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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004 
much greater experience in using RADARSAT- 1 data (Solberg 
et al., 2004). 
The sample size of 61 is not large enough to draw any final 
conclusions but further analysis of results of the planed 
campaign in 2004 and the currently conducted regional 
satellite/aireraft campaign will increase the reliability of the 
statistical analysis. 
5. SPATIAL AND TEMPORAL SATELLITE 
COVERAGE OF THE GERMAN EEZ 
The yearly satellite coverage of the German EEZ in the North 
Sea and the Baltic Sea were calculated based on query results 
from the ESA software DESCW 4.39 (Display Earth Remote 
Sensing Swath Coverage) and the RADARSAT Swath Planner 
Release 3.1 R1. The analysis war conducted for RADARSAT-] 
ScanSAR Narrow and ENVISAT Wide Swath image modes in 
the year 2003. 
The yearly satellite coverage of the German EEZ is depicted in 
Figure 4 and Figure 5. The figures shown the number of 
available satellite images (RADARSAT-1 and ENVISAT) 
versus the percentage of coverage of the German EEZ in the 
North Sea and Baltic Sea. 
Bl Envisat Baltic Sea 
EI Radarsat Baltic Sea 
  
      
  
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600 | 
e | 
500 | 
$ | 
3 | 
© i 
& 400 HE OE 5 BEL — | 
o | 
3 i 
5 : | 
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E : | 
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z | 
200 zEEEETERE dat = = | | 
m | | 
100 | | I | 
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| 
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Coverage in % 
Figure 4. Yearly RADARSAT and ENVISAT coverage of the 
German EEZ in the North Sea 
B Radarsat Noth Sea W Envisat North Sea 
Number of overpasses 
  
  
70 LE 
80 Ezzz 
85 
90 
75 EE { 
l7] : 
[m 
>95 IM | 
65 E 
Qn OC 
= NS D 
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i wn 
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Coverage in % 
Figure 5. Yearly RADARSAT and ENVISAT coverage of the 
German EEZ in the Baltic Sea 
Only 32 RADARSAT-1 and 20 ENVISAT images cover the 
EEZ in the North Sea more than 95%. The EEZ in the Baltic 
Sea is covered more than 95% by 30 RADARSAT-1 and 52 
ENVISAT images. During each aircraft surveillance flight the 
EEZ in the Baltic sea is covered to 93%. The mean aerial 
coverage of the EEZ in the North Sea is 55%. 
A daily coverage of the territorial waters of Germany is not 
possible. The daily coverage of the North Sea (German EEZ) in 
July 2004 using all images without considering the percentage 
of coverage is shown in Figure 6 (RADARSAT-1 ScanSAR 
Narrow and ENVISAT ASAR Wide Swath). 
| | | | | | 
0 | | | ; ; E I ; 
A SUI S «o9 o6 Qo 
N > 
Day of July 2004 
Number of images 
N œ 
— 
Figure 6. Number of RADARSAT-1 (black) and ENVISAT 
(grey) images covering the German EEZ in the North Sea in 
July 2004 
Number of images 
N w 
- 
© 
zz 
Lc] 
| 
| 
| 
Oe que. D o 
à qQ e 
Day of July 2004 ! 
^ % © A NS 
Figure 7. Number of RADARSAT-1 (black) and ENVISAT 
(grey) images covering the German EEZ in the North Sea more 
than 5094 in July 2004 
On certain days (e.g. 1. July, 7. July) no images are available at 
all. The maximum number of images is 6 images per day (2 
RADARSAT-1 and 4 ENVISAT ASAR, e.g. 12. July). If only 
images with a coverage of more than 5094 of the German EEZ 
in the North Sea are considered the number of available images 
is much smaller (Figure 7). 
Satellite overpasses are at relatively fixed times. Early morning 
and late afternoon for RADARSAT-1 and in the morning and 
evening for ENVISAT. Between these times no satellite 
surveillance is possible. 
6. CONCLUSION 
One important aspect for the use of SAR satellite data for 
operational oil slick monitoring is the accuracy of the oil slick 
detection. For oil slicks detected with a high and medium 
confidence in RADARSAT-1 images the results are promising. 
For ENVISAT images the results are not so good but these are 
the preliminary results based on a small sample size. By the end 
of 2004 more results from 2 satellite/aircraft campaign will be 
available and this will increase the reliability of the results. 
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