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

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

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

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

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

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

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

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

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

- 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 MYNN 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

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)

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

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!

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

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!

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

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

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

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