Picture: Water droplets. Credit: Inspired Images (Pixabay).
Using finer grids in global climate models could improve the simulation of precipitation extremes. This is an expected outcome because it would produce a finer representation of spatial contrasts (shape of land masses, sea-land complex interactions, etc). However, this expectation has not been verified using a consistent multi-model framework.
To address this issue, CLEX researchers and international colleagues used six of the latest generation global climate models to assess the influence of increasing spatial resolution on model performance. High and low-resolution runs from each of these models were compared.
Both high- and low-resolution model versions were kept as similar as possible to allow the influence of higher resolution to be assessed exclusively.
The researchers focused their attention on the recent climatology (1985-2014) of annual extremes for daily precipitation over global land. The model results were also compared to three in situ-based and satellite-based observations to take into account observational uncertainties.
The analysis highlights good agreement between all six models that precipitation extremes were more intense at higher resolution.
However, the findings suggest that increasing spatial resolution alone is not sufficient to obtain a systematic improvement in the simulation of precipitation extremes, and other improvements (e.g. physics, tuning) may be required.
Finally, they found that the spread among observations is substantial, which makes the quantitative evaluation of model performance difficult.
- Paper: Bador, M., Boé, J., Terray, L., Alexander, L. V., Baker, A., Bellucci, A., et al. ( 2020). Impact of higher spatial atmospheric resolution on precipitation extremes over land in global climate models. Journal of Geophysical Research: Atmospheres, 125, e2019JD032184. https://doi.org/10.1029/2019JD032184