Retrieval of aerosol profiles combining sunphotometer and ceilometer measurements in GRASP code

Román, Roberto; Benavent-Oltra, José Antonio; Casquero-Vera, Juan Andrés; Lopatin, Anton; Cazorla, A.; Lyamani, H.; Denjean, Cyrielle; Fuertes, David; Pérez-Ramírez, D.; Torres, Benjamín; Toledano, Carlos; Dubovik, Оleg; Cachorro, Victoria E.; Frutos, Ángel M. de; Olmo, F.J.; Alados-Arboledas, L.

doi:10.1016/j.atmosres.2018.01.021

Cited by 58 publications

(59 citation statements)

References 79 publications

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“…Also, using the GRASP algorithm, Tsekeri et al (2017) obtained an RRI value of 1.45 for a desert dust event at Finokalia (Crete, Greece). Nevertheless, the RRI values obtained here are lower than those used for desert dust by several models (RRI = 1.53 for the visible spectral region) (Shettle and Fenn, 1979;WMO, 1983;Koepke et al, 1997). However, the differences between RRI values obtained here for the desert dust event and those reported in the literature can be explained by the differences in the chemical composition of dust (e.g.…”

Section: Columnar Complex Refractive Indicescontrasting

confidence: 61%

Different strategies to retrieve aerosol properties at night-time with the GRASP algorithm

et al. 2019

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Abstract. This study evaluates the potential of the GRASP algorithm (Generalized Retrieval of Aerosol and Surface Properties) to retrieve continuous day-to-night aerosol properties, both column-integrated and vertically resolved. The study is focused on the evaluation of GRASP retrievals during an intense Saharan dust event that occurred during the Sierra Nevada Lidar aerOsol Profiling Experiment I (SLOPE I) field campaign. For daytime aerosol retrievals, we combined the measurements of the ground-based lidar from EARLINET (European Aerosol Research Lidar Network) station and sun–sky photometer from AERONET (Aerosol Robotic Network), both instruments co-located in Granada (Spain). However, for night-time retrievals three different combinations of active and passive remote-sensing measurements are proposed. The first scheme (N0) uses lidar night-time measurements in combination with the interpolation of sun–sky daytime measurements. The other two schemes combine lidar night-time measurements with night-time aerosol optical depth obtained by lunar photometry either using intensive properties of the aerosol retrieved during sun–sky daytime measurements (N1) or using the Moon aureole radiance obtained by sky camera images (N2). Evaluations of the columnar aerosol properties retrieved by GRASP are done versus standard AERONET retrievals. The coherence of day-to-night evolutions of the different aerosol properties retrieved by GRASP is also studied. The extinction coefficient vertical profiles retrieved by GRASP are compared with the profiles calculated by the Raman technique at night-time with differences below 30 % for all schemes at 355, 532 and 1064 nm. Finally, the volume concentration and scattering coefficient retrieved by GRASP at 2500 m a.s.l. are evaluated by in situ measurements at this height at Sierra Nevada Station. The differences between GRASP and in situ measurements are similar for the different schemes, with differences below 30 % for both volume concentration and scattering coefficient. In general, for the scattering coefficient, the GRASP N0 and N1 show better results than the GRASP N2 schemes, while for volume concentration, GRASP N2 shows the lowest differences against in situ measurements (around 10 %) for high aerosol optical depth values.

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Section: Columnar Complex Refractive Indicescontrasting

confidence: 61%

Different strategies to retrieve aerosol properties at night-time with the GRASP algorithm

et al. 2019

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“…However, the a posteriori R = 0.70 for AExp is slightly worse than the a priori (R = 0.74), which is likely related to the ∼ 20 % higher bias of the a posteriori AOD. Consistent with AAOD, the GEOS-Chem AAExp shows improvements from the a priori simulation (R = 0.01, MAE = 0.71, NMB = 6.84 %, MB = 0.15) to the a posteriori simulation (R = 0.62, MAE = 0.35, NMB = −7.35 %, MB = −0.11), which indicates a better representation of the spectral dependence of aerosol absorption (Russell et al, 2010;.…”

Section: Comparison With Aeronet Measurementsmentioning

confidence: 72%

Constraining global aerosol emissions using POLDER/PARASOL satellite remote sensing observations

et al. 2019

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We invert global black carbon (BC), organic carbon (OC) and desert dust (DD) aerosol emissions from POLDER/PARASOL spectral aerosol optical depth (AOD) and aerosol absorption optical depth (AAOD) using the GEOS-Chem inverse modeling framework. Our inverse modeling framework uses standard a priori emissions to provide a posteriori emissions that are constrained by POLDER/PARASOL AODs and AAODs. The following global emission values were retrieved for the three aerosol components: 18.4 Tg yr −1 for BC, 109.9 Tg yr −1 for OC and 731.6 Tg yr −1 for DD for the year 2010. These values show a difference of +166.7 %, +184.0 % and −42.4 %, respectively, with respect to the a priori values of emission inventories used in "standard" GEOS-Chem runs. The model simulations using a posteriori emissions (i.e., retrieved emissions) provide values of 0.119 for global mean AOD and 0.0071 for AAOD at 550 nm, which are +13.3 % and +82.1 %, respectively, higher than the AOD and AAOD obtained using the a priori values of emissions. Additionally, the a posteriori model simulation of AOD, AAOD, single scattering albedo, Ångström exponent and absorption Ångström exponent show better agreement with independent AERONET, MODIS and OMI measurements than the a priori simulation. Thus, this study suggests that using satellite-constrained global aerosol emissions in aerosol transport models can improve the accuracy of simulated global aerosol properties.

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“…Moreover, in situ instrumentation is able to provide a complete set of information in terms of chemical, optical and microphysical aerosol properties. The main drawback of in situ observatories is that they are only representative of the atmospheric layer closest to the surface and might not be useful to infer aerosol radiative properties at elevated layers (Rosati et al, 2016). For this reason, vertically resolved aerosol observations are needed to complement surface in situ measurements and column-integrated observations from satellites or ground-based photometers.…”

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confidence: 99%

Retrieval of aerosol properties from ceilometer and photometer measurements: long-term evaluation with in situ data and statistical analysis at Montsec (southern Pyrenees)

Titos¹,

Ealo²,

Román³

et al. 2019

Atmos. Meas. Tech.

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Abstract. Given the need for accurate knowledge of aerosol microphysical and optical properties with height resolution, various algorithms combining vertically resolved and column-integrated aerosol information have been developed in the last years. Here we present new results of vertically resolved extensive aerosol optical properties (backscattering, scattering and extinction) and volume concentrations retrieved with the GRASP (Generalized Retrieval of Aerosol and Surface Properties) algorithm over a 3-year period. The range-corrected signal (RCS) at 1064 nm measured with a ceilometer and the aerosol optical depth (AOD) and sky radiances from a sun/sky photometer have been used as input for this algorithm. We perform a detailed evaluation of GRASP retrievals with simultaneous in situ measurements performed at the same height, at the Montsec mountaintop observatory (MSA) in the Pre-Pyrenees (northeastern Spain). This is the first long-term evaluation of various outputs of this algorithm; previous evaluations focused only on the study of aerosol volume concentration for short-term periods. In general, our results show good agreement between techniques although GRASP inversions yield higher values than those measured in situ. The statistical analysis of the extinction coefficient vertical profiles shows a clear seasonality as well as significant differences depending on the air mass origin. The observed seasonal cycle is mainly modulated by a higher development of the atmospheric boundary layer (ABL) during warm months, which favors the transport of pollutants to MSA, and higher influence of regional and North African episodes. On the other hand, in winter, MSA is frequently influenced by free-troposphere conditions and venting periods and therefore lower extinction coefficients that markedly decrease with height. This study shows the potentiality of implementing GRASP in ceilometer and lidar networks for obtaining aerosol optical properties and volume concentrations at multiple sites, which will definitely contribute to enhancing the representativeness of the aerosol vertical distribution as well as to providing useful information for satellite and global model evaluation.

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Retrieval of aerosol profiles combining sunphotometer and ceilometer measurements in GRASP code

Cited by 58 publications

References 79 publications

Different strategies to retrieve aerosol properties at night-time with the GRASP algorithm

Different strategies to retrieve aerosol properties at night-time with the GRASP algorithm

Constraining global aerosol emissions using POLDER/PARASOL satellite remote sensing observations

Retrieval of aerosol properties from ceilometer and photometer measurements: long-term evaluation with in situ data and statistical analysis at Montsec (southern Pyrenees)

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