Analysis of convective indices over the northeastern Adriatic

1. Andrija Mohorovičić Geophysical Institute, Department of Geophysics, Faculty of Science, University of Zagreb 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

2. Introduction • 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 Analysis of convective indices over the northeastern Adriatic

3. Potential SB – Cb relationship • 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 twometeorological stations - the Pula-Airport and Pazin (Fig)observed during a 10-year period (1997–2006) Analysis of convective indices over the northeastern Adriatic

4. Corr coef= 0.81 Corr coef= 0.78 Analysis of convective indices over the northeastern Adriatic

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

6. NE Adriatic • NE Adriatic - the most convective area in Croatiamore than 60% of convective days in the warm part of the years 2006-2009 (Mikuš et al. 2012) SW (46%) large-scale flow 82% of all days with convective activity 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%) Dominant large-scale weather types the western back side of the cyclone (10%) the front side of the trough (12%) (T) Analysis of convective indices over the northeastern Adriatic

7. Mean convective indices Groenemeijer and van Delden (2007) soundings within 100 km of the storm's event can satisfactory described deep moistconvective conditions 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 Analysis of convective indices over the northeastern Adriatic

8. Numerical simulations • 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 flow 08 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. Analysis of convective indices over the northeastern Adriatic

9. Numerical simulations • 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) Analysis of convective indices over the northeastern Adriatic

10. Convective available potential energy (CAPE) NE large-scale flow SW large-scale flow NW large-scale flow Color: CAPE; arrows: 10 m wind field Analysis of convective indices over the northeastern Adriatic

11. Convective inhibition (CIN) NE large-scale flow SW large-scale flow NW large-scale flow Color: CIN; arrows: 10 m wind field Analysis of convective indices over the northeastern Adriatic

12. Bulk Richardson Number (RiB) NE large-scale flow SW large-scale flow NW large-scale flow Analysis of convective indices over the northeastern Adriatic

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

14. Summary • 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 Analysis of convective indices over the northeastern Adriatic

15. Thank you for your attention! Analysis of convective indices over the northeastern Adriatic

16. Analysis of convective indices over the northeastern Adriatic

17. Analysis of convective indices over the northeastern Adriatic