Cold versus warm water routes for the upper limb of the South Atlantic MOC

The surface water in the South Atlantic (σ2 < 35.7) is known to originate largely from the Indian Ocean via the Agulhas leakage (e.g., Beal et al., 2011; Gordon, 1986). It is carried northward below the surface mixed layer and brought to the surface via the equatorial Atlantic upwelling. Antarctic Intermediate Water (AAIW) that forms... Continue Reading →

Recent intensification of Amazonian flooding extremes is linked to the tropical Atlantic warming and tropical Pacific cooling

The Amazonian River basin hosts the one of the major global deep tropical convective systems, and thus drives the global Hadley and Walker circulations and the global hydrological cycle. Changes in the water cycle and deep convection activity in this region are, however, largely affected by remote oceans, especially the tropical Pacific, via the Walker circulation.... Continue Reading →

Deep Indo-Pacific Oceans are still in the Little Ice Age

The Little Ice Age (LIA) is a period of cold global average surface temperatures from around 1600 to 1850, following the Medieval Warm Period (950 ~ 1250). A new study published in Science suggested that since the ocean adjusts to the surface thermal anomalies with the time scales of 100 ~ 1,000 years, some parts of the... Continue Reading →

Glacial weakening of the AMOC and the associated increase in deep ocean carbon deposit

During the mid-Pleistocene between 1,250 and 700 kyr ago (ka), Earth’s climate oscillated between warmer interglacial periods and cooler glacial periods with reduced and expanded polar ice sheets, respectively. Paleo records indicate that the Atlantic meridional overturning circulation (AMOC)  was relatively weaker during glacial periods likely due to reduced evaporation and increased freshwater input from glaciers to the... Continue Reading →

Ocean storage of anthropogenic CO2 from 1994 to 2007

A paper published in Science estimated the oceanic sink of the anthropogenic CO2 (Cant) over the period of 1994 to 2007 by comparing observations collected from global repeated hydrography cruises between 2003 and 2007 to those from the World Ocean Circulation Experiment (WOCE) and Joint Global Ocean Flux Study (JGOFS) program during the 1980s and early 1990s. The... Continue Reading →

Emergence of a shallow aragonite-undersaturated layer in the Southern Ocean

As the ocean absorbs anthropogenic CO2, its pH and carbonate ion concentration  decrease, thereby decreasing the ratio of the concentration of dissolved carbonate ions in the sea water to the concentration of dissolved ions in a saturated solution of aragonite (i.e., aragonite saturation state ΩAr). If ΩAr falls below the threshold ΩAr=1, ocean acidification makes it harder... Continue Reading →

Ocean-ice momentum flux reversal and the associated stabilization of the Beaufort Gyre and freshwater accumulation

Driven by the Beaufort High and associated wind-stress curl, the anticyclonic ocean gyre over the Canada Basin, as known as the Beaufort Gyre, is a dominant feature of the Arctic Ocean circulation. The Beaufort Gyre is the largest freshwater reservoir in the Arctic Ocean  (Proshutinsky et al., 2009) and also is a region of the largest summer sea... Continue Reading →

New ocean observing system reveals a little contribution of the Labrador Sea Water production to the AMOC

A new study published in Science analyzed the first 21-month record of the Overturning in the Subpolar North Atlantic Program (OSNAP) observing system, which was launched in the summer of 2014. The OSNAP observing system comprises an integrated coast-to-coast array of two sections: OSNAP West, extending from the southeastern Labrador shelf to the southwestern tip... Continue Reading →

Ocean precursors to the extreme Atlantic 2017 hurricane season

A recent study published in nature communications investigated three ocean precursors, namely surface latent heat flux and wind stress curl over the main development region (MDR, 10–20°N, 20–80°W) and the Atlantic Meridional Overturning Circulation (AMOC) at 26.5°N, to the active hurricane seasons in 2005, 2010 and 2017. The study showed that in 2005 and 2010, a weakened... Continue Reading →

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