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SUMMARY:Deeper and Stronger North Atlantic Gyre During the Last Glacial Ma
 ximum - Dr. Jack Wharton (University College London)
DTSTART:20241120T173000Z
DTEND:20241120T190000Z
UID:TALK223225@talks.cam.ac.uk
CONTACT:91369
DESCRIPTION:Subtropical gyre (STG) depth and strength are controlled by wi
 nd stress curl and surface buoyancy forcing. Modern hydrographic data reve
 al that the STG extends to a depth of ~1 km in the Northwest Atlantic\, wi
 th its maximum depth defined by the base of the subtropical thermocline. D
 espite the likelihood of greater wind stress curl and surface buoyancy los
 s during the Last Glacial Maximum (LGM)\, previous work suggests minimal c
 hange in the depth of the glacial STG. Here we show a sharp glacial water 
 mass boundary between 33 and 36°N extending down to ~2-2.5 km—approxima
 tely 1 km deeper than today. Our findings arise from benthic foraminiferal
  δ18O profiles from sediment cores in two depth transects at Cape Hattera
 s (~36-39°N) and Blake Outer Ridge (~30-33°N) in the Northwest Atlantic.
  This result suggests that the STG was deeper and stronger during the LGM 
 than at present\, which we attribute to increased glacial wind stress curl
 \, as supported by climate model simulations\, as well as greater glacial 
 production of denser Subtropical Mode Waters. Our data suggest: (1) that s
 ubtropical waters likely contributed to the geochemical signature of what 
 is conventionally identified as Glacial North Atlantic Intermediate Water\
 , and (2) the STG helped sustain continued buoyancy loss\, water mass conv
 ersion\, and northward meridional heat transport in the glacial North Atla
 ntic. 
LOCATION:Latimer Room\, Clare College
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