Seasonal and monthly variations of columnar aerosol optical properties over east Asia determined from multi-year MODIS, LIDAR, and AERONET Sun/sky radiometer measurements

2007 ◽  
Vol 41 (8) ◽  
pp. 1634-1651 ◽  
Author(s):  
Sang-Woo Kim ◽  
Soon-Chang Yoon ◽  
Jiyoung Kim ◽  
Seung-Yeon Kim
Keyword(s):  
Optical Properties ◽  
East Asia ◽  
Aerosol Optical Properties ◽  
Monthly Variations

Variability of trends observed in Atmospheric Aerosol optical properties over Pune, India

2020 ◽  
Author(s):  
Sudeep Das ◽  
Govindan Pandithurai
Keyword(s):  
Optical Properties ◽  
Air Quality ◽  
Role Model ◽  
Anthropogenic Activities ◽  
Sea Salt ◽  
Negative Slope ◽  
Average Height ◽  
Aerosol Optical Properties ◽  
The City ◽  
Monthly Variations

<p>Long term trends of various aerosol optical properties are observed over the city of Pune, the ninth most populated city in India using ground and satellite based instruments such as AERONET, MODIS (Aqua and Terra), MISR, CALIOP and reanalysis tool MERRA. Annually, the Aerosol Optical Depth is observed to be increasing over all the types of instruments (2004-17) with values of 0.01 to 0.006 yr<sup>-1</sup>, whereas the Angstrom exponent has a negative slope (AERONET) which suggests that the fine aerosols are decreasing. Single scattering albedo (SSA) is also increasing (0.00657 yr<sup>-1</sup>), which means the emission of smaller darker particles like soot has decreased over the years. MISR shows that the Absorbing AOD trend is decreasing in the overall study period (-0.0001237 yr<sup>-1</sup>). All these annual trends are related to anthropogenic activities and show differing trends before and after 2008, the year when various pollution counter measures were introduced mainly in Pune and also in various nearby areas. After 2008, the AOD increasing slope reduces, and the AAOD reverses the trend from positive to a negative slope. The average height till various kinds of aerosols reach and their vertical profile is studied using CALIOP data. Monthly variations of AOD and their vertical distribution also observed and discussed. Aerosol characterization is done using the MERRA tool into dust, sea salt, sulfates, elementary carbon, and organic carbon. Their monthly variations are explained by source characterizations using the HySplit model. In summer, air from the Arabian sea brings in dust and sea salt into the city and in winter, aerosols come from central India dominantly as carbon and sulfates changing the air quality over there. This study lays its stress on the fact that even though aerosols cover over a city is mostly non-local, anthropogenic activities of that area do play a significant role and here the city of Pune is a role model to show how measures can be taken to improve air quality over any urban area.</p>

scholarly journals A study on the aerosol optical properties over East Asia using a combination of CMAQ-simulated aerosol optical properties and remote-sensing data via a data assimilation technique

2011 ◽  
Vol 11 (23) ◽  
pp. 12275-12296 ◽  
Author(s):  
R. S. Park ◽  
C. H. Song ◽  
K. M. Han ◽  
M. E. Park ◽  
S.-S. Lee ◽  
...  
Keyword(s):  
Optical Properties ◽  
Data Assimilation ◽  
East Asia ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Dust Particles ◽  
Aerosol Optical Properties ◽  
Fine Grid ◽  
Model Simulations ◽  
Particulate Pollution

Abstract. To more accurately estimate direct radiative forcing (DRF) by aerosols, and better investigate particulate pollution over East Asia, precise calculations of the optical properties of aerosols, such as aerosol optical depth (AOD), single scattering albedo (SSA) and aerosol extinction coefficient (σext), are of primary importance. The aerosol optical properties over East Asia were investigated in this study, based on US EPA Models-3/CMAQ v4.5.1 model simulations. The CMAQ model simulations in this study were improved in several ways compared to those in a previous study (Song et al., 2008). Although the details of the improvements were described in the manuscript, the following points should be emphasized: (1) two data assimilation techniques were employed for producing more accurate AOD products and meteorological fields over East Asia; (2) updated/upgraded emission inventories were used in the CMAQ model simulations with a fine grid resolution of 30 × 30 km2; and (3) the 4-D particulate composition calculated from the CMAQ model simulations was converted into 3-D or 4-D aerosol optical products, using the Malm and Hand (2007) algorithm with significant further modifications. The results from the CMAQ model simulations (without assimilation) showed great improvements compared to those from a previous study. For example, in terms of the regression coefficients (R), R values were increased from 0.48–0.68 (previous study) to 0.62–0.79 (this study). The monthly-averaged CMAQ-simulated single scattering albedo (SSA) also agreed well with the AERONET SSA, with the exceptions of the Hong Kong and Taipei sites, where the air qualities were strongly influenced by active biomass burning events from January to April. There were also excellent matches between the vertical profiles of the CMAQ-simulated σext and LIDAR-retrieved σext. It was also found that the contributions of (NH4)2SO4 during summer, NH4NO3 during winter, sea-salt particles during winter and dust particles during spring to the total AOD were large over East Asia. In particular, the largest contribution of NH4NO3 to the total AOD was found over East Asia during winter. Therefore, it was suggested that this contribution of NH4NO3 should not be neglected. In order to produce more accurate AOD products, the CMAQ-simulated AODs were further assimilated with the MODIS-retrieved AODs. Both of the assimilated and AERONET AODs were better correlated with each other than the CMAQ-simulated and AERONET AODs. The obvious benefits from this study would be that with these improved aerosol optical properties, the particulate pollution (e.g. AOD can be served as a proxy to PM2.5 or PM10) and DRF by aerosols over East Asia can be more satisfactorily investigated in future.

scholarly journals Sensitivity of formaldehyde (HCHO) column measurements from a geostationary satellite to temporal variation of the air mass factor in East Asia

2017 ◽  
Vol 17 (7) ◽  
pp. 4673-4686 ◽  
Author(s):  
Hyeong-Ahn Kwon ◽  
Rokjin J. Park ◽  
Jaein I. Jeong ◽  
Seungun Lee ◽  
Gonzalo González Abad ◽  
...  
Keyword(s):  
Optical Properties ◽  
East Asia ◽  
Temporal Variation ◽  
Temporal Changes ◽  
Geostationary Satellite ◽  
Retrieval Algorithm ◽  
Observation System ◽  
Aerosol Optical Properties ◽  
Air Mass ◽  
True Values

Abstract. We examine upcoming geostationary satellite observations of formaldehyde (HCHO) vertical column densities (VCDs) in East Asia and the retrieval sensitivity to the temporal variation of air mass factors (AMFs) considering the presence of aerosols. Observation system simulation experiments (OSSE) were conducted using a combination of a global 3-D chemical transport model (GEOS-Chem), a radiative transfer model (VLIDORT), and a HCHO retrieval algorithm developed for the Geostationary Environment Monitoring Spectrometer (GEMS), which will be launched in 2019. Application of the retrieval algorithm to simulated hourly radiances yields the retrieved HCHO VCDs, which are then compared with the GEOS-Chem HCHO VCDs as true values for the evaluation of the retrieval algorithm. In order to examine the retrieval sensitivity to the temporal variation of AMF, we examine three AMF specifications, AMFm, AMFh, and AMFmh, using monthly, hourly, and monthly mean hourly input data for their calculation, respectively. We compare the retrieved HCHO VCDs using those three AMFs and find that the HCHO VCDs with AMFh are in better agreement with the true values than the results using AMFmh and AMFm. AMFmh reflects diurnal variation of planetary boundary layer and other meteorological parameters, so that the results with AMFmh show a better performance than those with AMFm. The differences between AMFh and AMFm range from −0.76 to 0.74 in absolute value and are mainly caused by temporal changes in aerosol chemical compositions and aerosol vertical distributions, which result in −27 to 58 and −34 to 43 % changes in HCHO VCDs over China, respectively, compared to HCHO VCDs using AMFm. We apply our calculated AMF table together with OMI aerosol optical properties to OMI HCHO products in March 2006, when Asian dust storms occurred, and find −32 to 47 % changes in the retrieved HCHO columns due to temporal changes in aerosol optical properties in East Asia. The impact of aerosol temporal variability cannot be neglected for future geostationary observations.

Retrieval of Aerosol Optical Properties over East Asia from TROPOMI using GEMS Aerosol Algorithm 

2021 ◽  
Author(s):  
Yeseul Cho ◽  
Jhoon Kim ◽  
Sujung Go ◽  
Mijin Kim ◽  
Hyunkwang Lim ◽  
...  
Keyword(s):  
Optical Properties ◽  
Air Quality ◽  
East Asia ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Visible Range ◽  
Fine Scale ◽  
Aerosol Optical Properties ◽  
Aerosol Loading

<p>To better understanding the role of aerosols in climate change and their direct effects on human health, aerosol optical properties have been monitored by various satellite sensors. Successful operations of the Tropospheric Monitoring Instrument (TROPOMI) onboard the Copernicus Sentinel-5 Precursor satellite allow an improved understanding of the wide-ranging variation in aerosol distribution and properties with high spatial resolution since 2018. The Geostationary Environmental Monitoring Spectrometer (GEMS), onboard Geokompsat-2B (GK-2B) satellites, is the first air quality monitoring sensor in geostationary earth orbit and was successfully launched on February 19, 2020. GEMS measures hourly hyperspectral radiances with the spectral resolution of 0.6 nm in UV and visible range (300 – 500 nm) and the spatial resolution of 3.5 x 8 km<sup>2</sup> over Asia during the daytime to provide air quality information. TROPOMI which has similar specifications to GEMS, has the advantages of the sensitivity of aerosol absorption and aerosol height information in UV-Vis wavelengths. GEMS aerosol algorithm was applied to the Level 1B data of TROPOMI to retrieve aerosol optical properties such as aerosol optical depth (AOD), UV aerosol index (UVAI), single scattering albedo (SSA), and aerosol loading height (ALH). We present GEMS aerosol retrieval results to discuss high aerosol loading cases over East Asia and analysis results as a case study. Our results show that the GEMS aerosol products have the advantage to capture the fine-scale features of aerosol properties in high spatial resolution. Further, the results are compared to other aerosol products obtained from the Advanced Himawari Imager (AHI) onboard Himawari-8. Qualitatively good agreements and fine-scale features are shown in this case study.</p>

scholarly journals Aerosol optical properties derived from the DRAGON-NE Asia campaign, and implications for a single-channel algorithm to retrieve aerosol optical depth in spring from Meteorological Imager (MI) on-board the Communication, Ocean, and Meteorological Satellite (COMS)

2016 ◽  
Vol 16 (3) ◽  
pp. 1789-1808 ◽  
Author(s):  
M. Kim ◽  
J. Kim ◽  
U. Jeong ◽  
W. Kim ◽  
H. Hong ◽  
...  
Keyword(s):  
Optical Properties ◽  
East Asia ◽  
Size Distribution ◽  
Aerosol Optical Depth ◽  
Single Channel ◽  
Data Sets ◽  
Aerosol Optical Properties ◽  
Aerosol Model ◽  
Meteorological Satellite ◽  
Volume Size

Abstract. An aerosol model optimized for northeast Asia is updated with the inversion data from the Distributed Regional Aerosol Gridded Observation Networks (DRAGON)-northeast (NE) Asia campaign which was conducted during spring from March to May 2012. This updated aerosol model was then applied to a single visible channel algorithm to retrieve aerosol optical depth (AOD) from a Meteorological Imager (MI) on-board the geostationary meteorological satellite, Communication, Ocean, and Meteorological Satellite (COMS). This model plays an important role in retrieving accurate AOD from a single visible channel measurement. For the single-channel retrieval, sensitivity tests showed that perturbations by 4 % (0.926 ± 0.04) in the assumed single scattering albedo (SSA) can result in the retrieval error in AOD by over 20 %. Since the measured reflectance at the top of the atmosphere depends on both AOD and SSA, the overestimation of assumed SSA in the aerosol model leads to an underestimation of AOD. Based on the AErosol RObotic NETwork (AERONET) inversion data sets obtained over East Asia before 2011, seasonally analyzed aerosol optical properties (AOPs) were categorized by SSAs at 675 nm of 0.92 ± 0.035 for spring (March, April, and May). After the DRAGON-NE Asia campaign in 2012, the SSA during spring showed a slight increase to 0.93 ± 0.035. In terms of the volume size distribution, the mode radius of coarse particles was increased from 2.08 ± 0.40 to 2.14 ± 0.40. While the original aerosol model consists of volume size distribution and refractive indices obtained before 2011, the new model is constructed by using a total data set after the DRAGON-NE Asia campaign. The large volume of data in high spatial resolution from this intensive campaign can be used to improve the representative aerosol model for East Asia. Accordingly, the new AOD data sets retrieved from a single-channel algorithm, which uses a precalculated look-up table (LUT) with the new aerosol model, show an improved correlation with the measured AOD during the DRAGON-NE Asia campaign. The correlation between the new AOD and AERONET value shows a regression slope of 1.00, while the comparison of the original AOD data retrieved using the original aerosol model shows a slope of 1.08. The change of y-offset is not significant, and the correlation coefficients for the comparisons of the original and new AOD are 0.87 and 0.85, respectively. The tendency of the original aerosol model to overestimate the retrieved AOD is significantly improved by using the SSA values in addition to size distribution and refractive index obtained using the new model.

scholarly journals Improvements in AOD retrieval from geostationary measurements over Asia with aerosol optical properties derived from the DRAGON-Asia campaign

2015 ◽  
Vol 15 (7) ◽  
pp. 10773-10812 ◽  
Author(s):  
M. Kim ◽  
J. Kim ◽  
U. Jeong ◽  
W. Kim ◽  
B. Holben ◽  
...  
Keyword(s):  
Optical Properties ◽  
East Asia ◽  
Single Channel ◽  
Correlation Coefficients ◽  
Single Scattering ◽  
Aerosol Optical Properties ◽  
Aerosol Model ◽  
Sensitivity Tests ◽  
June July

Abstract. An aerosol model optimized for East Asia is improved by applying inversion data from both long-term monitoring of the Aerosol Robotic Network (AERONET) sun photometer and the Distributed Regional Aerosol Gridded Observation Networks (DRAGON)-Asia campaign from 2012. This model plays an important role in retrieving accurate aerosol optical depth (AOD) from satellite-based measurements. In particular, the performance of a single visible channel algorithm, limited to a specific aerosol type, from real-time measurements is strongly affected by the assumed aerosol optical properties (AOPs) for the measured scene. In sensitivity tests, a 4% difference in single scattering albedo (SSA) between modeled and measured values can cause a retrieval error in AOD of over 20%, and the overestimation of SSA leads to an underestimation of AOD. Based on the AERONET inversion datasets obtained over East Asia before 2011, seasonally analyzed AOPs can be summarized by SSAs (measured at 675 nm) of 0.92, 0.94, 0.92, and 0.91 for spring (March, April, and May), summer (June, July, and August), autumn (September, October, and November), and winter (December, January, and February), respectively. After DRAGON-Asia 2012, the SSA during spring shows a slight increase to 0.93. The large volume of data and spatially concentrated measurements from this campaign can be used to improve the representative aerosol model for East Asia. Accordingly, the AOD datasets retrieved from a single channel algorithm, which uses a pre-calculated look-up table (LUT) with the new aerosol model, show an improved correlation with the measured AOD during the DRAGON-Asia campaign (March to May 2012). Compared with the correlation of the AOD retrieved using the original aerosol model, the regression slope between the new AOD and the AERONET values is reduced from 1.08 to 1.00, while the change of the y-offset of −0.08 is significant. The correlation coefficients for the comparisons are 0.87 and 0.85, respectively. The tendency of the original aerosol model to overestimate the retrieved AOD is significantly improved by using the SSA values obtained using the new model.

scholarly journals A study on the aerosol optical properties over East Asia using a combination of CMAQ-simulated aerosol optical properties and remote-sensing data via a data assimilation technique

2011 ◽  
Vol 11 (8) ◽  
pp. 23801-23858 ◽  
Author(s):  
R. S. Park ◽  
C. H. Song ◽  
K. M . Han ◽  
M. E. Park ◽  
S.-S. Lee ◽  
...  
Keyword(s):  
Optical Properties ◽  
Data Assimilation ◽  
East Asia ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Dust Particles ◽  
Aerosol Optical Properties ◽  
Fine Grid ◽  
Model Simulations ◽  
Particulate Pollution

Abstract. To more accurately estimate direct radiative forcing (DRF) by aerosols, and better investigate particulate pollution over East Asia, precise calculations of the optical properties of aerosols, such as aerosol optical depth (AOD), single scattering albedo (SSA) and aerosol extinction coefficient (σext), are of primary importance. The aerosol optical properties over East Asia were investigated in this study, based on US EPA Models-3/CMAQ v4.5.1 model simulations. The CMAQ model simulations in this study were improved in several ways compared to those in a previous study (Song et al., 2008). Although the details of the improvements were described in the manuscript, the following points should be emphasized: (1) two data assimilation techniques were employed for producing more accurate AOD products and meteorological fields over East Asia; (2) updated/upgraded emission inventories were used in the CMAQ model simulations with a fine grid resolution of 30 × 30 km2; and (3) the 4-D particulate composition obtained from the CMAQ model simulations was converted into 3-D or 4-D aerosol optical products, using the Malm and Hand (2007) algorithm with significant further modifications. The results from the CMAQ model simulations (without assimilation) showed great improvements compared to those from a previous study. For example, in terms of the regression coefficients (R), R-values were increased from 0.48–0.68 (previous study) to 0.77–0.89 (this study). The monthly-averaged CMAQ-simulated single scattering albedo (SSA) also agreed well with the AERONET SSA, with the exceptions of the Honk Kong and Taipei sites, where the air qualities were strongly influenced by active biomass burning events from January to April. There were also excellent matches between the vertical profiles of the CMAQ-simulated σext and LIDAR-retrieved σext. It was also found that the contributions of (NH4)2SO4 during summer, NH4NO3 during winter, sea-salt particles during winter and dust particles during spring to the total AOD were large over East Asia. In particular, the largest contribution of NH4NO3 to the total AOD was found over East Asia during winter. Therefore, it was suggested that this contribution of NH4NO3 should not be neglected. In order to produce more accurate AOD products, the CMAQ-simulated AODs were further assimilated with the MODIS-retrieved AODs. Both the assimilated and AERONET AODs were better correlated with each other than the CMAQ-simulated and AERONET AODs. The obvious benefits from this study would be that with these improved aerosol optical properties, the particulate pollution (e.g. AOD can be served as a proxy to PM2.5 or PM10) and DRF by aerosols over East Asia can be more satisfactorily investigated in future.

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