highlow Atlantic native Lund

Core/Site name:

W167-79GGC, C166A-8GGC, and KNR166-2-62MC-A

Country/Region:

Gulf of Mexico

Elevation:

-530

Archive:

marine sediments (downcore)

Species:

Globigerinoides ruber (white)

Proxy measurement:

O18

Sampling resolution:

decadal

Climate sensitivity:

current density

Dating resolution:

radiometric, 1 x 14C per 250 years

Dating information:

radiometric; 8 14C dates

Startyear:

1 14C yr BP

Endyear:

4879 14C yr BP

All uncertainties:

(1) 0.08 per mil;

Description:

Planktonic foraminiferal d18O time series from three well-dated, high sedimentation rate cores near the Florida Keys (24.4N, 83.3W) exhibit repeated centennial to millennial-scale oscillations during the late Holocene. Isotopic shifts of 0.2-0.3% over the past 5200 years represent changes in sea-surface temperature (SST) of 1.0-1.5C or salinity variability of 1-2 psu. The largest significant isotopic events are centered at approximately 200, 2000, 3200, and prior to 4000 calendar years BP. High Florida Current d18O during the LittleIce Age (LIA) correlates with published records of high d18O in the Sargasso Sea and low SST off the coast of west Africa. An interval of generally low d18O in the Florida Straits from 1800 to 500 years BP is synchronous with the Medieval Warm Period off west Africa but leads low d18O in the Sargasso Sea by several hundred years. Synchronous cooling across the subtropical gyre during the LIA is difficult to explain using interannual North Atlantic Oscillation patterns but may be consistent with the simulated effects of reduced solar irradiance.At frequencies between 1/1000 and 1/300 years during the Late Holocene, Florida Current d18O is coherent with a published estimate of 14C production rate. Radiocarbon production seems to lead d18O at these frequencies, but uncertainty in the phase calculation precludes a clear lead-lag relationship. At frequencies lower than 1/300 years, Florida Current d18O is coherent and in phase with atmospheric D14C. The coherence of D14C and d18O at periods >1000 years implies oceanic circulation may play a role in modulating atmospheric radiocarbon on millennial timescales.

Data entered by name:

McGregor, Helen

Data entered by email:

This email address is being protected from spambots. You need JavaScript enabled to view it.

Main reference(s):

Lund, D.C. and W.B. Curry. 2004. Late Holocene variability in Florida Current surface density: Patterns and possible causes. Paleoceanography 19, PA4001.

Link to reference 1:

http://www.agu.org/pubs/crossref/2004/2004PA001008.shtml

Link to reference 2:

http://darchive.mblwhoilibrary.org:8080/bitstream/handle/1912/3431/2004PA001008.pdf?sequence=1

Data storage link 1:

http://hurricane.ncdc.noaa.gov/pls/paleox/f?p=519:1:4003672593528856::::P1_STUDY_ID:2645

Current dating method:

-- select --

Annual snow acc rate:

-- select --

Category: Ocean2k