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Dryad

CESM2 and E3SM variables used for diagnosing westerly wind events

Riley Dellaripa, Emily1; DeMott, Charlotte1; Ikuyajolu, Olawale2

Published Oct 18, 2023 on Dryad. https://doi.org/10.5061/dryad.63xsj3v88

Data files

Oct 18, 2023 version files 5.08 GB

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Abstract

This data set contains variables needed to identify and evaluate westerly wind events (WWEs) in a simulation using the Community Earth System Model version 2 (CESM2) and a simulation using the Energy Exascale Earth System Model (E3SM). The CESM2 simulation was a historical run from 1980–1999 that was restarted from the CMIP6 historical simulation. The E3SM was a 400-year pre-industrial simulation from which we analyzed the last 39 years. Only those last 39 years are included in the E3SM files. 

For both the CESM2 and E3SM simulations, meridionally-averaged zonal wind stress from 2.5°S – 2.5°N filtered from 5–90 days was used to identify westerly wind events in the Pacific Ocean (120°E – 280°E). Events were defined as patches of zonal wind stress in the time-longitude plane with zonal wind stress values of 0.04 Nm-2 or larger that lasted at least 5 days and were at least 10° longitude long. Meridional wind stress was also used along with the zonal wind stress to make spatiotemporal composite wind-stress vectors across all WWEs for each model. Outgoing longwave radiation (OLR) was also used as a proxy for convection. Again spatiotemporal composites were made of OLR centered on WWEs for each model. Finally, 1000-mb zonal wind speed was used to determine if WWEs defined by 5-90 day filtered zonal wind stress actually correspond to unfiltered westerly wind speeds.

These simulations were part of a larger set of simulations used to evalute the fidelity of WWEs in CMIP6 simulations through a variety of model diagnostics. WWEs are important to air-sea feedbacks as they can initiate ocean Kelvin waves that then propagate eastward altering the thermodynamic structure of the upper ocean. Most importantly, these WWE-generated Kelvin waves can play an important role in El Nino Southern Oscillation dynamics.