A study involving research teams from across Europe has presented the first multi-model ensemble of decade-long regional climate models run at kilometer scale.
The study, the CORDEX-FPS Flagship Pilot Study on convective phenomena, which included scientists from the CMCC Foundation – Euro-Mediterranean Center on Climate Change, focused on convective precipitation events and their evolution under human-induced climate change. It selected the Alpine space as a common target area on which to experiment.
Convection-permitting models were used to produce high-resolution simulations that predicted rainfall dynamics from 2000-2009. The simulated rainfall during this period was compared with observed rainfall data sets, assessing how well the models had simulated real events.
The configuration developed by the CMCC obtained particularly good results. Moreover, results were compared with lower resolution models, revealing that high-resolution models bring a significant improvement in model performance.
Paola Mercogliano, director of the CMCC division Regional Models and geo-Hydrological Impacts, and co-author of the study, said, “Although differences still exist between ultra-high-resolution simulations and observations, it is clear that these simulations perform better than simulations with lower resolution in representing precipitation in the current climate, and thus offer a promising prospect for studies on climate and climate change at local and regional scales.
“The most significant improvements of the high-resolution simulations compared to the lower resolution ones are found especially in summer, when the low-resolution model overestimated the frequency and underestimated the intensity of daily and hourly rainfall,” he added.
The benefit of a higher resolution was most pronounced for heavy rainfall events. On average, the low-resolution models underestimated summer heavy rainfall per hour by ~40%. The high-resolution models only underestimated this rainfall by ~3%. Moreover, the uncertainty ranges in the simulations – namely the variability between the models – were also almost halved at a high resolution for wet hour frequency.
Further studies are currently being developed within the CORDEX-FPS Flagship Pilot Study on convective phenomena to demonstrate the added value of ultra-high resolution configurations.
For more information on the study, click here.