which take the complementary data, the orbit could be lowered a bit. Should a 

 more polar orbit be chosen to accommodate other measurements, the 200-km swath 

 would become a minimum. 



The data-processing requirement for operational research problems calls 

 for daily processing of 30 minutes of data within 2 hours of acquisition. The 

 scientific program would require processed data at that speed only rarely — 1 

 or 2 minutes on 10 to 20 days per year — to support field efforts in areas 

 where rapid changes in ice conditions are common (for example, the open ocean 

 margin and the shear zone). For the remainder of the science program, data 

 turnaround time is not appreciably a problem. Geographically, science data 

 demand over a year will call for an uneven mix of zones of long-term 

 surveillance and zones of brief, intense observation to document specific 

 seasonal changes or to support field programs. Under most circumstances, data 

 products would not be in demand sooner than a month after acquisition. 

 However, the data required would need to be of optimum dynamic range and 

 calibration. Thus, the operational research need would call for some 3 x 10 

 km images per day with a 4-bit range and +.2-dB absolute calibration, while 

 the science program would require about half as much data processed on a 

 relaxed schedule, possibly involving use of processor time in the summer, but 

 calling for a 5-bit range and +.l-dB absolute calibration. 



As mentioned, the sea-ice science problems which would materially benefit 

 from an augmented SAR deployment are divided into three categories: oceanic 

 and atmospheric circulation, climatology, and materials response. The 

 circulation of the ocean and atmosphere are affected by sea ice because ice 

 changes the surface albedo, alters the fluxes of heat, mass, and momentum 

 between the water and the air, advects latent heat equatorward, changes the 

 stability of the upper ocean, and influences the surface stress on the water 

 column. Specific science questions on which significant progress could be 

 made using data from this program include: How do surface fluxes modify the 

 oceanic circulation of ice-covered seas? How do horizontal and vertical 

 fluxes near the ice edge affect the edge location? What is the net heat loss 

 of the Southern Ocean? What processes control the response of the ice pack to 

 forcing at the coastal boundary? The key measurements of sea ice required for 

 answering these questions are concentration, thickness, velocity, and pressure 

 ridge density. Of these, SAR does an excellent job with velocity, a good job 

 with concentration and ridge density, and provides some information on ice 

 thickness via the determination of ice type. Summary information requirements 

 for science are presented in Table 1. 



The research problems associated with future operations in sea-ice-laden 

 waters are divided into three categories: design of fixed installation, 

 navigation, and offshore activities. Ice is of operational interest because 

 it can damage both fixed or floating structures, it strongly influences 

 surface transport even by icebreaker, and it can impede or occasionally 

 enhance a wide variety of offshore support activities. Ice velocity, type, 

 concentration, and ridge density are key measurements for operational problems 

 just as they are for science problems. Specific research questions from 

 anticipated polar operations include: What is required to forecast the 

 location of navigational hazards and of areas of ice not under compression? 

 How can ridge parameters such as height be accurately determined? What kinds 



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