# Greenland Ice Core 60 Year Firn Air Carbon Monoxide Data 
#----------------------------------------------------------------------- 
#               World Data Center for Paleoclimatology, Boulder 
#                                  and 
#                     NOAA Paleoclimatology Program 
#----------------------------------------------------------------------- 
# NOTE: Please cite original reference when using these data, 
# plus the Online Resource and date accessed.
#
#
# Online_Resource: http://hurricane.ncdc.noaa.gov/pls/paleox/f?p=519:1:::::P1_STUDY_ID:13835
#
# Original_Source_URL: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/greenland2013co.txt
#
# Description/Documentation lines begin with #
# Data lines have no #
#
# Archive: Ice Cores
#--------------------
# Contribution_Date
#	Date: 2013-02-13
#--------------------
# Title
#	Study_Name: Greenland Ice Core 60 Year Firn Air Carbon Monoxide Data 
#--------------------
# Investigators
#	Investigators: Petrenko, V.V.; Martinerie, P.; Novelli, P.; Etheridge, D.M.; Levin, I.; Wang, Z.; Blunier, T.; Chappellaz, J.; Kaiser, J.; Lang, P.; Steele, L.P.; Hammer, S.; Mak, J.; Langenfelds, R.L.; Schwander, J.; Severinghaus, J.P.; Witrant, E.; Petron, G.; Battle, M.O.; Forster, G.; Sturges, W.T.; Lamarque, J.-F.; Steffen, K.; White, J.W.C.
#--------------------
# Description_and_Notes
# 
# Finalized carbon monoxide mixing ratios measured in firn air samples at three Greenland ice core sites 
# (NEEM, Summit and NorthGRIP). For NEEM, data from two separate boreholes are presented; data shown are 
# a combination of measurements from several laboratories.  The average atmospheric carbon monoxide history 
# over Greenland, reconstructed from the firn air data using an inverse model, is also presented. 
# All carbon monoxide mixing ratio data are on the WMO 2004 scale.
#
#--------------------
# Publication
#	Authors: V.V. Petrenko, P. Martinerie, P. Novelli, D.M. Etheridge, I. Levin, Z. Wang, T. Blunier, J. Chappellaz, J. Kaiser, P. Lang, L.P. Steele, S. Hammer, J. Mak, R.L. Langenfelds, J. Schwander, J.P. Severinghaus, E. Witrant, G. Petron, M.O. Battle, G. Forster, W.T. Sturges, J.-F. Lamarque, K. Steffen, and J.W.C. White
#       Published_Date_or_YEAR: 2012-08-02
#	Published_Title: A 60-yr record of atmospheric carbon monoxide reconstructed from Greenland firn air
#	Journal_Name: Atmospheric Chemistry and Physics Discussions
#	Volume: 12
#	Issue: 8 
#	Pages: 18993-19037
#	DOI: 10.5194/acpd-12-18993-2012
#	Abstract: We present a reconstruction of the Northern Hemisphere (NH) high latitude atmospheric carbon monoxide (CO) mole fraction from Greenland firn air. Firn air samples were collected at three deep ice core sites in Greenland (NGRIP in 2001, Summit in 2006 and NEEM in 2008). CO records from the three sites agree well with each other as well as with recent atmospheric measurements, indicating that CO is well preserved in the firn at these sites. CO atmospheric history was reconstructed back to the year 1950 from the measurements using a combination of two forward models of gas transport in firn and an inverse model. The reconstructed history suggests that Arctic CO was already higher in 1950 than it is today. CO mole fractions rose gradually until the 1970s and peaked in the 1970s or early 1980s, followed by a decline to today's levels. We compare the CO history with the atmospheric histories of methane, light hydrocarbons, molecular hydrogen, CO stable isotopes and hydroxyl radical (OH), as well as with published CO emission inventories and results of a historical run from a chemistry-transport model. We find that the reconstructed Greenland CO history cannot be reconciled with available emission inventories unless large changes in OH are assumed. We argue that the available CO emission inventories chronically underestimate NH emissions, and fail to capture the emission decline starting in the late 1970s, which was most likely due to reduced emissions from road transportation in North America and Europe.
#
#---------------------
# Funding_Agency 
#	Funding_Agency_Name: US National Oceanic and Atmospheric Administration
#	Grant: Postdoctoral Fellowship in Climate and Global Change
#---------------------
#	Funding_Agency_Name: US National Science Foundation
#	Grant: 0632222, 0806387, 0520460
#-------------------- 
# Site_Information 
#       Site_Name: GreenlandCO
#	Location: North America>Greenland
#	Country: 
#	Northernmost_Latitude: 77.43
# 	Southernmost_Latitude: 72.53
# 	Easternmost_Longitude: -38.28
# 	Westernmost_Longitude: -51.10
# 	Elevation:   m 
#------------------   
# Data_Collection  
#	Core_Name: Greenland2013CO
#	First_Year: 1950
#	Last_Year: 2008
#	Time_Unit: AD
#	Core_Length:    
#	Notes: 
#------------------
# Chronology 
#
# 
# 
#------------------
# Variables
# 
# End Description/Documentation (lines begin with #)
# Data lines follow (have no #)
# Data line variables format:  Variables list, one per line, shortname-tab-longname-tab-longname components (9 components: material, error, units, anomaly, period, archive, detail, method, C or N for Character or Numeric data) 
# Data line format: tab-delimited text, variable short name as header
# This is the average atmospheric CO mixing ratio scenario reconstructed from the firn air measurements	
#
## age_AD	Age (years AD), , ,AD, , , , ,N
## CO_ppb	CO concentration (ppb), , , ppb, , , , , N
# 
#------------------
# Data:
# Missing_Values: NA
age_AD	CO_ppb
1950.04	144.61
1950.12	144.677
1950.21	144.744
1950.29	144.811
1950.37	144.878
1950.46	144.944
1950.54	145.011
1950.62	145.077
1950.71	145.144
1950.79	145.21
1950.87	145.276
1950.96	145.343
1951.04	145.409
1951.12	145.475
1951.21	145.541
1951.29	145.607
1951.37	145.672
1951.46	145.738
1951.54	145.803
1951.62	145.869
1951.71	145.934
1951.79	146
1951.87	146.065
1951.96	146.13
1952.04	146.195
1952.12	146.26
1952.21	146.325
1952.29	146.39
1952.37	146.454
1952.46	146.519
1952.54	146.583
1952.62	146.648
1952.71	146.712
1952.79	146.776
1952.87	146.84
1952.96	146.904
1953.04	146.968
1953.12	147.032
1953.21	147.096
1953.29	147.159
1953.37	147.223
1953.46	147.286
1953.54	147.349
1953.62	147.413
1953.71	147.476
1953.79	147.539
1953.87	147.601
1953.96	147.664
1954.04	147.727
1954.12	147.789
1954.21	147.852
1954.29	147.914
1954.37	147.976
1954.46	148.038
1954.54	148.1
1954.62	148.162
1954.71	148.224
1954.79	148.285
1954.87	148.347
1954.96	148.408
1955.04	148.47
1955.12	148.531
1955.21	148.592
1955.29	148.653
1955.37	148.714
1955.46	148.774
1955.54	148.835
1955.62	148.895
1955.71	148.956
1955.79	149.016
1955.87	149.076
1955.96	149.136
1956.04	149.196
1956.12	149.255
1956.21	149.315
1956.29	149.374
1956.37	149.434
1956.46	149.493
1956.54	149.552
1956.62	149.611
1956.71	149.67
1956.79	149.729
1956.87	149.787
1956.96	149.846
1957.04	149.904
1957.12	149.962
1957.21	150.02
1957.29	150.078
1957.37	150.136
1957.46	150.194
1957.54	150.251
1957.62	150.308
1957.71	150.366
1957.79	150.423
1957.87	150.48
1957.96	150.536
1958.04	150.593
1958.12	150.65
1958.21	150.706
1958.29	150.762
1958.37	150.819
1958.46	150.875
1958.54	150.93
1958.62	150.986
1958.71	151.042
1958.79	151.097
1958.87	151.152
1958.96	151.207
1959.04	151.262
1959.12	151.317
1959.21	151.372
1959.29	151.427
1959.37	151.481
1959.46	151.535
1959.54	151.589
1959.62	151.643
1959.71	151.697
1959.79	151.751
1959.87	151.804
1959.96	151.857
1960.04	151.911
1960.12	151.964
1960.21	152.017
1960.29	152.069
1960.37	152.122
1960.46	152.174
1960.54	152.227
1960.62	152.279
1960.71	152.331
1960.79	152.382
1960.87	152.434
1960.96	152.486
1961.04	152.537
1961.12	152.588
1961.21	152.639
1961.29	152.69
1961.37	152.741
1961.46	152.791
1961.54	152.841
1961.62	152.892
1961.71	152.942
1961.79	152.991
1961.87	153.041
1961.96	153.091
1962.04	153.14
1962.12	153.189
1962.21	153.238
1962.29	153.287
1962.37	153.336
1962.46	153.384
1962.54	153.432
1962.62	153.481
1962.71	153.529
1962.79	153.577
1962.87	153.624
1962.96	153.672
1963.04	153.719
1963.12	153.766
1963.21	153.813
1963.29	153.86
1963.37	153.906
1963.46	153.953
1963.54	153.999
1963.62	154.045
1963.71	154.091
1963.79	154.137
1963.87	154.182
1963.96	154.227
1964.04	154.273
1964.12	154.318
1964.21	154.362
1964.29	154.407
1964.37	154.451
1964.46	154.495
1964.54	154.54
1964.62	154.583
1964.71	154.627
1964.79	154.67
1964.87	154.714
1964.96	154.757
1965.04	154.8
1965.12	154.842
1965.21	154.885
1965.29	154.927
1965.37	154.969
1965.46	155.011
1965.54	155.053
1965.62	155.094
1965.71	155.136
1965.79	155.177
1965.87	155.217
1965.96	155.258
1966.04	155.299
1966.12	155.339
1966.21	155.379
1966.29	155.419
1966.37	155.458
1966.46	155.498
1966.54	155.537
1966.62	155.576
1966.71	155.615
1966.79	155.653
1966.87	155.692
1966.96	155.73
1967.04	155.768
1967.12	155.806
1967.21	155.843
1967.29	155.88
1967.37	155.917
1967.46	155.954
1967.54	155.991
1967.62	156.027
1967.71	156.063
1967.79	156.099
1967.87	156.135
1967.96	156.17
1968.04	156.206
1968.12	156.241
1968.21	156.275
1968.29	156.31
1968.37	156.344
1968.46	156.378
1968.54	156.412
1968.62	156.445
1968.71	156.479
1968.79	156.512
1968.87	156.545
1968.96	156.577
1969.04	156.609
1969.12	156.641
1969.21	156.673
1969.29	156.705
1969.37	156.736
1969.46	156.767
1969.54	156.798
1969.62	156.828
1969.71	156.859
1969.79	156.889
1969.87	156.918
1969.96	156.948
1970.04	156.977
1970.12	157.006
1970.21	157.034
1970.29	157.063
1970.37	157.091
1970.46	157.119
1970.54	157.146
1970.62	157.173
1970.71	157.2
1970.79	157.227
1970.87	157.253
1970.96	157.279
1971.04	157.305
1971.12	157.331
1971.21	157.356
1971.29	157.381
1971.37	157.405
1971.46	157.43
1971.54	157.454
1971.62	157.477
1971.71	157.501
1971.79	157.524
1971.87	157.546
1971.96	157.569
1972.04	157.591
1972.12	157.613
1972.21	157.634
1972.29	157.655
1972.37	157.676
1972.46	157.696
1972.54	157.716
1972.62	157.736
1972.71	157.756
1972.79	157.775
1972.87	157.794
1972.96	157.812
1973.04	157.83
1973.12	157.848
1973.21	157.865
1973.29	157.882
1973.37	157.899
1973.46	157.915
1973.54	157.931
1973.62	157.947
1973.71	157.962
1973.79	157.977
1973.87	157.991
1973.96	158.005
1974.04	158.019
1974.12	158.032
1974.21	158.045
1974.29	158.058
1974.37	158.07
1974.46	158.081
1974.54	158.093
1974.62	158.104
1974.71	158.114
1974.79	158.125
1974.87	158.134
1974.96	158.144
1975.04	158.153
1975.12	158.161
1975.21	158.169
1975.29	158.177
1975.37	158.184
1975.46	158.191
1975.54	158.197
1975.62	158.203
1975.71	158.209
1975.79	158.214
1975.87	158.219
1975.96	158.223
1976.04	158.227
1976.12	158.23
1976.21	158.233
1976.29	158.235
1976.37	158.237
1976.46	158.239
1976.54	158.24
1976.62	158.24
1976.71	158.24
1976.79	158.24
1976.87	158.239
1976.96	158.238
1977.04	158.236
1977.12	158.234
1977.21	158.231
1977.29	158.227
1977.37	158.224
1977.46	158.219
1977.54	158.215
1977.62	158.209
1977.71	158.203
1977.79	158.197
1977.87	158.19
1977.96	158.183
1978.04	158.175
1978.12	158.167
1978.21	158.158
1978.29	158.148
1978.37	158.138
1978.46	158.128
1978.54	158.117
1978.62	158.105
1978.71	158.093
1978.79	158.081
1978.87	158.067
1978.96	158.054
1979.04	158.039
1979.12	158.025
1979.21	158.009
1979.29	157.993
1979.37	157.977
1979.46	157.96
1979.54	157.942
1979.62	157.924
1979.71	157.905
1979.79	157.885
1979.87	157.865
1979.96	157.845
1980.04	157.824
1980.12	157.802
1980.21	157.78
1980.29	157.757
1980.37	157.733
1980.46	157.709
1980.54	157.684
1980.62	157.659
1980.71	157.633
1980.79	157.607
1980.87	157.58
1980.96	157.552
1981.04	157.524
1981.12	157.495
1981.21	157.465
1981.29	157.435
1981.37	157.404
1981.46	157.372
1981.54	157.34
1981.62	157.308
1981.71	157.274
1981.79	157.24
1981.87	157.206
1981.96	157.17
1982.04	157.134
1982.12	157.098
1982.21	157.061
1982.29	157.023
1982.37	156.985
1982.46	156.945
1982.54	156.906
1982.62	156.865
1982.71	156.824
1982.79	156.782
1982.87	156.74
1982.96	156.697
1983.04	156.653
1983.12	156.609
1983.21	156.564
1983.29	156.518
1983.37	156.472
1983.46	156.425
1983.54	156.377
1983.62	156.329
1983.71	156.28
1983.79	156.23
1983.87	156.18
1983.96	156.129
1984.04	156.077
1984.12	156.025
1984.21	155.972
1984.29	155.918
1984.37	155.864
1984.46	155.809
1984.54	155.753
1984.62	155.697
1984.71	155.64
1984.79	155.582
1984.87	155.523
1984.96	155.464
1985.04	155.405
1985.12	155.344
1985.21	155.283
1985.29	155.221
1985.37	155.159
1985.46	155.096
1985.54	155.032
1985.62	154.967
1985.71	154.902
1985.79	154.836
1985.87	154.77
1985.96	154.703
1986.04	154.635
1986.12	154.566
1986.21	154.497
1986.29	154.427
1986.37	154.357
1986.46	154.285
1986.54	154.213
1986.62	154.141
1986.71	154.068
1986.79	153.994
1986.87	153.919
1986.96	153.844
1987.04	153.768
1987.12	153.692
1987.21	153.615
1987.29	153.537
1987.37	153.458
1987.46	153.379
1987.54	153.299
1987.62	153.219
1987.71	153.138
1987.79	153.056
1987.87	152.974
1987.96	152.891
1988.04	152.807
1988.12	152.723
1988.21	152.638
1988.29	152.552
1988.37	152.466
1988.46	152.379
1988.54	152.292
1988.62	152.204
1988.71	152.115
1988.79	152.026
1988.87	151.936
1988.96	151.846
1989.04	151.755
1989.12	151.663
1989.21	151.571
1989.29	151.478
1989.37	151.384
1989.46	151.29
1989.54	151.195
1989.62	151.1
1989.71	151.004
1989.79	150.908
1989.87	150.811
1989.96	150.713
1990.04	150.615
1990.12	150.517
1990.21	150.418
1990.29	150.318
1990.37	150.217
1990.46	150.117
1990.54	150.015
1990.62	149.913
1990.71	149.811
1990.79	149.708
1990.87	149.604
1990.96	149.5
1991.04	149.396
1991.12	149.291
1991.21	149.185
1991.29	149.079
1991.37	148.973
1991.46	148.866
1991.54	148.759
1991.62	148.651
1991.71	148.542
1991.79	148.434
1991.87	148.324
1991.96	148.215
1992.04	148.104
1992.12	147.994
1992.21	147.883
1992.29	147.771
1992.37	147.66
1992.46	147.547
1992.54	147.435
1992.62	147.322
1992.71	147.208
1992.79	147.094
1992.87	146.98
1992.96	146.866
1993.04	146.751
1993.12	146.636
1993.21	146.52
1993.29	146.404
1993.37	146.288
1993.46	146.171
1993.54	146.055
1993.62	145.937
1993.71	145.82
1993.79	145.702
1993.87	145.584
1993.96	145.466
1994.04	145.348
1994.12	145.229
1994.21	145.11
1994.29	144.991
1994.37	144.871
1994.46	144.752
1994.54	144.632
1994.62	144.512
1994.71	144.392
1994.79	144.272
1994.87	144.151
1994.96	144.031
1995.04	143.91
1995.12	143.789
1995.21	143.668
1995.29	143.547
1995.37	143.426
1995.46	143.305
1995.54	143.184
1995.62	143.063
1995.71	142.942
1995.79	142.821
1995.87	142.699
1995.96	142.578
1996.04	142.457
1996.12	142.336
1996.21	142.215
1996.29	142.094
1996.37	141.974
1996.46	141.853
1996.54	141.732
1996.62	141.612
1996.71	141.492
1996.79	141.372
1996.87	141.252
1996.96	141.133
1997.04	141.013
1997.12	140.894
1997.21	140.775
1997.29	140.657
1997.37	140.539
1997.46	140.421
1997.54	140.304
1997.62	140.187
1997.71	140.07
1997.79	139.954
1997.87	139.838
1997.96	139.723
1998.04	139.608
1998.12	139.494
1998.21	139.381
1998.29	139.268
1998.37	139.155
1998.46	139.043
1998.54	138.932
1998.62	138.822
1998.71	138.712
1998.79	138.603
1998.87	138.495
1998.96	138.387
1999.04	138.281
1999.12	138.175
1999.21	138.07
1999.29	137.967
1999.37	137.864
1999.46	137.762
1999.54	137.661
1999.62	137.561
1999.71	137.462
1999.79	137.364
1999.87	137.267
1999.96	137.172
2000.04	137.077
2000.12	136.984
2000.21	136.892
2000.29	136.801
2000.37	136.712
2000.46	136.624
2000.54	136.537
2000.62	136.451
2000.71	136.367
2000.79	136.284
2000.87	136.202
2000.96	136.122
2001.04	136.042
2001.12	135.964
2001.21	135.888
2001.29	135.812
2001.37	135.737
2001.46	136.086
2001.54	136.019
2001.62	135.954
2001.71	135.888
2001.79	135.824
2001.87	135.76
2001.96	135.696
2002.04	135.633
2002.12	135.569
2002.21	135.506
2002.29	135.443
2002.37	135.379
2002.46	135.316
2002.54	135.252
2002.62	135.189
2002.71	135.124
2002.79	135.06
2002.87	134.995
2002.96	134.929
2003.04	134.863
2003.12	134.796
2003.21	134.729
2003.29	134.661
2003.37	134.592
2003.46	134.523
2003.54	134.452
2003.62	134.381
2003.71	134.309
2003.79	134.237
2003.87	134.163
2003.96	134.089
2004.04	134.014
2004.12	133.938
2004.21	133.861
2004.29	133.784
2004.37	133.705
2004.46	133.626
2004.54	133.547
2004.62	133.466
2004.71	133.385
2004.79	133.303
2004.87	133.221
2004.96	133.138
2005.04	133.055
2005.12	132.972
2005.21	132.888
2005.29	132.803
2005.37	132.719
2005.46	132.634
2005.54	132.55
2005.62	132.465
2005.71	132.38
2005.79	132.295
2005.87	132.211
2005.96	132.127
2006.04	132.043
2006.12	131.959
2006.21	131.876
2006.29	131.793
2006.37	131.71
2006.46	131.628
2006.54	131.546
2006.62	131.464
2006.71	131.383
2006.79	131.301
2006.87	131.22
2006.96	131.139
2007.04	131.058
2007.12	130.978
2007.21	130.897
2007.29	130.817
2007.37	130.737
2007.46	130.657
2007.54	130.577
2007.62	130.497
2007.71	130.417
2007.79	130.337
2007.87	130.258
2007.96	130.178
2008.04	130.099
2008.12	130.02
2008.21	129.94
2008.29	129.861
2008.37	129.782
2008.46	129.702
2008.54	129.623