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

Abstract

However, the MCS frequency is significantly underestimated in the central US during late summer. We discuss the origin of this frequency biases and suggest strategies for model improvements.

Structure and Evolution of Mesoscale Convective Systems: Sensitivity to Cloud Microphysics in Convection‐Permitting Simulations Over the United States

“…The low bias of MCS in THOM is larger in July-August than May-June ( Figure S2). Similar summertime dry bias in CPM regional climate simulations using THOM microphysics were reported by Prein et al (2017) and attributed to weaker large-scale forcing in the summer months. Such dry biases were noticeably smaller in our MORR simulation ( Figures S2 and S3).…”

“…Similar to Prein et al (2017) who analyzed MCS precipitation in a 13-year WRF convection permitting climate simulation, we find that the simulated warm season mean patterns of MCS precipitation frequency and amount are in general agreement with observations ( Figure 5). MCSs contribute to approximately half of the warm season total precipitation in both simulations.…”

“…Despite the success in representing regional MCS precipitation variability, differences exist in almost all MCS properties between the two simulations with different microphysics parameterizations. Importantly, 3‐D NEXRAD radar data allow better characterization of MCS internal structures throughout their lifecycles that cannot be investigated using precipitation alone as in Prein et al () but are important for understanding the role of MCSs in the climate system. In general, the THOM simulation produces better agreement with observations in MCS upper‐level cloud shield and precipitation area, convective feature horizontal and vertical extents, and partitioning of precipitation types (Figure ).…”

“…This behavior is captured by the model simulations. Unlike Prein et al (2017), however, simulations using two cloud microphysics parameterizations revealed notable uncertainty in the MCS simulations. More specifically, the averaged model MCS precipitation over the central United States is biased somewhat high in MORR (13%) and low in THOM (À20%).…”

Larger Future Intensification of Rainfall in the West African Sahel in a Convection‐Permitting Model

“…Higher resolution convection‐permitting regional climate models (CPRCMs) are more successful at representing MCSs and the diurnal cycle of convection and provide a more realistic representation of precipitation extremes (Birch et al, ; Marsham et al, ; Maurer et al, ; Prein et al, ). They also improve the whole precipitation distribution where these processes represent a large share of total precipitation (e.g., Mediterranean, Berthou et al, ; United States, Prein et al, ; West Africa, Berthou et al, ; and East Africa, Finney et al, ).…”