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ISLSCP II GlobalView: Atmospheric Methane Concentrations
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Revision date: August 14, 2012

Summary:

The GlobalView Methane (CH4) data product contains synchronized and smoothed time series of atmospheric CH4 concentrations at selected sites that were created using the data extension and integration techniques described by Masarie and Tans (1995). The information needed to derive this time series is also in this data set, along with extensive documentation. The longest period of coverage is from 1984 to 1998 with some sites having shorter or longer temporal coverage.

These techniques were developed using CO2 measurements from the NOAA Climate Monitoring and Diagnostics Laboratory (CMDL) cooperative air sampling network and have been successfully applied to other trace gas measurement records. Methane data from other laboratories have been extended and integrated with the NOAA CMDL measurements into GlobalView-CH4 with careful attention to both methodology and standard scales.

Note that the GlobalView-CH4 data products are derived from measurements but contain no actual data. To facilitate heterogenous CH4 data use in carbon cycle modeling studies, the measurements have been processed (smoothed, interpolated, and extrapolated) resulting in extended records that are evenly incremented in time. Note that GLOBALVIEW CH4 data and documents are updated once every two years and the most up-to-date references are available at http://www.cmdl.noaa.gov/ccgg/globalview/.

There are 74 files with this data set which includes 71 *.zip data files. The other three files include 2 files with site information, one comma-delimited ASCII file (.csv), and one .dat file, and one .dat file which is a single reference marine boundary layer matrix file containing CH4 mixing ratios as a function of time and sine of latitude and is a by-product of the data extension procedure.

Additional information and GLOBALVIEW product updates maybe found at: http://www.esrl.noaa.gov/gmd/ccgg/globalview/.

Additional Documentation:

This data set is one of the products of the International Satellite Land-Surface Climatology Project, Initiative II (ISLSCP II) data collection which contains 50 global time series data sets for the ten-year period 1986 to 1995. A complete description of the data, it's derivation, project and workshop descriptions, acknowledgements, and references provided by the ISLSCP II Data Management Staff are included with this data set in the following companion files: 1_globalview_ch4_doc.pdf  and  2_gv_ch4_2001_doc.pdf.

ISLSCP II is a consistent collection of data sets that were compiled from existing data sources and algorithms, and were designed to satisfy the needs of modelers and investigators of the global carbon, water, and energy cycle. The data were acquired from a number of US and international agencies, universities, and institutions. The data and documentation have undergone two peer reviews.

ISLSCP is one of several projects of the Global Energy and Water Cycle Experiment (GEWEX) [http://www.gewex.org/] and has the lead role in addressing land-atmosphere interactions -- process modeling, data retrieval algorithms, field experiment design and execution, and the development of global data sets.

Related Data Sets:

Data Citation:

Cite this data set as follows:

Masarie, K.A. 2012. ISLSCP II GlobalView: Atmospheric Methane Concentrations. In Hall, Forrest G., G. Collatz, B. Meeson, S. Los, E. Brown de Colstoun, and D. Landis (eds.). ISLSCP Initiative II Collection. Data set. Available on-line [http://daac.ornl.gov/] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. http://dx.doi.org/10.3334/ORNLDAAC/1109

File Information:

The archived data sets for ISLSCP II have been organized by categories. This data set is in the Carbon category.

Data Set Spatial Extent: point measurements throughout the world

Westernmost Longitude: -180 W

Easternmost Longitude: 180 E

Northernmost Latitude: 90N

Southernmost Latitude: -90 S

Projection: Geographic

 

Data Set Temporal Extent: 1984 through 1998

Data File Format 

There are 74 data files with this data set, which includes 71 compressed *.zip files and 3 additional files described below:

0_gv_table_ch4.csv: contains a table with site information for all sites used in this data set and measurement labs.

0_globalview_ch4_sites.dat: contains the full names of the sites with the abbreviations, latitude, longitude, and temporal coverage for all sites used in this data set.

0_ref_mbl_mtx_ch4.dat: a single reference marine boundary layer matrix file which contains CH4 mixing ratios as a function of time and sine of latitude and is a by-product of the data extension procedure (see Masarie and Tans, 1995).

The 71 .zip files are named after the sampling site and the country or location of the site.

For example:

hat-japan_ch4.zip: Site location is Hateruma Island, Japan
pfa-alaska_ch4.zip: Site location is Poker Flats, Alaska, U.S.A.

When extrapolated 56 of the 71 zip files each contain 4 dat files.

The remaining 15 of the 71 zip files contain the following number of dat files:

aia-australia_ch4.zip: 28

alt-canada_ch4.zip: 12

brw-alaska_ch4.zip: 8

car-colorado_ch4.zip: 24

cgo-australia_ch4.zip: 8

haa-hawaii_ch4.zip: 32

itn-north_carolina_ch4.zip: 19

lef-wisconsin_ch4.zip: 19

mlo-hawaii_ch4.zip: 12

pfa-alaska_ch4.zip: 24

pocn-pacific_ocn_north_ch4.zip: 36

pocs-pacific_ocn_south_ch4.zip: 28

scsn-south_china_sea_ch4.zip: 28

spo-antarctica_s_pole_ch4.zip: 8

wlg-china_ch4.zip: 8

The .dat file names use the following format:

site/prog_data group_lab#_sampling strategy_sampling platform_qualifier_ch4.dat

where:

site/prog: 3-character alphanumeric field specifying site or program code.

data group: grouping of data within the file.

lab# (contributing laboratory): Two-character numeric field identifies the measurement laboratory (00-99).

Sampling strategy: Single alphanumeric character (0-9,a-z,A-Z) indicates the sampling strategy.

Sampling platform: Single alphanumeric character (0-9,a-z,A-Z) indicates the sampling platform.

Qualifier: Multiple alphanumeric character field (0-9,a-z,A-Z) identifies the file’s contents. Files with the “ext”, “wts”, “var”, and “seas” qualifier exist for all sites. Files with the “diu” qualifier accompany a subset of extended records derived from high-resolution measurement records where the diurnal cycle is a dominant feature of the observations.

Example data file names:

cgo_02D0_ext_ch4.dat: extended CH4 record derived from CSIRO discrete measurements at Cape Grim.

mlo_00D0_ext_ch4.dat: extended CH4 record derived from CMDL discrete measurements at Mauna Loa.

orl035_11D2_seas_ch4.dat: average seasonal cycle of CH4 derived from the LSCE discrete measurements from aircraft. Altitude bin is centered at 3.5 km.

lef011_00C3_diu_ch4.dat: average diurnal cycle of CH4 derived from CMDL continuous measurements from a tower. Sampling height is 11 m.

Refer to 0_globalview_ch4_sites.dat for site names and site information.

Refer to 0_globalview_ch4_readme.txt and 1_globalview_ch4_doc.pdf for a more complete description of the data files and naming conventions.

References:

Masarie, K.A. and P.P Tans, "Extension and Integration of Atmospheric Carbon Dioxide Data into a Globally Consistent Measurement Record. Journal of Geophysical Research, Vol. 100, No. D6, p. 11593-11610. June 1995.

Data Access:

This data is available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Data Archive Center:

Contact for Data Center Access Information:
E-mail: uso@daac.ornl.gov
Telephone: +1 (865) 241-3952