The MAT3FECHM or tavg3_3d_chm_Fe data product is the MERRA Data Assimilation System Chemistry 3-Dimensional chemistry on layers edges that is time averaged, 3D model levels, at reduced FV resolution. It is a history file that is intended for forcing off-line chemistry/aerosol models with the results of the reanalysis. Like other histories, they are produced from the GCM during the corrector segment of the IAU cycle. All collections from this group are at reduced horizontal resolution. MERRA, or the Modern Era Retrospective-analysis for Research and Application, is a NASA reanalysis for the satellite era (1979-2016) using the Goddard Earth Observing System Data Assimilation System Version 5 (GEOS-5 DAS). This data product contains fields that do not vary during the reanalysis. The data are on the GEOS-5 native 288 x 181 grid with 1.25 degree longitude x 1 degree latitude resolution. The files are compacted into a single daily file with the times: 1:30, 4:30, 7:30, 10:30, 13:30, 16:30, 19:30, 22:30 GMT. Data are archived in the HDF-EOS2 (Grid) format, based on HDF4. Sign Up for the MERRA-2 Mailing List Sign up for the MERRA-2 listserv to receive announcements on the latest data information, tools and services that become available, data announcements from GMAO and more! Contact the GES DISC User Services (gsfc-dl-help-disc@mail.nasa.gov) to be added to the list. MERRA-2 Science Data and Data Processing Questions Do you have a question about MERRA/MERRA-2? Take a look at the File Specification Document and if that doesn't answer your question, users can contact staff with questions on the data, data processing and science. Send questions to merra-questions@lists.nasa.gov.