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ANALYSIS OF UVB SOLAR RADIATION IN C.I.B.A. LABORATORY,
SPAIN.
J. Bilbao, A. de Miguel, A. Perez-Burgos and P.Salvador
Department of Applied Physics, University of Valladolid, Sciences Faculty.
Prado de la Magdalena s/n, Valladolid, 47005, Spain
983.423133; [email protected]
4 Conclusions
It can be seen that the average hourly values
recorded at solar noon range between 0.4
Wm-2 in February and 1.6 Wm-2 in June.
These average hourly irradiance values in
the central hours of the day show a
considerable symmetric evolution.
The SD of does not seem to follow any
defined pattern.
UVT (295-385nm)
2
40
1
20
UVB (280-315nm) (Wm-2)
UVT (295-385nm) (Wm-2)
60
0
4:00
8:00
12:00
16:00
20:00
Hour (UT)
Figure 1 Comparison of UVT and UV-B horizontal solar
irradiance.
2
2
July
August
January
September
February
1.6
March
April
May
1.2
June
0.8
1.6
December
1.2
0.8
0.4
0.4
0
0
4:00
8:00
12:00
16:00
October
November
8:00
20:00
12:00
16:00
20:00
Hour (UT)
Hour (UT)
Figure 3: Monthly mean hourly UVB irradiance, July to
December, (Wm-2).
Figure 2: Monthly mean hourly UVB irradiance, January and
June (Wm-2).
The statistical characteristics of UVB hourly mean values in July are shown in Figure 4.It can be seen that median values are higher
than the mean ones and the standard deviation increases in central hours of the day. Fluctuations of daily values are shown in
Figure 5.
2.5
2
Mean
Q1
SD
Q3
Median
1.5
1
0.5
0
50
DAILY
MONTHLY
UVB (280-315) kJm-2day-1
The measurements were recorded by a
Yankee UVB-1, TUVR for the UVT and
a Kipp-Zonen CM6B mounted in the
C.I.B.A. (Low Atmosphere Research
Centre). The measurements were
recorded by a datalogger every 10
minutes, (Miguel, 2005).
A statistical study of the most
representative indices of hourly and
daily values of UVB for each month of
the year has been carried out. These
indices are: Standard deviation, mean,
median, maximum, minimum, first and
third quartiles, variation coefficient etc.
30-07-2003
UVB (280-315nm)
0
UVB (280-315nm) Wm-2
2 Methods
Data for each month were arranged in upward order and the
statistical characteristics were evaluated. Figure 1 shows the
comparison between UVB and UVT (UV total) solar radiation
values, on 30th July 2003 at the measurement station. From the
results, it can be said that UVB is 4% of UVT.
The monthly average values of hourly UVB have been
.
evaluated and Figures 2 and 3 show the evolution from January
to June and from July to December, respectively.
It can be seen that the average hourly values recorded at solar
noon range between 0.2 Wm-2 in January and 1.6 Wm-2 in July
These average hourly irradiance values in the central hours of
the day show a considerable symmetric evolution.
UVB (280-315nm) Wm-2
The UVB solar radiation (280-315nm)
represents less than 1% of the total
radiation reaching the Earth surface, but it
is very important for the Earth-living
systems because it is a radiation of high
energy.
The objective of this work is the study
of UVB data with the purpose of
developing a standard climatology of the
region that is necessary to establish its
seasonal and geographical distribution and
its values and oscillations. In this way, its
evolution is determined with the purpose
of detecting changes that can take place in
short periods of time. And, finally, the
study serves us to evaluate processes that
affect to the amount of radiation of this
kind that reaches the terrestrial surface. It
is determined by the thickness of the
ozone layer, aerosols, etc.
3 Results and Discussion
UVB (280-315nm) (Wm-2)
1 Goals
3
40
30
20
10
0
8:00
12:00
16:00
20:00
Hour (UT)
Figure 4 Hourly evolution of UVB main statistical indices of UVB
(280-315nm), in July.
0
100
200
300
Day
Figure 5 Daily and monthly mean values of UVB (280-315nm)
solar irradiation, (kJ m-2 day-1).
References
Acosta,L.R., W.F.J.Evans, Design of the México City UV monitoring network: UV-B measurements at ground level in the urban environment. Journal of Geophysical Research 105, 5017-5026.
Martinez-Lozano, J.A., F.Tena, M.P. Utrillas, Measurements and analysis of ultraviolet solar irradiation in Valencia, Spain. International Journal of Climatology, 14, 93-102, 1996.
Miguel, A.H., J.Bilbao, P.Salvador, A study of UV total solar irradiation at rural area of Spain. Solaris 2005 2nd Joint Conference, Athens (Greece), 32-3, May 2005. Edit. Hellenic Illumination Committee.
Palancar, G.G., B.M. Toselli, Effects of meteorology and tropospheric aerosols on UV-B radiation: a 4-years study. Atmospheric Environment, 38, 2749-2757, 2004.
Acknowledgments
The authors gratefully acknowledge the financial support extended by the Spanish
Science and Technology Ministry under the Project: REN2003-04522/CLI.
6th Workshop on
ULTRAVIOLET RADIATION MEASUREMENTS
Davos, Switzerland, 20-21 October 2005