Characterization of medicanes with a minimal number of geopotential levels

Abstract

Medicanes are tropical-like cyclones that develop in the Mediterranean Sea. Due to their harmful potential, the study of medicanes has captured great attention from the scientific community. In the context of a changing climate, their future climatological characterization can only be achieved using climate model output. A frequently used method to characterize the thermal structure of medicanes is the cyclone phase space (CPS) described by Hart (2003). This requires geopotential data from 300 to 900 hPa every 50 hPa. However, in long, high-resolution climate simulations, model output requires very high storage space and only data from a few geopotential levels are saved. To overcome the lack of geopotential data at some levels, available data are vertically interpolated to obtain data for the 13 levels required. In this work, we use high horizontal resolution data from the ERA-5 reanalysis (1979-2018) to analyse the climatology of medicanes simulated using the 13 vertical levels required according to Hart (2003), as well as different combinations of geopotential data from a few selected levels. Our results allow us to propose, for the first time, a limited set of recommended geopotential levels required for an adequate climatological characterization of medicanes in the perspective of long climate change simulations, taking into account the associated limitations of output data storage.

Mediterranean cyclones: Current knowledge and open questions on dynamics, prediction, climatology and impacts

“…They confirmed this trend considering a higher number of medicanes, though an important inter-model uncertainty remained, as a few GCM-RCM pairs showed a decreasing intensity trend. More recently, González-Alemán et al (2019) and Gutiérrez-Fernández et al (2021) used coupled RCM models to further investigate the effect of explicitly resolved air-sea interactions on medicanes future trends. Despite the possible impacts of a negative intensity feedback in coupled simulations due to the SST cooling effect of strong winds, the main future trends of medicanes were not different in these two studies.…”

Moisture Sources for the Precipitation of Tropical-like Cyclones in the Mediterranean Sea: A Case of Study

“…However, Gaertner et al [51] highlighted that the method proposed by Picornell et al [52] is suitable for identifying TLCs. Previously, De la Vara et al [40] applied this algorithm for characterizing medicanes, while González-Alemán et al [19] obtained medcyclone trajectories by using the MSLP and the 700 hPa wind field and, then, filtered the TLCs using the cyclone phase space method proposed by Hart [53]. Here, we searched for potential TLCs over the domain 27-48 • N and 9 • W-48 • E (see Figure 1), in agreement with Zhang et al [7].…”

“…The ERA5 reanalysis has a grid spacing of 0.25 • × 0.25 • , 137 vertical levels, and 1-hourly temporal resolution. This reanalysis has been recently used for studying TLCs (e.g., [7,40]). Furthermore, we estimated the precipitation produced by the study case using the Multi-Source Weighted-Ensemble Precipitation (MSWEP) database [41] with a grid spacing of 0.1 • × 0.1 • and 3-hourly temporal resolution.…”

Comment on wcd-2021-55

“…Cavicchia et al 2014a). Recent studies used dynamical downscaling of ERA-Interim reanalysis (Gaertner et al, 2018;Ragone et al, 2018) and ERA5 reanalysis (Zhang et al, 2020;de la Vara et al, 2021) to identify medicanes in a climatological framework. Results showed rather large differences in their climatologies even among same model simulations but using different parameterizations.…”