Impact of Sea Surface Temperature on COSMO Forecasts of a Medicane over the Western Mediterranean Sea

Abstract

Abstract:The paper describes and analyzes the sensitivity of an operational atmospheric model to different SST (sea surface temperature) estimates. The model's sensitivity has been analyzed in a Medicane (Mediterranean hurricane) test case. Numerical simulations have been performed using the COSMO (consortium for small-scale modeling) atmospheric model, in the COSMO-ME configuration. The model results show that the model is capable of capturing the position, timing and intensity of the cyclone. Sensitivity experiments have been carried out using different SSTs surface boundary conditions for the COSMO forecasts. Four different experiments have been carried out: the first two using SST fields obtained from the OSTIA (operational sea surface temperature and sea ice analysis) system, while the other two using the SST analyses and forecasts from MFS (Mediterranean Forecasting System, Tonani et al., 2015;Pinardi and Coppini, 2010). The different boundary conditions determine differences in the trajectory, pressure minimum and wind intensity of the simulated Medicane. The sensitivity experiments showed that a colder than real SST field determines a weakening of the minimum pressure at the vortex center. MFS SST analyses and forecasts allow the COSMO model to simulate more realistic minimum pressure values, trajectories and wind speeds. It was found that MFS SST forecast, as surface boundary conditions for COSMO-ME runs, determines a significant improvement, compared to ASCAT observations, in terms of wind intensity forecast as well as cyclone dimension and location.

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

“…This reveals that the spatial and temporal distribution of deep convection and lightning activity is more similar to those of tropical cyclones than to intense Mediterranean extra-tropical cyclones. Romaniello et al (2015) showed a significant sensitivity of model simulations to the SST field (weaker cyclone for colder SST).…”

“…In such cases, convection is expected to significantly contribute to the development of the cyclones, even to play a leading role to their intensification (Kouroutzoglou et al, 2011(Kouroutzoglou et al, , 2012Raveh-Rubin and Wernli, 2016). In these regards, the availability of humidity within the Mediterranean and from remote sources, the air-sea interactions and the underlying sea surface temperatures (SST) are expected to be crucial for the intensity of convection and its role in cyclones development (Miglietta et al, 2011;Romaniello et al, 2015;Messmer et al, 2017;Pytharoulis, 2018;Flaounas et al, 2019).…”

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

“…In such cases, convection is expected to significantly contribute to the development of the cyclones and even to play a leading role in their intensification (Kouroutzoglou et al, 2011(Kouroutzoglou et al, , 2012Raveh-Rubin and Wernli, 2016). In these regards, the availability of humidity within the Mediterranean and from remote sources, the air-sea interactions, and the underlying sea surface temperatures (SSTs) are expected to be crucial for the intensity of convection and its role in cyclone development (Miglietta et al, 2011;Romaniello et al, 2015;Messmer et al, 2017;Pytharoulis, 2018;Flaounas et al, 2019).…”

Subtropical cyclones over the oceanic basins: a review

“…The absence of turbulent heat fluxes produces weaker systems mainly during maturity and the final phase. Romaniello et al ., through numerical simulation, highlighted that colder than observed SST fields result in higher values (weaker system) of the minimum central pressure in a medicane.…”