1. 2011-2012 winter RADIATION FOGS at CIBA (Spain): Observations compared to WRF simulations using different PBL parameterizations Carlos Román-Cascón (carlosromancascon@fis.ucm.es) Carlos Yagüe Mariano Sastre Gregorio Maqueda Universidad Complutense de Madrid EMS & ECAC 2012. Łódź, Poland 11th September 2012

2. 1.Introduction 2.Overview 3.Observations 4.WRF Model results 5.Conclusions 6.Future study CONTENTS 2/19

3. RADIATION FOGS - Effects on daily life – Transport. - Physical processes not well understood. - not well parameterized in NWP models. - no good forecasts of fogs. ROLE OF TURBULENCE OVER FOGS - It acts favoring the development (Welch et al.,1986). - It acts favoring the dissipation (Roach et al.,1976). - Turbulence threshold between development and dissipation (Zhou et al., 2008). MAIN GOALS - To improve the fog prediction and to improve the knowledge about the physical processes affecting the formation/dissipation of fogs. 1. INTRODUCTION 3/19

4. 2. OVERVIEW Iberian Peninsula 25 km Northern Spanish PlateauMontes Torozos 800 km 2 840m asl CIBA site CIBA SITE 4/19

5. 2. OVERVIEW 3-14 January 2012 (12 days) Synoptic Situation 500 hPa Geopotential (gpdm) & Sea level pressure (hPa) 5/19

6. Fog Thickness (m) Time (day at 00 UTC) 2. OVERVIEW Fog Thickness (approximation) 6/19

7. Fog thickness (m) Observed Temperature at different heights (ºC) 3. OBSERVATIONS Fog Thickness & Temperature Time (day at 00 UTC) 7/19

8. Fog thickness (m) Friction velocity (m/s) 3. OBSERVATIONS Fog Thickness & Friction velocity Time (day at 00 UTC) 0,163 0,263 0,094 0,082 0,056 0,067 0,079 0,100 0,046 0,054 0,057 0,094 8/19

9. Fog thickness (m) Fog thickness (m) 3. OBSERVATIONS Fog Thickness & Friction velocity relations Friction velocity (m/s) 9/19

10. - Horizontal domains - 4 nested domains - Grid - 27, 9, 3, 1 km - Boundary conditions - NCEP, 1º, 6 hours - Vertical resolution 50 levels “eta” (8 levels< 100 m) (28 levels< 1 km) - Time step - 90 s - Spin up -36 h (restart run) - SW radiation- Dudhia (1998) - LW radiation - RRTM 4. WRF SIMULATIONS - PBL parameterizations - MYJ - QNSE - MYNN 2.5 - MYNN 2.5 + Gravity settling - Microphysics parameterizations (QNSE fixed) - WSM3 (default) - Lin et al. - Goddard scheme - Land-surface parameterizations (QNSE & Goddard fixed) - Noah LSM (default) - RUC LSM Average of 17 points centered at CIBA CIBA 4 km 1 km 10/19

11. 4. WRF SIMULATIONS LWC (g/kg) PBL schemes MYJ QNSE MYNN 2.5 MYNN 2.5 GS LWC simulated by WRF (g/kg) Time (day at 00 UTC)

12. 4. WRF SIMULATIONS Temperature PBL schemes 2m Temp. simulated by WRF and obs. (ºC) Time (day at 00 UTC) OBS

13. 4. WRF SIMULATIONS LWC (g/kg) MICROPHYSICS schemes WSM3 (default) Jin et. al Goddard LWC simulated by WRF (g/kg) Time (day at 00 UTC) QNSE fixed!

14. 4. WRF SIMULATIONS Temperature & Mixing Ratio MICROPHYSICS schemes Temperature (ºC) Mixing ratio (g/kg) Time (day at 00 UTC) QNSE fixed!

15. 4. WRF SIMULATIONS LWC (g/kg) LAND-SURFACE schemes LWC simulated by WRF (g/kg) Time (day at 00 UTC) Noah (default) RUC QNSE & Goddard microph. fixed!

16. 4. WRF SIMULATIONS LWC (g/kg) LAND-SURFACE schemes Time (UTC) LWC simulated by WRF (g/kg) Noah (default) RUC QNSE & Goddard LSM fixed!

17. 5. CONCLUSIONS OBSERVATIONS - Certain degree of turbulence to extend the fog in the vertical. - Nocturnal turbulence ~ 0.05 m/s  Great surface thermal inversions  Shallower fogs. SIMULATIONS - Tendency to overestimate the temperature. - Tendency to “rise up” the fog. - Tendency to dissipate the fog at midday (not able to simulate persistent fogs) - Problems to predict shallow fogs related to high inversions. - QNSE and MYNN2.5 in general better. - Lin et al. & Goddard Microphysics  Improve the fog forecasting for days with difficulties. - RUC Land Surface  Improve more the fog forecasting - Combination of errors  good prediction of fog? - Many different processes working together! - Still many problems simulating fogs, and consequently affecting T2, SW, LW… 17/19

18. 6. FUTURE STUDY (soon) - Statistic with more data (bias, RMSE) - Detailed analysis of some concrete day - More data (ceilometer + visibilimeter)  Better comparison with simulations - Interaction between Internal Gravity waves & Fogs Filtered pressure (hPa) Wavelet analysis 35 m Temperature (ºC) 18/19

19. THANK YOU !! (this is not a radiation fog!!!) Thanks to EMS for the Young Scientist Travel Award (YSTA) 19/19