High Atlantic Native Winter

Core/Site name:

La Parguera

Country/Region:

Puerto Rico

Elevation:

-7

Archive:

corals

Species:

Montastrea faveolata

Proxy measurement:

O18, C13

Sampling resolution:

monthly

Climate sensitivity:

temperature

Dating resolution:

annual density banding

Dating information:

absolute

Startyear:

1700 AD

Endyear:

1989 AD

All uncertainties:

The O18 standard deviation(2 sigma; 95% confidence) for fifteen duplicate measurements of a powdered carbonate sample was +/-0.04 permil.

Description:

ABSTRACT:We determined the seasonal environmental conditions during the Little Ice Age (LIA) by interpreting isotope proxies in the coral skeleton of Montastrea faveolata from the northeast Caribbean. The oxygen isotope composition was determined for three time intervals during the LIA (1700-1705, 1780-1785, 1810-1815), thought to correspond to the coldest intervals. The period 1984-1989 was used to represent modern calibration conditions. We determined that SSTs from the LIA intervals are nearly 2-3C cooler than present. LIA cooling in the Caribbean may have resulted from regional oceanic and atmospheric circulation differences, especially in winter. We propose that a trough of cold air from the north Atlantic may have extended farther south than present, into the northern Caribbean.Although there are indications from Pacific corals that seasonality was greater during the LIA, this does not seem to be the case for the Caribbean.DESCRIPTION:Puerto Rico Coral Oxygen Isotope Data and LIA SST econstructionCorals and modern SST data collected at the University of Puerto Rico marine station, La Parguera, 17 55'N, 64 00'W, Water Depth 7m.M. faveolata colonies used in this study are situated on the southwestern shore of Puerto Rico. Two coral heads both located at 7m water depth adjacent to each other were used in this study. One was used to obtain modern isotope data (1984-1989) and the other was used to obtain isotope data from the Little Ice Age. The cores were hydraulically drilled on June 2, 1994 and subsequently slabbed and x-rayed to reveal high density (HD) and low density (LD) banding. The distance between HD bands was approximately 10 mm per year. Each LD-HD band couplet represents one year of growth and chronology was determined by counting number of couplets starting with the top layer, which represented the year 1994. Samples for isotopic analysis were extracted from the slabs by the method of Watanabe and Oba, 2000. Isotope values are reported vs PDB, and water temperature values are in degrees C.

Data entered by name:

Bryan, Sean

Data entered by email:

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Main reference(s):

Winter, A., T. Oba, H. Ishioroshi, T. Watanabe, and J. Christy, 2000. Tropical sea surface temperatures: two-to-three degrees cooler than present during the Little Ice Age. Geophys. Research Letters, 27 (20): 3365-3368.

Link to reference 1:

http://www.agu.org/journals/gl/v027/i020/2000GL011426/

Data storage link 1:

ftp://ftp.ncdc.noaa.gov/pub/data/paleo/coral/caribbean/la_parguera.txt

Comments:

4 monthly-resolved time-windows of 5 yrs

Current dating method:

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Annual snow acc rate:

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Category: Ocean2k