Scientists in the Physical Oceanography Research Division (PORD) investigate the physics of the ocean. Some PORD researchers study the large-scale circulation of the world's oceans or the specifics of smaller environments such as the continental shelf, marginal seas, straits, estuaries, or the surf zone of open shorelines. Others examine the interaction between the ocean and the atmosphere and the role of the ocean in the global climate system. Theoretical studies range from classical fluid dynamics problems to models of large-scale ocean circulation or the atmospheric marine boundary layer. PORD scientists also develop new sensors and measurement technologies for ocean studies--such as autonomous drifters and bottom-pressure and electromagnetic sensors--and new versions of acoustic Doppler current profilers. Many PORD investigators hold joint appointments in other areas at Scripps, which provide for cross-disciplinary research and communication.