Improving satellite-retrieved aerosol microphysical properties using GOCART data

Li, S.; Kahn, Ralph A.; Chin, Mian; Garay, M. J.; Liu, Yang

doi:10.5194/amt-8-1157-2015

Cited by 36 publications

(34 citation statements)

References 47 publications

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“…This approach has been and continues to be used (e.g., Koch et al, 2009;Bahadur et al, 2010;Chung et al, 2012;Buchard et al, 2015;Pan et al, 2015;Li et al, 2015). However, as shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Using only Level 2 retrievals of AAOD (i.e., for AOD 440 > 0.4) on a global scale (e.g., Koch et al, 2009;Bahadur et al, 2010;Chung et al, 2012;Buchard et al, 2015;Pan et al, 2015;Li et al, 2015) is likely to lead to significant overestimates of absorption in cleaner regions although it may be appropriate for conditions of high loading. Several different approaches of varying complexity have been developed to better represent absorbing aerosol for cleaner conditions.…”

Section: Discussionmentioning

confidence: 99%

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Comparison of AOD, AAOD and column single scattering albedo from AERONET retrievals and in situ profiling measurements

et al. 2017

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Abstract. Here we present new results comparing aerosol optical depth (AOD), aerosol absorption optical depth (AAOD) and column single scattering albedo (SSA) obtained from in situ vertical profile measurements with AERONET ground-based remote sensing from two rural, continental sites in the US. The profiles are closely matched in time (within ±3 h) and space (within 15 km) with the AERONET retrievals. We have used Level 1.5 inversion retrievals when there was a valid Level 2 almucantar retrieval in order to be able to compare AAOD and column SSA below AERONET's recommended loading constraint (AOD > 0.4 at 440 nm). While there is reasonable agreement for the AOD comparisons, the direct comparisons of in situderived to AERONET-retrieved AAOD (or SSA) reveal that AERONET retrievals yield higher aerosol absorption than obtained from the in situ profiles for the low aerosol optical depth conditions prevalent at the two study sites. However, it should be noted that the majority of SSA comparisons for AOD 440 > 0.2 are, nonetheless, within the reported SSA uncertainty bounds. The observation that, relative to in situ measurements, AERONET inversions exhibit increased absorption potential at low AOD values is generally consistent with other published AERONET-in situ comparisons across a range of locations, atmospheric conditions and AOD values. This systematic difference in the comparisons suggests a bias in one or both of the methods, but we cannot assess whether the AERONET retrievals are biased towards high absorption or the in situ measurements are biased low. Based on the discrepancy between the AERONET and in situ values, we conclude that scaling modeled black carbon concentrations upwards to match AERONET retrievals of AAOD should be approached with caution as it may lead to aerosol absorption overestimates in regions of low AOD. Both AERONET retrievals and in situ measurements suggest there is a systematic relationship between SSA and aerosol amount (AOD or aerosol light scattering) -specifically that SSA decreases at lower aerosol loading. This implies that the fairly common assumption that AERONET SSA values retrieved at high-AOD conditions can be used to obtain AAOD at low-AOD conditions may not be valid.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Comparison of AOD, AAOD and column single scattering albedo from AERONET retrievals and in situ profiling measurements

et al. 2017

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“…Validation of the Level 2 Version 22 product against ground-based observations from the Aerosol Robotic Network (AERONET) (Holben et al, 1998), including assessments of particle type retrievals, can be found in Kahn et al (2010) and Kahn and Gaitley (2015). The mixture type information in the MISR Version 22 aerosol product has been exploited by Li et al (2013) and Li et al (2015), for example, who used CCM in-formation to select from the complete set of passing mixtures to improve agreement with AERONET in the continental United States.…”

Section: Introductionmentioning

confidence: 99%

Climatology of the aerosol optical depth by components from the Multi-angle Imaging SpectroRadiometer (MISR) and chemistry transport models

et al. 2016

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Abstract. The Multi-angle Imaging SpectroRadiometer (MISR) Joint Aerosol (JOINT_AS) Level 3 product has provided a global, descriptive summary of MISR Level 2 aerosol optical depth (AOD) and aerosol type information for each month over 16+ years since March 2000. Using Version 1 of JOINT_AS, which is based on the operational (Version 22) MISR Level 2 aerosol product, this study analyzes, for the first time, characteristics of observed and simulated distributions of AOD for three broad classes of aerosols: spherical nonabsorbing, spherical absorbing, and nonspherical -near or downwind of their major source regions. The statistical moments (means, standard deviations, and skewnesses) and distributions of AOD by components derived from the JOINT_AS are compared with results from two chemistry transport models (CTMs), the Goddard Chemistry Aerosol Radiation and Transport (GOCART) and SPectral RadIatioN-TrAnSport (SPRINTARS). Overall, the AOD distributions retrieved from MISR and modeled by GOCART and SPRINTARS agree with each other in a qualitative sense. Marginal distributions of AOD for each aerosol type in both MISR and models show considerable high positive skewness, which indicates the importance of including extreme AOD events when comparing satellite retrievals with models. The MISR JOINT_AS product will greatly facilitate comparisons between satellite observations and model simulations of aerosols by type.

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“…The retrieval error of GOCART AOD is relatively small in dust and pollution regions, but has a low bias of 30-40% for biomass burning aerosols (Chin et al, 2009). In North/Central America, GOCART AOD is approximately 2 times lower than MODIS (Chin et al, 2004) and MISR (Li, S. et al, 2015). The GOCART 3-D simulations used in this analysis are the same temporal and vertical resolutions as GEOS-Chem, but with higher horizontal resolution (1° latitude × 1.25° longitude).…”

Section: Data Descriptionmentioning

confidence: 98%

Estimation of GEOS-Chem and GOCART Simulated Aerosol Profiles Using CALIPSO Observations over the Contiguous United States

Fan

Tao

et al. 2016

Aerosol Air Qual. Res.

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Model-simulated aerosol profiles can significantly improve a satellite's capability to estimate ground-level particle concentrations, but are difficult to validate due to the sparse network of ground-based lidars. We quantitatively evaluated aerosol vertical profiles simulated by the Global 3-D Atmospheric Chemical Transport model (GEOS-Chem) and the Goddard Chemistry Aerosol Radiation and Transport model (GOCART) over the contiguous United States using the CloudAerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). Model-simulated and satellite-retrieved Aerosol Optical Depth (AOD) are first validated with the Aerosol Robotic Network (AERONET) data. The large discrepancies between satellite and model are due to underestimation of GEOS-Chem AOD in the West and GOCART AOD in the East, along with overestimation of CALIPSO AOD during winter and in the West. Model-simulated Aerosol Extinction Coefficients (AEC) at three layers are evaluated against CALIPSO. Aggregating the data from daily and 2 × 2.5 degree model resolutions to a national or annual scale can significantly improve the correlation coefficient and regression slope. Both GEOS-Chem and GOCART underestimate AEC in the lower troposphere in the East, and in the free troposphere in the West than CALIPSO. We attribute these differences to the coarse horizontal resolution, missing aerosol components, and inappropriate emission inventory of the models. Additionally, the low signal-to-noise ratio and cloud and bright surface reflectance interfere with the satellite's measurements.

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Improving satellite-retrieved aerosol microphysical properties using GOCART data

Cited by 36 publications

References 47 publications

Comparison of AOD, AAOD and column single scattering albedo from AERONET retrievals and in situ profiling measurements

Comparison of AOD, AAOD and column single scattering albedo from AERONET retrievals and in situ profiling measurements

Climatology of the aerosol optical depth by components from the Multi-angle Imaging SpectroRadiometer (MISR) and chemistry transport models

Estimation of GEOS-Chem and GOCART Simulated Aerosol Profiles Using CALIPSO Observations over the Contiguous United States

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