from airborne and surface measurements

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1 Analysis of the thermal structure of the Ora del Garda wind from airborne and surface measurements Lavinia Laiti, Dino Zardi and Massimiliano de Franceschi Atmospheric Physics Group Department of Civil and Environmental Engineering University of Trento, Italy

2 1. Introduction to the study area 2. The Ora del Garda wind 3. The measurement campaign 4. Synoptic weather conditions 5. Analysis of surface observations 6. Analysis of airborne observations 7. Atmospheric Boundary Layer structure and evolution 8. The residual kriging technique 9. Kriging interpolation results 10.Conclusions 11.Future developments

3 LOCATION OF THE : northern Italy Source: Google Earth

4 LOCATION OF THE : northern Italy Trentino region Source: Google Earth

5 LOCATION OF THE : northern Italy Trentino region city of Trento In the north-eastern Italian Alps: Lake Garda (and small lakes) river Adige Valley river Sarca Valley Valley of Lakes Source: Google Earth

6 THE WIND WAS FIRSTLY INVESTIGATED IN: Defant A. (1908): Über die stehenden Seespiegelschwankungen (Seiches) in Riva am Gardasee [About the stationary fluctuations of lake level (seiches) at Riva del Garda]. S. B. Akad. Wiss. Wien, Math.-Nat. K1., 117, Abt.11a, S Defant A. (1949): Zur Theorie der Hangwinde nebst Bemerkungen zur Theorie der Berg- und Talwinde [A theory of slope winds, along with remarks on the theory of mountain winds and valley winds]. Archiv für Meteorologie, Geophysik und Bioklimatologie A1:

7 SPATIAL DEVELOPMENT: Ora del Garda wind Trento Source: Google Earth

8 SPATIAL DEVELOPMENT: Ora del Garda wind Adige Valley up-valley wind Trento Source: Google Earth

9 SPATIAL DEVELOPMENT: Ora del Garda wind Adige Valley up-valley wind Trento Source: Google Earth

10 8/7/2010: Lake Garda shore at Torbole 11:05 LST 15:48 LST 8-10 ms -1 Ora del Garda wind Adige Valley up-valley wind Trento Source: Google Earth

Source: http://www.girovagandointrentino.

11 Source: Tourism and water sports Source: Agriculture and wine production Ora del Garda wind Adige Valley up-valley wind Trento Source: Google Earth

12 PATH ALTIMETRY: Terlago (456 m ASL) Dro (123 m ASL) Arco (91 m ASL) Roncafort (194 m ASL) TRENTO (194 m ASL) Riva del Garda (73 m ASL) Rovereto (203 m ASL)

13 PATH ALTIMETRY: Arco (91 m ASL) Riva del Garda (73 m ASL) Dro (123 m ASL) Roncafort (194 m ASL) Terlago (456 m ASL)

1997-2004 : FLIGHTS IN THE (APG, Trento University) 24 Sep.

1999 12-15 LST INSTRUMENTED LIGHT AIRCRAFT position X/Y/Z pressure P

14 : FLIGHTS IN THE (APG, Trento University) 24 Sep LST 5 Aug LST 1 Sep LST INSTRUMENTED LIGHT AIRCRAFT position X/Y/Z pressure P temperature T relative humidity RH 23 Aug LST 23 Aug LST Source: Google Earth

15 23 rd AUG. 2001: 2 FLIGHTS + INTENSIVE SITE INSTRUMENTATION PERIOD MEASURED VARIABLES Roncafort (194 m ASL) Monte Terlago (730 m ASL) Study area (up to 2500 m ASL) Sonic anemometer Automatic weather station Instrumented light airplane Roncafort Monte Terlago 23 rd Jul. 24 th Aug th Aug. 11 th Sep rd Aug Wind speed Wind direction Wind speed Wind direction Air temperature Air humidity Position Air pressure Air temperature Sound celerity Global radiation Net radiation Air pressure Precipitation Air temperature Air humidity + DATA FROM STANDARD AWSs BELONGING TO: Meteotrentino (Province of Trento meteorological service) Edmund Mach Foundation Province of Trento Hydrographic Office Province of Bolzano Meteorological Service Source: Google Earth

16 FAIR SUMMER DAY: no intense synoptic forcing few clouds intense solar incoming radiation UNDISTURBED DEVELOPMENT OF THERMALLY DRIVEN LOCAL CIRCULATIONS 00:00 UTC 23 Aug :00 UTC 24 Aug Study area Study area Source:

2001 11:04 LST The estuary of the river Sarca at Torbole and Mount Brione.

17 FAIR SUMMER DAY: no intense synoptic forcing few clouds intense solar incoming radiation 23 Aug :04 LST The estuary of the river Sarca at Torbole and Mount Brione. UNDISTURBED DEVELOPMENT OF THERMALLY DRIVEN LOCAL CIRCULATIONS 12:28 UTC 23 Aug Aug :39 LST The Valley of Lakes (Santa Massenza Lake, Toblino Lake and Cavedine Lake). Source: University of Trento Atmospheric Physics Group archive Source:

Roncafort (on the Adige Valley floor, immediately under the 400 m-drop from Terlago saddle, where the Oradel

18 DATA ANALYSIS. TIME SERIES FOR THE 3 MOST REPRESENTATIVE STATIONS: 1. Riva del Garda (at Lake Garda shoreline, upflow with respect to Mount Brione) 2. Roncafort (on the Adige Valley floor, immediately under the 400 m-drop from Terlago saddle, where the Oradel Garda and the Adige Valley up-valley wind interact) 3. Trento South (on the Adige Valley floor, 5 km south of Trento) 1. Riva del Garda 2. Roncafort 3. Trento South Source: Google Earth

19 DATA ANALYSIS. TIME SERIES FOR THE 3 MOST REPRESENTATIVE STATIONS

20 DATA ANALYSIS. TIME SERIES FOR THE 3 MOST REPRESENTATIVE STATIONS 1. 11:00 19: :00 3. regular up-valley wind

21 DATA ANALYSIS TIME SERIES FOR THE 3 MOST REPRESENTATIVE STATIONS 1. 10:

22 DATA ANALYSIS. OBSERVED PROFILES FROM FLIGHTS, SOUNDINGS AND COMPARISON. EXAMPLE: Riva del Garda late morning perfect accord data soundings at upper levels lake water ground T of about 7 8 C thermal forcing to lake breeze development very shallow SL (< 200 m) persistence of a quite stable stratification (see mixing ratio profile vs. surface observation) LAKE GARDA WATER Lake Garda surface level: 65 m ASL Riva del Garda height: 66 m ASL

23 ATMOSPHERIC BOUNDARY LAYER STRUCTURE. OBSERVED PROFILES, SOUNDINGS AND. Riva del Garda (lake shoreline) vs. Pietramurata (mid-valley) late morning: very shallow SL (200 m) at Riva del Garda m ML starting to develop at Pietramurata Riva del Garda height: 66 m ASL Pietramurata height: 245 m ASL

24 ATMOSPHERIC BOUNDARY LAYER STRUCTURE. OBSERVED PROFILES, SOUNDINGS AND. Roncafort (Adige Valley) late morning vs. afternoon: very cold in the morning shallow SL (300 m) much warmer than in the plain (see 18 UTC sounding) in the afternoon CBL structure clear development and growth: ML grows up to 1300 m in the afternoon Roncafort height: 194 m ASL

25 ATMOSPHERIC BOUNDARY LAYER STRUCTURE. OBSERVED PROFILES, SOUNDINGS AND. Roncafort (Adige Valley) vs. Terlago saddle afternoon: Terlago profile is less clearly stratified shallower ML than at Roncafort (400 m vs m) Terlago profile upper part seems to be shifted upward with respect to Roncafort profile (subsidence due to the up-valley and up-slope winds and their compensation currents) Roncafort height: 194 m ASL Terlago saddle height: 600 m ASL

26 DATA INTERPOLATION TECHNIQUE: kriging: geostatistical interpolation technique kriging: exact interpolator at measurement points kriging: identifies and uses the characteristic spatial variability of fields NB: a dominant vertical pattern is previously fitted to the variables and residuals are finally interpolated on 2D vertical valley sections morning afternoon

27 INTERPOLATION RIVA DEL GARDA 11:30 LST cold lake breeze front moving northward more stable (larger gradient) profile above lake surface

28 INTERPOLATION RONCAFORT 10:30 LST cold air pool (about 500 m) still persisting on the Adige Valley bottom the upvalley circulation hasn t yet developed

29 INTERPOLATION RONCAFORT 15:30 LST the valley air has been completely warmed and a well mixed layer of about 1300 m developed (CBL growth)

30 INTERPOLATION TERLAGO 16:00 LST the air seems to be a little bit colder on the external side of the valley s curve (Ora del Garda colder flow inertia?)

31 identification of characteristic time pattern and micro-climatological effects determined by the Ora del Garda development (surface data analysis) presence of a very shallow BL at Lake Garda shoreline (200 m) BL grows in thickness along the Ora del Garda path and with the passing of time (daily cycle): transition from a stable profile to a more developed convective profile well developed ML in the Adige Valley / shallower ML where the Ora del Garda flows identification of a very clear cold front of lake breeze identification of local features and characteristic phases of investigated circulations

32 Completion of experimental data analysis and improvement of kriging results Simulation of the flights days by means of an atmospheric numerical model (ARPS or WRF) Comparison of experimental data and numerical results: validation Study of the dynamics of the Ora del Garda onset and development on the basis of numerical results Analysis on the basis of numerical results of wind fields and turbulence structure, especially at the confluence between the Ora del Garda and the Adige Valley upvalley wind Comparison between eddy correlation-analysis results from intensive observations (momentum and sensible heat fluxes, friction velocity, etc.) and numerical results: turbulence structure/characteristics (de Franceschi, M., Rampanelli, G., Zardi, D., Further investigations of the Ora del Garda valley wind, Proceedings of the 10th Conference on Mountain Meteorology and Mesoscale Alpine Programme MAP-Meeting 2002, Giugno 2002, Park City, Utah)

33 Thank you for your attention

Characterization of the solar irradiation field for the Trentino region in the Alps

Characterization of the solar irradiation field for the Trentino region in the Alps L. Laiti*, L. Giovannini and D. Zardi Atmospheric Physics Group University of Trento - Italy outline of the talk Introduction