Analysis of shipboard aerosol optical thickness measurements from multiple sunphotometers aboard the R/V Ronald H. Brown during the Aerosol Characterization Experiment—Asia
Mark A. Miller, Kirk Knobelspiesse, Robert Frouin, Mary Jane Bartholomew, R. Michael Reynolds, Christophe Pietras, Giulietta Fargion, Patricia Quinn, and François Thieuleux
Mark A. Miller,1
Kirk Knobelspiesse,2
Robert Frouin,3
Mary Jane Bartholomew,1
R. Michael Reynolds,1
Christophe Pietras,2
Giulietta Fargion,2
Patricia Quinn,4
and François Thieuleux5
1M. A. Miller (miller@bnl.gov), M. J. Bartholomew, and R. Michael Reynolds are with the Earth System Science Division, Building 490D, Brookhaven National Laboratory, Upton, New York 11973
2K. Knobelspiesse, C. Pietras, and G. Fargion are with Science Systems and Applications, Inc., NASA SIMBIOS Project, Goddard Space Flight Center, Greenbelt, Maryland 20771
3R. Frouin is with the Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093
4P. Quinn is with the Pacific Marine Environmental Laboratory, Seattle, Washington 98115
5F. Thieuleux is with the Laboratoire d’Optique At-mosphérerique, Université des Sciences et Technologies de Lille, Villeneuve d’Ascq, France
Mark A. Miller, Kirk Knobelspiesse, Robert Frouin, Mary Jane Bartholomew, R. Michael Reynolds, Christophe Pietras, Giulietta Fargion, Patricia Quinn, and François Thieuleux, "Analysis of shipboard aerosol optical thickness measurements from multiple sunphotometers aboard the R/V Ronald H. Brown during the Aerosol Characterization Experiment—Asia," Appl. Opt. 44, 3805-3820 (2005)
Marine sunphotometer measurements collected aboard the R/V Ronald H. Brown during the Aerosol Characterization Experiment—Asia (ACE-Asia) are used to evaluate the ability of complementary instrumentation to obtain the best possible estimates of aerosol optical thickness and Ångstrom exponent from ships at sea. A wide range of aerosol conditions, including clean maritime conditions and highly polluted coastal environments, were encountered during the ACE-Asia cruise. The results of this study suggest that shipboard hand-held sunphotometers and fast-rotating shadow-band radiometers (FRSRs) yield similar measurements and uncertainties if proper measurement protocols are used and if the instruments are properly calibrated. The automated FRSR has significantly better temporal resolution (2 min) than the hand-held sunphotometers when standard measurement protocols are used, so it more faithfully represents the variability of the local aerosol structure in polluted regions. Conversely, results suggest that the hand-held sunphotometers may perform better in clean, maritime air masses for unknown reasons. Results also show that the statistical distribution of the Ångstrom exponent measurements is different when the distributions from hand-held sunphotometers are compared with those from the FRSR and that the differences may arise from a combination of factors.
Jacqueline Lenoble, Timothy Martin, Mario Blumthaler, Rolf Philipona, Astrid Albold, Thierry Cabot, Alain de La Casinière, Julian Gröbner, Dominique Masserot, Martin Müller, Thomas Pichler, Günther Seckmeyer, Daniel Schmucki, Mamadou Lamine Touré, and Alexis Yvon Appl. Opt. 41(9) 1629-1639 (2002)
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Uncertainties for the Simbad and Simbada aerosol optical thickness values are estimated to be 0.012–0.019.11
SIMBIOS project sunphotometers are calibrated on land by a cross calibration to Cimel sunphotometers maintained by the AERONET project.20 The Cimel sunphotometers are calibrated by the Langley method at Mauna Loa. The uncertainty for the Microtops aerosol optical thickness values made at sea is 0.025.10,11
Calibration of this instrument is tied to satellite-measured extraterrestrial irradiance.14 The uncertainty of the aerosol optical thickness values determined by the FRSR is 0.03.14
Table 2
Calibration Information for Hand-Held Radiometers Used in This Study
Abbreviations: MTNA, NASA Simbios Microtops; MTMO, PMEL Microtops; SMBD, Simbad; SMBA, SimbadA; ANG, Ångström coefficient.
Bias, second instrument listed; first instrument listed for any pair of comparisons.
Table 4
Percentage of ACE-Asia Concurrent Measurements That Fall Within Calculated Uncertaintiesa
Uncertainties for the Simbad and Simbada aerosol optical thickness values are estimated to be 0.012–0.019.11
SIMBIOS project sunphotometers are calibrated on land by a cross calibration to Cimel sunphotometers maintained by the AERONET project.20 The Cimel sunphotometers are calibrated by the Langley method at Mauna Loa. The uncertainty for the Microtops aerosol optical thickness values made at sea is 0.025.10,11
Calibration of this instrument is tied to satellite-measured extraterrestrial irradiance.14 The uncertainty of the aerosol optical thickness values determined by the FRSR is 0.03.14
Table 2
Calibration Information for Hand-Held Radiometers Used in This Study
Abbreviations: MTNA, NASA Simbios Microtops; MTMO, PMEL Microtops; SMBD, Simbad; SMBA, SimbadA; ANG, Ångström coefficient.
Bias, second instrument listed; first instrument listed for any pair of comparisons.
Table 4
Percentage of ACE-Asia Concurrent Measurements That Fall Within Calculated Uncertaintiesa