ABSTRACT Murphy P. P., K. C. Kelly, R. A. Feely, and R. H. Gammon. 1995. Carbon Dioxide Concentrations in Surface Water and the Atmosphere During 1986-1989 PMEL Cruises in the Pacific and Indian Oceans. ORNL/CDIAC-75, NDP-047. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee. This document presents the carbon dioxide concentration data in surface water and the atmosphere collected during the Pacific Marine Environmental Laboratory (PMEL) expeditions during 1986-1989. Carbon dioxide was measured quasi-continuously on 5 PMEL expeditions (12 legs) in the Pacific and Indian Oceans. These cruises were conducted under support from the National Oceanic and Atmospheric Administration (NOAA). Carbon dioxide measurements in the atmosphere and in surface water were made by analyzing of mixing ratios of CO2 with an automated, temperature-controlled gas chromatographic system described by Murphy et al. (1991) and Bates et al. (1993). Instrument precision was determined by the average percent standard deviation of the standard response over a 6-hour period. The precision varied between cruises but was always less than 1.2% and was more typically around 0.4%. Air was pumped through 3/8-inch diameter, plastic-coated, aluminum tubing from the jackstaff on the bow of the ship (10 meters above the sea surface) to the oceanographic laboratory for analysis. Surface seawater entered the ship via a forward intake line located approximately 5 meters below the water level. Fifteen files are described in this report and distributed along with it including one documentation file (ndp047.txt) that provides an overview of the cruise network and describes details on the content and format of the thirteen data files; one FORTRAN 77 retrieval code (pmeldat.for) that may be used to read and print any of the data files; and thirteen data files, one (pmel8689.dat) that contains the data from all twelve legs, and separate files (12 total) for each leg. Each of the data files contains the same variables: cruise name; date (day, month, year); day of the year [Greenwich Mean Time (GMT)]; latitude and longitude (in decimal degrees); cumulative distance since the first sampling location on the leg; sea surface temperature (degrees C); warming temperature [indicates the degrees of warming (degrees C) for seawater as it transited from the intake line to the analysis site]; sea surface salinity; atmospheric pressure; reported atmospheric CO2 concentration,[X(CO2)]air which is the mole fraction of the dried air pumped from the bow line; reported surfase seawater CO2, concentration [X(CO2)]sw which is the mole fraction of the dried vapor drown from the equilibrator headspace; the calculated fugacity values for the air [f(CO2)air] and seawater [f(CO2)sw] given in the data tables are in situ fugacities which have been corrected for the warming of the seawater; and quality flags. The data set is available, free of charge, as a Numeric Data Package (NDP) from CDIAC. The NDP consists of printed documentation and machine-readable files. The data files also available on 9-track magnetic tape; IBM-formatted floppy diskettes; 8-mm tapes; 150-mB, quarter-inch tape cartridge; and from CDIAC's anonymous File Transfer Protocol (FTP) area via Internet. Printed document also contains an Appendix, which is a full reprint of NOAA Technical Memorandum ERL PMEL-101 authored by Murphy et al. 1994, which fully describes cruise information, sampling methods and instrumentation, and defines limitations and restrictions of the data. Keywords: Carbon dioxide; Pacific Ocean; Indian Ocean; Carbon cycle; fugacity; data file. 1. BACKGROUND INFORMATION A dramatic increase in the atmospheric concentration of carbon dioxide (CO2) has been directly observed over the past 30 years (Keeling et al, 1989). Although the present growth rate of CO2 in the atmosphere is about 3.4 gigatons of carbon per year (GtC/yr), the present estimate of anthropogenic CO2 sources to the atmosphere is much larger (approximately 6 GtC/yr; IPCC, 1990). Most of the CO2 (77%) released to the atmosphere originates from the combustion of fossil fuels (Marland and Rotty, 1989). The remainder is estimated to originate from deforestation and changing land use patterns (IPCC, 1990). Since the growth rate of CO2 in the atmosphere is less than the rate of carbon release, some of the anthropogenic carbon released to the atmosphere must be absorbed by either the terrestrial biosphere or the oceans. The oceans have been suggested as a repository for carbon dioxide from the atmosphere through a chemical and biological pathway. Carbon dioxide dissolves readily in the surface oceans. The dissolved gas reacts with water to form carbonic acid which rapidly dissociates to bicarbonate and carbonate ions. Ocean plants can also draw down CO2, some of which is converted to particulate matter which sinks out of surface waters. The uncertain role of the ocean in absorbing anthropogenic carbon from the atmosphere has stimulated interest in the cycling and fate of carbon in the sea. PMEL has made measurements on 12 cruise legs (5 expeditions) between 1986 and 1989 to determine the concentrations of trace gases in the atmosphere and in surface seawater. The purpose of this report is to present the CO2 results and to show the calculations which have been used to convert the raw values to fugacities in units of microatmospheres (uatm). 1.1 General Discussion of CO2 Measurements and Fugacity Field measurements of carbon dioxide gas concentrations are often observed as the mole fraction of CO2 in an aliquot of dried vapor. The concentration of CO2 expressed as the mole fraction in dry air is an absolute and observable quantity, but is not necessarily the quantity which geochemists need to evaluate air-sea fluxes or to examine the relationship of dissolved CO2 with other carbonate parameters. Geochemical assessments generally require the correction of CO2 concentrations from the measurement units and conditions to units of microatmospheres at the in situ sea surface conditions. Partial pressures of CO2 in units of uatm have been historically reported, but in recent years, fugacities have also been reported. We here offer a brief discussion of the distinction between fugacity and partial pressure, and the motivation for using fugacity in this report. Fugacity is an expression for the concentration of a real gas in a mixture of real gases, whereas partial pressure is an expression for the concentration of an ideal gas in a mixture of ideal gases. Ideal gases are conceptualized as comprising molecules which occupy no volume and between which no forces exist. The concept of fugacity is introduced in order to use for real gases the thermodynamic relationships established for ideal gases. Fugacity cannot be measured directly, as pressure is, yet the basis for discussion of equilibrium, solubility, etc. is based on the thermodynamic quantity of fugacity, not on the observable quantity of pressure. The thermodynamic equation of state for ideal gases is PV=nRT, where P is pressure, V is volume, n is number of moles of gas, R is the gas constant, and T is absolute temperature. This equation can be used to convert the number of moles of pure, ideal gas to the pressure of the gas. If we make a plot of pressure vs. PV/nRT for pure nitrogen (N2), pure carbon dioxide (CO2), and a pure ideal gas, we can see that an ideal gas is a line with zero slope and y-intercept=1. Nitrogen approximates an ideal gas at low pressures, but becomes less ideal at higher pressures as the volume of the molecules becomes significant relative to the total volume. CO2 is a highly non-ideal gas, even at low pressures. The negative deviation from ideality at low pressures suggests attractive forces between CO2 molecules. The significance of this factor becomes less important at higher pressures. The approximation of ideality for CO2 may be acceptable at ambient pressures when high accuracy is not required. The difference between pressure and fugacity for a typical ambient CO2 concentration is 1 to 1.5 uatm (~0.3%) over the temperature range 0 to 30 C. These calculations assume a binary gas mixture of CO2 and air, where air is treated as a homogeneous gas. For this report, fugacities rather than partial pressures are reported. 1.2 Summary of Data Presented The data presented in this report are from PMEL cruises conducted in the Pacific and Indian Oceans during 1986-1989 (Table 1). The data files provide a complete listing of the calculated fugacities, the warming-corrected mole fraction CO2 concentrations, and the data required to convert between in situ mole fraction and fugacity. Table 1. Summary of PMEL Cruises 1986 to 1989. The distance given is the distance over which data were collected along the cruise track. -------------------------------------------------------------------------------------------------- Year | Cruise Section | Imports | Dates | Distance (km) | -------------------------------------------------------------------------------------------------- 1986 | EPOCS | Balboa - Honolulu | 21 May - 20 June | 12172 | | | | | | 1986 | RITS/CO2 | Honolulu - Kodiak | 1 Luly - 23 July | 7709 | | | | | | 1987 | SAGA II, Transit| Hilo - Kuril Trench | 1 May - 8 May | 4503 | | | | | | 1987 | SAGA II, Leg 1 | Kuril Trench - Wellington | 8 May - 9 June | 11441 | | | | | | 1987 | SAGA II, Leg 2 | Wellington - Singapore | 12 June - 6 July | 11912 | | | | | | 1987 | TEW-3 | Townsville - Kwajalein | 13 July - 27 July | 3491 | | | | | | 1987 | RITS/CO2 | Kwajalein - Seattle | 29 July - 28 August | 10520 | | | | | | 1988 | RITS/CO2 | Dutch Harbor - Am. Samoa | 6 April - 5 May | 8648 | | | | | | 1988 | EPOCS | Am. Samoa - Honolulu | 9 May - 4 June | 8492 | | | | | | 1989 | RITS/CO2, Leg 1 | Seattle - Easter Island | 5 February - 1 March | 7097 | | | | | | 1989 | RITS/CO2, Leg 2 | Easter Island - Papeete | 4 March - 2 April | 11365 | | | | | | 1989 | RITS/CO2, Leg 3 | Papeete - Seattle | 7 April - 20 April | 7773 | -------------------------------------------------------------------------------------------------- The fugacities were calculated according to equations given in Murphy et al. (1994). The fugacity calculations use observations of dry gas concentrations in units of parts per million, sea surface temperature, equilibrator temperature, sea surface salinity, and atmospheric pressure. The relative humidity is assumed to be 100% at the sea surface. The vapor pressure of seawater is calculated from temperature and salinity, and the functional relationship between gas solubility and temperature used is from Weiss et al. (1982). The fugacity values given in the data tables are the in situ fugacities which have been corrected for the warming of the seawater in transiting to the equilibrator. The mole fraction values given in the data tables are the dry gas concentrations at the in situ temperature. For the air values, the reported concentration, X(CO2)air, is the mole fraction of the dried air pumped from the bow line. For the water values, the reported concentration, X(CO2)sw, is the mole fraction of the dried vapor drown from the equilibrator headspace which has been converted to fugacity, corrected for warming, and converted back to mole fraction. The warming values provided in the data tables indicate the degrees of warming ( C) for seawater as it transited from the intake line to the analysis site. The warming values were derived from the regression of hourly warming on hourly sea surface temperature. Detailed information on the temperatures data and analyses for each of these cruises are provided in Murphy et al. (1993). 2. METHODS 2.1 Measurement of CO2 in the Atmosphere and in Surface Seawater Carbon dioxide measurements in the atmosphere and in surface water were made on these cruises by Kimberly Kelly. Mixing ratios of CO2 were analyzed with an automated, temperature-controlled gas chromatographic system similar to that described by Weiss (1981), and Bates et al. (1993). Every 12 minutes one of four gases (atmospheric sample, standard 1, equilibrator vapor sample, or standard 2) was injected for analysis. Details of sample collection, gas standard calibration, and data reduction follow. Air was pumped through 3/8-inch O.D. plastic-coated aluminum tubing (Decoron) from the jackstaff on the bow of the ship, 10 meters above the sea surface, to the oceanographic laboratory for analysis. This line was continuously flushed at 8-10 L/min. Aliquots from this air stream were dried using phosphorous pentoxide and 2 milliliters were injected into a gas chromatograph (GC) where CO2 was separated from the other gases, catalytically reduced to methane, and routed to the flame ionization detector. The instrument response was compared with the response of standard gases for quantification. The standard gases were dried and treated in exactly the same manner as the air and equilibrator samples. Surface seawater entered the ship's seachest via a forward intake line located approximately 5 meters below the water level. From the seachest, the water was pumped up to a showerhead-type Plexiglas equilibrator designed by R. Weiss (Butler et al., 1988). Water rains through the equilibrator at 15-20 L/min and the gases dissolved in the seawater partition between the aqueous and vapor phases according to their solubilities at the temperature and salinity of the seawater in the equilibrator. Aliquots of the equilibrator vapor phase were sampled, dried, and analyzed as described above for atmospheric samples. The gas standards were dried, whole-air mixtures contained in aluminum cylinders. The working standards were calibrated against the primary standards before and after the 1987, 1988, and 1989 cruises. The primary standards (CC48232 - 352.47 ppm, CC48302 - 355.97 ppm, CC48314 - 353.39 ppm) were filled and calibrated by the National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostics Laboratory (NOAA/CMDL) in February 1987. Subsequent calibrations of these primary standards by CMDL in November 1987, June 1990 and August 1990 have shown that the CO2 mixing ratios remained constant during this 3.5 year period. The CO2 mixing ratios in the working standards ranged from 228.15 ppm to 460.43 ppm. The working standards were calibrated by CMDL in 1990. These calibrations agreed to within 0.5% of the values assigned to each tank by PMEL based on the primary standards and a linear FID detector response. The data reported here have been reduced using the CMDL calibrations of the working standards. The mixing ratios reported here are in the World Meteorological Organization (WMO) X85 scale (Thoning et al., 1987). The accuracies of the CO2 standards are given by CMDL as +/- 0.6% by comparison with the manometric analyses of C. D. Keeling at the Scripps Institution of Oceanography. Instrument precision was determined by the average percent standard deviation of the standard response over a 6-hour period. The precision varied between cruises but was always less than 1.2% and was more typically around 0.4% (Table 2). Table 2. Instrument precision in percent standard deviation from the standard value. --------------------------------------------- | Year | Cruise | % Std. Dev | --------------------------------------------- | 1986 | EPOCS | 0.94 | | | | | | 1986 | RITS/CO2 | 0.71 | | | | | | 1987 | SAGA II | 0.24 | | | | | | 1987 | TEW-3, RITS/CO2 | 0.32 | | | | | | 1988 | RITS/CO2 | 0.60 | | | | | | 1988 | EPOCS | 0.21 | | | | | | 1989 | RITS/CO2 | 0.37 | --------------------------------------------- The CO2 mixing ratios in the air and equilibrator samples were calculated as follows. The data were first visually filtered to eliminate any episodes of ship contamination. These episodes were quit evident from the extremely high carbon monoxide values that were measured simultaneously. The mixing ratios of CO2 in both the air and equilibrator samples were then computed based on peak area and either a 4- hour or 6-hour running mean single-point standard. These dry-air mixing ratios were then binned into hourly values based on the measurements made 30 minutes before and after the hour. 2.2 Ancillary measurements The ancillary measurements used to calculate in situ CO2 concentrations in the atmospheric and surface seawater samples are sea surface temperature, temperature of seawater in the equilibrator, salinity, and atmospheric pressure. Surface seawater temperature was measured near the bow intake line on most cruises with a thermosalinograph provided by the ship. The temperature of seawater in the equilibrator was measured by mercury thermometer and thermistors. Salinity was taken from the thermosalinograph located near the bow intake line, and atmospheric pressure was recorded hourly from a barometer located on the bridge deck of the ships. 3. CRUISE DESCRIPTIONS AND DATA RESULTS. All dates and times given in the text and the data files are Greenwich Mean Time (GMT). North latitudes and east longitudes are listed as positive values. South latitudes and west longitudes are given as negative values. The data flags used in the tables follow the WOCE water sample quality flag definitions. The value 2 in the flag column indicates acceptable X(CO2) sw data; the value 3 indicates questionable X(CO2)sw data; the value 5 indicates not reported data; and letter P in the flag column indicates questionable latitude and/or longitude. Positional data were checked against the available ship log records using two methods. First, plots of time vs. latitude and of time vs. longitude were made for each cruise. A given point was checked against the marine operations abstracts (moas) if it was judged to be sufficiently far from the trend. A second check was made by plotting time vs. the distance travelled in an hour. Most of the data show the ship speeds between 0 and 20 knots, but a few points suggested much higher speeds. The positions were checked against the moas if the speeds exceeded 25 knots. Since the original ship log records for the 1987 SAGA II expedition were not available for this comparison, the data were compared against the 3-hour positional data provided. No obvious problems were found with this record, and so the hourly positions, interpolated from the 3-hour record were used without corrections. These errors could decrease the cumulative distance totals for the SAGA II expeditions by several hundred kilometers. 3.1 EPOCS 1986 The EPOCS cruise designated EP2-86-OC began on 21 May (Day 141) 1986 aboard the NOAA Research Vessel (R/V) Oceanographer. The ship departed from Balboa, Panama and headed southwest to the equator at 97W. The cruise track continued west along the equator, diverting for mooring work along 110W and 140W. The cruise continued northwest from the equator at 143W, ending in Honolulu, Hawaii on 20 June (Day 171). CTD and oxygen measurements for this track are reported in Lynch et al. (1988). Chlorofluorocarbon (CFC) measurements are reported by Wisegarver et al. (1993). The mean atmospheric Fugacity, f(CO2)air, for this equatorial track was 334.7 +/- 1.1 uatm. Surface seawater values, f(CO2)sw, ranged between ~410 uatm and 430 uatm along the equator from 90W to 112W. Concentration dropped sharply (to ~370 uatm) when the ship diverted north into fresher, warmer waters to the north of 3N. f(CO2)sw rose to ~420 uatm as the cruise track returned to the equator, but dropped to ~360 uatm as the ship moved away from the equator near 143W, 6N. Concentrations continued low (~350 uatm) into Hawaii. The mean percent standard deviation of the standard gases on this leg was <1%. Seven points were anomalously low on this track. They are flagged in the data files. 3.2 RITS/CO2 1986 The RITS/CO2 cruise was continuation of the EPOCS 1986 cruise. The NOAA R/V Oceanographer sailed from Hawaii on 1 July (Day 182) and headed northeast, southeast, northeast, north along 135/145W, and into Kodiak, Alaska on 23 July (Day 204). Mean atmospheric f(CO2) along this section was 342.41 uatm with values ranging from 337 near 20N to 350 uatm near 52N. Surface seawater concentrations were near equilibrium or slightly undersaturated north of Hawaii to 30N. Supersaturations of ~15 uatm persisted from 30N but the waters became undersaturated by ~34uatm near 45N. f(CO2)sw remained slightly undersaturated along 50N, but dropped to ~290 uatm as the ship continued north and into the Gulf of Alaska. The mean percent standard deviation of the standard gases on this leg was <0.7%. 3.3 SAGA II 1987, Kamchatka Transit The expedition aboard the Russian vessel Akademik Korolev began in Hilo, Hawaii. The portion from Hilo to the Kuril Trench off Kamchatka, began 1 May (Day 121) 1987, and is termed the Kamchatka Transit. Data were collected sporadically along this transit, so the record is not continuous. The available surface seawater concentrations indicate general undersaturation by up to 50 uatm relative to atmospheric values. Surface water values were high approaching the Kuril Trench, but dropped sharply (from 412 to 256 uatm) over an hour near 48N. This steep gradient was also found by Butler et al. (1988) and attributed to high primary productivity. The mean percent standard deviation of the standard gases on this leg was 0.24%. 3.4 SAGA II 1987, Leg 1 Leg 1 began on 8 May (Day 128) from the Kuril Trench region and followed the 160E meridian south to 5S. After a jog to the east, the track continued south along the 170E meridian into Wellington, New Zealand on 9 June (Day 160). Atmospheric values were near 350 uatm in the north, dropping to 330 uatm just south of the equator and increasing to 345 uatm near 45S. Surface seawater values were high leaving the Kuril Trench area, but dropped to ~260 uatm near 40N. To the south f(CO2)sw increased to near saturation but dropped to ~300 uatm near 10S. Surface water values remained near 300 uatm as the ship continued south, but increased sharply as the ship approached New Zealand. The mean percent standard deviation of the standard gases on this leg was 0.24%. 3.5 SAGA II 1987, Leg 2 Leg 2 began out of Wellington on 12 June (Day 163) heading west into the Indian Ocean and concluding in Singapore on 6 July (Day 187). Atmospheric f(CO2) ranged from a low of 332 uatm near the end of the track to 349 uatm off the west coast of New Zealand. Surface seawater values were highly variable along this track, ranging from 290 to 410 uatm. The mean percent standard deviation of the standard gases on this leg was 0.24%. 3.6 TEW-3 1987 The NOAA Ship Oceanographer departed Townsville, Australia on 13 July (Day 194) for the TW3- 87-OC cruise and steamed northeast to 5S, 165E for station work in the Samoan Passage. The ship then continued north along 165E and into Kwajalein, Micronesia on 27 July (Day 208). Details of the CTD temperature, salinity, and oxygen data are given by Mangum et al. (1991). The mean atmospheric value for this section was 334.01 +/- 1.11 uatm. Surface seawater CO2 was largely undersaturated through the Coral Sea but increased rapidly to 353 uatm near 5S. Water values remained near saturation or supersaturated north to 1S. Across the equator surface seawater was undersaturated as far north as 2N, but dropped again quickly to undersaturation from 2N and north into Kwajalein. The mean percent standard deviation of the standard gases on this leg was 0.32%. 3.7 RITS/CO2 1987 The RITS/CO2 cruise was an continuation of the TEW-3 cruise, beginning on 29 July (Day 210) from Kwajalein. The cruise track continued north along 165E to 50N and then east into Dutch Harbor, Alaska. After a brief stop in Dutch Harbor on Days 233/234, the ship continued east along 50N and then into Seattle, Washington on 28 August (Day 240). Atmospheric f(CO2) values were steady at 334 uatm out of Kwajalein, but ranged from 330 to 343 uatm along the cruise track. Surface seawater CO2 was supersaturated from Kwajalein north to 36N. f(CO2)sw dropped sharply to 264 uatm near 40N and remained undersaturated until the ship diverted from its eastward track north into Dutch Harbor. After the ship returned to 50N f(CO2)sw returned to undersaturation. Values climbed to 375 uatm near 50N, 152W and then decreased to near- or undersaturation as the ship moved east and into Seattle. The mean percent standard deviation of the standard gases on this leg was 0.32%. 3.8 RITS/CO2 1988 The RITS/CO2 1988 cruise began on 6 April (Day 97) aboard the NOAA ship Oceanographer. They sailed from Dutch Harbor to the south along 170W to American Samoa, arriving on 5 May (Day 126). Atmospheric f(CO2) was highest near to the north (357 uatm) and generally decreased to ~ 335 uatm to the south along this track. Seawater f(CO2) values were low out of Dutch Harbor, but rose to 384 uatm near 48N and then dropped gradually to <300 uatm near 34N. This undersaturation persisted as far south as 10N. The surface waters across the equator from 10N to 6S were supersaturated by as much as 96 uatm relative to the atmosphere. Near 6N the f(CO2) values dropped sharply to undersaturation which persisted into Samoa. The mean percent standard deviation of the standard gases in this leg was 0.60%. 3.9 EPOCS 1988 The EPOCS 1988 cruise was a continuation of RITS/CO2. R/V Oceanographer sailed out of Samoa on 9 May (Day 130) north to the equator. They then continued east along the equator to 140W and then north to Honolulu, Hawaii on 4 June (Day 156). The temperature, salinity, and oxygen data from CTD measurements made on this cruise are given in Mangum et al. (1993). Atmospheric f(CO2) was lowest near Samoa (333 uatm) and increased to the north, reaching 345 uatm near 15N. Surface seawater values were also lowest near Samoa, but increased toward the equator. Supersaturation persisted along equator (~430 uatm), but CO2 concentrations dropped to near-saturation north of 5N and into Hawaii. The mean percent standard deviation of the standard gases on this leg was 0.21%. Two values were anomalously high on this track. They are flagged in the data set. 3.10 RITS/CO2 1989, Leg 1 The NOAA R/V Discoverer left Seattle on 5 February (Day 37) 1989. After two brief stops in San Diego and then Manzanillo, Mexico, the ship continued southward along 105W/110W and into Easter Island on 1 March. Atmospheric values were high off Baja, California, but dropped to a relatively stable value of ~339 uatm between 10N and Easter Island. Surface seawater values were supersaturated off Baja, but dropped to neat-saturation to the south. The pattern of f(CO2) across the equator is complex, rising to 423 uatm near 2S, dropping to saturation and then increasing to a maximum of 481 uatm at 4S. From there the values dropped slowly reaching 354 uatm near 16S. From 16S to Easter Island, surface seawater was supersaturated by up to 60 uatm. The mean percent standard deviation of the standard gases on this leg was 0.37%. 3.11 RITS/CO2 1989, Leg 2 Leg 2 began on 4 March (Day 63), with R/V Discoverer continuing south along 105W to 60S. The cruise track then turned northwest and the ship arrived in Tahiti on 2 April (Day 92). Atmospheric values were quite variable along this section, ranging from 328 uatm near 60S to 353 uatm near 45S. Surface seawater values were ~380 uatm south from Easter Island to 40S where they dropped to near-saturation. Surface seawater f(CO2) dropped suddenly near 61S from 332 to 266 uatm within 1 hour and stayed low for several hours. The system was shut down to remove krill from the equilibrator and to check instrument performance. When the system was started again near 58S, seawater f(CO2) had returned to equilibrium values. Seawater values close to saturation persisted into Tahiti. One anomalously high value (near 58S) is flagged in data file. The mean percent standard deviation of the standard gases on this leg was 0.37%. 3.12 RITS/CO2 1989, Leg 3 The final leg of the 1989 cruise began 7 April (Day 97) from Tahiti and ended 20 April (Day 110) in Seattle. Atmospheric f(CO2) values were 334 uatm in the southern hemisphere and rose to a high of 350 uatm approaching Seattle. Surface seawater values were oversaturated from Tahiti, and peaked at 440 uatm just south of the equator (2S), dropping to saturation near 14N. Seawater remained near- or under-saturated from 14N and dropped sharply on the approach to coastal waters. The mean percent standard deviation of the standard gases on this leg was 0.37%. 4. DATA CHECKS PERFORMED BY CDIAC An important part of the numeric data package (NDP) preparation process at the Carbon Dioxide Information Analysis Center (CDIAC) involves the quality assurance (QA) of data before distribution. Data received at CDIAC are rarely in a condition that would permit immediate distribution, regardless of the source. To guarantee data of the highest possible quality, CDIAC conducts extensive QA reviews. Reviews involve examining the data for completeness, reasonableness, and accuracy. Although they have common objectives, these reviews are tailored to each data set, often requiring extensive programming efforts. In short, the QA process is a critical component in the value-added concept of supplying accurate, usable data for researchers. The following summarizes the QA checks performed by CDIAC on the data obtained during the 1986-1989 PMEL cruises in Pacific and Indian Oceans. 1. These data were provided to CDIAC as twelve ASCII-formatted files with accompanying printed documentation (NOAA Technical Memorandum ERL PMEL-101). A FORTRAN 77 retrieval program was written and used to reformat the original twelwe files into twelwefiles with identical formats and to merge all data into a single file that was sorted and arranged chronologically. 2. All data were plotted to check for obvious outliers. 3. Dates, times, and coordinates were checked for bogus values (e.g., values of DAY <1 or >31; YEAR <1986 or >1989; DAYGMT <1.000 or >365.999; LAT <-90.000 or >90.000; LONG <-180.000 or >180.000). 4. All cruise tracks were plotted and compered with the maps and cruise information supplied by Murphy et al. (1994). 5. The data quality flags for missing values, given as "-99" in the original data files, were changed to "5". The data accuracy quality flags, also given as "-99" in the original data files, were changed to "2". These changes reflect the quality flag definitions specified by the WOCE Hydrographic Program (WHP) Data Reporting Requirements (1991). Under these guidelines, "5" and "2" denote "data not reported" and "acceptable measurements", respectively. 6. The designation for missing values, given as "-99.00" in the original files, was changed to "-999.9". 5. HOW TO OBTAIN THE DATA FILES This data base is available upon request in machine-readable form, free-of-charge from CDIAC. CDIAC will also distribute subsets of the data base as needed. It can be acquired on 9-track magnetic tape; 8-mm tape; 150 mB, quarter inch tape cartridge; IBM-formatted floppy diskettes; or from CDIAC's anonymous File Transfer Protocol (FTP) area via Internet (see FTP address below). Requests should include any specific media instructions (i.e., 1600 or 6250 BPI, labeled or nonlabeled, ASCII or EBCDIC characters, and variable- or fixed-length records; 3.5- or 5.25- inch floppy diskettes, high or low density; and 8200 or 8500 format 8-mm tape) required by the user to access the data. Magnetic tape requests not accompanied by specific instructions will be filled on 9-track, 6250 BPI, standard-labeled tapes with EBCDIC characters. Requests should be addressed to: Carbon Dioxide Information Analysis Center Oak Ridge National Laboratory Post Office Box 2008 Oak Ridge, Tennessee 37831-6335 U.S.A. Telephone: (615) 574-0390 or (615) 574-3645 Fax: (615) 574-2232 Electronic Mail: INTERNET: CDP@ORNL.GOV OMNET: CDIAC The data files can be also acquired from CDIAC's anonymous FTP account via Internet: FTP to cdiac.esd.ornl.gov (128.219.24.36) Enter "ftp" or "anonymous" as the userid Enter your electronic mail address as the password (e.g.,"alex@alex.esd.ornl.gov") Change to the directory "pub/ndp047" Acquire the files using the FTP "get" or "mget" command 6. REFERENCES Bates, T. S., K. C. Kelly, and J. E. Johnson. 1993. Concentrations and fluxes of dissolved biogenic gases (DMS, CH4, CO, CO2) in the equatorial Pacific during the SAGA-3 experiment. J. Geophysical Research, 98: 16969 16977. Butler, J. H., J. W. Elkins, C. M. Brunson, K. B. Egan, T. M. Thompson, T. J. Conway, and B. D. Hall. 1988. Trace gases in and over the West Pacific and East Indian Oceans during the El Nino-Southern oscillation event of 1987. NOAA Data Report ERL ARL-16, 104 pp. Broecker, W. S., and T.-H. Peng. 1982. Tracers in the Sea. Eldigio Press, Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York. Goff, J., and S. Gratch. 1946. Low-pressure properties of water from -160 to 212F. Transactions American Society of Heating and Ventilating Engineers, 52, 95-122. Guggenheim, E. A. 1967. Thermodynamics. North-Holland, Amsterdam, 5th ed., 390 pp. IPCC. 1990. Climate Change: The Intergovernmental Panel on Climate Change Assessment. Published for the IPCC, Cambridge University Press, Cambridge, 365 pp. Keeling, C. D., S. C. Piper, and M. Heimann. 1989. A tree-dimensional model of atmospheric CO2 transport based on observed winds, 4. Mean annual gradients and interannual variations, in Aspects of Climate Variability in the Pacific and the Western Americas, Geophys. Monogr. Ser., vol. 55 edited by D. H. Peterson, AGU, Washington, D.C, 305-363. Lynch, J. M., L. J. Mangum, and S. P. Hayes. 1988. CTD/O2 measurements during 1986 as part of the equatorial Pacific Ocean Climate Studies (EPOCS). NOAA Data Report ERL PMEL-24, 261 pp. Mangum L. J., J. M. Lynch, K. McTaggart, L. Stratton, and S. Hayes. 1991. CTD/O2 data measurements collected on TEW (Transport of equatorial waters) June-August 1987. NOAA Data Report ERL PMEL-33, 375 pp. Mangum L., J. Lynch, L. Stratton, and K. McTaggart. 1993. CTD/O2 measurements during 1987 and 1988 as part of the Equatorial Pacific Ocean Climate Studies (EPOCS). NOAA Data Report ERL PMEL- 46, 620 pp. Marland, G. and R. M. Rotty. 1984. Carbon dioxide emissions from fossil fuels: a procedure for estimation and results for 1950-1982. Tellus, 36B, 232-261. Murphy, P. P., R. A. Feely, R. H. Gammon, D. E. Harrison, K. C. Kelly, and L. S. Waterman. 1991. Assessment of the air-sea axchange of CO2 in the South Pacific during austral autumn. J. Geophys. Res., 96, 20455-20465. Murphy, P. P., C. Cosca, D. C. Lee, and R. A. Felly. 1993. Temperature calibration and correction report for PMEL trace gas cruises 1986-1989. NOAA Tech. Memo. ERL PMEL-97, 192 pp. Weiss, R. F. 1970. The solubility of nitrogen, oxygen and argon on water and seawater. Deep-Sea Res., 17, 721-735. Weiss, R. F. 1974. Carbon dioxide in water and seawater: The solubility of a non-ideal gas. Marine Chemistry 2:203-215. Weiss, R. F. 1981. Determinations of carbon dioxide and methane by dual catalyst flame ionization chromatography and nitrous oxide by electron capture chromatography. J. Chromatogr. Sci., 19, 611-616. Weiss, R. F., R. A. Jahnke, and C. D. Keeling. 1982. Seasonal effects of temperature and salinity on the partial pressure of CO2 in seawater. Nature, 300, 511-513. Weiss, R. F., and B. A. Price. 1980. Nitrous oxide solubility in water and seawater. Marine Chemistry, 8, 347-359. Wisegarver, D. P., J. L. Bullister, R. H. Gammon, F. A. Menzia, and K. C. Kelly. 1993. NOAA chlorofluorocarbon tracer program air and seawater measurements: 1986-1989. NOAA Data Report ERL PMEL-43, 417 pp. WOCE Operations Manual, Rev. 1. 1991. WHP Office Report WHPO 90-1. WOCE Report No. 67/91. Vol. 3, Sec. 3.1, Part 3.2.1. 6. FILE DESCRIPTIONS This section describes the content and format of each of the 15 files that comprise this NDP (see Table 1). Because CDIAC distributes the data set in a variety of media (e.g., via anonymous FTP and 9-track magnetic tape), each of the 15 files is referenced by both an ASCII filename, which is given in lower-case, bold-faced type (e.g., ndp047.txt), and a file number. The remainder of this section describes (or lists, where appropriate) the contents of each of the 15 files. The files are discussed in the order in which they appear on the magnetic tapes. Table 3. Content, size, and format of data files ---------------------------------------------------------------------------------------- File number, name, Logical FTP file Block Record and description records size in bytes size length ---------------------------------------------------------------------------------------- 1. ndp047.txt: 890 54,347 8,000 80 a detailed description of the cruise network and data files 2. pmeldat.for: 48 1,894 8,000 80 a FORTRAN 77 data retrieval routine that may be used to read and print all data files (Files 3 15) 3. pmel8689.dat: 6,013 829,797 6,850 137 data file containing CO2 measurements, hydrographic measurements, and the calculations of in situ fugacities of CO2 for all PMEL cruises during 1986-89 4. ep86.dat: 637 87,906 6,850 137 data file containing CO2 measurements, hydrographic measurements, and the calculations of in situ fugacities of CO2 for the EPOCS 1986 cruise 5. rt86.dat: 461 63,618 6,850 137 data file containing CO2 measurements, hydrographic measurements, and the calculations of in situ fugacities of CO2 for the RITS/CO2 1986 cruise 6. sa0_87.dat: 218 30,084 6,850 137 data file containing CO2 measurements, hydrographic measurements, and the calculations of in situ fugacities of CO2 for the SAGA II 1987 cruise, Transit 7. sa1_87.dat: 633 87,354 6,850 137 data file containing CO2 measurements, hydrographic measurements, and the calculations of in situ fugacities of CO2 for the SAGA II 1987 cruise, Leg 1 8. sa2_87.dat: 501 69,138 6,850 137 data file containing CO2 measurements, hydrographic measurements, and the calculations of in situ fugacities of CO2 for the SAGA II 1987 cruise, Leg 2 9. tw87.dat: 297 40,986 6,850 137 data file containing CO2 measurements, hydrographic measurements, and the calculations of in situ fugacities of CO2 for the TEW-3 1987 cruise 10. rt87.dat: 669 92,322 6,850 137 data file containing CO2 measurements, hydrographic measurements, and the calculations of in situ fugacities of CO2 for the RITS/CO2 1987 cruise 11. rt88.dat: 668 92,184 6,850 137 data file containing CO2 measurements, hydrographic measurements, and the calculations of in situ fugacities of CO2 for the RITS/CO2 1988 cruise 12. ep88.dat: 547 75,486 6,850 137 data file containing CO2 measurements, hydrographic measurements, and the calculations of in situ fugacities of CO2 for the EPOCS 1988 cruise 13.rt1_89.dat: 398 54,924 6,850 137 data file containing CO2 measurements, hydrographic measurements, and the calculations of in situ fugacities of CO2 for the RITS/CO2 1989 cruise, Leg 1 14. rt2_89.dat: 686 94,668 6,850 137 data file containing CO2 measurements, hydrographic measurements, and the calculations of in situ fugacities of CO2 for 15. rt3_89.dat: 298 41,124 6,850 137 data file containing CO2 measurements, hydrographic measurements, and the calculations of in situ fugacities of CO2 for the RITS/CO2 1989 cruise, Leg 3 ----- ------ --------- Total 12,964 1,715,832 --------------------------------------------------------------------------------------- ndp047.txt (File 1) This file provides an overview of the dataset and a detailed description of the thirteen oceanographic data files. It exists primarily for the benefit of individuals who do not have copies of this documentation or acquire the data files from CDIAC's anonymous FTP area. pmeldat.for (File 2) This file contains a FORTRAN 77 data retrieval routine that may be used to read and print any of the 13 data files (Files 3 15). The following is a listing of this program. For additional information regarding variable definitions and format statements, please see the description for pmel8689.dat-rt3_89.dat files on pages 16-18. c*************************************************************** c* This is a FORTRAN 77 retrieval code to read and print the * c* Carbon Dioxide concentrations data in surface water and * c* atmosphere: PMEL cruises 1986-1989 * c*************************************************************** c*Defines variables* INTEGER DAY, YEAR CHARACTER CRUISE*19, MONTH*3, FLAG*1 REAL DAYGMT, LAT, LONG, DIST, TEMP, WARM, SAL, APRE REAL XCO2A, XCO2SW, FCO2A, FCO2SW OPEN (unit=1, file='file.in') OPEN (unit=2, file='file.out') WRITE (2, 5) c*Writes out column labels* 5 FORMAT (8x,'CRUISE NAME',2X,'CRUISE DATE',2X,'DAY GMT',3X, 1 'LATIT',5X,'LONGIT',2X,'DISTAN',4X,'TEMP',1X,'WARMING',2X, 2 'SALINITY',1X,'ATM.PRE',1X,'X(CO2)a',1X,'X(CO2)w',1X, 3 'f(CO2)a',1x,'f(CO2)w',1X,'QF',/,20X,'day mon year',10X, 4 'dec.deg',4X,'dec.deg',6X,'km',3X,'deg.C',3X,'deg.C',7X, 5 'ppt',4X,'mbar',5X,'ppm',5X,'ppm',4X,'uatm',4X,'uatm',//) c*Sets up a loop to read and format all the data in the file* 7 CONTINUE READ (1, 10, end=999) CRUISE, DAY, MONTH, YEAR, DAYGMT, LAT, 1 LONG, DIST, TEMP, WARM, SAL, APRE, XCO2A, XCO2SW, FCO2A, 2 FCO2SW, FLAG 10 FORMAT (A19, 2X, I2, 1X, A3, 1X, I4, 2X, F7.3, 1X, F7.3, 3X, 1 F8.3, 1X, F7.1, 1X, F7.2, 1X, F7.2, 2X, F8.3, 2X, F6.1, 1X, 2 F7.2, 1X, F7.2, 1X, F7.2, 1X, F7.2, 2X, A1) WRITE (2, 20) CRUISE, DAY, MONTH, YEAR, DAYGMT, LAT, 1 LONG, DIST, TEMP, WARM, SAL, APRE, XCO2A, XCO2SW, FCO2A, 2 FCO2SW, FLAG 20 FORMAT (A19, 2X, I2, 1X, A3, 1X, I4, 2X, F7.3, 1X, F7.3, 3X, 1 F8.3, 1X, F7.1, 1X, F7.2, 1X, F7.2, 2X, F8.3, 2X, F6.1, 1X, 2 F7.2, 1X, F7.2, 1X, F7.2, 1X, F7.2, 2X, A1) GOTO 7 999 CLOSE(unit=1) CLOSE(unit=2) STOP END pmel8689.dat-rt3_89.dat (Files 3 15) These 13 data files containing CO2 measurements, hydrographic measurements, and the calculations of in situ fugacities of CO2 for PMEL cruises conducted from 1986-1989. All 13 data files have the same format and can be read by using the following FORTRAN 77 code [contained in pmeldat.for (File 2)]: INTEGER DAY, YEAR CHARACTER CRUISE*19, MONTH*3, FLAG*1 REAL DAYGMT, LAT, LONG, DIST, TEMP, WARM, SAL, APRE REAL XCO2A, XCO2SW, FCO2A, FCO2SW 7 READ (1, 10, end=999) CRUISE, DAY, MONTH, YEAR, DAYGMT, LAT, 1 LONG, DIST, TEMP, WARM, SAL, APRE, XCO2A, XCO2SW, FCO2A, 2 FCO2SW, FLAG 10 FORMAT (A19, 2X, I2, 1X, A3, 1X, I4, 2X, F7.3, 1X, F7.3, 3X, 1 F8.3, 1X, F7.1, 1X, F7.2, 1X, F7.2, 2X, F8.3, 2X, F6.1, 1X, 2 F7.2, 1X, F7.2, 1X, F7.2, 1X, F7.2, 2X, A1) GOTO 7 999 CLOSE 1 STOP The contents of these data files are listed in Table 4. Table 4. Description of contents of pmel8689.dat rt3_89.dat (Files 3 15) ------------------------------------------------------------------------------ Variable Variable Variable Starting Ending name type width column column ------------------------------------------------------------------------------ CRUISE Character 19 1 19 DAY Numeric 2 22 23 MONTH Character 3 25 27 YEAR Numeric 4 29 32 DAYGMT Numeric 7 35 41 LAT Numeric 7 43 49 LONG Numeric 8 53 60 DIST Numeric 7 62 68 TEMP Numeric 7 70 76 WARM Numeric 7 78 84 SAL Numeric 8 87 94 APRE Numeric 6 97 102 XCO2A Numeric 7 104 110 XCO2SW Numeric 7 112 118 FCO2A Numeric 7 120 126 FCO2SW Numeric 7 128 134 FLAG Character 1 137 137 ------------------------------------------------------------------------------ Where: CRUISE is the cruise name; DAY is the day of sampling (GMT); MONTH is the month of sampling; YEAR is the year of sampling; DAYGMT is the day of the year [expressed in decimal time (GMT)]; LAT is the latitude of the sampling location (decimal degrees; negative values indicate the Southern Hemisphere); LONG is the longitude of the sampling location (decimal degrees; negative values indicate the Western Hemisphere); DIST is the cumulative distance since the first sampling location on the leg (km); TEMP is the sea-surface temperature ( deg C); WARM is the warming temperature [indicates the degrees of warming (deg C) for seawater as it transited from the intake line to analysis site]; SAL is the sea-surface salinity [Practical Salinity Scale (PSS)]; APRE is the atmospheric pressure (mbar); XCO2A is the observed mole fraction of CO2 in air [ppm (dry air)]; XCO2SW is the observed mole fraction of CO2 in surface water [corrected for warming, ppm (dry air)]; FCO2A is the calculated in situ fugacity of CO2 in air [ uatm (moist air)]; FCO2SW is the calculated in situ fugacity of CO2 in surface water (corrected for warming, uatm (moist air)]; FLAG is the data quality flag: 2 = Acceptable measurements of X(CO2)sw; 3 = Questionable measurements of X(CO2)sw; 5 = Data were not reported; P = Questionable latitude and/or longitude; Missing values for variables are represented by -999.9.