Abyssal currents generated by diffusion and geothermal heating over rises
Abstract A continuously stratified (in both salinity and temperature) diffusive time-dependent one-dimensional f -plane model over a sloping bottom is constructed. The model is used to investigate the role of mixing of density near the bottom on large-scale abyssal flow near mid-ocean rises. For realistic abyssal values, both geothermal heating from the bottom and diffusion can be important to the dynamics of flow over mid-ocean rises. When diffusion dominates, buoyancy is transported toward the bottom and the θ - S (potential temperature-salinity) relation remains nearly linear. When geothermal heating dominates, the θ - S relation hooks near the bottom and a convectively driven mixed layer forms. Both effects reduce the density and stratification near the bottom. In contrast, bottom-intensified diffusion has the same effect near the bottom but results in an increase of density and stratification some distance above the bottom. If the bottom slopes, a horizontal density gradient results, setting up a geostrophic, bottom-intensified, along-slope flow that can effect mass transport. Evidence of the importance of these processes is found in the abyssal Pacific. Just over the western flank of the East Pacific Rise, a 700–900 m thick layer of low N 2 (buoyancy frequency) is warmer, saltier, and lighter than interior water at the same depth. This layer is described with CTD data from recent hydrographic sections at nominal latitudes 15°S and 10°N. If the interior is motionless, this low N 2 layer transports 4 and 8 × 10 6 m 3 s −1 equatorward above the western flank of the rise at 15°S and 10°N, respectively. This equatorward current, a direct result of diffusion and heating over a sloping sea-floor, has a volume transport comparable to those of the deep western boundary current at these latitudes.
원문보기 무료다운로드 유료다운로드
- 무료 원문 정보가 존재하지 않습니다.
유료 다운로드의 경우 해당 사이트의 정책에 따라 신규 회원가입, 로그인, 유료 구매 등이 필요할 수 있습니다. 해당 사이트에서 발생하는 귀하의 모든 정보활동은 NDSL의 서비스 정책과 무관합니다.
NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니 담기를 통하여 원문복사서비스 이용이 가능합니다.