Environmental Forecasting Program 



Long-range and accurate environmental forecasting re- 

 quire knowledge of the processes and mechanisms at work in 

 the oceans and the atmosphere. The Environmental Forecast- 

 ing Program focuses on projects designed to explain the 

 coupling between the ocean and atmosphere, and the influence 

 of the oceans on weather and climate. Experiments and studies 

 include: the Midocean Dynamics Experiment (MODE); the 

 North Pacific Experiment (NORPAX); the International 

 Southern Ocean Study (ISOS); and Climate— Long-Range 

 Investigation, Mapping, and Prediction (CLIMAP) Study. In 

 addition, the waters overlying the continental shelf are being 

 investigated to determine if an IDOE Shelf Dynamics Project 

 should be undertaken. 





MODE 



Midocean Dynamics Experiment (MODE) 



The purpose of MODE is to establish the dynamics and 

 statistics of mesoscale motions in the ocean, their energy source, 

 and their role in the general circulation. The experiment is 

 jointly funded by the National Science Foundation IDOE and 

 U.S. Navy Office of Naval Research (ONR). It consists of 

 independent research projects. These range from field investi- 

 gations through theoretical studies. Activities are coordinated 

 through a scientific council and its various panels. Committee 

 meetings and special workshops are convened periodically to 

 access the status and give direction to MODE. 



MODE began in July 1971. MODE-O included prelim- 

 inary studies for planning purposes, formulation of theoretical 

 models and schemes for objective analyses, and field trials and 

 preliminary field experiments at the MODE site south of Ber- 

 muda (28°N, 69°40'W) near the Tropic of Cancer. MODE-1, 

 the main field experiment, was conducted during the spring 

 and summer of 1973 in the MODE-1 area south of Bermuda. 

 This area was 300 km in diameter, had an average depth of 

 5 km, and was divided into three concentric zones extending 

 outward from the site to limits of 100, 200, and 300 km. The 

 accurate mapping area extends to 100 km, the pattern recog- 

 nition area to 200 km, and the extended area of pattern rec- 

 ognition to 300 km (fig. 11). 



The number of instruments and sampling rates were great- 

 est in the accurate mapping area within the inner circle of 

 100 km radius. Velocity and density fields were subjected to 

 the greatest intensity of sampling. Instruments were spaced 

 about 50 km apart. Within the second zone, the spacing of 

 instruments was roughly 100 km and observations of density 



BLAKE 



BAHAMA 



SLOPE 



I ACCURATE MAPPING AREA 

 PATTERN RECOGNITION AREA 

 I I EXTENDED AREA OF PATTERN RECOGNITION 



Figure 11.— MODE-1 field area. 



were farther apart. In the third zone, between 200 and 300 km, 

 there were few permanent instrument moorings. Expendable 

 air-dropped probes were used to help delineate patterns of flow, 

 and the large SOFAR floats (fig. 12), released in the inner 

 circles, were permitted to drift outward through this zone 

 before retrieval. Density observations were not planned for this 

 outer zone. 



The year following the MODE-1 field experiment has 

 been spent in data analysis and comparison of field results 

 with theoretical models. Work groups are to be convened 

 during the summer of 1974 to bring together the results of 

 the various projects and subprojects. These results will be 

 published in scientific journals by the individual investigators. 

 In addition, it is planned to publish summary volumes as fol- 

 lows: maps and sections of observed field results and some 

 derived quantities, an analysis of the intercomparison of dif- 

 ferent types of measurements, and a definitive statement on the 

 nature of the dynamics of eddies (medium-scale motions) as 

 revealed by the experiment. A joint US-USSR experiment, 

 POLY-MODE, is being planned for an area somewhat east of 

 the MODE-1 area. 



11 



