Aircraft Observations of Air-mass Modification Over the Sea of Okhotsk during Sea-ice Growth

• Published in: Boundary-layer meteorology 2005-10, Vol.117 (1), p.111-129
• Main Authors: Inoue, Jun, Kawashima, Masayuki, Fujiyoshi, Yasushi, Wakatsuchi, Masaaki
• Format: Article
• Language: English
• Subjects: Atmospheric boundary layer; Marine; Meteorological aircraft; Meteorology; Ocean-atmosphere interaction; Sea ice
• ISSN: 0006-8314; 1573-1472
• DOI: 10.1007/s10546-004-3407-y

In order to quantitatively investigate the role of leads and sea-ice in air-mass modification, aircraft observations were conducted over the partially ice-covered Sea of Okhotsk. We investigated two cold-air outbreak events with different sea-ice concentrations. In both cases, the difference between the temperatures of surface air and the sea surface (DT) dropped rapidly with the accumulated fetch-width of leads up to about 35-40 km, and then decreased very slowly. The surface sensible heat flux originating from open water was about 300 W m-2 within a few kilometres from the coast and decreased with increasing accumulated fetch-width. The sensible heat flux was about 100 W m-2 on average. These results indicate that the downwind air-mass modification depends mainly on the total (accumulated) extent of open water. The total buoyancy flux[Equation] calculated by the joint frequency distribution method correlated very well with ice concentration. Such a relationship was not clear in the case of the moisture flux[Equation]. The ratio between rising thermals[Equation] and cold downdrafts[Equation] differed significantly between upwind and downwind regions; that is, the buoyancy flux was dominated by[Equation] in the developing stage of the boundary layer, while[Equation] also became important after the development of the boundary layer.