Merged L2 methane data from 2003 to 2024 derived from satellite observations

This dataset contains Level 2 (L2) atmospheric column-average dry-air mole fractions of atmospheric methane (XCH4) derived from satellite data and related variables. The dataset was generated by merging an ensemble of different L2 input products with the ensemble median algorithm (EMMA) in its version 5.1. The different L2 input products were retrieved from multiple space-born instruments and retrieval algorithms. The dataset was validated against the ground-based Total Carbon Column Observing Network (TCCON), showing long-term stability and no significant biases. The corresponding publication describing this dataset, the merging algorithm used to generate this dataset, the input and output data, as well as the validation results will be made available soon. A gridded version of this dataset in Obs4MIPs format and monthly 1ºx1º resolution, together with its documentation and validation results will be made available through the Copernicus Climate Data Store. Data format The data set is a L2 product that contains, for each individual sounding, information on the XCH4 and its uncertainty, and other related variables such as time, longitude and latitude of the measurement, averaging kernels and a priori profiles, etc. The data content is conform with ESA’s Product Specification Document (PSD) for the Essential Climate Variable Greenhouse Gases. The data format is classic NetCDF and the product is in-line with CF (Climate and Forecasting) convention 1.6. All the variables contained in the dataset are explained in each file. The data files are stored in multiple .zip files, each of them containing the data corresponding to multiple years. Each of the .nc files contains data corresponding to one day, which is reflected in the filename, i.e. IUP-GHG-L2-CH4-EMMA-YYYYMMDD-v5.1.nc, where YYYY is the year, MM the month and DD the day.