Meridional freshwater transport (MFT) in the Atlantic Ocean (Atlantic meridional freshwater transport (AMFT)) plays a vital role in the Atlantic Ocean circulations, but an accurate estimate of AMFT time series remains challenging. This study uses an indirect approach that combines ocean salinity, surface evaporation and precipitation observations to derive AMFT and its uncertainty by solving the ocean freshwater budget equation. Climatologically, AMFT is southward between 18.5°S and 34.5°S, but northward from 18.5°S to 66.5°N. AMFT also shows substantial inter-annual variability with a clear separation at ∼40°N and is more coincident with the Atlantic Meridional Overturning Circulation (AMOC) at 26°N than 47°N across latitudes. The derived time series indicates that throughout the Atlantic Ocean, there is a positive trend in the AMFT from 2004 to 2020, resulting in an AMFT convergence in the tropical Atlantic and an AMFT divergence in the subtropical North Atlantic.

中文翻译：

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基于观测的大西洋经向淡水运输估计


大西洋的经向淡水输送 （MFT） （大西洋经向淡水输送 （AMFT）） 在大西洋环流中起着至关重要的作用，但准确估计 AMFT 时间序列仍然具有挑战性。本研究采用一种间接方法，结合海洋盐度、地表蒸发和降水观测，通过求解海洋淡水收支方程来推导出 AMFT 及其不确定性。从气候学上讲，AMFT 在南纬 18.5°至南纬 34.5°之间向南移动，但从南纬 18.5°至北纬 66.5°向北移动。AMFT 还显示出很大的年际变化，在 ∼40°N 处有明显的分离，并且在纬度上与 26°N 的大西洋经向翻转环流 （AMOC） 比 47°N 更重合。推导的时间序列表明，在整个大西洋，2004 年至 2020 年，AMFT 呈正趋势，导致热带大西洋的 AMFT 收敛和副热带北大西洋的 AMFT 辐散。