Scientific Sponsorship Statement - SSSAES.TXT
                For UV-Biometers Radiation data from the University of Panama
                     National Radiometric Network (issued 2005 – 09 – 30)


  Panama 1998 –
  David      2002 –
  Santiago 2003 –

General Methodology

The UV- Radiation data is obtained from three 501 UV-Biometers which are installed in the three sites of the National Radiometric Network which is managed by the Laboratory of Atmospheric Physics of the University of Panama.  At sites 1 (Panama City) and 2 (David City), global solar radiation and other atmospheric parameters are being measured.  Global solar radiation is measured by means of Pyranometers Eppley, model PSP as well as model BW and Pyranometers Kipp and Zonen.  For the monitoring of the rest of the atmospheric parameters, Campbell meteorological stations have been installed at sites 1 and 2.  At site N° 3 (Santiago City), only UV-B radiation is measured up to now.  We are planning to install another Campbell meteorological station at site N°3 on October 2005.

At site N° 1, the monitoring process was initiated on July 1997.  At site N° 2, the monitoring process was initiated on December 2001.  At site N° 3, the monitoring process was initiated on March 2002.  Radiometers and other sensors store data every five minutes, in a continuous way.  Data from the three monitoring sites are downloaded from the Laboratory of Atmospheric Physics (Main Campus) through INTERNET by means of a software called PC ANYWHERE.  Raw data is then processed, using statistical and graphical software (SIGMA PLOT).  By means of SIGMA PLOT, daily totals, UV Indexes, Maximum daily irradiance and graphics are obtained.

The following table shows the Serial Number of each of the Broadband meters used, as well as their last calibration date:

Site	            Instrument	       Model	    S/N	        Last calibration
Panama   (N°1)	    UV- Biometer	501	    2934	Mid April 2005
David    (N° 2      UV- Biometer	501	    6587	February 2005
Santiago (N° 3)	    UV- Biometer	501	    4371	December 2004

The 501 meters are sent yearly to the Solar Light Co. for calibration and inspection of electronic circuitry.

The maximum measurement error on UV irradiance, compared with the calculated irradiance, for a total ozone column of 300 DU and a solar zenith angle of 70° is  ±6 %.  The accuracy of 501 meters is within ± 5 % for daily total.  Each radiometric site has personnel who cleans weekly the dome of 501 meters.  UV-B data from the monitoring sites, could be seen in real time, by means of PC ANYWHERE.  UV-B irradiance data are analyzed daily with the software SIGMA PLOT.  Through this process, data quality is assured.

The display value of the UV irradiance (SUVdisp) is calculated internally by the instrument, according to the following algorithm:

      SUVdisp = (SUVmeas * SCALE – OFFSET) / TCORR             (1)

where SUVmeas is the measured value of UV irradiance, SCALE and OFFSET are system variables that can be changed by the user and TCORR is the temperature correction factor.

      TCORR = 1 + (Tdet – Tnom) * eT                           (2)

Where Tnom and Tdet are the nominal detector temperature and Tdet is the actual detector temperature, respectively.  Here, eT is the thermal coefficient of the detector, whose value is 0.0097 / °C.

Due to the fact that the tropical climate of Panama is characterized by maximum temperatures that could rise to 37 ° C during the dry season, occasionally, the detector temperature doesn’t get stabilized at 25 °C.  When this situation occurs, the display UV data is corrected by means of algorithm (1).  If this situation persists, the detector is sent to the manufacturer, in order to get checked.

Results
The Laboratory technician visits Site N° 2 (David) and Site N° 3 (Santiago) once every month for basic maintenance (detector, data logger, PC and software). The time period during which, the technician stays at each Site is seven days.

During this process, a 501 UV-Biometer which is normally kept inside the main installations of the Laboratory of Atmospheric Physics, is transferred to each of the Radiometric Sites, in order to do an intercomparison of data.

Up to now, it has been established that the difference between the SUV  output values of the 501 meters located at the three monitoring sites and the 501 UV – Biometer used for reference is about 2 %.

References
Ref 1.  Berger, D.: The sunburning ultraviolet meter, design and performance: Photochemical, Photobiology, 24, 587 – 593, 1976.

Ref2.  Blumthaler, M., Ambach, M., Morys, J., Slomka: Comparison of Robertson-Berger UV Meters from Innsbruck and Belsk: Publs. Inst. Geophys. Polish Academy of Science, D-32 (230), 1989, Warsaw.