North Atlantic Mollusc Isotopes: Readme file  
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                   NOAA Paleoclimatology Program  
                                 and  
               World Data Center A for Paleoclimatology  
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NOTE: PLEASE CITE PRIMARY REFERENCE WHEN USING THIS DATA!!!!!  
  
CONTRIBUTORS: Weidman, C.R, Jones, G.A., Woods Hole Oceanographic Institution
IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER:  95-018.  
NAME OF DATA SET: North Atlantic Mollusc Isotopes
LAST UPDATE: 8/95 (Original receipt date by NOAA Paleo)   
GEOGRAPHIC REGION: northern North Atlantic
PERIOD OF RECORD: 1956-1968
LIST OF FILES: Acal2, sampall, Tmon, readme.  
DESCRIPTION: 
I. "Acal2"  is calibration data for same period as stable isotope records and 
includes (from L to R) : 1) the date (based on 8-month (May-Dec) growth year 
and centered at mid-month); 2) mean monthly T C (based on ~daily BT 
records w/ linear interpolated gaps); 3) mean monthly Salinity (based on 
~weekly BS records w/ linear interpolated gaps); 4) "monthly" shell d18O data 
(based on linear seasonal shell growth assumption); 5) estimated monthly 
d18O-water based on salinity and Fairbanks' [1982] relationship for Gulf of 
Maine; 6)  "monthly" shell d18O minus est. monthly d18O-water.   

II. "Tmon" are all the mean monthly T & S records for 1956-1971 from the 
Nantucket Lightship and includes: 1) date (centered at mid-month); 2) mean 
monthly BT C (based on ~daily BT records w/ linear interpolated gaps except 
where gaps are too large (>1or 2 months); 3) mean monthly BS (based on 
~weekly BS records w/ linear interpolated gaps except where gaps are too 
large (>1or 2 months).

III. "sampall" are raw shell d18O records and includes: 1) shell surface 
position (cm); 2) raw shell d18O; and 3) sequential sample # (214 out of 219 
original samples w 5 samples lost during analysis). 

Location Data:
Nantucket Lightship (1956-1967): 40 33'N, 69 28'W, 55m depth
Nantucket Lightship (1968-1971): 40 30'N, 69 28'W, 58m depth
Shell Capture site (sp.#231-4): 40 40'N, 69 40'W, 54m depth

The calibration is not as straight forward as comparing raw shell d18O data 
with lightship T and S records. This is so for primarily two reasons:
1) lightship bottom records while good are gappy at the daily level, 
and so interpolated records were created to fill the gaps, and then a low pass
filter was applied to the combined set to get monthly averages;
2) an ~8-month shell growth period was determined and a linear growth
assumed over this period to get 8 "monthly" shell d18O values for each growth year.

For these reasons, the authors suggest using the "Acal2" file.
The monthly lightship T & S records and the raw shell data with position are also provided. 

ORIGINAL REFERENCE:
Weidman, C.R., G.A. Jones, Kyger, 1994, The long-lived mollusc Arctica islandica:
A new paleoceanographic tool for the reconstruction of bottom temperatures for
the continental shelves of the northern North Atlantic Ocean, Journal of 
Geophysical Research, v99, No C9, pp18,305-18,314, 1994.

SUGGESTED DATA CITATION:
Weidman, C., 1995, North Atlantic Mollusc Isotope Data.  IGBP PAGES/World Data Center-A for
Paleoclimatology Data Contribution Series # 95-018.  NOAA/NGDC Paleoclimatology Program,
Boulder CO, USA.