# Greenland Ice Core 60 Year Firn Air Carbon Monoxide Data 
#----------------------------------------------------------------------- 
#               World Data Center for Paleoclimatology, Boulder 
#                                  and 
#                     NOAA Paleoclimatology Program 
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# 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
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# Description/Documentation lines begin with #
# Data lines have no #
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# 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.
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# 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: NEEM
#	Location: North America>Greenland
#	Country: 
#	Northernmost_Latitude: 77.43
# 	Southernmost_Latitude: 77.43
# 	Easternmost_Longitude: -51.10
# 	Westernmost_Longitude: -51.10
# 	Elevation: 2500 m 
#------------------   
# Data_Collection  
#	Core_Name: NEEM-EU2008CO
#	First_Year: 1950
#	Last_Year: 2008
#	Time_Unit: AD
#	Core_Length: 77.75
#	Notes: 
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# Chronology 
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# 
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# Variables
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# 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
#
## depth_m	Depth (m), , , m, , , , ,N
## CO_ppb	CO concentration (ppb), , , ppb, , , , , N
## CO_ppb_err	CO concentration (ppb) error, , , ppb, , , , , N
# 
#------------------
# Data:
# Missing_Values: NA
depth_m	CO_ppb	CO_ppb_err
0.00	88.3	3.6
4.90	106.3	1.7
10.10	134.3	1.7
14.80	133.7	1.7
19.75	135.9	3.0
27.54	136.8	1.7
34.72	134.8	1.7
50.00	132.8	1.7
57.40	134.3	1.7
59.90	135.9	1.7
61.95	135.2	1.7
63.85	140.4	1.7
65.75	146.1	1.7
68.05	154.5	3.3
70.05	157.0	1.7
72.00	152.4	1.7
74.08	146.7	1.7
75.90	141.7	3.1
77.75	135.9	1.7