1. Radiative transfer simulations of the ATR-42 SW and LW irradiance profiles above Lampedusa Island Daniela Meloni with contributions from: ChArMEx/ADRIMED SOP1a meeting, Paris, 5-6 June 2014

2. ATR-42 flights above Lampedusa 22 June 28 June

3. 22 June – F35 (descent) AOD (500 nm)=0.38±0.02 α (500, 870)=0.53±0.03 SZA (TOP)=15° SZA (BOTTOM)=12° TIME (TOP)=10:23 UT TIME (BOTTOM)=11:26 UT

4. 28 June – F38 (descent) AOD (500 nm)=0.213±0.004 α (500, 870)=0.76±0.03 TIME (TOP)=12:25 UT TIME (BOTTOM)=13:30 UT SZA (TOP)=20° SZA (BOTTOM)=32°

5. Radiative transfer model simulations MODTRAN 5.3 MODEL INPUTDATA p, T, RH profilesATR-42, radiosounding Aerosol extinction profilelidar Aerosol optical propertiesCimel Surface albedo - seaJin et al. (2004) Surface albedo - LampedusaJin et al. (2004) + MODTRAN barren Surface emissivityMODTRAN Sea surface temperatureItalian tide gauge network Columnar O 3 Brewer Surface CO 2 Picarro O 3, CO 2 profilesMid-latitude standard atmos. Over SEA: upward and downward SW and LW irradiance profiles Over LAMPEDUSA: downward global, direct and diffuse irradiances, downward LW irradiance, downward WINDOW irradiance

6. Aerosol optical properties AERONET retrieval of the aerosol size distribution and the spectral refractive index (440, 500, 870, 1020 nm) closest in time to the flight Mie calculations with AERONET size distributions SW simulations: AERONET refractive index LW simulations: OPAC (Hess et al., 1998) mineral refractive index

7. Results- 22 June - F35 Downward SW irradiance Pitch angle < 1° Roll angle < 2°

8. Results- F35 Upward SW irradiance

9. Results- F35 Downward LW irradiance

10. Results- F35 Upward LW irradiance

11. Results Surface irradiances SZA=12° MEASUREMENT (Wm -2 ) UNCERTAINTY (%) MODEL (Wm -2 ) DIFFERENCE (%) Downward SW global 979.9±2.0 (daily totals) 953.3-2.7 Downward SW diffuse 220.5±4.0244.9+11.1 Direct SW725.6±2.0 (hourly totals) 708.4-2.4 Downward LW359.9±1.4354.1-1.6 Downward WINDOW 82.5±2.485.9+4.1

12. Possible reasons Discrepancies in the measured and modeled spectral AOD Sphericity Complex refractive index (real part 1.41-1.43, imaginary part 0.004-0.006) Differences in columnar and in situ aerosol size distributions and refractive index. Differences in columnar and in situ spectral aerosol properties. Differences in measured and modeled direct spectral irradiances: comparison with MFRSR/ HyperOCR Satlantic/SP02 Middleton/PSR. Differences in measured and modeled diffuse spectral irradiances: comparison with MFRSR/ HyperOCR Satlantic. Differences in measured and modeled global spectral actinic fluxes: comparison with METCON DAS.

13. In situ size distributions 22 June – F35

14. Results- 28 June - F38 Downward SW irradiance Pitch angle < 1° Roll angle < 2°

15. Results- F38 Upward SW irradiance

17. Results- F38 Downward LW irradiance

18. Results- F38 Upward LW irradiance

19. Conclusions Preliminary comparison of ATR-42 SW and LW irradiance vertical profiles and surface measurements at Lampedusa. To do: Improve the modeled spectral AOD; Use in situ aerosol size distributions and refractive indices; Compare modeled and measured spectral irradiances/actinic fluxes.