Figure 2. Map of Öresund 
plant. Very limited studies. 
D - parts of this shallow bay was planned to be 
filled up. The effect on the circulation in the bay 
was investigated using a physical model. 
- location of second sea outfall for treated se 
wage water was determined on the basis of field simu 
lations of discharges by means of tracers. 
E - planned extension of small island was anticipa 
ted to influence water exchange at nearby beach. 
Field measurements of some representative flow pat 
terns were used as a basis for assessment. 
F - sand suction activities have been going on for 
a long time in Oresund, producing a number of holes 
on the bottom. In areas with weak circulation there 
is a risk for deteriorating water quality of the wa 
ter in the holes. 
Satellite derived data might be used for these 
kinds of problems in different respects 
1) contributing a data base for the flow behaviour 
in Oresund 
2) contributing in the development and use of flow 
models. 
3 SATELLITE DATA 
Digital NOAA data and Landsat TM-data have been stu 
died - mainly contrast-stretched - on an EBBA-II 
image processing system. Water surface temperature 
and suspended mterial (pollen, silt) were used as in 
dicators of water movements and identification of 
different water masses. As for NOAA far-infrared data 
the eight least significant bits were used because of 
the small water temperature differences involved. 
Fig. 3 shows two consecutive passages of NOAA-7: 
CH 4: 1984-08-22 at 14.10 and 1984-08-23 at 13.58 
The darker the water surface the colder is the water. 
In both cases (especially on the 23rd) the surface 
waters of Oresund seem to be colder than the water of 
Kattegatt or the Baltic. One possible explanation for 
these temperature conditions is the behaviour of Öre 
sund as a stratified estuary. A surface flow directed 
northwards is mostly accompanied by a dense, cold 
bottom flow of high salinity to the south and this 
cold water is entrained into the surface water thus 
lowering its temperature. Another indication of this 
explanation is the fact that the cold water region 
seems to start in the Copenhagen-Malmö area where a 
sill is located. 
The discharge of the cold Öresund water into Katte 
gatt takes place as a plume somewhat growing in the 
NW-direction during the 24h. According to field ob 
servations the flow was directed to the north during 
this period. 
Another interesting detail of Fig. 3 is the seeming 
ly developing eddy outside the southern coast - just 
Figure 3. NOAA-7 1984-08-22 and 1984-08-23 CH 4. 
Öresund and the Baltic 
Figure 4. Landsat-2 1975-08-08 CH5. The waters out 
side Falsterbo - SW Sweden. 
Figure 5. Landsat-5 1984-05-13 TM 6 Oresund and 
part of Kattegatt. 
Figure 6. 
Southern S 
Figure 7. 
Figure 8. 
Barsebäck 
a dark debt 
23rd. The 
24h. 
The west’ 
could also 
CH5 1975-0i 
eddy outsi- 
rotating a: 
enters the 
It is, how< 
phenomenon 
Baltic (Joi 
726