Investigating Characteristics of Air-Sea Interactions in the Wave and Surface Layers
Abstract
We were funded to participate in the Coupled Boundary Layers/Air-Sea Transfer under low wind (CBLAST-Low) pilot experiment in 2001 and main experiment in 2003 and analyze the data collected from both field campaigns. Our focuses are air-sea interactions under weak winds by analyzing simultaneous measurements of directional waves and atmospheric turbulence. We found that air-sea interactions strongly depend on whether the oceanic wave energy peak is dominated by swell or windsea especially under weak winds. Under weak winds and swell sea, the vertical variation of the momentum transfer is small. As swell dominates oceanic waves and travels in the same direction as wind, low-level jets are commonly observed. As swell dominates oceanic waves and travels in the opposite direction as wind, wind speed tends to increase slightly towards the sea surface and upward momentum flux transfer was observed over the region. As a result, the drag coefficient under weak winds is larger over swell than over wind sea, which explains the previously observed puzzle that the drag coefficient increases with decreasing wind speed under weak winds.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 02, 2008
- Accession Number
- ADA483185
Entities
People
- Jielun Sun
Organizations
- National Center for Atmospheric Research