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Derived CH4 Products


Product Information

The methane (CH4) data files available for ftp on this website contain vertical profiles of atmospheric methane between 100 and 0.1 hPa pressure. These are derived using coincident measurements of atmospheric water vapor (H2O), carbon monoxide (CO), and nitrous oxide (N2O) from the EOS MLS (Earth Observing System Microwave Limb Sounder) instrument on the NASA Aura satellite. Full details of the derivation are given in Minschwaner and Manney ("Derived Methane in the Stratosphere and Lower Mesosphere from Aura Microwave Limb Sounder Measurements of Nitrous Oxide, Water Vapor, and Carbon Monoxide", J. Atmos. Chem., 2015). Each file contains CH4 profiles for one day in a standard L2GP (Level 2 Geophysical Product), HDF-EOS (version 5) format, in a manner consistent with all of the standard EOS MLS data products. The naming convention also follows that of the other EOS MLS products,

MLS-Aura_L2GP-CH4_v<xx>-c<xx>_<yyyy><ddd>.he5


where <yyyy> is the year, and <ddd> is the day number in that year (001 = Jan 1). The version and cycle numbers, "v<xx>", "c<xx>", are variable depending on the day and year of each file. Currently the dataset contains methane profiles over the date range Aug 2004 through Aug 2013, and it will be updated as newer data are processed.



Obtaining the Files

The EOS MLS Derived CH4 data products can be obtained at:

ftp://mls.jpl.nasa.gov/pub/outgoing/ch4





File Contents

Variable Name Description
Latitude latitude (degrees) of each vertical profile
Longitude longitude (degrees) of each profile
Time tai93 time
SolarZenithAngle solar zenith angle for the time and location of each profile
Pressure standard pressure levels used for all profiles
L2gpvalue methane mixing ratio
L2gpPrecision precision in methane mixing ratio based on uncertainties in the derivation technique
Convergence convergence is set equal to one for all data since this property does not apply
Quality quality is equal to 1e6 for all data since this property is not used




For additional questions, please contact Ken Minschwaner (krm@nmt.edu).




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