Deep Atlantic Multidecadal Variability
GEOPHYSICAL RESEARCH LETTERS(2024)
摘要
Investigating deep-sea temperature variability is essential for understanding deep-sea variability and its profound impacts on climate. The first mode in the Atlantic is referred to as Deep Atlantic Multidecadal Variability (DAMV), characterized by a north-south dipole pattern in the mid-high latitudes with a quasi-period of 20-50 years. The DAMV and Atlantic Multidecadal Variability, despite a statistical discrepancy, may be different responses to ocean heat transport (OHT) driven by the Atlantic Meridional Overturning Circulation (AMOC) at distinct depths separately. The relationship between the DAMV and the AMOC is established, indicating the AMOC is likely to transport surface heat downwards by deep convection and contribute to such dipole pattern in the deep Atlantic. Furthermore, meridional OHT proves the AMOC can explain the DAMV variation as a dynamic driver. These results reinforce the importance of deep-sea studies concerning the Atlantic climate system. The deep sea is an indispensable component of the Earth's climate system, owing to its substantial heat capacity. Despite challenges posed by the reliability of ocean data sets deeper than 2,000 m, exploration of the deep sea is of immense social and scientific significance. This study identifies the dominant mode of deep Atlantic potential temperature at a depth of approximately 3,000 m, known as Deep Atlantic Multidecadal Variability (DAMV). The DAMV exhibits a dipole pattern in the mid-high latitudes, cooling (warming) in the North Atlantic and warming (cooling) in the South Atlantic during its positive (negative) phase. The DAMV is a multidecadal variability with a meaningful quasi-period of 20-50 years, similar to the Atlantic Multidecadal Variability (AMV). However, statistical methods indicate that the DAMV and the AMV are distinct climate variabilities, closely connected by the AMOC. By lead-lag correlation and ocean heat transport analysis, deep convection of the AMOC might facilitate the surface heat downward transport over approximately a decade. As a result, it is highly likely that the DAMV pattern can be attributed to the AMOC. Deep Atlantic Multidecadal Variability (DAMV) displays a mid-high latitudes north-south dipole pattern with a quasi-period of 20-50 yearsThe meridional ocean heat transport, driven by the Atlantic Meridional Overturning Circulation (AMOC), can explain the DAMV variationThe AMOC transports surface heat downwards over more than a decade and contributes to the DAMV pattern in the deep Atlantic
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关键词
deep Atlantic,dominant mode,climate variability,Atlantic Meridional Overturning Circulation
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