Claire Lavigne,1
Antoine Roblin,1
Patrick Chervet,1
and Patrick Chazette2
1C. Lavigne (c.lavigne@onera.fr), A. Roblin, and P. Chervet are with the Département d’Optique Théorique et Appliquée, Office National des Etudes et Recherches Aérospatiales, Chemin de la Hunière, 91761 Palaiseau Cedex, France.
2Laboratoire des Sciences du Climat et de l’Environnement, Laboratoire Mixte Commissariat a l’Energie–Centre National de la Recherche Scientifique, F-91191 Gif-Sur-Yvette, France.
Claire Lavigne, Antoine Roblin, Patrick Chervet, and Patrick Chazette, "Experimental and theoretical studies of the aureole about a point source that is due to atmospheric scattering in the middle ultraviolet," Appl. Opt. 44, 1250-1262 (2005)
In the atmosphere, pointlike sources are surrounded by aureoles because of molecular and aerosol scattering. In various meteorological conditions, this variance field can be a nonnegligible part of the signal detected by a large-field-of-view sensor. A model based on a Monte Carlo technique has been developed to simulate the propagation of radiation coming from a UV point source. The model was validated with an experimental comparison by a photon-counting technique, and good agreement between experimental and theoretical results was found.
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Characteristic Parameters of the Three Log-Normal Size Distributionsa
Mode 1
Mode 2
Mode 3
Period
rm (μm)
σg
N0 (μm−3)
rm (μm)
σg
N0 (μm−3)
rm (μm)
σg
N0 (μm−3)
Relative Humidity
1 (day) days 21–24
0.029
1.32
0.8586
0.076
1.44
0.1400
0.44
1.27
0.0014
79 ± 9%
1 (night) days 21–24
0.017
1.52
0.6227
0.057
1.76
0.3758
0.49
1.05
0.0015
85 ± 6%
2 (day) days 24.3–27
0.029
1.85
0.8734
0.13
1.37
0.1230
0.42
1.15
0.0036
79 ± 10%
2 (night) days 24.3–27
0.032
1.42
0.7930
0.092
1.49
0.2050
0.49
1.05
0.0020
84 ± 5%
3 day 26 between 1:40 pm and 3:50 pm
0.026
1.97
0.8816
0.13
1.27
0.1125
0.38
1.21
0.0059
70 ± 1%
rm is the modal radius, σg is the standard deviation of the radius, and N0 is the total number density of particles.
Table 3
Average Atmospheric Parameters Determined during Scattering Measurementsa
Date
βR at 270 nm (km−1)
αm at 270 nm (km−1)
kext at 270 nm (km−1)
Albedo at 270 nm
21 March
0.223
0.046
0.707
0.010
0.986
0.27
22 March
0.225
0.019
0.693
0.004
0.941
0.26
23 March
0.223
0.019
0.727
0.004
0.973
0.24
26 March
0.232
0.150
0.347
0.034
0.763
0.50
27 March
0.225
0.055
0.595
0.013
0.888
0.31
βR, Rayleigh scattering coefficient; βA, aerosol scattering coefficient; αm, ozone absorption coefficient; αA, aerosol absorption coefficient; kext, total extinction coefficient. The albedo corresponds to the total single-scattering albedo.
Table 4
Evaluation of Uncertainties in Photon Flux Density Calculated with the Monte Carlo Code when the Source Intensity’s Angular Dependence is Perfectly Knowna
Type of Signal
Uncertainties Caused by the Experimental Protocol (%)
Total Uncertainties (%)
Direct signal
30
40
Scattered signal
45
50
Uncertainties caused by atmospheric parameters are 20% for both direct and scattered signals.
Tables (4)
Table 1
Description of Equipment at the Mobile Aerosol Station Used to Determine Aerosol Properties
Instrument to Monitor Atmospheric Aerosol Properties In Situ
Sampling Period
Measured Quantity (Uncertainty)
To monitor optical properties
Nephelometer (TSI)
1 min
Scattering coefficients at 450, 550, and 700 nm (5%) Spectral dependency (10%)
To monitor chemical components
Aethalometer (Magee Scientific)
5 min
Mass concentration of soot (10%)
Microbalance (TEOM)
15 min
Total aerosol mass concentration (20%)
Cascade impactor (DEKATI)
Entire rain-free period
Elementary aerosol size distribution for 13 diameter classes from 0.03 to 10 μm (10–20%)
Filter integrated samples
12 h
Mass concentration of soot, organic, and inorganic aerosol mass concentrations (10–15%)
To monitor size distribution
Condensation particle counter (TSI)
1 min
Number of particles with diameters from 7 nm to 3 μm (5%)
Optical granulometer (Rion Company)
1 min
Aerosol size distribution for five diameter classes from 0.1 to 0.5 3m (10%)
Optical granulometer (MetOne)
45 min
Aerosol size distribution for six diameter classes from 0.3 to 5 μm (10%)
Characteristic Parameters of the Three Log-Normal Size Distributionsa
Mode 1
Mode 2
Mode 3
Period
rm (μm)
σg
N0 (μm−3)
rm (μm)
σg
N0 (μm−3)
rm (μm)
σg
N0 (μm−3)
Relative Humidity
1 (day) days 21–24
0.029
1.32
0.8586
0.076
1.44
0.1400
0.44
1.27
0.0014
79 ± 9%
1 (night) days 21–24
0.017
1.52
0.6227
0.057
1.76
0.3758
0.49
1.05
0.0015
85 ± 6%
2 (day) days 24.3–27
0.029
1.85
0.8734
0.13
1.37
0.1230
0.42
1.15
0.0036
79 ± 10%
2 (night) days 24.3–27
0.032
1.42
0.7930
0.092
1.49
0.2050
0.49
1.05
0.0020
84 ± 5%
3 day 26 between 1:40 pm and 3:50 pm
0.026
1.97
0.8816
0.13
1.27
0.1125
0.38
1.21
0.0059
70 ± 1%
rm is the modal radius, σg is the standard deviation of the radius, and N0 is the total number density of particles.
Table 3
Average Atmospheric Parameters Determined during Scattering Measurementsa
Date
βR at 270 nm (km−1)
αm at 270 nm (km−1)
kext at 270 nm (km−1)
Albedo at 270 nm
21 March
0.223
0.046
0.707
0.010
0.986
0.27
22 March
0.225
0.019
0.693
0.004
0.941
0.26
23 March
0.223
0.019
0.727
0.004
0.973
0.24
26 March
0.232
0.150
0.347
0.034
0.763
0.50
27 March
0.225
0.055
0.595
0.013
0.888
0.31
βR, Rayleigh scattering coefficient; βA, aerosol scattering coefficient; αm, ozone absorption coefficient; αA, aerosol absorption coefficient; kext, total extinction coefficient. The albedo corresponds to the total single-scattering albedo.
Table 4
Evaluation of Uncertainties in Photon Flux Density Calculated with the Monte Carlo Code when the Source Intensity’s Angular Dependence is Perfectly Knowna
Type of Signal
Uncertainties Caused by the Experimental Protocol (%)
Total Uncertainties (%)
Direct signal
30
40
Scattered signal
45
50
Uncertainties caused by atmospheric parameters are 20% for both direct and scattered signals.