This file (ndp057.txt) describes the content and format of each of the 21 files that compose the Nydal and Lövseth atmospheric carbon isotope database. DATABASE NAME: Carbon-14 Measurements in Atmospheric CO2 from Northern and Southern Hemisphere Sites, 1962-1993 AUTHORS: Reidar Nydal and Knut Lövseth Radiological Dating Laboratory The Norwegian Institute of Technology Trondheim, Norway DATE OF COMPLETION: November 1996 SUGGESTED CITATION: Nydal, R., and K. Lövseth. 1996. Carbon-14 Measurements in Atmospheric CO2 from Northern and Southern Hemisphere Sites, 1962-1993. ORNL/CDIAC-93, NDP-057. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee. 67 pp. DATA FILES This NDP consists of the following 21 files: - a descriptive file that contains an overview of the Nydal and Lövseth atmospheric carbon isotope database and detailed descriptions of the data files (ndp057.txt); - one FORTRAN 77 data retrieval routine to read and print any of the 15 data files containing estimates of del (Greek small delta symbol) 14C, del 13C, and DELTA (Greek capital delta symbol, i.e., triangle) 14C in atmospheric CO2 from air samples collected at 14 sites (ndp057.for); - one SAS® data retrieval routine to read and print any of the 15 data files (ndp057.sas); - one ASCII data file containing estimates of del 14C, del 13C, and DELTA 14C in atmospheric CO2 from all 14 sites (nydal.asc); - 14 ASCII data files (one for each sampling location) containing estimates of del 14C, del 13C, and DELTA 14C in atmospheric CO2 (**.asc - see description of "LABREF" below), - one FORTRAN 77 data retrieval routine to read and print the file containing estimates of del 14C, del 13C, and DELTA 14C in atmospheric CO2 collected in the lower stratosphere from aircraft during 1965 (strat.for); - one SAS® data retrieval routine (strat.sas) to read and print the file "strat.dat"; and - one ASCII data file containing estimates of del 14C, del 13C, and DELTA 14C in atmospheric CO2 collected in the lower stratosphere from aircraft during 1965 (strat.dat) DATA FILE FORMATS (*.ASC) This database contains 15 data files that provide 1619 estimates of del 14C, del 13C, and DELTA 14C in atmospheric CO2 from 14 locations. The period of record differs by station. The earliest measurements were made in 1962, and the latest estimates are from 1993. Most stations have records only for the 1960s. All of the data files have the same format and none contain missing values. Some del 13C values are flagged as mean values; users are urged to pay attention to these flags before analyzing or interpreting the corresponding values. Each file is sorted by sample collection date and may be read with the following FORTRAN 77 code: character labref*9, samdat*13, flag13*1 real delC14, delC13, corC14 open(unit=5,file='F.asc') open(unit=6) read(5,10) 10 format(///////////////) 13 continue read (5,15, end=99) labref,week,samdat,delC14,delC13,flag13, 1 corC14,sigma 15 format(A9,1X,I4,2X,A13,4X,F6.1,2X,F5.1,A1,2X,F6.1,4X,I2) The following SAS® input statement may also be used to read these files: input labref $ 1-9 week 11-15 samdat $ 17-30 @34 delC14 7.1 @42 delC13 5.1 flag13 $ 47 corC14 50-55 sigma 60-61; Stated in tabular form, the contents include the following: ________________________________________________________________________________ Variable Variable Starting Ending Variable type format column column ________________________________________________________________________________ LABREF Alphanumeric 9 1 9 WEEK Numeric 5 11 15 SAMDAT Alphanumeric 14 17 30 DELC14 Numeric 7.1 34 40 DELC13 Numeric 5.1 42 46 FLAG13 Character 1 47 47 CORC14 Numeric 6.1 50 55 SIGMA Numeric 2 60 61 ________________________________________________________________________________ where LABREF is a seven-to-eight character site code and sample reference number (e.g., D_00034). The 5-digit sample reference number follows the site code and is separated from the site code by an underscore (i.e., "_") character. All laboratory reference numbers are unique. The site codes and the sampling stations they represent are as follows: V Kapp Linné, Spitsbergen, Norway F Fruholmen, Nordkapp, Norway K Gråkallen, Trondheim, Norway KV Vassfjellet, Trondheim, Norway L Lindesnes, Norway S Santiago de Compostela, Spain IZ Izaña, Tenerife, Canary Islands M Mas Palomas, Grand Canary Island R Rehovot, Israel D Popenguine, Dakar, Senegal DF Université Dakar-Fann, Dakar, Senegal TC N'Djamena, Chad E Debre Zeit, Addis Ababa, Ethiopia G Fianarantsoa, Madagascar WEEK is the week the NaOH tray was exposed relative to the first week of 1963. Values range from -34 to 1591. Zero refers to the week of December 29, 1962 to January 7, 1963. Negative values denote the number of weeks before 1963 (e.g., -34 refers to the week from April 30, 1962, to May 3, 1962). SAMDAT is a thirteen-character field that represents the days, months, and years of the sampling period, typically 4 to 7 day periods. The beginning date (yy/mm/dd) and ending date (yy/mm/dd) are separated by a hyphen. The earliest sampling date is 620430-620503 (from Gråkallen) and the latest sampling period is 930621-930624 (from Fruholmen). DELC14 is the uncorrected (for decay) measurement of excess 14C in atmospheric CO2 expressed as del 14C in per mil relative to the US National Institute of Standards and Technology (NIST, formerly the National Bureau of Standards) oxalic acid standard; 95% of the 14C concentration in this standard represents the normal activity in recent wood for the year 1950 A.D. Values for DELC14 range from 108.5 to 1036.0. DELC13 represents the deviation in the 13C/12C ratio expressed in per mil relative to the Pee Dee Belemnite or (Pee Dee River, South Carolina) or PDB standard (Craig 1961). The 13C/12C ratio was measured by mass spectrometry. The del 13C values provided are given as a guide for the calculation of the DELTA 14C values. When fractionation was not measured, a mean value, normally based on 20-40 samples was used and is denoted by an asterisk (see description of "FLAG13"). Values for DELC13 range from -31.7 to -11.3. FLAG13 is a one-character flag code used to denote whether the DEL13C estimate was measured (blank) or represents a mean value (asterisk). CORC14 is the atmospheric 14C content expressed as DELTA 14C in per mil (not as a percentage). Delta 14C is corrected for isotopic fractionation through del 13C (DELC13), and for radioactive decay of the 14C reference standard (NIST). Values range from 110.4 to 1040.4. SIGMA is the standard deviation for CORC14 expressed as an integer. Values range from 3 to 42. DATA FILE FORMAT (STRAT.DAT) This database contains one data file that provides eleven estimates of del 14C, del 13C, and DELTA 14C in atmospheric CO2 from the low stratosphere during 1965. High-altitude samples were collected in the Trondheim area using aircraft from the Norwegian Air Force. Flights originated from Örlandet Airport and covered the region bounded by 62-65° N and 6-10° E, at altitudes of 9000-12600 m. Samples were collected using a filter with a 1.4 kg molecular sieve that absorbs CO2 from the penetrating air. The filter container was placed under the wing of the plane and opened and closed with electrically-operated shutters at both ends. With the plane traveling at a speed of approximately 900 km/hr the filter shutters were opened 10-15 minutes to allow sufficient amounts of CO2 to be absorbed. The file may be read with the following FORTRAN 77 code: character sample*6, flag13*1 real delC13, corC14 open(unit=5,file='strat.dat') open(unit=6) read(5,10) 10 format(///////////////) write(6,15) 15 format('Sample',3X,'Altitude',3X,'Date of Collection',6X, 1 'delta',6X,'delta',2X,'Corrected',4X,'Sigma',/,11X,'(m)', 2 6X,'(Year, Month, Day)',7X,'C14',8X,'C13',3X,'delta C14', 3 /) 20 continue read (5,25, end=99) sample,alt,samdat,delC14,delC13,flag13, 1 corC14,sigma 25 format(A6,4X,I5,11X,I6,12X,I4,4X,F5.1,A1,4X,I4,8X,I2) The following SAS® input statement may also be used to read this file: input sample $ 1-6 alt 11-15 samdat 27-32 delC14 45-48 @53 delC13 5.1 flag13 $ 58 corC14 63-66 sigma 75-76; Stated in tabular form, the contents include the following: ________________________________________________________________________________ Variable Variable Starting Ending Variable type format column column ________________________________________________________________________________ SAMPLE Alphanumeric 6 1 6 ALT Numeric 5 11 15 SAMDAT Numeric 6 27 32 DELC14 Numeric 4 45 48 DELC13 Numeric 5.1 53 57 FLAG13 Character 1 58 58 CORC14 Numeric 4 63 66 SIGMA Numeric 2 75 76 ________________________________________________________________________________ where SAMPLE is a six character site code and sample reference number (e.g., AS-001). The 3-digit sample reference number follows the site code and is separated from the site code by a hyphen. All laboratory reference numbers are unique. Laboratory reference numbers range from 001 to 013. The site code is always "AS" denoting aircraft sampling. ALT is the altitude where the air sample was collected expressed in meters. Values range from 9000 to 12600. SAMDAT is a six-digit field that represents the day, month, and year of the sampling date expressed in a yymmdd format. Values range from 650407 to 651014. DELC14 is the uncorrected (for decay) measurement of excess 14C in atmospheric CO2 expressed as del 14C in per mil relative to the US National Institute of Standards and Technology (NIST, formerly the National Bureau of Standards) oxalic acid standard; 95% of the 14C concentration in this standard represents the normal activity in recent wood for the year 1950 A.D. Values for DELC14 range from 599 to 1718. DELC13 represents the deviation in the 13C/12C ratio expressed in per mil relative to the Pee Dee Belemnite (Pee Dee River, South Carolina) or PDB standard (Craig 1961). The 13C/12C ratio was measured by mass spectrometry. The del 13C values provided are given as a guide for the calculation of the DELTA 14C values. When fractionation was not measured, a mean value, based on 4 samples was used and is denoted by an asterisk (see description of "FLAG13"). Values for DELC13 range from -11.4 to -3.3. FLAG13 is a one-character flag code used to denote whether the DEL13C estimate was measured (blank) or represents a mean value (asterisk). Seven of the eleven DELC13 values are flagged with an asterisk. CORC14 is the atmospheric 14C content expressed as DELTA 14C in per mil (not as a percentage). Delta 14C is corrected for isotopic fractionation through del 13C (DELC13), and for radioactive decay of the 14C reference standard (NIST). Values range from 554 to 1626. SIGMA is the standard deviation for CORC14 expressed as an integer. Values range from 17 to 47. REFERENCES Craig, H. 1961. Mass-spectrometer analysis of radiocarbon standards. American Journal of Science Radiocarbon Supplement 3:1-3. Nydal, R., and K. Lövseth. 1983. Tracing bomb 14C in the atmosphere 1962 1980. Journal of Geophysical Research 88:3621-42.