Title: SD WACCM-X v2.1 Description: The Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X) is a comprehensive numerical model, spanning the range of altitude from the Earth’s surface to the upper thermosphere. The history files herein contain refer to a 1980-2017 specified dynamics (SD) WACCM-X version v2.1 simulation with nudging of Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) data from the surface up to ~50 km. "longrun" data is update for 1 Jan 2000 - 31 Dec 2017. The unspecified time frequency data is "hs output"; these files contain the variable instr_num which is set equal to 40 for the CHAMP satellite, 41 for GRACE, 42 for GOCE, 43 for SWARM-A, and 44 for SWARM-B. Metadata URL: https://www.earthsystemgrid.org/dataset/id/94cda8b0-82d1-404a-8f77-971e6af4196c.html