1. Analysis of convective indices over the northeastern Adriatic Karmen Babić, Gabrijela Poljak, Marko Kvakić, Maja Telišman Prtenjak Croatian-USA Workshop on Mesometeorology 18-20 June 2012, Ekopark Kraš Resort Andrija Mohorovičić Geophysical Institute, Department of Geophysics, Faculty of Science, University of Zagreb

2. Introduction 2Analysis of convective indices over the northeastern Adriatic19 June 2012 The northeastern Adriatic coast – a good example of a very complex coastline Target of research regarding the sea/land breeze phenomenon Specific features in the mesoscale wind field – the convergence zone Previous studies of SB – primarily focused on the wind characteristics The relationship between SB and Cb clouds was not investigated

3. Potential SB – Cb relationship 3Analysis of convective indices over the northeastern Adriatic19 June 2012 We focus on the summer months (from June to September), when the SB development is frequent (e.g., Prtenjak and Grisogono, 2007) Surface measurements for two meteorological stations - the Pula-Airport and Pazin (Fig) observed during a 10-year period (1997–2006) Pula-Airport Number of SB days563 SB frequency51% Pazin Number of days with Cb clouds in Pazin99 Frequency of the daytime Cb during warm months8.4% Pula-Airport Pazin Number of days with SB and Cb clouds51 Frequency of the daytime Cb during SB events at the coast9.1% StationφλH (m)D (km)NMV Pula- Airport 44° 54 N13° 55 E 63101097V, T Pazin45° 14 N13° 56 E291251220V, T, N, P

4. 4Analysis of convective indices over the northeastern Adriatic19 June 2012 Corr coef= 0.81 Corr coef= 0.78

5. Potential SB – Cb relationship 5Analysis of convective indices over the northeastern Adriatic19 June 2012 Determination of potential SB-Cb relationship based only on the surface measurements of two measuring sites What we still do not know: What we know: Simultaneously observed above Istria The nature of SB- Cb interaction

6. NE Adriatic 6Analysis of convective indices over the northeastern Adriatic19 June 2012 NE Adriatic - the most convective area in Croatia more than 60% of convective days in the warm part of the years 2006-2009 (Mikuš et al. 2012) Dominant large-scale weather types 82% of all days with convective activity SW (46%) large-scale flow NE (18%) large-scale flow NW (18%) large-scale flow non-gradient pressure field (21%) (NG) the center of the cyclone (21%) (C) the eastern front sector of the cyclone (20%) the western back side of the cyclone (10%) the front side of the trough (12%) (T)

7. Mean convective indices 7Analysis of convective indices over the northeastern Adriatic19 June 2012 ± σ ± σ weather type NG428.7 ± 438.6-71.5 ± 95.7-1.0 ± 2.377.7 ± 140.829.0 ± 4.9 C230.5 ± 351.2-68.5 ± 65.90.8 ± 2.732.9 ± 97.427.2 ± 5.8 T507.5 ± 575.1-72.5 ± 59.7-0.5 ± 3.284.5 ± 202.429.8 ± 6.0 large-scale wind SW332.2 ± 490.6-74.2 ± 67.80.4 ± 3.050.4 ± 236.328.8 ± 5.3 NE237.4 ± 327.3-70.3 ± 63.1-0.1 ± 2.131.8± 85.127.2 ± 6.4 NW529.6 ± 629.0-47.9 ± 100.5-0.2 ± 3.6146.8 ± 260.127.8 ± 8.3 Based on the dataset of convective days (2006-2009) for the NE Adriatic region – calculation of stability indices from the Udine (46.03°N, 13.18°E) radiosounding station soundings within 100 km of the storm's event can satisfactory described deep moist convective conditions Groenemeijer and van Delden (2007)

8. Numerical simulations 8Analysis of convective indices over the northeastern Adriatic19 June 2012 WRF-ARW mesoscale model simulations of Three chosen cases simultaneous occurrence of SB and daytime Cb above Istria an interaction of SB with one of the dominant types of large-scale wind: NE, SW and NW above Istria Numerical sensitivity test NE large-scale wind without microphysics scheme (A0 case) 09 July 2006 - NE large-scale flow08 August 2006 - NW large-scale flow Satellite images in the combined (VIS + IR; channel CH139) channel received from Meteosat 8. The pink color represents the convective clouds.

9. Numerical simulations 9Analysis of convective indices over the northeastern Adriatic19 June 2012 Only partial similarities with average convective indices in Udine The most prominent CAPE values - during the superposition of SW large-scale and the SB flow (accompanied by the relative small RiB (< 45)) As expected, the NW case has the largest RiB (> 60)

10. Convective available potential energy (CAPE) 10Analysis of convective indices over the northeastern Adriatic19 June 2012 NE large-scale flowSW large-scale flowNW large-scale flow Color: CAPE; arrows: 10 m wind field

11. Convective inhibition (CIN) 11Analysis of convective indices over the northeastern Adriatic19 June 2012 NE large-scale flowSW large-scale flowNW large-scale flow Color: CIN; arrows: 10 m wind field

12. Bulk Richardson Number (RiB) 12Analysis of convective indices over the northeastern Adriatic19 June 2012 NE large-scale flowSW large-scale flowNW large-scale flow

13. Numerical sensitivity test 13Analysis of convective indices over the northeastern Adriatic19 June 2012 CAPE RiB Case A Case A0

14. Summary 14Analysis of convective indices over the northeastern Adriatic19 June 2012 Mean stability indices derived from the Udine radiosounding station – High mean values of CAPE and KI, negative LI values correspond to T and NG weather types – Lower values of the same indices – for the C type due to its seasonal occurrance – NW / NE flow regime followed by the highest / lowest atmospheric instability Simulations of three chosen cases – Most prominant CAPE values during the superposition of SW large-scale and SB flow – The largest CIN values for the SW flow regime and the lowest for the NW flow regime – RiB values are the highest for NW and lowest for NE large-scale flow Possible reasons of disagreement – Distance of Udine radiosounding station from NE Adriatic – Seasonal character influences mean values of convective indices, while simulated cases correspond to summer conditions

15. Thank you for your attention! 19 June 2012Analysis of convective indices over the northeastern Adriatic15

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