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THE ALE/GAGE/AGAGE NETWORK (Last revision-August 2014, Last data update-May 2014)

The following material provides a brief history of the ALE/GAGE/AGAGE
program, which has consisted of 3 stages corresponding to major advances
and upgrades in instrumentation and resulting increases in measurement
frequency, precision, and number of gaseous species that could be
measured.   The first stage, ALE(Atmospheric Lifetime Experiment), began
in 1978 using Hewlett-Packard (HP) 5840 gas chromatographs (gc) with an
electron-capture detector (ECD) to measure five species (CFC-11 (CCl3F),
CFC-12 (CCl2F2), methyl chloroform (CH3CCl3), carbon tetrachloride (CCl4)
and nitrous oxide (N2O)) 4 times daily.  In the 1981-1985 time frame, ALE
was phased into GAGE (Global Atmospheric Gases Experiment) which used HP
5880 chromatographs and flame ionization detectors (FIDs) to measure the
original suite of gases plus chloroform (CHCl3), CFC-113 (CCl2FCClF2 )
and methane (CH4).  During GAGE the frequency of measurement was also
increased to 12 times per day.  Data for all the above species except
chloroform were given.  During 1993-1996, GAGE was phased into AGAGE
(Advanced Global Atmospheric Gases Experiment) which has continued to
the present, and is measuring an increasing number of atmospheric gases
as measurement capabilities increase.  Measurements of hydrogen (H2) and
carbon monoxide (CO) began at Cape Grim in 1993 and at Mace Head in 1994.

The original (ALE) measurements were made at 5 globally distributed
stations, 2 of which ceased operation during the GAGE period and have
since been replaced.  The 5 current station locations were: Mace Head,
Ireland (53N, 10W); Cape Grim, Tasmania (41S, 145E); Cape Matatula,
American Samoa (14S, 171W); Ragged Point, Barbados (13N, 59W); and
Trinidad Head, California (41N, 124W).  Stations also previously existed
at Cape Meares, Oregon (45N, 124W) and Adrigole, Ireland (52N, 10W).
The Mace Head station came on line in January, 1987 as a replacement for
the Adrigole station which ceased operations at the end of December, 1983;
the Trinidad Head station began operations during AGAGE in October 1995,
as an essential replacement for the Cape Meares station from which GAGE
data were not available after June, 1989.

More recently, two more stations have been added.  The first is
Jungfraujoch, Switzerland (46N, 7E and 3580 masl).  Data here for some
species extend back to January 2000.  The second is Zeppelin Station,
Ny Alesund, Norway (78N, 11E and 474 masl).  Data for some species at
this station go back to January 2001.


The ongoing AGAGE has two instrumental components:

The first is an HP 5890 Series II chromatograph multidetector (gc-md)
system incorporating an ECD, a FID, and, at 2 stations (Mace Head, Ireland
and Cape Grim, Tasmania), a mercuric oxide reduction detector (MRD).
Measurements of the above listed 8 gases, plus carbon monoxide (CO)
and hydrogen (H2) at Mace Head and Cape Grim, are made 36 times per day.
Two sets of data appear for the multiple-detection (md) species.  One set
(xYmon) consists of background values only and the other set (xYmop)
includes all data, including concentrations in air from the direction
of nearby pollution sources.

The second component incorporates automated gas chromatograph-mass spectrometers 
(gc-ms).   A gc-ms, based on a Finnigan Magnum Iron Trap coupled to a custom-
built (Bristol University) adsorption-desorption system (ADS), was installed at 
the Mace Head station in October 1994.  In 1997, two new identical ADS gc-ms 
instrument systems incorporating Hewlett Packard 5973 quadrupole mass 
spectrometers were installed at Mace Head (October) and Cape Grim (November).  
These instruments measure a wide range of hydrochloroflurocarbons, 
hydroflurocarbons, and other gases.  Around the beginning of 2004, newly 
developed Medusa cryogenic trapping systems replaced the ADSs at the Mace Head 
and Cape Grim locations, and have since been installed at the other 
current AGAGE stations.  These greatly improved trapping systems allow 
measurement of a broader range of volatile perfluorocarbons that have high 
global warming potentials.

Species not listed above for which data are given include: HCFC-141b
(CH3CCl2F), HCFC-142b (CH3CClF2), HFC-134a (CH2FCF3), HFC-152a (CH3CHF2),
HFC-22 (CHClF2), methyl chloride (CH3Cl), methyl bromide (CH3Br), halons
1211 (CBrClF2) and 1301 (CBrF3), sulfur hexafluoride (SF6), HFC-365mfc
(a chlorine-free substitute for HCFC-141b), dichloromethane (CH2Cl2)
trichloroethylene (CHClCCl2), perchlorooethylene (CCl2CCl2), sulfuryl
fluoride (SO2F2), chlorofluorocarbon 115 (CClF2CF3), hydrofluorocarbons
23 (CHF3), 125 (CHF2CF3), 227ea (CF3CHFCF3), 236fa (CF3CH2CF3) and 245fa
(CHF2CH2CF3), and perfluorocarbons 14 (CF4), 116 (C2F6) and 218 (C3H8).
Units are dry air mole fractions in parts per 10**12 (picomoles/mole)
for all halocarbons and SF6, and parts per 10**9 (nanomoles/mole) for
nitrous oxide, methane, carbon monoxide and hydrogen.

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Important information for ALE/GAGE/AGAGE data users

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1. Citation agreement.



The measurements available from CDIAC represent a major effort by the 
ALE/GAGE/AGAGE investigators over the past several decades.  We ask as a basic 
professional courtesy (and as a condition for its use by you) that when 
you refer to this data set in publications you cite one or more of the 
following papers depending on what parts of the data set you use:

  (a) Overall Introduction:

Prinn, R.G., R.F. Weiss, P.J. Fraser, P.G. Simmonds, D.M. Cunnold,
F.N. Alyea, S. O'Doherty, P. Salameh, B.R. Miller, J. Huang, R.H.J. Wang,
D.E. Hartley, C. Harth, L.P. Steele, G.  Sturrock, P.M. Midgley, and
A. McCulloch, A History of Chemically and Radiatively Important Gases in
Air deduced from ALE/GAGE/AGAGE, J. Geophys. Res., 105, 17,751-17,792,
2000.

Prinn, R.G., J. Huang, R.F. Weiss, D.M. Cunnold, P.J. Fraser,
P.G. Simmonds, A. McCulloch, C.Harth, P. Salameh, S. O'Doherty,
R.H.J. Wang, L. Porter, and B.R. Miller, Evidence for significant
variations of atmospheric hydroxyl radicals in the last two decades,
Science, 292.  1882-1888, 2001

  (b) Species from gc-md measurements 
  
     (i) For CFC-11 and/or CFC-12:

D.E. Hartley, T. Kindler, D.E. Cunnold, and R.G. Prinn. Evaluating chemical 
transport models: Comparison of effects of different CFC-11 emission 
scenarios. J. Geophys. Res., 101, 14381-14385, 1996.
 
D. Cunnold, R. Weiss, R. Prinn, D. Hartley, P. Simmonds, P. Fraser,
B. Miller, F. Alyea, and L. Porter. GAGE/AGAGE measurements indicating
reductions in global emissions of CCl3F and CCl2F2 in 1992-1994. J.
Geophys. Res., 102, 1259-1269, 1997.

     (ii) For Methyl Chloroform:

R. Prinn, D. Cunnold, P. Simmonds, F. Alyea, R. Boldi, A. Crawford, P. 
Fraser, D. Gutzler, D. Hartley, R. Rosen, and R. Rasmussen.  Global 
average concentration and trend for hydroxyl radicals deduced from 
ALE/GAGE trichloroethane (methyl chloroform) data for 1978-1990.  J. 
Geophys. Res., 97, 2445-2461, 1992.

R.G. Prinn, R.F. Weiss, B.R. Miller, J. Huang, F.N. Alyea, D.M. Cunnold,
P.B. Fraser, D.E. Hartley, and P.G. Simmonds.  Atmospheric trends and
lifetime of trichloroethane and global average hydroxyl radical 
concentrations based on 1978-1994 ALE/GAGE measurements.
Science, 187-192, 1995.

Prinn, R.G., J. Huang, R.F. Weiss, D.M. Cunnold, P.J. Fraser,
P.G. Simmonds, A. McCulloch, C.  Harth, S. Reimann, P. Salameh,
S. O'Doherty, R.-H.J. Wang, L.W. Porter, B.R. Miller, and P.B. Krummel,
Evidence for variability of atmospheric hydroxyl radicals over
the past quarter century, Geophys. Res, Lett., 32, L07809,
doi:10.1029/2004GL022228, 2005.

Prinn, R.G., J. Huang, R.F. Weiss, D.M. Cunnold, P.J. Fraser,
P.G. Simmonds, A. McCulloch, C.Harth, P. Salameh, S. O'Doherty,
R.H.J. Wang, L. Porter, and B.R. Miller, Evidence for significant
variations of atmospheric hydroxyl radicals in the last two decades,
Science, 292.  1882-1888, 2001.

  (for european stations)
Reimann, S., J.M. Alister, P.G. Simmonds, D.M. Cunnold, R.H.J. Wang,
J. Li, A. McCulloch, R.G. Prinn, J. Huang, R.F. Weiss, P.J. Fraser,
S. O'Doherty, B.B. Greally, K. Stemmler, M. Hill and D. Folini, Low
European methyl chloroform emissions inferred from long-term atmospheric
measurements, Nature, 433, 506-509,2004.


     (iii) For Carbon Tetrachloride:

P. Simmonds, D. Cunnold, F. Alyea, C. Cardelino, A. Crawford, P. Fraser, 
R. Prinn, R. Rasmussen and R. Rosen.  Carbon tetrachloride lifetime and 
emissions determined from daily global measurements during 1978-1985. J. 
Atmos. Chem., 7, 35-58, 1988.
 
P.G. Simmonds, D.M. Cunnold, R.F. Weiss, R.G. Prinn, P.J. Fraser, 
A. McCulloch, F.N. Alyea, and S. O'Doherty.  Global trends and emission 
estimates of CCl4 from in situ background observations from July 1978 
to June 1996.  J. Geophys. Res., 103(D13), 16017-16027, 1998.

     (iv) For Nitrous Oxide:

R.G. Prinn, D. Cunnold, R. Rasmussen, P. Simmonds, F. Alyea, A. 
Crawford, P. Fraser, and R. Rosen.  Atmospheric emissions and trends of 
nitrous oxide deduced from ten years of ALE/GAGE data. J. Geophys. Res., 
95, 18369-18385, 1990.

     (v) For CFC-113:

P. Fraser, D. Cunnold, F. Alyea, R. Weiss, R. Prinn, P. Simmonds, and B.
Miller.  Lifetime and Emission Estimates of 1,1,2-Trichlorotrifluorethane
(CFC-113) from Daily Global Background Observations, June 1982-June 1994.
J. Geophys. Res., 101, 12585-12599, 1996.

     (vi) For Methane:

Cunnold, D.M., L.P. Steele, P.J. Fraser, P.G. Simmonds, R.G. Prinn,
R.F. Weiss, L.W. Porter, R.L. Langenfelds, H.J. Wang, L. Emmons,
X.X. Tie, and E.J. Dlugokencky, In situ measurements of atmospheric
methane at GAGE/AGAGE sites during 1985-2000 and resulting source
inferences. J. Geophys. Res., 107, 2002.


     (vii)  For Chloroform

O'Doherty, S., D. Cunnold, G.A. Sturrock, D. Ryall, R.G. Derwent,
H.J. Wang, P. Simmonds, P.J. Fraser, R.F. Weiss, P. Salameh, B.R. Miller,
and R.G. Prinn, In-situ chloroform measurements at AGAGE atmospheric
research stations from 1994-1998, J. Geophys. Res., 106, 20,429-20,444,
2001.


     (viii) For Carbon Monoxide:

Derwent, R. G., D. B. Ryall, S. G. Jennings, T. G. Spain, and
P. G. Simmonds, Black carbon aerosol and carbon monoxide in European
regionally-polluted air masses at Mace Head, Ireland during 1995-1998,
Atmos. Environ., 35, 6371-6378, 2001.


     (ix) For Hydrogen:

Simmonds, P.G., R.G. Derwent, S. O'Doherty, D.B. Ryall, L.P. Steele,
R.L. Langenfelds, P.  Salameh, H.J. Wang, C.H. Dimmer, L.E. Hudson,
Continuous high-frequency observations of hydrogen at the Mace Head
baseline atmospheric monitoring station over the 1994-1998 period,
J. Geophys. Res., 105, 12105-12121, 2000.


  (c) Species from gc-ms measurements

     (i) For Methyl Chloride and Methyl Bromide

Simmonds, P.G., S. O'Doherty, R.G. Derwent, A.J. Manning, D.B. Ryall,
P. Fraser, L. Porter, P. Krummel, R. Weiss, B. Miller, P. Salameh,
D. Cunnold, R. Wang, and R. Prinn, AGAGE observations of methyl bromide
and methyl chloride at the Mace Head, Ireland and Cape Grim, Tasmania,
1998-2001, J. Atmos. Chem., vol 47, issue 3, p 243-269, March 2004.

Cox. M.L. G.A. Sturrock, P.J. Fraser, S.T. Siems, P.B. Krummel,
and S. O'Doherty, Regional sources of methyl chloride, chloroform and
dichloromethane identified from AGAGE observations at Cape Grim, Tasmania,
1998-2000., J. Atmos. Chem., vol 45, issue 1, p79-99, May 2003.

     (ii) For HFC-134a, HCFC-141b, 142b, and 22

O'Doherty, S., D.M. Cunnold, P.G. Simmonds, G. Sturrock, J. Huang,
R.G. Prinn, L.W. Porter, P.J. Fraser, P.B. Krummel, B.R. Miller,
P. Salameh, R.F. Weiss, R.H.J. Wang, A. McCulloch, S.  Montzka,
A. Manning, D. Ryall, and R.G. Derwent, Rapid growth of hydrofluorocarbon
134a and hydrochlorofluorocarbons 141b, 142b, and 22 from Advanced
Global Atmospheric Gases Experiment (AGAGE) observations at Cape Grim,
Tasmania, and Mace Head, Ireland, J.  Geophys. Res., vol 109, No D6,
D06310, 10.1029/2003JD004277, March 2004.

Miller, B.R., J. Huang, R.F. Weiss, R.G. Prinn and P.J. Fraser,
Atmospheric trend and lifetime of chlorodifluoromethane (HCFC-22)
and the global tropospheric OH concentrations, J. Geophys.  Res., 103,
13,237-13,248, 1998.


     (iii) For Halons 1211 and 1301

Sturrock, G. A., D. M. Etheridge, C. M. Trudinger, P. J. Fraser, and
A. M. Smith,  Atmospheric histories of halocarbons from analysis of
Antarctic firn air: Major Montreal Protocol species, J.  Geophys. Res.,
107(D24), 4765, doi:10.1029/2002JD002548, 2002.

Fraser, P. J., L. W. Porter, P. B. Krummel, B. Dunse, N. Derek,
and G. A. Sturrock, HCFCs, HFCs, Halons, minor CFCs and Halomethans:
The AGAGE insitu GC-MS program at Cape Grim, 1998-2000, in Baseline
Atmospheric Program (Australia) 1999-2000, Bureau of Meteorology and
CSIRO Atmospheric Research, p.93-97, 2003.

Krummel P. B., L. W. Porter, P. J. Fraser, S. B. Baly, B. Dunse,
and N. Derek, HCFCs, HFCs, Halons, minor CFCs, PCE and Halomethans:
The AGAGE insitu GC-MS program at Cape Grim, 1998-2002, in Baseline
Atmospheric Program (Australia) 2001-2002, Bureau of Meteorology and
CSIRO Atmospheric Research, p.57-64, 2004.

2. Updating of CDIAC data base.

New data submissions and revisions to existing data will occur 
approximately every six months.  Data checking and validation are 
usually achieved within 24 months of the actual measurement times.  
Hence, data will generally be submitted to CDIAC within 24 months or 
less of its acquisition.  Data are provided here for all of the ALE/GAGE/AGAGE
experiments. Please note, however, that CF2ClCFCl2 (CFC-113) and methane were
not included in the original ALE suite of measurements and only became
available in the GAGE segment of the program. Chloroform (CHCl3), 
CH3CCl2F (HCFC-141b), CH3CClF2 (HCFC-142b), CH2FCF3 (HFC-134a), and
halons 1211 and 1301 were added more recently during the AGAGE segment.

To provide outside users access to ALE/GAGE/AGAGE data in this timely way, 
some of the data provided here may be subject to change from additional
checks on the various standards against which the measurements are calibrated.
Also, the absolute calibration for the entire data set for each compound is
subject to change as better absolute standards are developed.  Hence, we
recommend strongly that, before submitting papers for publication or making 
large computer runs using the data, you contact CDIAC to ensure that you are
using the latest version of the data.  Information on possible impending 
changes not yet recorded in the data base can be obtained by contacting 
the AGAGE Principal Investigators, Ron Prinn (rprinn@mit.edu) or
Ray Weiss (rfweiss@ucsd.edu).


3. Calibration

Units are dry air mole fractions multiplied by 1 trillion (10**12) for all 
halocarbons and dry air mole fractions multiplied by 1 billion (10**9) for 
nitrous oxide, methane, carbon dioxide and hydrogen.  All of the data included 
here are referenced to the current primary standards used in the program and 
are thus in final calibrated form. 

During late 1999 and the first part of 2000, the ALE/GAGE/AGAGE program
adopted new primary standards for its entire data base. CFC-11, CFC-12,
CH3CCl3 (methyl chloroform), CCl4 (provisional), N2O, and CFC-113 values were
based upon the "SIO-1998" scale maintained at the Scripps Institution of
Oceanography (R. Weiss, et. al.). In 2006 all these data were recalibrated to
the SIO-2005 scale.  The CH4 data originally depends upon primary
standards being maintained at CSIRO by P. Steele (the "CSIRO94" scale).
The previous CSIRO methane standard is multiplied by 1.01069 to convert it
to the Tohoku University standard developed by T. Nakazawa and co-workers (Aoki
et al., 1992). Details on these primary standards and their application to
the data base can be found in Prinn et al. (2000).

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Contents of the "ale_gage_Agage" directory

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This "pub" directory, "ale_gage_Agage", contains three subdirectories:
(1) "ale", presenting all of the data from the Atmospheric Lifetime Experiment;
(2) "gage", presenting all of the data from the Global Atmospheric Gases
Experiment; and (3) "Agage", presenting all of the data processed to date from
the Advanced Global Atmospheric Gases Experiment.

The subdirectories, "ale", "gage" and "Agage", each contain two additional
subdirectories: (1) "complete", presenting data for all individual measurements
(generally made 4 times daily at each site for ALE, 12 times daily at each site
for GAGE), and about 30 times daily at each site for AGAGE; (2) "monthly",
presenting monthly summary averages of the individual measurements. Please note
that for the "ale" and "gage" data sets all of the time values are quoted in
terms the local standard time appropriate to the individual station. For the 
"Agage" data, however, all time values are in universal (UTC, formerly GMT)
time. The "Agage" subdirectory also includes a third additional subdirectory, 
(3) "precisions", presenting daily standard deviations of instrument precision
data for each compound at each station. 

Each subdirectory "complete" contains five further subdirectories, one for each
monitoring site.  For subdirectory "ale/complete", the five divisions are 
"adrigole", "barbados", "oregon", "samoa", and "tasmania". For subdirectory
"gage/complete", the five divisions are "barbados", "macehead", "oregon",
"samoa", and "tasmania" and for subdirectory "Agage/complete", the five
divisions are "barbados", "california", "macehead", "samoa", and "tasmania".
These site-specific subdirectories contain data files, which include all of the
measurements for one month at that site. The data files are named according to
the convention:

                      wxyyzzz.dat (example: aa78aug.dat)

where 

    w    is a one-character code that identifies the site (a = adrigole, 
         b = barbados, c = california, m = mace head, o = oregon, s = samoa,
         t = tasmania); Capital case (i.e. M and T) indicates results based
         on GC-MS instrument. 

    x    is a one-character code that identifies the experiment (a = ALE, 
         g = GAGE, A = Agage); 

   yy    is the year of the record, given as a two digit abbreviation 
         (i.e., 19yy);

  zzz    is the month of the record, given as a standard three letter 
         abbreviation;


The subdirectory "monthly" contains data files, which each present monthly 
summary averages for the entire record period at one site. The data files 
are named according to the convention:
                      
                      wxppp.sum (example cAmop.sum)

where
 
    w    is a one-character code that identifies the site (a = adrigole, 
         b = barbados, c = california, m = mace head, o = oregon, s = samoa,
         t = tasmania); Capital case indicates results based on GC-MS instrument.

    x    is a one-character code that identifies the experiment (a = ALE, 
         g = GAGE, A = Agage); 

  ppp    is a three character code that identifies the type of data used in
         the monthly summaries. The code  in which "ppp" is replaced by "mon"
         means that the data includes only those values considered to be
         "unpolluted" while the code "mop" means that the data incorporates all
         values, including those considered to be influenced by pollution events.

The subdirectory "precisions" in the "Agage" data base contains five further
subdirectories, one for each monitoring site, "barbados", "california",
"macehead", "samoa", and "tasmania". These site-specific subdirectories contain
data files which each present, for a given month, the daily standard deviations
for individual calibration tank measurements divide by the mean of the two
surrounding (in time) measurements (times 100; units are in percent). These data
files are named according to the convention:

                        wxyyzzz.pre

where w, x, yy, and zzz have the same meaning as for the "dat" files above.