Consistency of two global MODIS aerosol products over ocean on Terra and Aqua CERES SSF datasets

Ignatov, Alexander; Minnis, Patrick; Wielicki, Bruce A.; Loeb, Norman G.; Remer, L. A.; Kaufman, Yoram J.; Miller, Walter F.; Sun‐Mack, Sunny; László, István; Geier, Erika

doi:10.1117/12.577927

Cited by 25 publications

(48 citation statements)

References 15 publications

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“…Many authors reported a positive correlation between aerosol optical thickness and cloud fraction retrieved using various platforms and algorithms (e.g., Ignatov et al, 2005;Kaufman et al, 2005;Loeb and Manalo-Smith, 2005;Loeb and Schuster, 2008). Most recently, a study by Chand et al (2012) analyzing 11 yr of MODIS observations found that 25 % enhancement in cloud fraction leads to a 0.05 increase in clear sky optical depth.…”

Section: Reasons For Near-cloud Enhancements Of Solar Reflectancementioning

confidence: 99%

Multi-satellite aerosol observations in the vicinity of clouds

2013

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Improved characterization of aerosol properties in the vicinity of clouds is important for better understanding two critical aspects of climate: aerosol–cloud interactions and the direct radiative effect of aerosols. Satellite measurements have provided important insights into aerosol properties near clouds, but also suggested that the observations can be affected by 3-D radiative processes and instrument blurring not considered in current data interpretation methods. This study examines systematic cloud-related changes in particle properties and radiation fields that influence satellite measurements of aerosols in the vicinity of low-level maritime clouds. For this, the paper presents a statistical analysis of a yearlong global dataset of co-located MODIS and CALIOP observations and theoretical simulations. The results reveal that CALIOP-observed aerosol particle size and optical thickness, and MODIS-observed solar reflectance increase systematically in a wide transition zone around clouds. It is estimated that near-cloud changes in particle populations – including both aerosols and undetected cloud particles – are responsible for roughly two thirds of the observed increase in 0.55 μm MODIS reflectance. The results also indicate that 3-D radiative processes significantly contribute to near-cloud reflectance enhancements, while instrument blurring contributes significantly only within 1 km from clouds and then quickly diminishes with distance from clouds

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Section: Reasons For Near-cloud Enhancements Of Solar Reflectancementioning

confidence: 99%

Multi-satellite aerosol observations in the vicinity of clouds

2013

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“…Most recently, analyzing Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data, [20] showed (Figure 1) that data sampling can also make overall statistics of aerosol properties change with distance to clouds, given that far-from-cloud aerosol statistics are dominated by data from scenes with lower cloud fraction (CF), while near-cloud aerosol statistics are dominated by data from scenes with higher CF. This may lead to a statistical increase of aerosol optical thickness (AOT) near clouds because, as reported in several papers [21][22][23][24], AOT is positively correlated with CF-though cloud detection uncertainties and 3D radiative processes may make this correlation appear stronger than it really is [19,25,26]. We note that while CF (defined for 30 km and 40 km size areas in [20] and in this paper, respectively) represents large-scale conditions, the distance from the nearest cloud reflects individual pixel conditions.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cloud Fraction on Near-Cloud Aerosol Behavior in the MODIS Atmospheric Correction Ocean Color Product

Várnai

Marshak

2015

Remote Sensing

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Abstract:Characterizing the way satellite-based aerosol statistics change near clouds is important for better understanding both aerosol-cloud interactions and aerosol direct radiative forcing. This study focuses on the question of whether the observed near-cloud increases in aerosol optical thickness and particle size may be explained by a combination of two factors: (i) Near-cloud data coming from areas with higher cloud fractions than far-from-cloud data and (ii) Cloud fraction being correlated with aerosol optical thickness and particle size. This question is addressed through a statistical analysis of aerosol parameters included in the MODIS (MODerate resolution Imaging Spectroradiometer) ocean color product. Results from ten Septembers (2002-2011) over part of the northeast Atlantic Ocean confirm that the combination of these two factors working together explains a significant but not dominant part (in our case, 15%-30%) of mean optical thickness changes near clouds. Overall, the findings show that cloud fraction plays a large role in shaping the way aerosol statistics change with distance to clouds. This implies that both cloud fraction and distance to clouds are important to consider when aerosol-cloud interactions or aerosol direct radiative effects are examined in satellite or modeling studies.

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“…cloud contamination or illumination bias than physical processes (e.g., Ignatov et al, 2005;Zhang et al, 2005;Zhang and Reid, 2006;Marshak et al, 2008;Smirnov et al, 2012;Reid et al, 2013). Thus, a significant challenge to the climate science community is to link remote-sensing measurements of potential changes in aerosol optical depth (AOD) to Cloud Condensation Nuclei Concentration (e.g., Kaufman and Fraser, 1997) or to secondary particle production, free of retrieval artifacts.…”

Section: T F Eck Et Al: Rapid Aerosol Optical Depth Enhancements Nmentioning

confidence: 99%

Observations of rapid aerosol optical depth enhancements in the vicinity of polluted cumulus clouds

et al. 2014

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Abstract. During the July 2011 Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field experiment in Maryland, significant enhancements in Aerosol Robotic Network (AERONET) sun-sky radiometer measured aerosol optical depth (AOD) were observed in the immediate vicinity of non-precipitating cumulus clouds on some days. Both measured Ångström exponents and aerosol size distribution retrievals made before, during and after cumulus development often suggest little change in fine mode particle size; therefore, implying possible new particle formation in addition to cloud processing and humidification of existing particles. In addition to sun-sky radiometer measurements of large enhancements of fine mode AOD, lidar measurements made from both ground-based and aircraftbased instruments during the experiment also measured large increases in aerosol signal at altitudes associated with the presence of fair weather cumulus clouds. These data show modifications of the aerosol vertical profile as a result of the aerosol enhancements at and below cloud altitudes. The airborne lidar data were utilized to estimate the spatial extent of these aerosol enhancements, finding increased AOD, backscatter and extinction out to 2.5 km distance from the cloud edge. Furthermore, in situ measurements made from aircraft vertical profiles over an AERONET site during the experiment also showed large increases in aerosol scattering and aerosol volume after cloud formation as compared to before. The 15-year AERONET database of AOD measurements at the Goddard Space Flight Center (GSFC), Maryland site, was investigated in order to obtain a climatological perspective of this phenomenon of AOD enhancement. Analysis of the diurnal cycle of AOD in summer showed significant increases in AOD from morning to late afternoon, corresponding to the diurnal cycle of cumulus development.

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Consistency of two global MODIS aerosol products over ocean on Terra and Aqua CERES SSF datasets

Cited by 25 publications

References 15 publications

Multi-satellite aerosol observations in the vicinity of clouds

Multi-satellite aerosol observations in the vicinity of clouds

Effect of Cloud Fraction on Near-Cloud Aerosol Behavior in the MODIS Atmospheric Correction Ocean Color Product

Observations of rapid aerosol optical depth enhancements in the vicinity of polluted cumulus clouds

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