scholarly journals Modulation of the aerosol absorption and single-scattering albedo due to synoptic scale and sea breeze circulations: United Arab Emirates experiment perspective

2007 ◽  
Vol 112 (D5) ◽  
Author(s):  
J. Remiszewska ◽  
P. J. Flatau ◽  
K. M. Markowicz ◽  
E. A. Reid ◽  
J. S. Reid ◽  
...  
Keyword(s):  
United Arab Emirates ◽  
Sea Breeze ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Synoptic Scale ◽  
Aerosol Absorption

scholarly journals Global maps of aerosol single scattering albedo using combined CERES-MODIS retrieval

2021 ◽  
Author(s):  
Archana Devi ◽  
Sreedharan Krishnakumari Satheesh
Keyword(s):  
Climate Models ◽  
Radiant Energy ◽  
Energy System ◽  
Single Scattering ◽  
Global Scale ◽  
Single Scattering Albedo ◽  
Accurate Information ◽  
Climatic Impact ◽  
Aerosol Absorption ◽  
Moderate Resolution Imaging Spectroradiometer

Abstract. Single Scattering Albedo (SSA) is a leading contributor to the uncertainty in aerosol radiative impact assessments. Therefore accurate information on aerosol absorption is required on a global scale. In this study, we have applied a multi-satellite algorithm to retrieve SSA using the concept of ‘critical optical depth.’ Global maps of SSA were generated following this approach using spatially and temporally collocated data from Clouds and the Earth’s Radiant Energy System (CERES) and Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on board Terra and Aqua satellites. The method has been validated using the data from aircraft-based measurements of various field campaigns. The retrieval uncertainty is ±0.03 and depends on both the surface albedo and aerosol absorption. Global mean SSA estimated over land and ocean is 0.93 and 0.97, respectively. Seasonal and spatial distribution of SSA over various regions are also presented. The global maps of SSA, thus derived with improved accuracy, provide important input to climate models for assessing the climatic impact of aerosols on regional and global scales.

scholarly journals Vertical profiles of sub-micron aerosol single scattering albedo over Indian region immediately before monsoon onset and during its development: Research from the SWAAMI field campaign

2019 ◽  
Author(s):  
Mohanan R. Manoj ◽  
Sreedharan K. Satheesh ◽  
Krishnaswamy K. Moorthy ◽  
Hugh Coe
Keyword(s):  
Active Phase ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Development Research ◽  
Aerosol Absorption ◽  
South West ◽  
Aerosol Scattering ◽  
First Time ◽  
Geographical Locations

Abstract. Vertical structures of aerosol single scattering albedo (SSA), from near the surface through the free troposphere, have been estimated for the first time at distinct geographical locations over the Indian mainland and adjoining oceans, using in-situ measurements of aerosol scattering and absorption coefficients aboard the FAAM BAe-146 aircraft during the South West Asian Aerosol Monsoon Interactions (SWAAMI) campaign from June to July 2016. These are used to examine the spatial variation of SSA profiles and also to characterize its transformation from just prior to the onset of Indian Summer Monsoon (June 2016) to its active phase (July 2016). Very strong aerosol absorption, with SSA values as low as 0.7, persisted in the lower altitudes (

scholarly journals Vertical profiles of submicron aerosol single scattering albedo over the Indian region immediately before monsoon onset and during its development: research from the SWAAMI field campaign

2020 ◽  
Vol 20 (6) ◽  
pp. 4031-4046
Author(s):  
Mohanan R. Manoj ◽  
Sreedharan K. Satheesh ◽  
Krishnaswamy K. Moorthy ◽  
Hugh Coe
Keyword(s):  
Active Phase ◽  
Single Scattering ◽  
Monsoon Onset ◽  
Single Scattering Albedo ◽  
Transfer Model ◽  
Heating Rates ◽  
Atmospheric Measurements ◽  
Middle Troposphere ◽  
Submicron Aerosol ◽  
Aerosol Absorption

Abstract. Vertical structures of aerosol single scattering albedo (SSA), from near the surface through the free troposphere, have been estimated for the first time at distinct geographical locations over the Indian mainland and adjoining oceans, using in situ measurements of aerosol scattering and absorption coefficients aboard the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft during the South West Asian Aerosol Monsoon Interactions (SWAAMI) campaign from June to July 2016. These are used to examine the spatial variation of SSA profiles and also to characterize its transformation from just prior to the onset of Indian Summer Monsoon (June 2016) to its active phase (July 2016). Very strong aerosol absorption, with SSA values as low as 0.7, persisted in the lower altitudes (<3 km) over the Indo-Gangetic Plains (IGP), prior to the monsoon onset, with a west-to-east gradient; lower values occurred in the north-western arid regions, peaking in the central IGP and somewhat decreasing towards the eastern end. During the active phase of the monsoon, the SSA is found to increase remarkably, indicating far less absorption. Nevertheless, significant aerosol absorption persisted in the lower and middle troposphere over the IGP. Inputting these SSA and extinction profiles into a radiative transfer model, we examined the effects of using height-resolved information in estimating atmospheric heating rates due to aerosols, over similar estimates made using a single columnar value. It was noted that use of a single SSA value leads to an underestimation (overestimation) of the heating rates over regions with low (high) SSA, emphasizing the importance of height-resolved information. Further, the use of realistic profiles showed significant heating of the atmosphere by submicron aerosol absorption at the middle troposphere, which may have strong implications for clouds and climate.

scholarly journals Observations and Modeling of the Surface Aerosol Radiative Forcing during UAE2

2008 ◽  
Vol 65 (9) ◽  
pp. 2877-2891 ◽  
Author(s):  
K. M. Markowicz ◽  
P. J. Flatau ◽  
J. Remiszewska ◽  
M. Witek ◽  
E. A. Reid ◽  
...  
Keyword(s):  
United Arab Emirates ◽  
Radiative Forcing ◽  
Sea Breeze ◽  
Single Scattering ◽  
Land Breeze ◽  
Gulf Region ◽  
Diurnal Variability ◽  
Aerosol Radiative Forcing ◽  
Aerosol Forcing ◽  
Aerosol Radiative

Abstract Aerosol radiative forcing in the Persian Gulf region is derived from data collected during the United Arab Emirates (UAE) Unified Aerosol Experiment (UAE2). This campaign took place in August and September of 2004. The land–sea-breeze circulation modulates the diurnal variability of the aerosol properties and aerosol radiative forcing at the surface. Larger aerosol radiative forcing is observed during the land breeze in comparison to the sea breeze. The aerosol optical properties change as the onshore wind brings slightly cleaner air. The mean diurnal value of the surface aerosol forcing during the UAE2 campaign is about −20 W m−2, which corresponds to large aerosol optical thickness (0.45 at 500 nm). The aerosol forcing efficiency [i.e., broadband shortwave forcing per unit optical depth at 550 nm, W m−2 (τ500)−1] is −53 W m−2 (τ500)−1 and the average single scattering albedo is 0.93 at 550 nm.

scholarly journals Seasonal differences in the vertical profiles of aerosol optical properties over rural Oklahoma

2011 ◽  
Vol 11 (4) ◽  
pp. 11939-11957 ◽  
Author(s):  
E. Andrews ◽  
P. J. Sheridan ◽  
J. A. Ogren
Keyword(s):  
Seasonal Variability ◽  
Seasonal Cycle ◽  
Gulf Coast ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Vertical Profiles ◽  
Seasonal Differences ◽  
Aerosol Loading ◽  
Aerosol Absorption ◽  
Aerosol Scattering

Abstract. A small airplane made more than 450 aerosol optical property (light absorption and light scattering) vertical profile measurements (up to 4 km) over a rural Oklahoma site between March 2000 and July 2005. These profiles suggest significant seasonal differences in aerosol properties. The highest amounts of scattering and absorbing aerosol are observed during the summer, while the relative contribution of aerosol absorption is highest in the winter (i.e., single scattering albedo is lowest in winter). Aerosol absorption generally decreased with altitude below ∼1.5 km and then was relatively constant above that. Aerosol scattering decreased sharply with altitude below ∼1.5 km but, unlike absorption, also decreased at higher altitudes, albeit less sharply. The seasonal variability observed for aerosol loading is consistent with other aerosol measurements in the region including AERONET aerosol optical depth (AOD), CALIPSO vertical profiles, and IMPROVE aerosol mass. The column averaged single scattering albedo derived from in situ airplane measurements shows a similar seasonal cycle as the AERONET single scattering albedo inversion product, but a comparison of aerosol asymmetry parameter from airplane and AERONET platforms suggests differences in seasonal variability. The observed seasonal cycle of aerosol loading corresponds with changes in air mass back trajectories: the aerosol scattering was higher when transport was from polluted areas (e.g., the Gulf Coast) and lower when the air came from cleaner regions and/or the upper atmosphere.

scholarly journals Seasonal differences in the vertical profiles of aerosol optical properties over rural Oklahoma

2011 ◽  
Vol 11 (20) ◽  
pp. 10661-10676 ◽  
Author(s):  
E. Andrews ◽  
P. J. Sheridan ◽  
J. A. Ogren
Keyword(s):  
Seasonal Variability ◽  
Gulf Coast ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Ambient Conditions ◽  
Seasonal Differences ◽  
Aerosol Loading ◽  
Aerosol Absorption ◽  
Aerosol Scattering

Abstract. A small airplane made 597 aerosol optical property (light absorption and light scattering) vertical profile measurements over a rural Oklahoma site between March 2000 and December 2007. The aerosol profiles obtained during these 8 yr of measurements suggest significant seasonal differences in aerosol loading (scattering and absorption). The highest amounts of scattering and absorbing aerosol are observed during the summer and the lowest loading occurs during the winter. The relative contribution of aerosol absorption is highest in the winter (i.e., single scattering albedo is lowest in winter), particularly aloft. Aerosol absorption generally decreased with altitude below ~1.5 km and then was relatively constant or decreased more gradually above that. Aerosol scattering decreased sharply with altitude below ~1.5 km but, unlike absorption, also decreased at higher altitudes, albeit less sharply. Scattering Ångström exponents suggest that the aerosol was dominated by sub-micron aerosol during the summer at all altitudes, but that larger particles were present, especially in the spring and winter above 1 km. The seasonal variability observed for aerosol loading is consistent with AERONET aerosol optical depth (AOD) although the AOD values calculated from in situ adjusted to ambient conditions and matching wavelengths are up to a factor of two lower than AERONET AOD values depending on season. The column averaged single scattering albedo derived from in situ airplane measurements are similar in value to the AERONET single scattering albedo inversion product but the seasonal patterns are different – possibly a consequence of the strict constraints on obtaining single scattering albedo from AERONET data. A comparison of extinction Ångström exponent and asymmetry parameter from the airplane and AERONET platforms suggests similar seasonal variability with smaller particles observed in the summer and fall and larger particles observed in spring and winter. The observed seasonal cycle of aerosol loading corresponds with changes in air mass back trajectories: the aerosol scattering was higher when transport was from polluted areas (e.g., the Gulf Coast) and lower when the air came from cleaner regions and/or the upper atmosphere.

scholarly journals Long term trends in aerosol optical characteristics in the Po Valley (IT)

2014 ◽  
Vol 14 (7) ◽  
pp. 9041-9065
Author(s):  
J. P. Putaud ◽  
F. Cavalli ◽  
S. Martins dos Santos ◽  
A. Dell'Acqua
Keyword(s):  
Radiative Forcing ◽  
Mass Concentration ◽  
Measurement Data ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Po Valley ◽  
Aerosol Absorption ◽  
Aerosol Scattering ◽  
The One

Abstract. Aerosols properties have been monitored by ground-based in situ and remote sensing measurements at the station for atmospheric research located in Ispra on the edge of the Po Valley for almost one decade. In-situ measurements are performed according to Global Atmosphere Watch recommendations, and quality is assured through the participation in regular inter-laboratory comparisons. Sunphotometer data are produced by AERONET. Data show significant decreasing trends over 2004–2010 for a number of variables including particulate matter (PM) mass concentration, aerosol scattering, backscattering and absorption coefficients, and aerosol optical thickness (AOT). In-situ measurement data show no significant trend in the aerosol backscatter ratio, but a significant decreasing trend of about −0.7 ± 0.3% in the aerosol single scattering albedo in the visible light range. Similar trends are observed in the aerosol single scattering albedo retrieved from sunphotometer measurements. Correlations appear between in situ PM mass concentration and aerosol scattering coefficient on the one hand, and elemental carbon (EC) and aerosol absorption coefficient on the other hand, however, no increase in the EC / PM ratio was observed, which could have explained the decrease in SSA. The application of a simple approximation to calculate the direct radiative forcing by aerosols suggests a significant diminution in their cooling effect, mainly due to the decrease in AOT. Applying the methodology we present to those sites where the necessary suite of measurements is available would provide important information to inform future policies for air quality enhancement and fast climate change mitigation.

scholarly journals Aerosol spectral absorption in the Mexico City area: results from airborne measurements during MILAGRO/INTEX B

2010 ◽  
Vol 10 (13) ◽  
pp. 6333-6343 ◽  
Author(s):  
R. W. Bergstrom ◽  
K. S. Schmidt ◽  
O. Coddington ◽  
P. Pilewskie ◽  
H. Guan ◽  
...  
Keyword(s):  
Optical Properties ◽  
Gulf Of Mexico ◽  
Mexico City ◽  
Optical Depth ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Gas Absorption ◽  
Aerosol Optical Properties ◽  
City Area ◽  
Aerosol Absorption

Abstract. This paper presents estimates of the spectral solar absorption due to atmospheric aerosols during the 2006 MILAGRO/INTEX-B (Megacity Initiative-Local And Global Research Observations/Phase B of the Intercontinental Chemical Transport Experiment) field campaign. The aerosol absorption was derived from measurements of the spectral solar radiation and the spectral aerosol optical depth made on the J31 aircraft flying over the Gulf of Mexico and over Mexico City. We present the spectral single scattering albedo (SSA) and aerosol absorption optical depth (AAOD) for two flights over the Gulf of Mexico and three flights over Mexico City for wavelengths from 350 to approximately 1650 nm. The spectral aerosol optical properties of each case are different and illustrate the variability of the aerosol optical properties in the Mexico City area. The results can be described in terms of three different wavelength regions: The 350–500 nm region where the aerosol absorption often falls off sharply presumably due to organic carbonaceous particles and windblown dust; the 500–1000 nm region where the decrease with wavelength is slower presumably due to black carbon; and the near infrared spectral region (1000 nm to 1650 nm) where it is difficult to obtain reliable results since the aerosol absorption is relatively small and the gas absorption dominates. However, there is an indication of a small and somewhat wavelength independent absorption in the region beyond 1000 nm. For one of the flights over the Gulf of Mexico near the coastline it appears that a cloud/fog formation and evaporation led to an increase of absorption possibly due to a water shell remaining on the particles after the cloud/fog had dissipated. For two of the Mexico City cases, the single scattering albedo is roughly constant between 350–500 nm consistent with other Mexico City results. In three of the cases a single absorption Angstrom exponent (AAE) fits the aerosol absorption optical depth over the entire wavelength range of 350 to 1650 nm relatively well (r2> 0.86).

scholarly journals Comparisons of spectral aerosol single scattering albedo in Seoul, South Korea

2018 ◽  
Vol 11 (4) ◽  
pp. 2295-2311 ◽  
Author(s):  
Jungbin Mok ◽  
Nickolay A. Krotkov ◽  
Omar Torres ◽  
Hiren Jethva ◽  
Zhanqing Li ◽  
...  
Keyword(s):  
South Korea ◽  
Surface Albedo ◽  
Near Infrared ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Satellite Measurements ◽  
Absorption Properties ◽  
Invariant Surface ◽  
Aerosol Absorption ◽  
Gaseous Absorption

Abstract. Quantifying aerosol absorption at ultraviolet (UV) wavelengths is important for monitoring air pollution and aerosol amounts using current (e.g., Aura/OMI) and future (e.g., TROPOMI, TEMPO, GEMS, and Sentinel-4) satellite measurements. Measurements of column average atmospheric aerosol single scattering albedo (SSA) are performed on the ground by the NASA AERONET in the visible (VIS) and near-infrared (NIR) wavelengths and in the UV-VIS-NIR by the SKYNET networks. Previous comparison studies have focused on VIS and NIR wavelengths due to the lack of co-incident measurements of aerosol and gaseous absorption properties in the UV. This study compares the SKYNET-retrieved SSA in the UV with the SSA derived from a combination of AERONET, MFRSR, and Pandora (AMP) retrievals in Seoul, South Korea, in spring and summer 2016. The results show that the spectrally invariant surface albedo assumed in the SKYNET SSA retrievals leads to underestimated SSA compared to AMP values at near UV wavelengths. Re-processed SKYNET inversions using spectrally varying surface albedo, consistent with the AERONET retrieval improve agreement with AMP SSA. The combined AMP inversions allow for separating aerosol and gaseous (NO2 and O3) absorption and provide aerosol retrievals from the shortest UVB (305 nm) through VIS to NIR wavelengths (870 nm).

scholarly journals Simultaneous measurement of the relative humidity dependent aerosol light extinction, scattering, absorption and single-scattering albedo with a humidified cavity-enhanced albedometer

2020 ◽  
Author(s):  
Jiacheng Zhou ◽  
Xuezhe Xu ◽  
Weixiong Zhao ◽  
Bo Fang ◽  
Qianqian Liu ◽  
...  
Keyword(s):  
Growth Factors ◽  
Relative Humidity ◽  
Radiative Forcing ◽  
Field Studies ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Light Extinction ◽  
Hygroscopic Growth ◽  
Model Calculations ◽  
Aerosol Absorption

Abstract. Hygroscopic aerosols take up water and grow with increasing relative humidity (RH), giving rise to large changes in light extinction (bext), scattering (bscat), absorption (babs), and single scattering albedo (SSA, ω). The optical hygroscopic growth factors for each parameter (f(RH)ext,scat,abs,ω) are thus important for assessing aerosol effects on regional air quality, atmospheric visibility, and radiative forcing. The RH dependence of aerosol scattering and extinction has been studied in many laboratory and field studies. However, owing partly to the absence of suitable instrumentation, there are few reports of the RH dependence of aerosol absorption and ω. In this work, we report the development of a humidified cavity-enhanced albedometer (H-CEA) for simultaneous measurements of f(RH)ext,scat,abs,ω at λ = 532 nm from 10 % to 90 % RH. The instrument’s performance was evaluated with laboratory-generated ammonium sulphate, sodium chloride and nigrosin aerosols. Measured hygroscopic growth factors for different parameters were in good agreement with model calculations and literature reported values, demonstrating the accuracy of the H-CEA for measuring RH-dependent optical properties.

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