Extreme, wintertime Saharan dust intrusion in the Iberian Peninsula: Lidar monitoring and evaluation of dust forecast models during the February 2017 event

Fernández, Alfonso; Sicard, Michaël; Costa, María João; Guerrero-Rascado, Juan Luís; Gómez-Amo, José Luís; Molero, Francisco; Barragán, Rubén; Basart, Sara; Bortoli, Daniele; Bedoya-Velásquez, Andrés Esteban; Utrillas, M. P.; Salvador, P.; Granados-Muñoz, María José; Potes, Miguel; Ortiz-Amezcua, Pablo; Martínez‐Lozano, J. A.; Artı́ñano, Begoña; Muñoz-Porcar, Constantino; Salgado, Rui; Román, Roberto; Rocadenbosch, Francesc; Salgueiro, Vanda; Benavent-Oltra, José Antonio; Rodríguez-Gómez, Alejandro; Alados-Arboledas, Lucas; Comerón, Adolfo; Pujadas, M.

doi:10.1016/j.atmosres.2019.06.007

Cited by 58 publications

(44 citation statements)

References 56 publications

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“…The paper is mainly focused on the city of Granada (Spain). Granada is located in the Western Mediterranean basin and it is frequently affected by long-range transport of Saharan dust (Lyamani et al, 2005;Fernández et al, 2019;Soupiona et al, 2019) and biomass burning, both from near sources (Alados-Arboledas et al, 2011) and those at large distances (e.g. Ortiz-Amezcua et al, 2017;Sicard et al, 2019).…”

Section: Andalusian Global Observatory Of the Atmospherementioning

confidence: 99%

“…Furthermore, we used a sky camera SONA (Sistema de Observación de Nubosidad Automático -Automatic Cloud Observation System), which provides hemispherical sky images during the day and at night (González et al, 2012). This system is composed of a CCD (charge-coupled device) camera with a fisheye lens providing RGB images, the effective wavelengths of which correspond to 469, 533 and 608 nm (Román et al, 2017a) for night scenarios.…”

Section: Remote-sensing Measurementsmentioning

confidence: 99%

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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: Andalusian Global Observatory Of the Atmospherementioning

confidence: 99%

Section: Remote-sensing Measurementsmentioning

confidence: 99%

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

et al. 2019

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“…However, satellite and ground-based observations such as AERONET have some limitations because of which they are likely to miss some important details of these dust events. For example, many large-scale dust events are accompanied by cloud cover, which restricts the retrieval of aerosol optical properties in the visible bands (Fernández et al, 2019). Extreme dust events are nonetheless important from a research perspective because they provide an opportunity to understand the associated physical processes.…”

Section: Introductionmentioning

confidence: 99%

Interaction of Dust Aerosols with Land/Sea Breezes over the Eastern Coast of the Red Sea from LIDAR Data and High-resolution WRF-Chem Simulations

Parajuli

Stenchikov

Ukhov

et al. 2020

Preprint

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Abstract. With advances in modeling approaches and the application of satellite and ground-based data in dust-related research, our understanding of the dust cycle has significantly improved in recent decades. However, two aspects of the dust cycle, namely the vertical profiles and diurnal cycles, are not yet adequately understood, mainly due to the sparsity of direct observations. Measurements of backscattering caused by atmospheric aerosols have been ongoing since 2014 at the King Abdullah University of Science and Technology (KAUST) campus using a micro-pulse LIDAR with a high temporal resolution. KAUST is located on the east coast of the Red Sea (22.3° N, 39.1° E), and currently hosts the only operating LIDAR system in the Arabian Peninsula. We use the data from this LIDAR together with other collocated observations and high-resolution WRF-Chem model simulations to study the following aspects of aerosols, with a focus on dust over the Red Sea Arabian coastal plains. Firstly, we investigate the vertical profiles of aerosol extinction and concentration in terms of their seasonal and diurnal variability. Secondly, we evaluate how well the WRF-Chem model performs in representing the vertical distribution of aerosols over the study site. Thirdly, we explore the interactions between dust aerosols and land/sea breezes, which are the most influential components of the local diurnal circulation in the region. We found a substantial variation in the vertical profile of aerosols in different seasons. We also discovered a marked difference in the daytime and nighttime vertical distribution of aerosols at the study site, as revealed by the LIDAR data. The LIDAR data also identified a prominent dust layer at ∼5–7 km during the nighttime, which represented the long-range transported dust brought to the site by the easterly flow from remote inland deserts. The vertical profiles of aerosol extinction in different seasons were largely consistent between the LIDAR, MERRA-2 reanalysis, and CALIOP data, as well as in the WRF-Chem simulations. The sea breeze circulation was much deeper (∼2 km) than the land breeze circulation (∼1 km), but both breeze systems prominently affected the distribution of dust aerosols over the study site. We observed that sea breezes push the dust aerosols upwards along the western slope of the Sarawat Mountains, which eventually collide with the dust-laden northeasterly trade winds coming from nearby inland deserts, causing elevated dust maxima at a height of ∼1.5 km above sea level over the mountains. Moreover, the sea and land breezes intensified dust emissions from the coastal region during the daytime and nighttime, respectively. The WRF-Chem model successfully captured the onset, demise, and height of a large-scale dust event that occurred in 2015, compared to LIDAR data. Our study, although focused on a particular region, has broader environmental implications as it highlights how aerosols and dust emissions from the coastal plains can affect the Red Sea climate and marine habitats.

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“…This must be caused by the increased emission of heating systems and the higher urban traffic typical of this time of the year [14], furthermore the small size of this aerosols explain the high Angström exponent 440-870 (wavelength dependency) of the winter lower layers. There is an unusual high standard deviation between 1500 and 4000 meters caused by two extremely strong Saharan dust outbreaks in 2016 [12] and 2017 [30], both in February. However at the sight of the mean extinction value at these levels, a very clear atmosphere can be found normally in these heights.…”

Section: Granada Extinction Vertical Profilesmentioning

confidence: 99%

Evaluation of retrieved aerosol extinction profiles using as reference the aerosol optical depth differences between various heights

Herreras

Román

Cazorla

et al. 2019

Atmospheric Research

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Aerosol extinction vertical profiles at Granada (Spain) are calculated with the GRASP (Generalized Retrieval of Aerosol and Surface Properties) code using as input Aerosol Optical Depth (AOD) and sky radiance measurements from AERONET (AEerosol RObotic NETwork) and ceilometer RCS (Range Corrected Signal) profiles, both corresponding to the Granada (Spain) station. This methodology is so called GRASP pac due to the combination of sun/sky photometer and ceilometer on GRASP. In order to evaluate the accuracy of these retrieved extinction profiles at Granada, two more nearby AERONET stations, located at different altitudes, are used. The AOD difference of the three choosen AERONET sun/sky photometers have been used to calculate the Integrated Aerosol Extinction (IAE) at different height layers. These three AERONET sun/sky photometers are used as a reference and compared against the integrated extinction at the same layers from the extinction profiles retrieved by GRASP pac. The differences between AERONET and GRASP pac retrieved IAE values indicate that GRASP pac aerosol extinction profiles are at least within the uncertainty of the sun/sky photometer measurements, but GRASP pac method overestimates the AERONET extinction at low altitudes and underestimates it at high levels. The most accurate and precise retrieved extinction correspond to the intermediate layer with a mean bias error (MBE ± standard deviation) of 0.00 ± 0.01 (0 ± 59%) for 1020 nm, and the worst integrated extinction results were obtained for the upper layers with a MBE of-0.01 ± 0.02 (28 ± 36%) for 1020 nm. In general these MBE values increases for shorter wavelengths. In order to obtain a complete characterization of this bias, the dependence of the obtained differences on the aerosol size and the solar zenith angle, among others, are analysed in detail. Finally, the behaviour of vertically-resolved aerosol extinction at Granada is evaluated using averages of the retrieved profiles from November of 2012 to December of 2017. The highest IAE values are found in Summer with mean values of 0.09 for the lower layers and 0.07 for the upper ones, both at 440 nm wavelength. is no standard LiDAR instrument, however, EARLINET (European Aerosol Research LiDAR NETwork)[7] guarantees the standardization and homogenization of the data. GRASP (Generalized Retrieval of Aerosol and Surface Properties) code [8] is an open algorithm which following GARRLiC/GRASP strategy [9], where multi-wavelength LiDAR and sun/sky photometer measurements are combined, enables the retrieval of optical and micro-physical aerosol properties. Due to LiDAR technical characteristics, two aerosol modes (coarse and fine) are available along the column. Thus, an independent characterization for both modes of vertical extinction profiles, SSA (Single Scattering Albedo) or complex refractive index, between others, can be obtained as in [10]. Despite the advantages of multi-wavelength LiDAR instruments, its elevated cost and operative difficulties are the responsible of its scarce geographical...

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Extreme, wintertime Saharan dust intrusion in the Iberian Peninsula: Lidar monitoring and evaluation of dust forecast models during the February 2017 event

Cited by 58 publications

References 56 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

Interaction of Dust Aerosols with Land/Sea Breezes over the Eastern Coast of the Red Sea from LIDAR Data and High-resolution WRF-Chem Simulations

Evaluation of retrieved aerosol extinction profiles using as reference the aerosol optical depth differences between various heights

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