On the effective aerodynamic and scalar roughness length of Weddell Sea ice

摘要

We study the effective aerodynamic roughness length z0_eff and scalar roughness length for temperature zT_eff over different compact sea ice types in the Antarctic Weddell Sea by aircraft measurements during two austral summer seasons. z0_eff and zT_eff are highly variable in the Weddell Sea ice area. The averaged value of zT_eff in all main sea ice areas was smaller than the averaged value of z0_eff . The ratio between the two roughness lengths was relatively small for new/young sea ice with z0_eff /zT_eff ≈ 2, but the ratio became significantly large for the multiyear pack ice with z0_eff /zT_eff ≈ 227. For the pack ice area, with sea ice concentration ranging between 95% to 100%, we determined a median z0_eff = 4.1 × 10-~(03) m and a median zT_eff = 1.8 × 10-~(05) m. In the new, young sea ice area, with sea ice concentration ranging between 98% and 100%, we observed a median z0_eff = × 10-~(04) m and a median zT_eff = 2.2 × 10-~(04) m. These values of z0_eff and zT_eff differ from published observations conducted in a pack ice and new, young sea ice area in the northern hemisphere, such as the Arctic. Most model parameterizations require the roughness lengths as constant values as boundary input parameters. Our study shows that by using the z0_eff and zT_eff values of this study, instead of commonly used sea ice roughness length values, the accuracy of arameterized heat and momentum fluxes in the Weddell Sea ice area can significantly be improved.