scholarly journals Saharan dust transport to the Caribbean during PRIDE: 1. Influence of dust sources and removal mechanisms on the timing and magnitude of downwind aerosol optical depth events from simulations of in situ and remote sensing observations

2003 ◽  
Vol 108 (D19) ◽  
Author(s):  
P. R. Colarco
Keyword(s):  
Remote Sensing ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Saharan Dust ◽  
Dust Transport ◽  
Removal Mechanisms ◽  
Dust Sources ◽  
The Caribbean

scholarly journals Sun photometer retrievals of Saharan dust properties over Barbados during SALTRACE

2019 ◽  
Vol 19 (23) ◽  
pp. 14571-14583 ◽  
Author(s):  
Carlos Toledano ◽  
Benjamín Torres ◽  
Cristian Velasco-Merino ◽  
Dietrich Althausen ◽  
Silke Groß ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Saharan Dust ◽  
Caribbean Region ◽  
The Sun ◽  
Concentration Data ◽  
The Caribbean ◽  
Sun Photometer ◽  
Dust Events

Abstract. The Saharan Aerosol Long-Range Transport and Aerosol–Cloud-Interaction Experiment (SALTRACE) was devoted to the investigation of Saharan dust properties over the Caribbean. The campaign took place in June–July 2013. A wide set of ground-based and airborne aerosol instrumentation was deployed at the island of Barbados for a comprehensive experiment. Several sun photometers performed measurements during this campaign: two AERONET (Aerosol Robotic Network) Cimel sun photometers and the Sun and Sky Automatic Radiometer (SSARA). The sun photometers were co-located with the ground-based multi-wavelength lidars BERTHA (Backscatter Extinction lidar Ratio Temperature Humidity profiling Apparatus) and POLIS (Portable Lidar System). Aerosol properties derived from direct sun and sky radiance observations are analyzed, and a comparison with the co-located lidar and in situ data is provided. The time series of aerosol optical depth (AOD) allows identifying successive dust events with short periods in between in which the marine background conditions were observed. The moderate aerosol optical depth in the range of 0.3 to 0.6 was found during the dust periods. The sun photometer infrared channel at the 1640 nm wavelength was used in the retrieval to investigate possible improvements to aerosol size retrievals, and it was expected to have a larger sensitivity to coarse particles. The comparison between column (aerosol optical depth) and surface (dust concentration) data demonstrates the connection between the Saharan Air Layer and the boundary layer in the Caribbean region, as is shown by the synchronized detection of the successive dust events in both datasets. However the differences of size distributions derived from sun photometer data and in situ observations reveal the difficulties in carrying out a column closure study.

scholarly journals Sun photometer retrievals of Saharan dust properties over Barbados during SALTRACE

2019 ◽  
Author(s):  
Carlos Toledano ◽  
Benjamín Torres ◽  
Cristian Velasco-Merino ◽  
Dietrich Althausen ◽  
Silke Groß ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Saharan Dust ◽  
Caribbean Region ◽  
The Sun ◽  
Concentration Data ◽  
The Caribbean ◽  
Sun Photometer ◽  
Dust Events

Abstract. The Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE) was devoted to the investigation of Saharan dust properties over the Caribbean. The campaign took place in June–July 2013. A wide set of ground-based and airborne aerosol instrumentation was deployed at Barbados island for a comprehensive experiment. Several sun photometers performed measurements during this campaign: two AERONET Cimel sun photometers and the Sun and Sky Automatic Radiometer (SSARA). The sun photometers were co-located with the ground-based multi-wavelength lidars BERTHA and POLIS. Aerosol properties derived from direct sun and sky radiance observations are analyzed, and a comparison with the co-located lidar and in-situ data is provided. The time series of aerosol optical depth allows identifying successive dust events with short periods in between in which the marine background conditions were observed. Moderate aerosol optical depth in the range 0.3 to 0.6 was found during the dust periods. The sun photometer infrared channel at 1640 nm wavelength was used in the retrieval to investigate possible improvements and expected larger sensitivity to coarse particles. The comparison between column (AOD) and surface (dust concentration) data demonstrates the connection between the Saharan Air Layer and the boundary layer in the Caribbean region, as it is shown by the synchronized detection of the successive dust events in both data sets. However the comparison of size distributions derived from sun photometer data and in-situ observations reveal the difficulties to carry out a column closure study.

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

2019 ◽  
Vol 19 (22) ◽  
pp. 14149-14171 ◽  
Author(s):  
Jose Antonio Benavent-Oltra ◽  
Roberto Román ◽  
Juan Andrés Casquero-Vera ◽  
Daniel Pérez-Ramírez ◽  
Hassan Lyamani ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Sierra Nevada ◽  
Volume Concentration ◽  
In Situ Measurements ◽  
Saharan Dust ◽  
Scattering Coefficient ◽  
Night Time ◽  
Aerosol Properties

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.

scholarly journals Extreme Saharan dust event over the southern Iberian Peninsula in september 2007: active and passive remote sensing from surface and satellite

2009 ◽  
Vol 9 (4) ◽  
pp. 15673-15723
Author(s):  
J. L. Guerrero-Rascado ◽  
F. J. Olmo ◽  
I. Avilés-Rodríguez ◽  
F. Navas-Guzmán ◽  
D. Pérez-Ramírez ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Iberian Peninsula ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Saharan Dust ◽  
Dust Event ◽  
Passive Remote Sensing ◽  
Angstrom Exponent ◽  
Ångström Exponent ◽  
Ångstrom Exponent

Abstract. This study investigates aerosol optical properties during the extreme Saharan dust event detected from 3 to 7 September 2007 over Granada, southern Iberian Peninsula, with both active and passive remote sensing instrumentation from surface and satellite. The intensity of the event was visualized on the aerosol optical depth series obtained by the sun-photometer Cimel CE 318-4 operated at Granada in the framework of AERONET from August 2004 until December 2008 (level 2 data). A combination of large aerosol optical depth (0.86–1.50) at 500 nm, and reduced Angström exponent (0.1–0.25) in the range 440–870 nm, was detected on 6 September during daytime. This Saharan dust event also affected other Iberian Peninsula stations included in AERONET (El Arenosillo and Évora stations). During the most intense stage, on 6 September, maximum aerosol backscatter values were a factor of 8 higher than other maxima during this Saharan dust event. Values up to 1.5×10−2 km−1 sr−1 at 355 and 532 nm were detected in the layer with the greatest aerosol load between 3–4 km a.s.l., although aerosol particles were also detected up to 5.5 km a.s.l. In this stage of the event, dust particles at these altitudes showed a backscatter-related Angström exponent between −0.44 and 0.53 for the two spectral intervals considered. The results from different measurements (active/passive and ground-based/satellite) reveal the importance of performing multi-instrumental measurements to properly characterize the contribution of different aerosol types from different sources during extreme events.

scholarly journals The MERRA-2 Aerosol Reanalysis, 1980 Onward. Part II: Evaluation and Case Studies

2017 ◽  
Vol 30 (17) ◽  
pp. 6851-6872 ◽  
Author(s):  
V. Buchard ◽  
C. A. Randles ◽  
A. M. da Silva ◽  
A. Darmenov ◽  
P. R. Colarco ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Fine Particulate Matter ◽  
Saharan Dust ◽  
Ozone Monitoring Instrument ◽  
Dust Transport ◽  
Earth Observing System ◽  
Rim Fire ◽  
Independent Observations ◽  
Moderate Resolution Imaging Spectroradiometer

The Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), is NASA’s latest reanalysis for the satellite era (1980 onward) using the Goddard Earth Observing System, version 5 (GEOS-5), Earth system model. MERRA-2 provides several improvements over its predecessor (MERRA-1), including aerosol assimilation for the entire period. MERRA-2 assimilates bias-corrected aerosol optical depth (AOD) from the Moderate Resolution Imaging Spectroradiometer and the Advanced Very High Resolution Radiometer instruments. Additionally, MERRA-2 assimilates (non bias corrected) AOD from the Multiangle Imaging SpectroRadiometer over bright surfaces and AOD from Aerosol Robotic Network sunphotometer stations. This paper, the second of a pair, summarizes the efforts to assess the quality of the MERRA-2 aerosol products. First, MERRA-2 aerosols are evaluated using independent observations. It is shown that the MERRA-2 absorption aerosol optical depth (AAOD) and ultraviolet aerosol index (AI) compare well with Ozone Monitoring Instrument observations. Next, aerosol vertical structure and surface fine particulate matter (PM2.5) are evaluated using available satellite, aircraft, and ground-based observations. While MERRA-2 generally compares well to these observations, the assimilation cannot correct for all deficiencies in the model (e.g., missing emissions). Such deficiencies can explain many of the biases with observations. Finally, a focus is placed on several major aerosol events to illustrate successes and weaknesses of the AOD assimilation: the Mount Pinatubo eruption, a Saharan dust transport episode, the California Rim Fire, and an extreme pollution event over China. The article concludes with a summary that points to best practices for using the MERRA-2 aerosol reanalysis in future studies.

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

2019 ◽  
Author(s):  
Jose Antonio Benavent-Oltra ◽  
Roberto Román ◽  
Juan Andrés Casquero-Vera ◽  
Daniel Pérez-Ramírez ◽  
Hassan Lyamani ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Sierra Nevada ◽  
Volume Concentration ◽  
In Situ Measurements ◽  
Saharan Dust ◽  
Scattering Coefficient ◽  
Night Time ◽  
Aerosol Properties

Abstract. This study evaluates the potential of 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 lidar ground-based 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 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 the aerosol optical depth values.

scholarly journals Extreme Saharan dust event over the southern Iberian Peninsula in september 2007: active and passive remote sensing from surface and satellite

2009 ◽  
Vol 9 (21) ◽  
pp. 8453-8469 ◽  
Author(s):  
J. L. Guerrero-Rascado ◽  
F. J. Olmo ◽  
I. Avilés-Rodríguez ◽  
F. Navas-Guzmán ◽  
D. Pérez-Ramírez ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Iberian Peninsula ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Aerosol Particles ◽  
Saharan Dust ◽  
Dust Event ◽  
Passive Remote Sensing ◽  
Angstrom Exponent ◽  
Ångström Exponent

Abstract. This study investigates aerosol optical properties during the extreme Saharan dust event detected from 3 to 7 September 2007 over Granada, southern Iberian Peninsula, with both active and passive remote sensing instrumentation from surface and satellite. The intensity of the event was visualized on the aerosol optical depth series obtained by the sun-photometer Cimel CE 318-4 operated at Granada in the framework of AERONET from August 2004 until December 2008 (level 2 data). A combination of large aerosol optical depth (0.86–1.50) at 500 nm, and reduced Angström exponent (0.1–0.25) in the range 440–870 nm, was detected on 6 September during daytime. This Saharan dust event also affected other Iberian Peninsula stations included in AERONET (El Arenosillo and Évora stations), and it was monitored by MODIS instrument on board Aqua satellite. Vertically resolved measurements were performed by a ground-based Raman Lidar and by CALIPSO satellite. During the most intense stage, on 6 September, maximum aerosol backscatter values were a factor of 8 higher than other maxima during this Saharan dust event. Values up to 1.5×10−2 km−1 sr−1 at 355 and 532 nm were detected in the layer with the greatest aerosol load between 3–4 km a.s.l., although aerosol particles were also detected up to 5.5 km a.s.l. In this stage of the event, dust particles at these altitudes showed a backscatter-related Angström exponent between –0.44 and 0.53 for the two spectral intervals considered. The results from different measurements (active/passive and ground-based/satellite) reveal the importance of performing multi-instrumental measurements to properly characterize the contribution of different aerosol types from different sources during extreme events. The atmospheric stabilization effect of the aerosol particles has been characterized by computing the solar heating rates using SBDART code.

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