A hierarchy of global ocean models coupled to CESM1

Data associated with the following publication: Hsu, T. Y., Primeau, F.
W., & Magnusdottir, G. (2022). A Hierarchy of Global Ocean Models
Coupled to CESM1. Paper Abstract: We develop a hierarchy of simplified
ocean models for coupled ocean, atmosphere, and sea ice climate
simulations using the Community Earth System Model version 1 (CESM1). The
hierarchy has four members: a slab ocean model, a mixed-layer model with
entrainment and detrainment, an Ekman mixed-layer model, and an ocean
general circulation model (OGCM). Flux corrections of heat and salt are
applied to the simplified models ensuring that all hierarchy members have
the same climatology. We diagnose the needed flux corrections from
auxiliary simulations in which we restore the temperature and salinity to
the daily climatology obtained from a target CESM1 simulation. The
resulting 3-dimensional corrections contain the interannual variability
fluxes that maintain the correct vertical gradients of temperature and
salinity in the tropics. We find that the inclusion of mixed-layer
entrainment and Ekman flow produces sea surface temperature and surface
air temperature fields whose means and variances are progressively more
similar to those produced by the target CESM1 simulation. We illustrate
the application of the hierarchy to the problem of understanding the
response of the climate system to the loss of Arctic sea ice. We find that
the shifts in the positions of the mid-latitude westerly jet and of the
Inter-tropical Convergence Zone (ITCZ) in response to sea-ice loss depend
critically on upper ocean processes. Specifically, heat uptake associated
with the mixed-layer entrainment influences the shift in the westerly jet
and ITCZ. Moreover, the shift of ITCZ is sensitive to the form of Ekman
flow parameterization.