Assessing the impact of sea surface temperatures on a simulated medicane using ensemble simulations

Noyelle, Robin; Ulbrich, Uwe; Becker, Nico; Meredith, Edmund P.

doi:10.5194/nhess-19-941-2019

Cited by 22 publications

(18 citation statements)

References 46 publications

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“…Several sensitivity studies investigated the impact of a uniform SST change, for instance to anticipate the possible effect of the warming of Mediterranean surface waters due to climate change. Consistent tendencies were obtained in different case studies (Homar et al, 2003, case of September 1996Miglietta et al, 2011, case of September 2006Pytharoulis, 2018, case of November 2014Noyelle et al, 2019, case of October 1996. As expected, warmer (colder) SSTs lead to more (less) intense cyclones even though changes of SST by less than ±2 • C result in no significant change in the track, duration or intensity of the cyclone.…”

Section: Introductionsupporting

confidence: 76%

“…The Meso-NH model shares its physical representation of parameters, including the surface flux parameterisation, with the French operational model AROME (Seity et al, 2011) used for the Météo-France NWP with a current horizontal grid spacing of 1.3 km. In this configuration, deep convection is explicitly represented, while shallow convection is parameterised using the eddy diffusivity Kain-Fritsch scheme (Pergaud et al, 2009).…”

Section: Atmospheric Modelmentioning

confidence: 99%

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Surface processes in the 7 November 2014 medicane from air–sea coupled high-resolution numerical modelling

Bouin

Brossier

2020

Atmos. Chem. Phys.

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Abstract. A medicane, or Mediterranean cyclone with characteristics similar to tropical cyclones, is simulated using a kilometre-scale ocean–atmosphere coupled modelling platform. A first phase leads to strong convective precipitation, with high potential vorticity anomalies aloft due to an upper-level trough. Then, the deepening and tropical transition of the cyclone result from a synergy of baroclinic and diabatic processes. Heavy precipitation results from uplift of conditionally unstable air masses due to low-level convergence at sea. This convergence is enhanced by cold pools, generated either by rain evaporation or by advection of continental air masses from northern Africa. Back trajectories show that air–sea heat exchanges moisten the low-level inflow towards the cyclone centre. However, the impact of ocean–atmosphere coupling on the cyclone track, intensity and life cycle is very weak. This is due to a sea-surface cooling 1 order of magnitude weaker than for tropical cyclones, even in the area of strong enthalpy fluxes. Surface currents have no impact. Analysing the surface enthalpy fluxes shows that evaporation is controlled mainly by the sea-surface temperature and wind. Humidity and temperature at the first level play a role during the development phase only. In contrast, the sensible heat transfer depends mainly on the temperature at the first level throughout the medicane lifetime. This study shows that the tropical transition, in this case, is dependent on processes widespread in the Mediterranean Basin, like advection of continental air, rain evaporation and formation of cold pools, and dry-air intrusion.

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Section: Introductionsupporting

confidence: 76%

Section: Atmospheric Modelmentioning

confidence: 99%

Surface processes in the 7 November 2014 medicane from air–sea coupled high-resolution numerical modelling

Bouin

Brossier

2020

Atmos. Chem. Phys.

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show abstract

“…Several sensitivity studies investigated the impact of a uniform SST change on the cyclone development and lifecycle, for instance to anticipate the possible effect of the Mediterranean surface waters warming due to climate change. Consistent tendencies were obtained on different case studies (Homar et al, 2003, case of September 1996Miglietta et al, 2011, case of September 2006Pytharoulis, 2018, case of November 2014Noyelle et al, 2019, case of October 1996, showing that, as expected, warmer (respectively colder) SSTs lead to more (resp. less) intense cyclones through a change in the surface enthalpy fluxes.…”

Section: Introductionsupporting

confidence: 81%

Surface processes in the 7 November 2014 medicane from air–sea coupled high-resolution numerical modelling

Bouin¹,

Brossier²

2019

Preprint

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<p><strong>Abstract.</strong> A medicane, or Mediterranean cyclone with characteristics similar to tropical cyclones, is simulated using a kilometre-scale ocean&#8211;atmosphere coupled modelling platform. A first baroclinic phase of the cyclone leads to strong convective precipitation, with high potential vorticity anomalies aloft due to an upper-level trough. The deepening and tropicalization of the cyclone is due first to the crossing of the upper-level jet, then to low-level convergence and uplift of conditionally unstable air masses by cold pools, resulting either from rain evaporation or from advection of continental air masses from North Africa. Backtrajectories show that air&#8211;sea heat exchanges warm and moisten the low-level inflow feeding the latent heat release during the mature phase of the medicane. However, the impact of ocean&#8211;atmosphere coupling on the cyclone track, intensity and lifecycle is very weak, due to a surface cooling one order of magnitude weaker than for tropical cyclones, even on the area of strong enthalpy fluxes. Isolating the influence of the surface parameters on the surface fluxes at sea during the different phases of the cyclone confirms the impact of the cold pools on the surface processes. The evaporation is controlled mainly by the sea surface temperature and wind, with a significant additional impact of the humidity and temperature at first level during the development phase. The sensible heat flux is influenced mainly by the temperature at first level throughout the whole medicane lifetime. This study shows that the tropical transition, in this case, is dependent on processes widespread in the Mediterranean Basin, like advection of continental air, rain evaporation, and dry air intrusion.</p>

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“…The importance of the water surface temperature in the creation, evolution, and intensity of Mediterranean cyclones has received a lot of attention in previous studies. These were mainly focused on the implementation of uniform warm or cold SST anomalies [4,8,59]. The current work approached this issue with the use of static and dynamic SST fields from various sources in the simulation of three cyclonic events.…”

Section: Discussionmentioning

confidence: 99%

The Role of Sea Surface Temperature Forcing in the Life-Cycle of Mediterranean Cyclones

et al. 2020

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Air–sea interface processes are highly associated with the evolution and intensity of marine-developed storms. Specifically, in the Mediterranean Sea, the air–ocean temperature deviations have a profound role during the several stages of Mediterranean cyclonic events. Subsequently, this enhances the need for better knowledge and representation of the sea surface temperature (SST). In this work, an analysis of the impact and uncertainty of the SST from different well-known datasets on the life-cycle of Mediterranean cyclones is attempted. Daily SST from the Real Time Global SST (RTG_SST) and hourly SST fields from the Operational SST and Sea Ice Ocean Analysis (OSTIA) and the NEMO ocean circulation model are implemented in the RAMS/ICLAMS-WAM coupled modeling system. For the needs of the study, the Mediterranean cyclones Trixi, Numa, and Zorbas were selected. Numerical experiments covered all stages of their life-cycles (five to seven days). Model results have been analyzed in terms of storm tracks and intensities, cyclonic structural characteristics, and derived heat fluxes. Remote sensing data from the Integrated Multi-satellitE Retrievals (IMERG) for Global Precipitation Measurements (GPM), Blended Sea Winds, and JASON altimetry missions were employed for a qualitative and quantitative comparison of modeled results in precipitation, maximum surface wind speed, and wave height. Spatiotemporal deviations in the SST forcing rather than significant differences in the maximum/minimum SST values, seem to mainly contribute to the differences between the model results. Considerable deviations emerged in the resulting heat fluxes, while the most important differences were found in precipitation exhibiting spatial and intensity variations reaching 100 mm. The employment of widely used products is shown to result in different outcomes and this point should be taken into consideration in forecasting and early warning systems.

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Assessing the impact of sea surface temperatures on a simulated medicane using ensemble simulations

Cited by 22 publications

References 46 publications

Surface processes in the 7 November 2014 medicane from air–sea coupled high-resolution numerical modelling

Surface processes in the 7 November 2014 medicane from air–sea coupled high-resolution numerical modelling

Surface processes in the 7 November 2014 medicane from air–sea coupled high-resolution numerical modelling

The Role of Sea Surface Temperature Forcing in the Life-Cycle of Mediterranean Cyclones

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