NSF UV SPECTRORADIOMETER NETWORK 2007-2008 OPERATIONS REPORT
7.5. San Diego, California
San Diego is the only network site at low latitude. In contrast to most other locations, data is presented over
the whole year. Figure 7.5.1 shows the seasonal variation of total column ozone at San Diego. The
variability in ozone is much smaller when compared to Arctic and Antarctic sites, and there is virtually no
trend in ozone over the period considered (1991-2008). Average ozone levels and variability in the column
are larger in spring than in fall.
Figure 7.5.2 shows spectral irradiance measurements integrated over the wavelength range 298.51 303.03 nm. Of all measurements presented, this integral is the most sensitive to changes in total column
ozone and solar angle. Due to the seasonal cycle in solar angle, summer values are more than a factor of 10
larger than winter values. The maximum daily UV Index is shown in Figure 7.5.3. The maximum UV
Index in summer is about 11. Winter indices are about 3.
The general pattern observed in noon-time measurements can also be seen in daily doses (Figure 7.5.4 –
Figure 7.5.5). The variability in daily dose is higher in spring than in fall. Data from the 400-600 nm band
(Figure 7.5.6) also indicate higher variability in February-July than August-January, which is caused by
seasonal differences in coastal fog and cloudiness.
550
San Diego: Total Column Ozone
Total Column Ozone (DU)
500
1991-2005
Average 1992-2005
2006
2007
2008
450
400
350
300
250
200
1-Jan
20-Feb
10-Apr
30-May
19-Jul
7-Sep
27-Oct
16-Dec
Date
Figure 7.5.1. Total column ozone at San Diego. OMI measurements from 2006-2008 are contrasted with
ozone data from the years 1991-2005 recorded by TOMS /Nimbus-7(1991-1993) and, TOMS/Earth Probe
(1996-2005) satellites. TOMS data is from the Version 8 data set.
PAGE 7-18
BIOSPHERICAL INSTRUMENTS INC.
CHAPTER 7: EXAMPLES OF NETWORK DATA
Integrated Spectral Irradiance (µW/cm²)
12
San Diego: 298.507 - 303.03 nm Integrated Spectral Irradiance
10
8
1992-2005
Average 1992-2005
2006
2007
2008
6
4
2
0
1-Jan
20-Feb
10-Apr
30-May
19-Jul
7-Sep
27-Oct
16-Dec
Date
Figure 7.5.2. Noontime integrated spectral UV irradiance (298.51 - 303.03 nm) at San Diego.
Measurements from 2006-2008 are contrasted with individual data points and the average of
measurements taken between 1992 and 2005.
14
1991-2005
Average 1992-2005
2006
2007
2008
San Diego: Daily Maximum UV Index
Daily Maximum UV Index
12
10
8
6
4
2
0
1-Jan
20-Feb
10-Apr
30-May
19-Jul
7-Sep
27-Oct
16-Dec
Date
Figure 7.5.3. The daily maximum UV Index at San Diego 2006-2008 is contrasted with individual data
points and the average of measurements taken between 1992 and 2005.
BIOSPHERICAL INSTRUMENTS INC.
PAGE 7-19
NSF UV SPECTRORADIOMETER NETWORK 2007-2008 OPERATIONS REPORT
0.14
DNA-Weighted Daily Dose (kJ/m²)
San Diego: DNA Damaging Daily Dose
1992-2005
Average 1992-2005
2006
2007
2008
0.12
0.1
0.08
0.06
0.04
0.02
0
1-Jan
20-Feb
10-Apr
30-May
19-Jul
7-Sep
27-Oct
16-Dec
Date
Figure 7.5.4. Daily DNA-weighted dose for San Diego. Volume 16 and 17 measurements from 2006-2008
are contrasted with individual data points and the average of measurements taken between 1992 and 2005.
7
San Diego: Erythemally (CIE) Weighted Daily Dose
1992-2005
Average 1992-2005
2006
2007
2008
Erythemal Daily Dose (kJ/m²)
6
5
4
3
2
1
0
1-Jan
20-Feb
10-Apr
30-May
19-Jul
7-Sep
27-Oct
16-Dec
Date
Figure 7.5.5. Daily erythemal dose for San Diego. Volume 16 and 17 measurements from 2006-2008 are
contrasted with individual data points and the average of measurements taken between 1992 and 2005.
PAGE 7-20
BIOSPHERICAL INSTRUMENTS INC.
CHAPTER 7: EXAMPLES OF NETWORK DATA
14000
Daily 400-600 nm Integrated Irradiation
(kJ/m²)
San Diego: Daily 400-600 nm Integrated Irradiation
12000
1992-2005
Average 1992-2005
2006
2007
2008
10000
8000
6000
4000
2000
0
1-Jan
20-Feb
10-Apr
30-May
19-Jul
7-Sep
27-Oct
16-Dec
Date
Figure 7.5.6. Daily irradiation of the 400-600 nm band for San Diego. Volume 16 and 17 measurements
from 2006-2008 are contrasted with individual data points and the average of measurements taken between
1992 and 2005.
BIOSPHERICAL INSTRUMENTS INC.
PAGE 7-21