edu.ucar.opensky::articles:42299 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-24T18:11:41.040493 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.net/ark:/85065/d7v12932 https://doi.org/10.22033/ESGF/CMIP6.10071 https Related Dataset #1 NCAR CESM2-WACCM model output prepared for CMIP6 CMIP historical https://doi.org/10.22033/ESGF/CMIP6.7733 https Related Dataset #2 NCAR CESM2 model output prepared for CMIP6 CMIP piControl https://doi.org/10.24381/cds.143582cf https Related Dataset #3 Complete ERA5 global atmospheric reanalysis https://doi.org/10.17874/800dee57d13 https Related Report #1 SPARC Report No. 10, WCRP Report 6/2021 A momentum budget study of the semi‐annual oscillation in the Whole Atmosphere Community Climate Model 2024-07-01T00:00:00Z publication https://n2t.net/ark:/85065/d7v12932 https://doi.org/10.1002/qj.4782 Jaison, A. M. author Gray, L. J. author Osprey, S. author Smith, Anne K. author García, Rolando R. author UCAR/NCAR - Library publisher The representation of the semi&#8208;annual oscillation (SAO) in climate models shows a common easterly bias of several tens of metres per second compared to observations. These biases could be due to deficiencies in eastward tropical wave forcing, the position or strength of the climatological summertime jet or the strength/timing of the Brewer&#8211;Dobson circulation. This motivates further analysis of the momentum budget of the upper stratosphere within models and a more detailed comparison with reanalyses to determine the origin of the bias. In this study, the transformed Eulerian mean momentum equation is used to evaluate the different forcing terms that contribute to the SAO in the MERRA2 reanalysis dataset. This is then compared with the equivalent analysis using data from a climate simulation of the Whole Atmosphere Community Climate Model (WACCM). The comparison shows that WACCM underestimates eastward forcing by both resolved and parameterised waves at equatorial latitudes when compared with MERRA2 and also has a weaker tropical upwelling above&#160;1&#8201;hPa. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication <style type="text/css"></style><span style="font-family:Arial;font-size:10pt;font-style:normal;" data-sheets-root="1">Copyright author(s). This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.</span> None eng geoscientificInformation