Assessing the Ability of Gridded Datasets to Identify Local Extreme
Weather Events
Abstract
Reanalysis products, or gridded datasets more broadly, are often used in
place of surface observations. While they have been shown to capture
long-term statistics on global or regional levels, it is still unclear
how well they perform at the tails of the distribution, especially on
daily timescales. Four widely used datasets, ERA5, ERA5-Land, MERRA-2,
and PRISM, were assessed for their ability to capture extreme heat,
extreme cold, and heavy precipitation events over the contiguous US
(CONUS). While biases are evident in each dataset, particularly across
the western US for temperature and along the Gulf Coast for heavy
precipitation, all datasets do reasonably well in capturing extreme
events and trends. Extreme heat is better represented than extreme cold
or heavy precipitation. While no dataset emerges as a clear best for
extreme heat, PRISM generally performs best for extreme cold and the
bias-adjusted MERRA-2 dataset generally performs best for heavy
precipitation days.