65 
Satellite altimetry measurements of the ocean surface provide a potentially powerful tech- 
nique for investigating ocean dynamics, and such altimetry will be central to the planned TOPEX 
mission and World Ocean Circulation Experiment (WOCE). Its principal application to deep water 
formation will probably be to provide information on the large-scale circulation from a com- 
bination of altimetry, scatterometry and known and measured hydrography. The objective would 
be to compute the net flows of surface water in and deeper water out, thus providing estimates 
of the rates, and changes in the rates, of water mass conversion. Also, it is possible that 
altimetry could be used to detect and monitor deep water formation events, based on measure- 
ment of the surface water depression which should accompany such events. Because of the epi- 
sodic nature of deep water formation, it is desirable to have the greater spatial coverage 
obtainable from radar with side-scan capability, for example, synthetic aperture or multiple beam 
radar. However, it seems appropriate to first look for deep water formation events with 
existing real aperture nadir pointing radar. If satellite altimetry is carried out at high latitudes 
it will also allow the possibility of monitoring the Greenland ice sheet mass balance and thus 
deduction of corresponding freshwater inputs to the ocean. 
Satellite microwave monitoring at high latitudes is needed to reveal the coverage and pro- 
perties of sea ice. This includes accurate determination of the open water fractions within ice 
covered areas of thin ice which contribute the most to air-sea exchanges. The sea ice moni- 
toring needs to continue on a long-term basis in order to reveal any trends in the nature and 
coverage of sea ice which presage or accompany changes in deep water formation. 
Finally, the capability of satellites to relay data from automatic oceanographic stations 
needs to be fully exploited. A strong high-technology effort should be made to develop the 
capability to make a broader range of high-precision measurements from buoys. Such capability 
is probably the best hope for obtaining adequate oceanographic monitoring on an oceanwide or 
global basis. 
In summary, the principal needs related to satellites are: 
1) Monitoring of quantities required to infer air-sea fluxes, specifically radiation budget, sea 
state (for surface winds) and sea ice. 
2) Repeated altimetry of the North Atlantic to help monitor the large scale circulation and to 
detect and monitor surface water depression associated with deep water formation events. 
3) Development and use of greater capabilities for high precision measurements from moored and 
free-floating buoys with satellite data relay. 
Modeling 
We believe there is a strong rationale for a focused effort at modeling the North Atlantic 
ocean/climate system. In order to include the various processes of importance to deep water 
formation, the ocean, ice and atmosphere must all be modeled at a sufficiently fine resolution. 
This makes a global model unrealistic at the present time. However, the North Atlantic ocean 
volume is only about one tenth that of the world ocean, so it should be practical to use high 
Spatial resolution for the North Atlantic with the most powerful existing computers. The North 
Atlantic is also relatively well observed, as is the climate of neighboring continental regions. 
Furthermore, the North Atlantic contains the physical processes of interest, including inter- 
mediate and deep water formation, sea ice and other high latitude processes, and large fresh 
water and Mediterranean saltwater inputs. Because of the diverse ocean processes represented 
in the North Atlantic, it should be possible to generalize successful modeling approaches to the 
global ocean. 
Modeling of the North Atlantic ocean per se can proceed along a number of different 
approaches, as discussed in the presentation by Semtner. Ideally, successful modeling will 
include as outputs the rate and locations of deepwater formation and its primary characteristics 
(such as temperature, salinity, and chemical constituents) plus the modifications of these charac- 
teristics as the water descends. 
High latitude processes, including sea ice formation, need to be modeled with increasing 
realism and incorporated into the ocean models. There are indications that sea ice is involved 
in significant ways in deep water formation, and these processes must be realistically portrayed 
if we are to be able to correctly project any changes in deepwater formation which may accom- 
pany global warming due to carbon dioxide and trace gases. 
