Scientific Sponsorship Statement - NSF_SUV_V2.txt
for
"Version 2" spectral UV data of the
NSF UV Spectral Irradiance Monitoring Network (UVSIMN),
operated by Biospherical Instruments Inc.
(BSI)
Germar Bernhard, 12-November-2008
IMPORTANT NOTES:
(1) This document refers to measurements of SUV-100
and SUV-150B spectroradiometers. Information
on GUV multi-filter radiometers are
provided in a separate Scientific Sponsorship Statement.
(2) The UVSIMN website at
http://www/biospherical/com/NSF should be consulted before using data.
1- List of Stations:
-------------------
WMO-ID UVSIMN-ID Site Instrument Longitude Latitude
Established
----------------------------------------------------------------------------------------
689 A McMurdo, Antarctica SUV-100
166º40'E 77º50'S March 1988
698
B Palmer, Antarctica SUV-100 64º03'W
64º46'S May 1988
111
C South Pole,
Antarctica SUV-100 -
90º00'S February 1988
339 D Ushuaia, Argentina SUV-100 68º19'W
54º49'S November 1988
239
E San Diego,
California SUV-100 117º12'W
32º46'N November 1992
199
F Barrow, Alaska SUV-100 156º41'W
71º19'N December 1990
799
J Summit, Greenland SUV-150B 38°27'W
72 34'N August 2004
2- Instrumentation
------------------
Data are collected by spectroradiometers of
(type SUV-100
and SUV-150B from Biospherical Instruments Inc.
Instruments are based on a temperature-stabilized, scanning,
double-monochromator that is coupled to a photomultiplier tube (PMT) detector.
The SUV-100 uses a diffuser as irradiance collector that is coupled via a relay
lens to the monochromator. The SUV-150B employs an integrating sphere that is
coupled via a quartz-fiber bundle. Both systems have internal mercury-vapor and
tungsten-halogen lamps for tracking the instrument's stability. Spectra of
these lamps are typically recorded once per day. Spectra of global spectral irradiance
from 280 to 605 nm are measured every 15 minutes (60 minutes before 1997) when
the solar zenith angle is smaller than 92°. The bandwidth of the SUV-100 is approximatley 1.0 nm full width at half
maximum (FWHM). The bandwidth of the SUV-150B is 0.63 nm FWHM. More details on
the instruments and their specificaitons can be found in Chapter 2 of Network
Operations Reports [e.g., Bernhard et al., 2008a].
3- Network Operation
--------------------
Instruments are visited daily by Research
Associates (RAs) who clean collectors and check that the systems are
functioning normally. RAs also calibrate instruments every two weeks using
200-Watt irradiance standards that are mounted on top of the instrument using a
fixture designed for this purpose. The calibration of these standards is
traceable to the source-based irradiance scale of NIST from 1990 [Walker et
al., 1987]. RAs are trained at BSI before their deployment. Data are downloaded
daily from the system's control computers, and are processed and reviewed on a
weekly basis. Remedial action will be initiated if data review indicates
problems. Network sites are visited by BSI personnel typically once per year
for comparison of the site irradiance standards with "traveling"
standards; instrument characterization; maintenance and repairs; and hardware
and software upgrades. Data collected during these visits will be used for
annual production of final, quality-controlled data products. More information
on network operation can also be found in Chapters 2 of Network Operations Reports [e.g., Bernhard et al.,
2008a].
4- Data Analysis and Quality Control
------------------------------------
Data are recorded in a
binary format and are converted to ASCII using the program SUV_READ. This
programs also applies wavelength and irradiance calibrations to the data taking
into account daily scans of the internal mercury and halogen lamps, and the
bi-weekly scans of 200-Watt irradiance standards. Data
are quality controlled and made available to the public as "Version 0 data
of the UVSIMN." The final step is to convert "Version 0 data" to
"Version 2 data," which are corrected for the instrument's cosine
error; spectrally aligned against a reference solar spectrum by means of a
Fraunhofer-line correlation algorithm; normalized to a wavelength-independent
bandwidth of 1.0 nm (SUV-100) or 0.63 nm (SUV-150B); and re-gridded to a
uniform wavelength scale. In addition, two spectra are calculated with the
radiative transfer model libRadtran/UVSPEC [Mayer and Kylling, 2005] for every
measured spectrum. One model spectrum is a clear-sky spectrum, the second takes
cloud attenuation into account. Version 2 data have to pass a second rigorous
quality control procedure before they are disseminated to the public.
Quality control steps include: review of the
traceability chain of calibration standards and re-calibration if necessary;
comparison of internal instrument parameters with target values; check of
wavelength accuracy by means of Fraunhofer-line correlation [Bernhard et al.,
2004]; comparison of GUV and SUV data; comparison of SUV data with modeling
results; comparison with historical data for detecting possible drifts in
calibrations; and documentation of quality control results in Operations
Reports and metadata files.
The dataset made available in WOUDC format is
based on Version 2 data with the exception of data from San Diego, which is
based on Version 0 data. Binary raw data as well as Version 0 and Version 2
data are also available in their native formats through WOUDC. Data products
that are part of the two versions are discussed in Section 6 below.
The procedure of converting binary data to
Version 0 data is described in Chapter 4 of Network Operation Reports [e.g., Bernhard et al., 2008a].
Results on Quality Control of Version 0 data, including review of irradiance
standards, are provided in Chapter 5 of those reports. The procedure of
converting Version 0 to Version 2 is described in the technical supplement by
Bernhard et al. [2004]. A summary of all Quality Control steps is provided in
the document QC.PDF.
5- Uncertainties
----------------
A comprehensive uncertainty budget for
Version 2 data from South Pole is provided by Bernhard et al. [2004]. Expanded
relative uncertainties (coverage factor k = 2, equal to +/- 2 sigma) depend on
wavelength and solar zenith angle, amongst other factors, and vary between 4.6%
and 13.4%. Expanded uncertainties for spectral irradiance at 310 nm range
between 6.2% and 6.4% and are dominated by uncertainties related to
calibration, stability, and wavelength errors. At larger wavelengths, the
greatest uncertainty arises from insufficient knowledge of the contribution of
direct irradiance to global irradiance required for the cosine-error correction
procedure. Expanded uncertainties for spectral irradiance at 600 nm range
between 4.6% for overcast conditions and 13.4% for periods with variable
cloudiness. Expanded uncertainties for erythemal irradiance and the UV Index
vary between 5.8% and 6.4%, and are only slightly influenced by sky condition.
The expanded wavelength uncertainty of Version 2 spectra is 0.08 nm at 300 nm
and about 0.06 nm at wavelength in the UV-A and visible.
Uncertainty budgets for other sites were
established based on the procedure by Bernhard et al. [2004] and can be found
in the following documents:
McMurdo: Bernhard et al., 2007
Palmer:
Uncertainty_Palmer.pdf
Barrow:
Uncertainty_Barrow.pdf
Summit:
Uncertainty_SUV150B.pdf
The uncertainty budgets for these four sites
are similar to that for South Pole, particularly in the UV-B. Comprehensive
uncertainty budgets for Ushuaia and San Diego are not yet available. The budget
for Ushuaia should be similar than that of other sites. UV-B measurements for
San Diego are too small by 5% as data are based on Version 0 data that have not
been corrected for the cosine error.
6- Version 0 and Version 2 Data Products
----------------------------------------
In addition to data that are part of the
official WOUDC catalogue, native Version 0 and Version 2 data are also
available through the WOUDC. All data are provided as comma-separated ASCII
tables.
"Version 0 data" include:
- Solar spectra of global irradiance between
280 and 605 nm
- System parameters sampled during solar
scans ("Database 1")
- Measurements at specific wavelengths,
extracted from full-resolution spectra ("Database 2").
- Spectral integrals (e.g., UV-B and UV-A)
and "dose-rates" (e.g. erythemal UV) based on six
action spectra ("Database 3")
- Information from scans of the internal lamp
("Database 5")
- Spectral integrals and dose-rates from
Database 3 integrated over 24 hour time periods
Contents and format of Version 0 data is
described in Chapter 6 of Network
Operations Reports [e.g., Bernhard et al., 2008a].
"Version 2 data" include:
- Solar spectra of global irradiance between
280 and 600 nm, re-gridded and normalized to
1 nm
FWHM
- Measurements at specific wavelengths,
extracted from full-resolution spectra.
- Spectral integrals (e.g., UV-B and UV-A)
and "dose-rates" based on 15 action spectra
- Spectral integrals and dose-rates from
Database 3 integrated over 24 hour time periods.
- Total ozone
- Effective surface albedo
- Cloud optical depth at 450 nm
- Model spectra for clear and cloudy sky and
model input parameters
- Results of Quality Control (wavelength
accuracy, presence of spikes in spectra, wavelength from
which
onward spectrum can be trusted, etc.)
Contents and format of each of these datasets
is described in separate PDF documents, see Documentation_Overview.PDF
7- Publications
---------------
As of November 2008, at least 173 publications
have used UVSIMN data, of which 102 are peer-reviewed. These publications include
work in atmospheric sciences (45%); effects research (30%); and validation of
satellite, model, and instrument data (25%). The following publications are
particularly relevant.
7.1. Network overview
- Annual Operations Reports: e.g. Bernhard et
al., 2008
- Initial network setup: Booth et al., 1994
7.2. Data processing and quality control
- Version 0 processing: Annual Operation
Reports, e.g. Bernhard et al., 2008
- Version 2 processing: Bernhard et al., 2004
7.3. Publications by site:
- McMurdo Station: Bernhard et al., 2006
- Palmer Station: Bernhard et al., 2005b
- South Pole: Bernhard et al., 2004
- Ushuaia: Diaz et al., 2001
- San Diego: Diaz et al., 2001
- Barrow: Bernhard et al., 2008
- Summit: Bernhard et al., 2008b
- Comparison all sites: Bernhard et al., 2009
- Austral sites: Liao and Frederick, 2005
7.4. Result of intercomparison campaigns
- SUV-100: Bernhard et al., 2008c, Lantz et
al., 2002, Seckmeyer et al., 1995
- SUV-150: Wuttke et al., 2006
7.5. Validation of satellite UV data:
- Based on Version 0 data: Kalliskota et al.,
2000
- Based on Version 2 data: Tanskanen et al.,
2007
7.6. Validation of total ozone data
- Against satellites: Bernhard et al., 2003
- Against Dobson and Brewer: Bernhard et al.,
2003 and 2005a
7.7. Effect of UV radiation on the biosphere
See complete list of references:
References_UVSIMN.PDF
8- Contact information
----------------------
Germar Bernhard or Rocky Booth
Biospherical Instruments Inc
5340 Riley Street
San Diego, CA 92110-2621
USA
Phone:
+1-619-686-1888
FAX:
+1-619-686-1887
Email:
nsfdata_at_biospherical.com
Internet:
http://www/biospherical/com/NSF
9- Data Use Policy
------------------
Data can be used with no restriction, but we
kindly ask to
(1) Include the following acknowledgement in
publications using UVSIMN data:
UV
data was provided by the NSF UV Monitoring Network, operated by Biospherical
Instruments Inc
under
a contract from the United States National Science Foundation's Office of Polar
Programs
via
Raytheon Polar Services Company.
(2) Notify us of publications that have use
UVSIMN data and send PDF copies, if possible.
10- References
-------------
A complete list of references is provided in:
References_UVSIMN.PDF
Bernhard, G., C.R. Booth, and R.D. McPeters.
(2003). Calculation of total column ozone from global UV spectra at high
latitudes. J. Geophys Research, 108(D17), 4532, doi:10.1029/2003JD003450.
Bernhard, G., C. R. Booth, and J. C.
Ehramjian. (2004). Version 2 data of the National Science Foundation’s
Ultraviolet Radiation Monitoring Network: South Pole, J. Geophys. Res., 109,
D21207, doi:10.1029/2004JD004937.
Bernhard, G., R.D. Evans, G.J. Labow, and
S.J. Oltmans. (2005a). Bias in Dobson Total Ozone Measurements at High
Latitudes due to Approximations in Calculations of Ozone Absorption
Coefficients and Airmass. J. Geophys. Res., 110, D10305,
doi:10.1029/2004JD005559, 2005.
Bernhard, G., C. R. Booth, and J. C.
Ehramjian. (2005b). UV climatology at Palmer Station, Antarctica, in:
Ultraviolet Ground- and Space-based Measurements, Models, and Effects V, edited
by G. Bernhard, J. R. Slusser, J. R. Herman, W. Gao, Proc. SPIE Int. Soc. Opt.
Eng., 588607-1 - 588607-12.
Bernhard G., C.R. Booth, J.C. Ehramjian, and
S.E. Nichol. (2006) UV climatology at McMurdo Station, Antarctica, Based on
Version 2 data of the National Science Foundation’s Ultraviolet Radiation
Monitoring Network, J. Geophys. Res., 111, D11201, doi:10.1029/2005JD005857.
Bernhard, G., C. R. Booth, J. C. Ehramjian,
R. Stone, and E. G. Dutton (2007), Ultraviolet and visible radiation at Barrow,
Alaska: Climatology and influencing factors on the basis of version 2 National
Science Foundation network data, J. Geophys. Res., 112, D09101,
doi:10.1029/2006JD007865.
Bernhard, G., C. R. Booth, J. C. Ehramjian, and
V. V. Quang. (2008a). NSF Polar Programs UV Spectroradiometer Network 2006-2007
Operations Report Volume 16.0, Biospherical Instruments Inc., San Diego.
Bernhard, G., C. R. Booth, and J. C.
Ehramjian. (2008b). Comparison of UV irradiance measurements at Summit,
Greenland; Barrow, Alaska; and South Pole, Antarctica, Atmos. Chem. Phys., 8,
4799–4810.
Bernhard, G., R. L. McKenzie, M. Kotkamp, S.
Wood, C. R. Booth, J. C. Ehramjian, P. Johnston, and S. E. Nichol. (2008c).
Comparison of ultraviolet spectroradiometers in Antarctica, J. Geophys. Res,
113, D14310, doi:10.1029/2007JD009489.
Bernhard, G., C. R. Booth, and J. C.
Ehramjian. (2009). Climatology of Ultraviolet Radiation at High Latitudes
Derived from Measurements of the National Science Foundation’s Ultraviolet
Spectral Irradiance Monitoring Network, accepted for publication in: UV
Radiation in Global Change: Measurements, Modeling and Effects on Ecosystems,
edited by W. Gao and J. Slusser, Springer-Verlag and Tsinghua University Press.
Booth, C.R., T.B. Lucas, J.H. Morrow, C.S.
Weiler, and P.A. Penhale. (1994). The United States National Science
Foundation's Polar Network for Monitoring Ultraviolet Radiation. Antarctic
Research Series, edited by C.S. Weiler and P.A. Penhale, 62, 17-37, American Geophysical
Union, Washington, D.C.
Kalliskota, S., J. Kaurola, P. Taalas, J.
Herman, E. Celarier and N. Krotkov. (2000). Comparison of daily UV doses
estimated from Nimbus 7/TOMS measurements and ground-based spectroradiometric
data, J. Geophys. Res., 105(D4), 5059-5067.
Lantz, K., P.Disterhoft, E.A.Early,
J.DeLuisi, A.Thompson, J.Berndt, L.Harrison, P.Kiedron, J.Ehramjian,
G.Bernhard, L.Cabasug, J.Robertson, W.Mou, T.Taylor, J.Slusser, D.Bigelow,
B.Durham, G.Janson, D.Hayes, M.Beaubien, and A.Beaubien. (2002). The 1997 North
American interagency intercomparison of ultraviolet spectroradiometers
including narrowband filter radiometers. J. Res. Natl. Inst. Stand. Technol.,
107, 19-62.
Liao, Y. and J.E. Frederick. (2005). The
ultraviolet radiation environment of high southern latitudes: springtime
behavior over a decadal timescale, Photochem. Photobiol., 81, 320-324.
Mayer, B., and A. Kylling. (2005). Technical
note: The libRadtran software package for radiative transfer
calculations—Description and examples of use, Atmos. Chem. Phys. Disc., 5,
1319– 1381.
Seckmeyer, G., B. Mayer, G. Bernhard, R.L.
McKenzie, P.V. Johnston, M. Kotkamp, C.R. Booth, T.B. Lucas, T. Mestechkina,
C.R. Roy, H.P. Gies, and D. Tomlinson. (1995). Geographical differences in the
UV measured by intercompared spectroradiometers. Geophysical Research Letters,
22(14), 1889-1892.
Tanskanen, A., A, Lindfors, A. Määttä, N.
Krotkov, J. Herman, J. Kaurola, T. Koskela, K. Lakkala, V. Fioletov, G.
Bernhard, R. McKenzie, Y. Kondo, M. O’Neill, H. Slaper, P. den Outer, A. F.
Bais, and J. Tamminen. (2007). Validation of daily erythemal doses from Ozone
Monitoring Instrument with ground-based UV measurement data, J. Geophys. Res.,
112, D24S44, doi:10.1029/2007JD008830.
Walker, J.H., R.D. Saunders, J.K. Jackson,
and D.A. McSparron. (1987). Spectral irradiance calibrations, NBS Spec. Publ.
U.S., 250-20.
Wuttke S., G. Seckmeyer, G. Bernhard, J.
Ehramjian, R. McKenzie, P. Johnston, and M. O'Neil. (2006). New
spectroradiometers complying with the NDSC standards, J. Atmos. Ocean. Tech.,
23(2), pages 241–251.