scholarly journals Seasonal Variations of Aerosol Optical Properties and Identification of Different Aerosol Types Based on AERONET Data over Sub-Sahara West-Africa

2016 ◽  
Vol 06 (01) ◽  
pp. 13-28 ◽  
Author(s):  
Mukhtar Balarabe ◽  
Khiruddin Abdullah ◽  
Mohd Nawawi
Keyword(s):  
Optical Properties ◽  
West Africa ◽  
Seasonal Variations ◽  
Aerosol Optical Properties ◽  
Aerosol Types

scholarly journals Long-term multi-source data analysis about the characteristics of aerosol optical properties and types over Australia

2020 ◽  
Author(s):  
Xingchuan Yang ◽  
Chuanfeng Zhao ◽  
Yikun Yang
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Seasonal Variations ◽  
Dust Aerosol ◽  
Northern Australia ◽  
Aerosol Optical Properties ◽  
Austral Spring ◽  
Modis Aod ◽  
Central Australia ◽  
Aerosol Types

Abstract. The spatiotemporal distributions of aerosol optical properties and major aerosol types, along with the vertical distribution of major aerosol types over Australia, are investigated based on multi-year AERONET observations at nine sites, the Moderate Resolution Imaging Spectroradiometer (MODIS), Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2), Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), and back-trajectory analysis from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT). The annual aerosol optical depth (AOD) at most sites showed increasing trends (0.002–0.028 yr−1) except for that at three sites of Canberra, Jabiru, and Lake Argyle, which showed decreasing trends (−0.004–−0.002 yr−1). In contrast, the annual Ångström exponent (AE) showed decreasing tendencies at most sites (−0.044–−0.005 yr−1). The results showed strong seasonal variations in AOD with high values in the austral spring and summer and relatively low values in the austral fall and winter, and weak seasonal variations in AE with the highest mean values in the austral spring at most sites. Spatially, the MODIS AOD showed obvious spatial heterogeneity with higher values appeared over the Australian tropical savanna regions, Lake Eyre Basin, and southeastern regions of Australia, while low values appeared over the arid regions in western Australia. Monthly averaged AOD increases from August to next austral spring peak (typically December–January), and decreases during the March–July. Classification of Australian aerosols revealed that the mixed type of aerosols (biomass burning and dust aerosol) are dominated in all seasons at nine sites, followed by biomass burning aerosol and dust aerosol. The MERRA-2 showed that carbonaceous over northern Australia, dust over central Australia, sulfate over densely populated northwestern and southeastern Australia, and sea salt over Australian coastal regions are the major types of atmospheric aerosols over Australia. The CALIPSO showed that polluted dust is the dominant aerosol type detected at heights 0.5–5 km during all seasons. Australian aerosol has similar source characteristics due to intercontinental transport of aerosols over Australia, especially for biomass burning and dust aerosols. However, the dust-prone characteristic of aerosol is more prominent over the central Australia, while the biomass burning-prone characteristic of aerosol is more prominent in northern Australia.

scholarly journals Long-term multi-source data analysis about the characteristics of aerosol optical properties and types over Australia

2021 ◽  
Vol 21 (5) ◽  
pp. 3803-3825
Author(s):  
Xingchuan Yang ◽  
Chuanfeng Zhao ◽  
Yikun Yang ◽  
Hao Fan
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Seasonal Variations ◽  
Northern Australia ◽  
Aerosol Optical Properties ◽  
Austral Spring ◽  
Australian Continent ◽  
Modis Aod ◽  
Central Australia ◽  
Aerosol Types

Abstract. The spatiotemporal distributions of aerosol optical properties and major aerosol types, along with the vertical distribution of major aerosol types over Australia, are investigated based on multi-year Aerosol Robotic Network (AERONET) observations at nine sites, the Moderate Resolution Imaging Spectroradiometer (MODIS), Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2), Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), and back-trajectory analysis from the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT). During the observation period from 2001–2020, the annual aerosol optical depth (AOD) at most sites showed increasing trends (0.002–0.029 yr−1), except for that at three sites, Canberra, Jabiru, and Lake Argyle, which showed decreasing trends (−0.004 to −0.014 yr−1). In contrast, the annual Ångström exponent (AE) showed decreasing tendencies at most sites (−0.045 to −0.005 yr−1). The results showed strong seasonal variations in AOD, with high values in the austral spring and summer and relatively low values in the austral fall and winter, and weak seasonal variations in AE, with the highest mean values in the austral spring at most sites. Monthly average AOD increases from August to December or the following January and decreases during March–July. Spatially, the MODIS AOD showed obvious spatial heterogeneity, with high values appearing over the Australian tropical savanna regions, Lake Eyre Basin, and southeastern regions of Australia, while low values appeared over the arid regions in western Australia. MERRA-2 showed that carbonaceous aerosol over northern Australia, dust over central Australia, sulfate over densely populated northwestern and southeastern Australia, and sea salt over Australian coastal regions are the major types of atmospheric aerosols. The nine ground-based AERONET sites over Australia showed that the mixed type of aerosols (biomass burning and dust) is dominant in all seasons. Moreover, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) showed that polluted dust is the dominant aerosol type detected at heights 0.5–5 km over the Australian continent during all seasons. The results suggested that Australian aerosol has similar source characteristics due to the regional transport over Australia, especially for biomass burning and dust aerosols. However, the dust-prone characteristic of aerosol is more prominent over central Australia, while the biomass-burning-prone characteristic of aerosol is more prominent in northern Australia.

scholarly journals STUDY OF AEROSOL OPTICAL PROPERTIES OVER TWO SITES IN THE FOOTHILLS OF THE CENTRAL HIMALAYAS

2018 ◽  
Vol XLII-3 ◽  
pp. 1493-1497 ◽  
Author(s):  
D. Rupakheti ◽  
S. Kang ◽  
Z. Cong ◽  
M. Rupakheti ◽  
L. Tripathee ◽  
...  
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Asymmetry Parameter ◽  
Monsoon Season ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Optical Properties ◽  
Central Himalayas ◽  
Aerosol Types ◽  
Volume Size

Atmospheric aerosol possesses impacts on climate system and ecological environments, human health and agricultural productivity. The environment over Himalayas and Tibetan Plateau region are continuously degraded due to the transport of pollution from the foothills of the Himalayas; mostly the Indo-Gangetic Plain (IGP). Thus, analysis of aerosol optical properties over two sites; Lumbini and Kathmandu (the southern slope of central Himalayas) using AERONET’s CIMEL sun photometer were conducted in this study. Aerosol optical depth (AOD at 500 nm), angstrom exponent (α or AE), volume size distribution (VSD), single scattering albedo (SSA) and asymmetry parameter (AP) were studied for 2013–2014 and the average AOD was found to be: 0.64 ± 0.41 (Lumbini) and 0.45 ± 0.30 (Kathmandu). The average AE was found to be: 1.25 ± 0.24 and 1.26 ± 0.18 respectively for two sites. The relation between AOD and AE was used to discriminate the aerosol types over these sites which indicated anthropogenic, mixed and biomass burning origin aerosol constituted the major aerosol types in Lumbini and Kathmandu. A clear bi-modal distribution of aerosol volume size was observed with highest volume concentration during the post-monsoon season in fine mode and pre-monsoon season in coarse mode (Lumbini) and highest value over both modes during pre-monsoon season in Kathmandu. The single scattering albedo (SSA) and asymmetry parameter (AP) analyses suggested aerosols over the Himalayan foothills sites are dominated by absorbing and anthropogenic aerosols from urban and industrial activities and biomass burning. Long-term studies are essential to understand and characterize the nature of aerosol over this research gap zone.

scholarly journals Overview of aerosol optical properties over southern West Africa from DACCIWA aircraft measurements

2020 ◽  
Vol 20 (8) ◽  
pp. 4735-4756 ◽  
Author(s):  
Cyrielle Denjean ◽  
Thierry Bourrianne ◽  
Frederic Burnet ◽  
Marc Mallet ◽  
Nicolas Maury ◽  
...  
Keyword(s):  
Optical Properties ◽  
West Africa ◽  
Black Carbon ◽  
Biomass Burning ◽  
Aerosol Particles ◽  
Anthropogenic Pollution ◽  
Aerosol Optical Properties ◽  
Air Masses ◽  
Carbon Particles ◽  
Biomass Burning Particles

Abstract. Southern West Africa (SWA) is an African pollution hotspot but a relatively poorly sampled region of the world. We present an overview of in situ aerosol optical measurements collected over SWA in June and July 2016 as part as of the DACCIWA (Dynamics-Aerosol-Chemistry-Clouds Interactions in West Africa) airborne campaign. The aircraft sampled a wide range of air masses, including anthropogenic pollution plumes emitted from the coastal cities, long-range transported biomass burning plumes from central and southern Africa and dust plumes from the Sahara and Sahel region, as well as mixtures of these plumes. The specific objective of this work is to characterize the regional variability of the vertical distribution of aerosol particles and their spectral optical properties (single scattering albedo: SSA, asymmetry parameter, extinction mass efficiency, scattering Ångström exponent and absorption Ångström exponent: AAE). The first findings indicate that aerosol optical properties in the planetary boundary layer were dominated by a widespread and persistent biomass burning loading from the Southern Hemisphere. Despite a strong increase in aerosol number concentration in air masses downwind of urban conglomerations, spectral SSA were comparable to the background and showed signatures of the absorption characteristics of biomass burning aerosols. In the free troposphere, moderately to strongly absorbing aerosol layers, dominated by either dust or biomass burning particles, occurred occasionally. In aerosol layers dominated by mineral dust particles, SSA varied from 0.81 to 0.92 at 550 nm depending on the variable proportion of anthropogenic pollution particles externally mixed with the dust. For the layers dominated by biomass burning particles, aerosol particles were significantly more light absorbing than those previously measured in other areas (e.g. Amazonia, North America), with SSA ranging from 0.71 to 0.77 at 550 nm. The variability of SSA was mainly controlled by variations in aerosol composition rather than in aerosol size distribution. Correspondingly, values of AAE ranged from 0.9 to 1.1, suggesting that lens-coated black carbon particles were the dominant absorber in the visible range for these biomass burning aerosols. Comparison with the literature shows a consistent picture of increasing absorption enhancement of biomass burning aerosol from emission to remote location and underscores that the evolution of SSA occurred a long time after emission. The results presented here build a fundamental basis of knowledge about the aerosol optical properties observed over SWA during the monsoon season and can be used in climate modelling studies and satellite retrievals. In particular and regarding the very high absorbing properties of biomass burning aerosols over SWA, our findings suggest that considering the effect of internal mixing on absorption properties of black carbon particles in climate models should help better assess the direct and semi-direct radiative effects of biomass burning particles.

Columnar-integrated aerosol optical properties and classification of different aerosol types over the semi-arid region, Anantapur, Andhra Pradesh

2015 ◽  
Vol 527-528 ◽  
pp. 507-519 ◽  
Author(s):  
Rama Gopal K ◽  
Arafath S.Md ◽  
Balakrishnaiah G ◽  
Raja Obul Reddy K ◽  
Siva Kumar Reddy N ◽  
...  
Keyword(s):  
Optical Properties ◽  
Arid Region ◽  
Andhra Pradesh ◽  
Aerosol Optical Properties ◽  
Semi Arid Region ◽  
Aerosol Types ◽  
Semi Arid

scholarly journals Measurement report: Long-term changes in black carbon and aerosol optical properties from 2012 to 2020 in Beijing, China

2022 ◽  
Vol 22 (1) ◽  
pp. 561-575
Author(s):  
Jiaxing Sun ◽  
Zhe Wang ◽  
Wei Zhou ◽  
Conghui Xie ◽  
Cheng Wu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Black Carbon ◽  
Seasonal Variations ◽  
Radiative Forcing ◽  
Action Plan ◽  
Aerosol Optical Properties ◽  
Long Term Changes ◽  
Clean Air ◽  
Beijing China

Abstract. Atmospheric aerosols play an important role in the radiation balance of the earth–atmosphere system. However, our knowledge of the long-term changes in equivalent black carbon (eBC) and aerosol optical properties in China is very limited. Here we analyze the 9-year measurements of eBC and aerosol optical properties from 2012 to 2020 in Beijing, China. Our results showed large reductions in eBC by 71 % from 6.25 ± 5.73 µg m−3 in 2012 to 1.80 ± 1.54 µg m−3 in 2020 and 47 % decreases in the light extinction coefficient (bext, λ = 630 nm) of fine particles due to the Clean Air Action Plan that was implemented in 2013. The seasonal and diurnal variations of eBC illustrated the most significant reductions in the fall and at nighttime, respectively. ΔeBC / ΔCO also showed an annual decrease from ∼ 7 to 4 ng m−3 ppbv−1 and presented strong seasonal variations with high values in spring and fall, indicating that primary emissions in Beijing have changed significantly. As a response to the Clean Air Action Plan, single-scattering albedo (SSA) showed a considerable increase from 0.79 ± 0.11 to 0.88 ± 0.06, and mass extinction efficiency (MEE) increased from 3.2 to 3.8 m2 g−1. These results highlight the increasing importance of scattering aerosols in radiative forcing and a future challenge in visibility improvement due to enhanced MEE. Brown carbon (BrC) showed similar changes and seasonal variations to eBC during 2018–2020. However, we found a large increase of secondary BrC in the total BrC in most seasons, particularly in summer with the contribution up to 50 %, demonstrating an enhanced role of secondary formation in BrC in recent years. The long-term changes in eBC and BrC have also affected the radiative forcing effect. The direct radiative forcing (ΔFR) of BC decreased by 67 % from +3.36 W m−2 in 2012 to +1.09 W m−2 in 2020, and that of BrC decreased from +0.30 to +0.17 W m−2 during 2018–2020. Such changes might have important implications for affecting aerosol–boundary layer interactions and the improvement of future air quality.

Monthly and seasonal variations of aerosol optical properties and direct radiative forcing over Zanjan, Iran

2017 ◽  
Vol 164 ◽  
pp. 268-275 ◽  
Author(s):  
Maryam Gharibzadeh ◽  
Khan Alam ◽  
Yousefali Abedini ◽  
Abbasali Aliakbari Bidokhti ◽  
Amir Masoumi
Keyword(s):  
Optical Properties ◽  
Seasonal Variations ◽  
Radiative Forcing ◽  
Aerosol Optical Properties ◽  
Direct Radiative Forcing

scholarly journals Analysis of Atmospheric Aerosol Optical Properties in the Northeast Brazilian Atmosphere with Remote Sensing Data from MODIS and CALIOP/CALIPSO Satellites, AERONET Photometers and a Ground-Based Lidar

Atmosphere ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 594 ◽  
Author(s):  
Aline M. de Oliveira ◽  
Cristina T. Souza ◽  
Nara P. M. de Oliveira ◽  
Aline K. S. Melo ◽  
Fabio J. S. Lopes ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Optical Properties ◽  
Atmospheric Chemistry ◽  
Atmospheric Aerosol ◽  
Remote Sensing Data ◽  
Orthogonal Polarization ◽  
Aerosol Optical Properties ◽  
Modis Aod ◽  
Ground Based Lidar ◽  
Aerosol Types

A 12-year analysis, from 2005 to 2016, of atmospheric aerosol optical properties focusing for the first time on Northeast Brazil (NEB) was performed based on four different remote sensing datasets: the Moderate Resolution Imaging Spectroradiometer (MODIS), the Aerosol Robotic Network (AERONET), the Cloud-Aerosol LIDAR with Orthogonal Polarization (CALIOP) and a ground-based Lidar from Natal. We evaluated and identified distinct aerosol types, considering Aerosol Optical Depth (AOD) and Angström Exponent (AE). All analyses show that over the NEB, a low aerosol scenario prevails, while there are two distinct seasons of more elevated AOD that occur every year, from August to October and January to March. According to MODIS, AOD values ranges from 0.04 to 0.52 over the region with a mean of 0.20 and occasionally isolated outliers of up to 1.21. Aerosol types were identified as sea spray, biomass burning, and dust aerosols mostly transported from tropical Africa. Three case studies on days with elevated AOD were performed. All cases identified the same aerosol types and modeled HYSPLIT backward trajectories confirmed their source-dependent origins. This analysis is motivated by the implementation of an atmospheric chemistry model with an advanced data assimilation system that will use the observational database over NEB with the model to overcome high uncertainties in the model results induced by still unvalidated emission inventories.

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