High Impact Weather (HIW), particularly Heavy Precipitation Events (HPE), are common phenomena affecting the Western Mediterranean (WMED) especially in the fall period. Understanding and evaluating the capability to adequately represent such events in model simulations is one of the main goals of the Hydrological cycle in the Mediterranean Experiment (HyMeX) and the main motivation of this investigation. In order to gain a better knowledge of the representation of HPE and related processes across a broad range of modelling spatial-scales, simulations at different horizontal resolutions (from 2 km to 20 km) are considered in a seamless weather-climate approach. The performance of nine models is compared by analysing precipitation, as well as convection-relevant parameters. An Intensive Observation Period (IOP12) from the HyMeX-SOP1 (Special Observation Period) campaign is used to illustrate the results. During IOP12, HPE affected the whole north-WMED region, from Spain to Italy, as a consequence of Mesoscale Convective Systems (MCSs) which initiated and intensified in the area. Results show that: (i) the timing of the maximum precipitation seems to be linked with the representation of large-scale conditions rather than differences among models, (ii) Convection Permitting Models (CPMs) exhibit differences among each other, but better represent the short-intense convective events (iii) among the four convection-parameterised models investigated, only the higher resolution forecast model was able to represent similar intense and short lasting events as CPMs on the same grid. All four convection-parameterised models produce larger number of weak and long-lasting events, especially Regional Climate Models (RCMs). These differences do not seem to come from mean moisture or Convective Available Potential Energy (CAPE) which are in the range of the CPMs, but rather from the representation of convection, such as differences in the variability and vertical distribution of moisture as well as vertical wind velocity in the lower atmosphere.
A seamless weather-climate multi-model intercomparison on the representation of high impact weather in the western Mediterranean: HyMeX IOP12
S Davolio;
2015
Abstract
High Impact Weather (HIW), particularly Heavy Precipitation Events (HPE), are common phenomena affecting the Western Mediterranean (WMED) especially in the fall period. Understanding and evaluating the capability to adequately represent such events in model simulations is one of the main goals of the Hydrological cycle in the Mediterranean Experiment (HyMeX) and the main motivation of this investigation. In order to gain a better knowledge of the representation of HPE and related processes across a broad range of modelling spatial-scales, simulations at different horizontal resolutions (from 2 km to 20 km) are considered in a seamless weather-climate approach. The performance of nine models is compared by analysing precipitation, as well as convection-relevant parameters. An Intensive Observation Period (IOP12) from the HyMeX-SOP1 (Special Observation Period) campaign is used to illustrate the results. During IOP12, HPE affected the whole north-WMED region, from Spain to Italy, as a consequence of Mesoscale Convective Systems (MCSs) which initiated and intensified in the area. Results show that: (i) the timing of the maximum precipitation seems to be linked with the representation of large-scale conditions rather than differences among models, (ii) Convection Permitting Models (CPMs) exhibit differences among each other, but better represent the short-intense convective events (iii) among the four convection-parameterised models investigated, only the higher resolution forecast model was able to represent similar intense and short lasting events as CPMs on the same grid. All four convection-parameterised models produce larger number of weak and long-lasting events, especially Regional Climate Models (RCMs). These differences do not seem to come from mean moisture or Convective Available Potential Energy (CAPE) which are in the range of the CPMs, but rather from the representation of convection, such as differences in the variability and vertical distribution of moisture as well as vertical wind velocity in the lower atmosphere.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
