Radiative transfer simulations of the ATR-42 SW and LW irradiance profiles above Lampedusa Island...
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Transcript of Radiative transfer simulations of the ATR-42 SW and LW irradiance profiles above Lampedusa Island...
Radiative transfer simulations of the ATR-42 SW and LW irradiance profiles above
Lampedusa Island
Daniela Meloniwith contributions from:
ChArMEx/ADRIMED SOP1a meeting, Paris, 5-6 June 2014
ATR-42 flights above Lampedusa
22 June 28 June
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
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°
Radiative transfer model simulationsMODTRAN 5.3
MODEL INPUT DATA
p, T, RH profiles ATR-42, radiosounding
Aerosol extinction profile lidar
Aerosol optical properties Cimel
Surface albedo - sea Jin et al. (2004)
Surface albedo - Lampedusa Jin et al. (2004) + MODTRAN barren
Surface emissivity MODTRAN
Sea surface temperature Italian tide gauge network
Columnar O3 Brewer
Surface CO2 Picarro
O3, CO2 profiles Mid-latitude standard atmos.
Over SEA: upward and downward SW and LW irradiance profilesOver LAMPEDUSA: downward global, direct and diffuse irradiances,
downward LW irradiance, downward WINDOW irradiance
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
Results- 22 June - F35Downward SW irradiance
Pitch angle < 1°Roll angle < 2°
Results- F35Upward SW irradiance
Results- F35Downward LW irradiance
Results- F35Upward LW irradiance
ResultsSurface 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 ±4.0 244.9 +11.1
Direct SW 725.6 ±2.0(hourly totals)
708.4 -2.4
Downward LW 359.9 ±1.4 354.1 -1.6
Downward WINDOW
82.5 ±2.4 85.9 +4.1
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.
In situ size distributions 22 June – F35
Results- 28 June - F38Downward SW irradiance
Pitch angle < 1°Roll angle < 2°
Results- F38Upward SW irradiance
Results- F38Downward LW irradiance
Results- F38Upward LW irradiance
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.