Global map showing upper-level atmospheric winds
Snapshot showing upper-level atmospheric winds associated with mid-latitude storm tracks, and the nesting strategy that allows the author to capture their genesis. The nests are located over a region of enhanced sea-surface temperatures, designed to mimic the effects of western boundary currents in triggering extratropical cyclogenesis. To put the simulations in context, even the coarsest (20 kilometer mesh) grid is fivefold finer than what is typically used in models of the global climate system. Credit: Schemm [2023], Figure 1
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Journal of Advances in Modeling Earth Systems

Climate models have many persistent and longstanding circulation biases that greatly reduce their utility for adaptation and risk mitigation studies. Among these are large and well documented biases in the representation of rain bearing systems across the globe. In the extra-tropics, these biases are manifested in the too equatorward, the too zonal orientation, and the too tepid intensification of storm tracks.

Schemm [2023] uses a nesting technique to better resolve the storm track genesis region, which allows a more physical representation of the dynamics of storm-track growth, while still simulating enough storms to wrestle meaningful signals of their mean behavior from the noise of internal variability. Doing so in an idealized context, with nesting over one hemisphere but not in the other, allows the author to simultaneously compute a control, and shows that resolving the storms, even with a grid as coarse as 5 kilometers, substantially reduces these long-standing biases. This work adds to a growing body of literature that promises an improved representation of the climate system as climate models move toward kilometer-scale (storm-resolving) grids.

Citation: Schemm, S. (2023). Toward eliminating the decades-old “too zonal and too equatorward” storm-track bias in climate models. Journal of Advances in Modeling Earth Systems, 15, e2022MS003482.

—Bjorn Stevens, Associate Editor, JAMES

Text © 2023. The authors. CC BY-NC-ND 3.0
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