Amplification of high precipitation in the Western Mediterranean by Corsica island flow and convection

Transcription

1 Amplification of high precipitation in the Western Mediterranean by Corsica island flow and convection Ch. Kottmeier, Karlsruhe Institute of Technology With contributions by B. Adler, I.Kraut, B. Vogel, K.-U. Nerding, U.Corsmeier, F. Ehmele, N. Kalthoff

2 Amplification of high precipitation in the Western Mediterranean by Corsica island flow and convection Questions adressed: What are the processes amplifying precipitation over Corsica? Does Corsica effect larger scale processes? Are there downstream island effects on HIW at the French and Italian coasts? 2

3 Example of island convection and high precipitation on Aug. 26, 2009 GFS MSLP in hpa (white isolines), 500 hpa in gpdm (black isolines), and relative topography in gpdm (colour code) at 1200 UTC on 26 Aug (bottom right). The red circles indicate Corsica. 3

4 Island convection, Aug Meteosat visible images on 26 Aug at 11, 13, 14 and 15 UTC 4

5 Example of island convection and high precipitation on Aug. 26, 2009 GFS MSLP in hpa (white isolines), 500 hpa in gpdm (black isolines), and relative topography in gpdm (colour code) at 1200 UTC on 26 Aug (bottom right). The circles indicate Corsica. Accumulated rainfall in mm on 26 Aug derived by TRMM multi-satellite precipitation analysis (TMPA) 5

6 What are the processes amplifying precipitation over Corsica? studied in some detail within the HyMeX IOP1 -> Ph.D. work of Bianca Adler KITcube atmospheric observing system 6

7 Island convection Aug. 19, 2012 Cross section SW-NE Radial Doppler Lidar velocities at Corte with upwind flow towards the mountain ranges and continuous downdraft over the valley B. Adler, 2014 Top view, 2 km circle 7

8 Conceptual model of complex convective boundary layers over Corsica Diurnal evolution at Corte, valley inland B. Adler,

9 Amplification of high precipitation in the Western Mediterranean by Corsica island flow and convection Questions adressed: What are the processes amplifying precipitation over Corsica? Does Corsica effect larger scale processes? Are there downstream island effects on HIW at the French and Italian coasts? 9

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11 Downstream convection Aug Meteosat visible images on 26 Aug at 11, 13, 14 and 15 UTC 11

12 Downstream convection Aug Outflow from convective cell oder Sardinia induces convective HPE oder southern Corsica COSMO-modelling: F. Ehmele, U. Corsmeier,

13 Amplification of high precipitation in the Western Mediterranean by Corsica island flow and convection Questions adressed: What are the processes amplifying precipitation over Corsica? Does Corsica island convection effect larger scale processes? Are there downstream island effects on HIW at the French and Italian coasts? Processes identified 13

14 Are there downstream island effects on HIW at the French and Italian coasts? Processes identified: 1) Dynamical effects of the flow through the strait of Bonifacio on Genua cyclogenesis 14 F. Ehmele, U. Corsmeier, KIT Genua cyclogenesis and HPE June 15, 2010

15 Are there downstream island effects on HIW at the French and Italian coasts? Processes identified: 1) Dynamical effects of the flow through the strait of Bonifacio on Genua cyclogenesis 15 F. Ehmele, U. Corsmeier, KIT Genua cyclogenesis and HPE June 15, 2010

16 Are there downstream island effects on HIW at the French and Italian coasts? Processes identified: 1) Dynamical effects of the flow through the strait of Bonifacio on Genua cyclogenesis 16 F. Ehmele, U. Corsmeier, KIT Genua cyclogenesis and HPE June 15, 2010

17 Are there downstream island effects on HIW at the French and Italian coasts? Processes identified: 1) Dynamical effects of the flow through the strait of Bonifacio on Genua cyclogenesis 17 F. Ehmele, U. Corsmeier, KIT Genua cyclogenesis and HPE June 15, 2010

18 But there are also other processes 2) Wind driven uptake of sea salt Medicane Rolf Medicane Rolf Sea salt transport Nov. 6, 2011 Model-Setup COSMO-ART version 4.21 Initial and boundary conditions: GME Triple nesting, highest resolution: 2.8 km, 50 layers Simulation period: November 5 to November 9 Two-Moment cloud microphysics scheme (Seifert and Beheng, 2006) Wind dependent uptake of sea salt (Lundgren et al., 2013) I. Kraut, B. Vogel,

19 19 Medicane Rolf Sea salt transport Nov. 6, 2011

20 But there are also other processes 3) Moisture supply from the surrounding ocean surfaces (effected by orographic flow of Corsica) 32 Dornier128 flights 21 days during HyMEx SOP1 Eddy covariance measurements P. Gasch, A. Wieser, U. Corsmeier 20

21 Buoyancy flux B / sensible heat flux H measured Buoyancy flux B and sensible heat flux H vs. latent heat flux V Latent heat flux V measured Latent heat flux V (measured and modelled with AROME- WMED) Latent heat flux V modelled Latent heat flux V measured 21

22 Amplification of high precipitation in the Western Mediterranean by Corsica island flow and convection Summary What are the processes amplifying precipitation over Corsica? Mountain surface heating, land-sea contrast, interacting sea breeze/valley wind/slope wind circulations, tropospheric forcing Does Corsica effect larger scale processes? Yes, via downstream convection, flow around island, induced convergence lines over sea Are there downstream island effects on HIW at the French and Italian coasts? Probably, via dynamical triggering of Genua cyclogenesis, wind effects on sea salt uptake and moisture supply 22

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