GLOBALVIEW-CH4, 2009 is the 5th annual update of this product. Since 1999, GLOBALVIEW-CH4 has been accessed more than 4000 times by users from over 55 countries. The GLOBALVIEW-CH4 FTP server averages 32 product requests each month. This update includes 221 extended records derived from observations made by 12 laboratories from 11 countries. Data updates through 2008 (where available) have been used to derive GLOBALVIEW-CH4, 2009. The data product includes extended records from January 1, 1984 to January 1, 2009.
GLOBALVIEW-CH4 is a product of the Cooperative Atmospheric Data Integration Project. While the project is coordinated and maintained by the Carbon Cycle Greenhouse Gases Group of the National Oceanic and Atmospheric Administration, Earth System Research Laboratory (NOAA ESRL), it is a cooperative effort among the many organizations and institutions making high-quality atmospheric CH4 measurements.
GLOBALVIEW-CH4 is derived from measurements but contains no actual data. To facilitate use with carbon cycle modeling studies, the measurements have been processed (smoothed, interpolated, and extrapolated) resulting in extended records that are evenly incremented in time. Be aware that information contained in the actual data may be lost in this process. Users are encouraged to review the actual data in the literature, in data archives (CDIAC, WDCGG), or by contacting the participating laboratories.
GLOBALVIEW-CH4 is derived using the data extension and data integration techniques described by Masarie and Tans, [1995]. These techniques were developed using CO2 measurements from the NOAA ESRL cooperative air sampling network. Carbon dioxide measurement records from other laboratories have been extended and integrated with the NOAA ESRL measurements into GLOBALVIEW-CH4 with careful attention to both methodology and standard scales.
The impetus for the work done by the many cooperating organizations and institutions is to make atmospheric measurements of trace gas species that will facilitate a better understanding of the processes controlling their abundance. These and other measurements have been widely used to constrain atmospheric models that derive plausible source/sink scenarios. Serious obstacles to this approach are the paucity of sampling sites and the lack of temporal continuity among observations from different locations. Consequently, there is the potential for models to misinterpret these spatial and temporal gaps resulting in derived source/sink scenarios that are unduly influenced by the sampling distribution. GLOBALVIEW-CH4 is an attempt to address these issues of temporal discontinuity and data sparseness and is a tool intended for use in carbon cycle modeling.