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Abstract
The National Center for Atmospheric Research (NCAR) operated a radiosonde sounding system and a UHF wind profiler radar on the R/V Knorr in the North Atlantic in early 2007 in support of the CLIMODE project. The CLIMODE (CLIvar Mode Water Dynamic Experiment) project, lead by PIs from the Woods Hole Oceanographic Institute (WHOI), MIT, the University of Connecticut, and other groups, is a large oceanographic study of warm waters in the North Atlantic Gulf Stream. WHOI's R/V Knorr made multiple traverses of the northwestern boundary of the Gulf Stream off the north-east coast of the U.S. The radisondes and wind profiler were deployed to examine the response of the atmospheric boundary layer in this region of very strong air-sea exchange. The radiosondes were typically launched at three to six hourly intervals, whereas the wind profiler operated continuously. In addition to measuring the wind and atmospheric reflectivity, the profiler included a Radio Acoustic Sounding System (RASS) to measure virtual temperature aloft. Strong signals were seen in all systems. For example, crossing into the warmer waters of the Gulf Stream produced a strong response in the atmosphere, with both a warming and deepening of the atmospheric boundary layer. Soundings and atmospheric reflectivity sometimes showed complex structure with multiple inversions and reflectivity gradients, representing the history of the atmosphere as it passed over waters of varying temperature and air-sea exchange.