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12th EMS Annual Meeting & 9th European Conference on Applied Climatology (ECAC) EUROPEAN METEOROLOGICAL SOCIETY. Atmospheric Boundary Layer evening transitions: a comparison between two experimental sites (CIBA-Spain and BLLAST-France).
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12th EMS Annual Meeting & 9th European Conference on Applied Climatology (ECAC) EUROPEAN METEOROLOGICAL SOCIETY Atmospheric Boundary Layer evening transitions: a comparison between two experimental sites (CIBA-Spain and BLLAST-France) M. Sastre (1), C. Yagüe (1), C. Román-Cascón (1), G. Maqueda (2). (1) Dept. Geofísica y Meteorología. University Complutense of Madrid, Spain. (msastrem@fis.ucm.es) (2) Dept. Astrofísica y Ciencias de la Atmósfera. University Complutense of Madrid, Spain. 11th September 2012
Contents 1.- Introduction 2.- Methodology 3.- Experimental data 4.- WRF model 5.- Results 6.- Summary and conclusions
1.- Introduction • Evening transition processes in the ABL: from convection to stability • Comparison at two experimental sites • Simulations: differences between sites?
x x 2.- Methodology • Data from two experimental sites: CIBA site (Spain) and the BLLAST campaign site (France).
2.- Methodology BLLAST campaign site: land-use crops Forest deciduous meadow 1 P town village Forest pines industrial moor meadow corn
x x 2.- Methodology • Data from two experimental sites: CIBA site (Spain) and the BLLAST campaign site (France). • Days studied from two summer periods: 2009 (CIBA) and 2011 (BLLAST). • Times related to sunset for every site and day (t=0 => tsunset). • Simulations using WRF model. • MRFD technique employed.
3.- Experimental data • Sonic anemometer (CIBA and BLLAST) • BLLAST 60m-tower instruments (2, 15, 30, 45, 60 m) • CIBA 10m-mast instruments (1.5, 3, 5, 7.5, 10 m) Focus on: • Wind speed and direction • Temperature • Turbulent parameters Friction velocity:
4.- WRF model • Weather Research and Forecast (WRF) mesoscale model. • Test three PBL parameterizations: MYJ, MYNN, QNSE. • More about model configuration: • Initial and boundary conditions from NCEP-NCAR (1º resolution; data every 6 hours). • 4 nested domains whose grids are: 27, 9, 3 and 1km. • Time step: 81 seconds. • 50 eta vertical levels. • Spin up: 12 h. • SW radiation: Dudhia (1998). • LW radiation RRTM. • Microphysics package: WSM3.
5.- Results • Days selected: 28-29-30 August 2009 (CIBA) and 24-25-26 June 2011 (BLLAST). • Similar synoptic situations: stability and weak pressure gradient. 30/August/2009 – 00:00 UTC Geopotential at 500 hPa (gpdm) and surface pressure reduced to sea level (reanalysis taken from: www.wetterzentrale.de)
5.- Results Comparison of MRFD Friction velocity (U*) 29 Aug 2009 (CIBA) 24 Jun 2011 (BLLAST) m s-1 t=0 => tsunset
5.- Results Comparison of MRFD Friction velocity (U*) 29 Aug 2009 (CIBA) 24 Jun 2011 (BLLAST) m s-1 t=0 => tsunset
5.- Results Comparison of temperature and friction velocity U* T CIBA BLLAST
wind speed wind direction 5.- Results Katabatic event - CIBA
24 Jun 2011 5.- Results WRF simulations Friction velocity (U*) 28 Aug 2009 CIBA BLLAST 30 Aug 2009 26 Jun 2011
5.- Results WRF simulations Temperature 30 Aug 2009 (CIBA) 25 Jun 2011 (BLLAST)
5.- Results WRF simulations Wind speed 28 Aug 2009 (CIBA) 26 Jun 2011 (BLLAST)
6.- Summary and conclusions • Evening transition processes have been evaluated at two different experimental sites. • MRFD timescales: similar evolution, but with some differences. • Radiative cooling: seems to be influenced by soil moisture. • Simulations: tend to overestimate the turbulence after sunset at one of the sites (the less dried).
THANK YOUFOR YOUR ATTENTION Acknowledgements: • Spanish Ministry of Science and Innovation projects CGL2006-12474-C03-03, CGL2009-12797-C03-03 and CGL2011-13477-E . • UCM fellowship (reference BE45/10). • BLLAST project, especially M. Lothon and F. Saïd for the 60m-tower data. • EMS Young Scientist Travel Award (YSTA).