Data downloaded from  https://www.esrl.noaa.gov/gmd/webdata/ccgg/trends/co2/co2_mm_mlo.txt on 4/20/2021

# --------------------------------------------------------------------
# USE OF NOAA GML DATA
# 
# These data are made freely available to the public and the
# scientific community in the belief that their wide dissemination
# will lead to greater understanding and new scientific insights.
# The availability of these data does not constitute publication
# of the data.  NOAA relies on the ethics and integrity of the user to
# ensure that GML receives fair credit for their work.  If the data 
# are obtained for potential use in a publication or presentation, 
# GML should be informed at the outset of the nature of this work.  
# If the GML data are essential to the work, or if an important 
# result or conclusion depends on the GML data, co-authorship
# may be appropriate.  This should be discussed at an early stage in
# the work.  Manuscripts using the GML data should be sent to GML
# for review before they are submitted for publication so we can
# ensure that the quality and limitations of the data are accurately
# represented.
# 
# Contact:   Pieter Tans (303 497 6678; pieter.tans@noaa.gov)
# 
# File Creation:  Wed Apr  7 09:46:58 2021
# 
# RECIPROCITY
# 
# Use of these data implies an agreement to reciprocate.
# Laboratories making similar measurements agree to make their
# own data available to the general public and to the scientific
# community in an equally complete and easily accessible form.
# Modelers are encouraged to make available to the community,
# upon request, their own tools used in the interpretation
# of the GML data, namely well documented model code, transport
# fields, and additional information necessary for other
# scientists to repeat the work and to run modified versions.
# Model availability includes collaborative support for new
# users of the models.
# --------------------------------------------------------------------
#  
#  
# See www.esrl.noaa.gov/gmd/ccgg/trends/ for additional details.
#  
# Data from March 1958 through April 1974 have been obtained by C. David Keeling
# of the Scripps Institution of Oceanography (SIO) and were obtained from the
# Scripps website (scrippsco2.ucsd.edu).
# Monthly mean CO2 constructed from daily mean values
# Scripps data downloaded from http://scrippsco2.ucsd.edu/data/atmospheric_co2
# Monthly values are corrected to center of month based on average seasonal
# cycle. Missing days can be asymmetric which would produce a high or low bias.
# Missing months have been interpolated, for NOAA data indicated by negative stdev
# and uncertainty. We have no information for SIO data about Ndays, stdv, unc
# so that they are also indicated by negative numbers