Importance of Regional Climate Model Grid Spacing for the Simulation of Heavy Precipitation in the Colorado Headwaters

Abstract

Summer and winter daily heavy precipitation events (events above the 97.5th percentile) are analyzed in regional climate simulations with 36-, 12-, and 4-km horizontal grid spacing over the headwaters of the Colorado River. Multiscale evaluations are useful to understand differences across horizontal scales and to evaluate the effects of upscaling finescale processes to coarser-scale features associated with precipitating systems.Only the 4-km model is able to correctly simulate precipitation totals of heavy summertime events. For winter events, results from the 4-and 12-km grid models are similar and outperform the 36-km simulation. The main advantages of the 4-km simulation are the improved spatial mesoscale patterns of heavy precipitation (below ;100 km). However, the 4-km simulation also slightly improves larger-scale patterns of heavy precipitation.

Connecting spatial and temporal scales of tropical precipitation in observations and the MetUM-GA6

“…Wehner et al, 2010;Kopparla et al, 2013;Prein et al, 2013;Tripathi and Dominguez, 2013). However, several of these studies compare the results on the native grid of each model with observations at resolutions that are often higher than in any of the model configurations.…”

“…This will, naturally, highlight the improved representation of the natural spatial variability of rainfall arising from local dynamical gradients, orography, etc., in higher-resolution models. Indeed, Prein et al (2013) commented that "The major advantages of high-resolution simulations are found for small scales" and that, at scales above ∼ 100 km, their higher-resolution runs show only "small advantages" over their lower-resolution runs. However, Kopparla et al (2013) point out that such comparisons differ between regions.…”

“…Fosser et al, 2015;Kendon et al, 2012;Prein et al, 2013) suggests that, while such models do exhibit improved sub-daily characteristics and diurnal cycles of rainfall, problems remain with excessive rainfall rates and too persistent precipitation events at these resolutions. It is clear that similar analyses of tropical rainfall characteristics in convectionpermitting models at resolutions < ∼ 1 km would be enlightening and of significant use in model development.…”

Local impact analysis of climate change on precipitation extremes: are high-resolution climate models needed for realistic simulations?

“…Also, other authors reported no improvements in the simulations of daily mean precipitation by the convection-permitting models compared with large-scale climate models (Chan et al, 2013;Fosser et al, 2015). Some other researchers found improvements, especially over mountainous areas (Prein et al, 2013b;Ban et al, 2014), implying region and model dependency for simulation of daily mean precipitation. In our study, the higher skill of the ALARO CNRM-CM3 model in sim- ulation of summer precipitation extremes appears to be because of a better representation of the small-scale characteristics and spatial variability relevant for convection (Fig.…”

Simulating North American mesoscale convective systems with a convection-permitting climate model

“…The nudging ensures that synoptic-scale features are similar to the observations while sub-synopticscale processes such as the upscale growth and organization of MCSs can freely evolve. The final model setup is based on a series of sensitivity test that incorporated model physics (Liu et al 2011(Liu et al , 2016 and model grid spacing (Ikeda et al 2010;Prein et al 2013b). Additional information about the simulation can be found in Liu et al (2016).…”