Using the OMI aerosol index and absorption aerosol optical depth to evaluate the NASA MERRA Aerosol Reanalysis

Buchard, Virginie; Silva, A. M. da; Colarco, Peter R.; Darmenov, Anton; Randles, C. A.; Govindaraju, Ravi; Torres, Omar; Campbell, James; Spurr, R. J. D.

doi:10.5194/acp-15-5743-2015

Cited by 205 publications

(159 citation statements)

References 63 publications

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“…Positive values of AI are associated with UV absorbing aerosols, mainly mineral dust, smoke, and volcanic aerosols. Negative values of AI are associated with non-absorbing aerosols (for example sulfate and sea-salt particles) from both natural and anthropogenic sources (Torres et al, 1998;Buchard et al, 2015;Hammer et al, 2016). Values near zero indicate cloud fields.…”

Section: Satellite-derived Products: Modis and Omi Retrievalsmentioning

confidence: 99%

Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe on 21–22 August 2017

et al. 2018

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Abstract. Light extinction coefficients of 500 Mm −1 , about 20 times higher than after the Pinatubo volcanic eruptions in 1991, were observed by European Aerosol Research Lidar Network (EARLINET) lidars in the stratosphere over central Europe on 21-22 August 2017. Pronounced smoke layers with a 1-2 km vertical extent were found 2-5 km above the local tropopause. Optically dense layers of Canadian wildfire smoke reached central Europe 10 days after their injection into the upper troposphere and lower stratosphere which was caused by rather strong pyrocumulonimbus activity over western Canada. The smoke-related aerosol optical thickness (AOT) identified by lidar was close to 1.0 at 532 nm over Leipzig during the noon hours on 22 August 2017. Smoke particles were found throughout the free troposphere (AOT of 0.3) and in the pronounced 2 km thick stratospheric smoke layer at an altitude of 14-16 km (AOT of 0.6). The lidar observations indicated peak mass concentrations of 70-100 µg m −3 in the stratosphere. In addition to the lidar profiles, we analyzed Moderate Resolution Imaging Spectroradiometer (MODIS) fire radiative power (FRP) over Canada, and the distribution of MODIS AOT and Ozone Monitoring Instrument (OMI) aerosol index across the North Atlantic. These instruments showed a similar pattern and a clear link between the western Canadian fires and the aerosol load over Europe. In this paper, we also present Aerosol Robotic Network (AERONET) sun photometer observations, compare photometer and lidar-derived AOT, and discuss an obvious bias (the smoke AOT is too low) in the photometer observations. Finally, we compare the strength of this recordbreaking smoke event (in terms of the particle extinction coefficient and AOT) with major and moderate volcanic events observed over the northern midlatitudes.

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Section: Satellite-derived Products: Modis and Omi Retrievalsmentioning

confidence: 99%

Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe on 21–22 August 2017

et al. 2018

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“…A closer look should be taken at observations in mixing areas where biomass burning aerosols may have different chemical composition and/or mineral dust has heavy loadings in order to generalize the clear separation observed in the spectral dependences of mineral dust and biomass burning (Bahadur et al, 2012). This aspect is relevant to the development of remote-sensing retrievals of light absorption by aerosols from space and their assimilation in climate models (Torres et al, 2007;Buchard et al, 2015;Hammer et al, 2016).…”

Section: Conclusive Remarksmentioning

confidence: 99%

Spectral- and size-resolved mass absorption efficiency of mineral dust aerosols in the shortwave spectrum: a simulation chamber study

et al. 2017

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Abstract. This paper presents new laboratory measurements of the mass absorption efficiency (MAE) between 375 and 850 nm for 12 individual samples of mineral dust from different source areas worldwide and in two size classes: PM 10.6 (mass fraction of particles of aerodynamic diameter lower than 10.6 µm) and PM 2.5 (mass fraction of particles of aerodynamic diameter lower than 2.5 µm). The experiments were performed in the CESAM simulation chamber using mineral dust generated from natural parent soils and included optical and gravimetric analyses.The results show that the MAE values are lower for the PM 10.6 mass fraction (range 37-135 × 10 −3 m 2 g −1 at 375 nm) than for the PM 2.5 (range 95-711 × 10 −3 m 2 g −1 at 375 nm) and decrease with increasing wavelength as λ −AAE , where the Ångström absorption exponent (AAE) averages between 3.3 and 3.5, regardless of size. The size independence of AAE suggests that, for a given size distribution, the dust composition did not vary with size for this set of samples. Because of its high atmospheric concentration, light absorption by mineral dust can be competitive with black and brown carbon even during atmospheric transport over heavy polluted regions, when dust concentrations are significantly lower than at emission. The AAE values of mineral dust are higher than for black carbon (∼ 1) but in the same range as light-absorbing organic (brown) carbon. As a result, depending on the environment, there can be some ambiguity in apportioning the aerosol absorption optical depth (AAOD) based on spectral dependence, which is relevant to the development of remote sensing of light-absorbing aerosols and their assimilation in climate models. We suggest that the sample-to-sample variability in our dataset of MAE values is related to regional differences in the mineralogical composition of the parent soils. Particularly in the PM 2.5 fraction, we found a strong linear correlation between the dust lightPublished by Copernicus Publications on behalf of the European Geosciences Union. 7176 L. Caponi et al.: Spectral-and size-resolved mass absorption efficiency of mineral dust aerosols absorption properties and elemental iron rather than the iron oxide fraction, which could ease the application and the validation of climate models that now start to include the representation of the dust composition, as well as for remote sensing of dust absorption in the UV-vis spectral region.

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“…The MERRA aerosol data are the basis for the OCO-2 forward model's aerosol types, as described in detail in JPL (2015, pages 28-31). MERRA aerosol data consisting of five composite types, namely dust (DU), sea salt (SS), sulfate (SU), black carbon (BC), and organic carbon (OC), have nearly zero bias and a correlation coefficient of ∼ 0.9 with respect to the collocated aerosol optical depth (AOD) measurements from AErosol RObotic NETwork (AERONET), Multi-angle Imaging SpectroRadiometer (MISR), and Ozone Monitoring Instrument (OMI) (Buchard et al, 2015). At each sounding location, the two composite types most common at that location are included in the state vector for the operational retrieval, along with liquid water and ice cloud, and are retrieved by the L2 algorithm.…”

Section: Aerosol and Cloudmentioning

confidence: 99%

Quantification of uncertainties in OCO-2 measurements of XCO<sub>2</sub>: simulations and linear error analysis

et al. 2016

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Abstract. We present an analysis of uncertainties in global measurements of the column averaged dry-air mole fraction of CO 2 (XCO 2 ) by the NASA Orbiting Carbon Observatory-2 (OCO-2). The analysis is based on our best estimates for uncertainties in the OCO-2 operational algorithm and its inputs, and uses simulated spectra calculated for the actual flight and sounding geometry, with measured atmospheric analyses. The simulations are calculated for land nadir and ocean glint observations. We include errors in measurement, smoothing, interference, and forward model parameters. All types of error are combined to estimate the uncertainty in XCO 2 from single soundings, before any attempt at bias correction has been made. From these results we also estimate the "variable error" which differs between soundings, to infer the error in the difference of XCO 2 between any two soundings. The most important error sources are aerosol interference, spectroscopy, and instrument calibration. Aerosol is the largest source of variable error. Spectroscopy and calibration, although they are themselves fixed error sources, also produce important variable errors in XCO 2 . Net variable errors are usually < 1 ppm over ocean and ∼ 0.5-2.0 ppm over land. The total error due to all sources is ∼ 1.5-3.5 ppm over land and ∼ 1.5-2.5 ppm over ocean.

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Using the OMI aerosol index and absorption aerosol optical depth to evaluate the NASA MERRA Aerosol Reanalysis

Cited by 205 publications

References 63 publications

Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe on 21–22 August 2017

Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe on 21–22 August 2017

Spectral- and size-resolved mass absorption efficiency of mineral dust aerosols in the shortwave spectrum: a simulation chamber study

Quantification of uncertainties in OCO-2 measurements of XCO<sub>2</sub>: simulations and linear error analysis

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Using the OMI aerosol index and absorption aerosol optical depth to evaluate the NASA MERRA Aerosol Reanalysis

Cited by 205 publications

References 63 publications

Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe on 21–22 August 2017

Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe on 21–22 August 2017

Spectral- and size-resolved mass absorption efficiency of mineral dust aerosols in the shortwave spectrum: a simulation chamber study

Quantification of uncertainties in OCO-2 measurements of XCO&lt;sub&gt;2&lt;/sub&gt;: simulations and linear error analysis

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Quantification of uncertainties in OCO-2 measurements of XCO<sub>2</sub>: simulations and linear error analysis