there than in Germany when he conducted a comparison a
few years ago.

I therefore encourage New Zealand to continue its important measurements
of broadband UV-B. Yes, I know the program costs money. But consider
the following:

I have just returned from presenting a calibrated UV-B radiometer
to Rebecca Brawner, a school teacher in Asuncion, Paraguay,
who is among the original members of the Sun Photometer
Atmospheric Network. When Rebecca returns to Paraguay
next week, she will add measurements of total UV-B to her
daily observations of total ozone, total water vapor, direct UV-B
and optical thickness of the atmosphere. Rebecca receives nothing for
her volunteer work with SPAN. Neither do I. All our instruments
and time are either donated or purchased with our own funds.
SPAN now has sites that measure total ozone and UV-B in Paraguay,
Falkland Islands, Togo, South Africa, Hawaii, Papua New Guinea,
Cook Islands, Vanuatu, Pohpei, California, Colorado and Texas. We will
soon add a sixth Pacific site (either Marshall Islands or Pohnpei).
When time and funds permit, we hope to post all our data on the World
Wide WEb. (Soon, the Pacific data will appear in a WWW page
established by the University of Oklahoma.)

SPAN emphasizes sites where UV-B and ozone have never been measured,
especially in the tropics and the Southern Hemisphere. New Zealand
is an especially important site for such monitoring, and I am very
hopeful its broadband program will continue. If it is discontinued,
SPAN will ask permission to assist with UV-B monitoring in New Zealand.
 But it would be far better for the continuity of the ongoing work if
exisiting instruments be kept in place. Therefore, I am very hopeful that
the current program can be kept.

Thank you for allowing me to express these views. I will be happy to
answer any questions.

Forrest M. Mims III
Sun Photometer Atmospheric Network (SPAN)
fmims@aol.com

From: fmims@aol.com (FMims)
Newsgroups: sci.environment
Subject: Re: Record low ozone over Hawaii, winter 1994-5
Date: 17 Jul 1996 20:27:51 -0400

Josh Halpern wrote (in part):

>Well, I was being cautious and nice.  I am no expert in this field
>but what worries me are the constant assertions by Forrest
>Mims, and to a lesser extent Jim Scanlon that there is little
>support for UV-B measurements, when, within a half hour or so
>in a university library I can find indications of many such
>programs that have been established on the national and
>international level (see below).  Someone is supporting these
>programs.

NOAA ceased funding the US UV-B network in 1988. New Zealand is
cancelling its broadband UV-B program. There is presently no coordinated,
international UV-B monitoring network. Many different instruments
are used and in comparisons (as in Boulder last month) they often
disagree by 5-10%. The new US Dept. of Agriculture program is
an excellent network. However, it is not designed for public advisories.
UV-B forecasts based on satellite data tend to overestimate UV-B
since they cannot adequately considerthe effects of haze and clouds.

Forrest M. Mims III
Sun Photometer Atmospheric Network (SPAN)

From: fmims@aol.com (FMims)
Newsgroups: sci.environment
Subject: Re: Record low ozone over Hawaii, winter 1994-5
Date: 18 Jul 1996 11:06:32 -0400

jbh@ILP.Physik.Uni-Essen.DE (Joshua B. Halpern) wrote (in part):

>Mims, look at what you wrote.  You wrote that the ACTION SPECTRA...
>PEAKS at about 308-310 nm.  Look at what I wrote, I provided a
>source which clearly shows that the action spectrum has no peak,
>but increases strongly with decreasing wavelenth.  You were wrong.
>You now have shifted your argument to talk about the effective peak
>being at 308 nm, because ozone (fortunately) absorbs more strongly
>at 300 than 320.

But I am discussing the real world of UV-B measurements on
Earth and not in space where there is no ozone.
It is common usage among those who measure UV-B to
discuss the erythemal action spectrum in terms of the
effect of UV-B on people in the real world (i.e.
protected by a layer of ozone and other absorbers).
Tests with laboratory lamps called solar simulators
show that the action spectrum without the presence of
such absorbers (i.e. outside the Earth's atmosphere)
peaks in the UV-C, not the UV-B. In the real world,
however, the effective peak is not in the UV-C but in
the UV-B at about 308 nm.

This is discussed in many publications, among the most
recent being C. S. Long et al., Ultraviolet Index Forecasts
Issued by the National Weather Service, Bulletin of the
American Meteorolgical Society 77, 729-748, 1996.
For example, the caption of Fig. 2 reads: "The product
of spectral irradiances and the erythemal action spectrum
is plotted. Note that the peak occurs between 308 and 310 nm."

The peak changes slightly as the ozone column swings
through its seasonal pattern (spring maximum and winter
minimum), an effect which is partially compensated by
the seasonal change in Sun angle, hence the amount of
ozone through which sunlight must pass.

[deletion...]

>What is clear is that Mims assertions that

>-no one else cares about UV-B measurementsi

Where is your reference? I have never made such an assertion.

>-that agencies are scared UV-B measuremnets will upset their
>  apple cart

Individual scientists have often voiced their concerns about this
at various conferences I have attended. I have asked several to post
comments on the net, but so far they have declined.

>-that no one else is studying cloud and haze effects

Where is your reference? I have never made such an assertion.
Indeed, I am working with one government agency and a university
on a paper on this very subject and am sharing data with a second
university.

>-etc
>are a crock.

Forrest M. Mims III
Sun Photometer Atmospheric Network (SPAN)

From: fmims@aol.com (FMims)
Newsgroups: sci.environment
Subject: Re: Increase in ultraviolet
Date: 17 Aug 1996 23:42:45 -0400

charliew asked:

>Let me re-phrase the question.  Does anyone know the average
>solar flux, during the summertime, of UV-A and UV-B in a city
>such as Houston, Texas?

I am nearly due west of Houston. In the summer the typical
solar UV-B index ranges from 10 to 11.5. It can be as high
as 12.5 when there is little haze and large cumulus clouds.
Since total ozone is usually rather stable in summer (fluctuating
from 275-280 Dobson units most of this summer--which is
several percent lower than last summer), most of the variation is
caused by haze and clouds.

By comparison, on a beach in Hawaii with the Sun directly overhead
and an ozone column of about 265 Dobson units, the UV-B index is
from 11.5 to 12.5. It is around 15 to 20% higher than that at Mauna Loa
Observatory (3.4 km MSL).

Forrest M. Mims III
Sun Photometer Atmopsheric Network (SPAN)