Assessment of the Representativeness of MODIS Aerosol Optical Depth Products at Different Temporal Scales Using Global AERONET Measurements

Assessments of long-term changes of air quality and global radiative forcing at a large scale heavily rely on satellite aerosol optical depth (AOD) datasets, particularly their temporal binning products. Although some attempts focusing on the validation of long-term satellite AOD have been conducted, there is still a lack of comprehensive quantification and understanding of the representativeness of satellite AOD at different temporal binning scales. Here, we evaluated the performances of the Moderate Resolution Imaging Spectroradiometer (MODIS) AOD products at various temporal scales by comparing the MODIS AOD datasets from both the Terra and Aqua satellites with the entire global AErosol RObotic NETwork (AERONET) observation archive between 2000 and 2017. The uncertainty levels of the MODIS hourly and daily AOD products were similarly high, indicating that MODIS AOD retrievals could be used to represent daily aerosol conditions. The MODIS data showed the reduced quality when integrated from the daily to monthly scale, where the relative mean bias (RMB) changed from 1.09 to 1.21 for MODIS Terra and from 1.04 to 1.17 for MODIS Aqua, respectively. The limitation of valid data availability within a month appeared to be the primary reason for the increased uncertainties in the monthly binning products, and the monthly data associated uncertainties could be reduced when the number of valid AOD retrievals reached 15 times in one month. At all three temporal scales, the uncertainty levels of satellite AOD products decreased with increasing AOD values. The results of this study could provide crucial information for satellite AOD users to better understand the reliability of different temporal AOD binning products and associated uncertainties in their derived long-term trends.

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Relationship Between MODIS-based Aerosol Optical Depth and PM10 over Sumatra to Overcome the Limitations of Air Quality Monitoring Data Availability

Oriental Journal Of Chemistry ◽

10.13005/ojc/3404058 ◽

2018 ◽

Vol 34 (4) ◽

pp. 2163-2169 ◽

Cited By ~ 1

Author(s):

Syafrijon Syafrijon ◽

Marzuki Marzuki ◽

Emriadi Emriadi ◽

Ridho Pratama

Keyword(s):

Air Quality ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Forest Fire ◽

Correlation Coefficients ◽

Data Availability ◽

Near Surface ◽

Modis Aod ◽

Moderate Resolution ◽

Moderate Resolution Imaging Spectroradiometer

The present study uses the aerosol optical depth (AOD) obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite as a proxy to estimate the surface particulate matter (PM) concentrations over Sumatra. The daily average PM10 data collected during 2015 from three air quality stations across Sumatra, i.e., Kototabang, Jambi and Pekanbaru, were analyzed. The 2015 Indonesian forest fire significantly increased the PM10 concentrations and MODIS AOD values. The ratios of the mean PM10 concentrations and AOD values during the peak forest fire period to those during the period of normal conditions varied from 6 to 9. MODIS AOD may be a good indicator of the near-surface PM10 concentrations over Sumatra, as the correlation coefficients of the linear regressions were 0.86 (Kototabang), 0.80 (Jambi), and 0.81 (Pekanbaru). The linear regression functions of PM10 and satellite-observed AOD can be used to estimate the surface PM10 concentrations, and the correlation coefficient is 0.84.

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Comparison of PMCAMx aerosol optical depth predictions over Europe with AERONET and MODIS measurements

Geoscientific Model Development ◽

10.5194/gmd-9-4257-2016 ◽

2016 ◽

Vol 9 (11) ◽

pp. 4257-4272

Author(s):

Antigoni Panagiotopoulou ◽

Panagiotis Charalampidis ◽

Christos Fountoukis ◽

Christodoulos Pilinis ◽

Spyros N. Pandis

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Transport Model ◽

Chemical Transport Model ◽

Secondary Aerosol ◽

The Balkans ◽

Modis Aod ◽

Moderate Resolution ◽

Moderate Resolution Imaging Spectroradiometer ◽

High Dust

Abstract. The ability of chemical transport model (CTM) PMCAMx to reproduce aerosol optical depth (AOD) measurements by the Aerosol Robotic Network (AERONET) and the Moderate Resolution Imaging Spectroradiometer (MODIS) over Europe during the photochemically active period of May 2008 (EUCAARI campaign) is evaluated. Periods with high dust or sea-salt levels are excluded, so the analysis focuses on the ability of the model to simulate the mostly secondary aerosol and its interactions with water. PMCAMx reproduces the monthly mean MODIS and AERONET AOD values over the Iberian Peninsula, the British Isles, central Europe, and Russia with a fractional bias of less than 15 % and a fractional error of less than 30 %. However, the model overestimates the AOD over northern Europe, most probably due to an overestimation of organic aerosol and sulfates. At the other end, PMCAMx underestimates the monthly mean MODIS AOD over the Balkans, the Mediterranean, and the South Atlantic. These errors appear to be related to an underestimation of sulfates. Sensitivity tests indicate that the evaluation results of the monthly mean AODs are quite sensitive to the relative humidity (RH) fields used by PMCAMx, but are not sensitive to the simulated size distribution and the black carbon mixing state. The screening of the satellite retrievals for periods with high dust (or coarse particles in general) concentrations as well as the combination of the MODIS and AERONET datasets lead to more robust conclusions about the ability of the model to simulate the secondary aerosol components that dominate the AOD during this period.

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Long-term aerosol optical depth datasets over China retrieved from satellite data

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-4-6643-2011 ◽

2011 ◽

Vol 4 (6) ◽

pp. 6643-6678 ◽

Cited By ~ 7

Author(s):

Y. Xue ◽

H. Xu ◽

Y. Li ◽

L. Yang ◽

L. Mei ◽

...

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Dust Storms ◽

The Tibetan Plateau ◽

Hysplit Model ◽

The North ◽

Moderate Resolution ◽

Dust Weather ◽

Moderate Resolution Imaging Spectroradiometer

Abstract. Nine years of daily aerosol optical depth (AOD) measurements have been derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) data using the Synergetic Retrieval of Aerosol Properties (SRAP) method over China for the period from August 2002 to August 2011, comprising AODs at 470, 550, and 660 nm. Then, the variation over China over the nine years was determined from the derived AOD data. Preliminary daily results show the agreement between the Aerosol Robotic Network (AERONET) AOD data and the derived AOD data. From 1219 daily collocations, representing mutually cloud-free conditions, we find that more than 54% of SRAP-MODIS retrieved AOD values comparing with AERONET-observed values within an expected error envelop of 20%. From 222 monthly averaged collocations, representing mutually cloud-free conditions, we find that more than 63% of SRAP-MODIS retrieved AOD values comparing with AERONET-observed values within an expected error envelop of 15% and more than 70% within an expected error envelop of 20%. In addition, the long-term SRAP AOD dataset has been implemented in analysing case studies involving dust storms, haze and the characteristics of AOD variation over China over the past nine years. It was found that areas in China with high AOD values generally appear in the Inner Mongolia, the North China Plain, Tarim Basin, the Sichuan Basin, the Tibetan Plateau and the middle and lower reaches of the Yangtze River and area with low AOD values generally appear in the Fujian Province, the Yungui Plateau, and northeast plain. The seasonal averaged AOD results indicate that AOD values generally reach their maximum in spring and their minimum in winter. The yearly mean and monthly mean SRAP AOD were also used to study the spatial and temporal aerosol distributions over China. The results indicate that the AOD over China exhibited no obvious change. Monthly averaged AOD in August in Beijing experienced one decreasing processes from 2006 to 2010, especially after 2007. The monthly mean AOD decreased from 0.46 in 2007 to 0.29 in 2010. SRAP AODs were used to study one haze case and dust case. Combining AOD data from the SRAP AOD dataset and HYSPLIT model can forecast the transport of haze. SRAP AOD data are also sensitive enough to reflect the occurrence and intensity of dust weather. Thus, the SRAP AOD dataset can be used to precisely reflect the spatial distribution, concentration distribution and transmission path of dust.

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Influence of observed diurnal cycles of aerosol optical depth on aerosol direct radiative effect

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-7895-2013 ◽

2013 ◽

Vol 13 (15) ◽

pp. 7895-7901 ◽

Cited By ~ 22

Author(s):

A. Arola ◽

T. F. Eck ◽

J. Huttunen ◽

K. E. J. Lehtinen ◽

A. V. Lindfors ◽

...

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Radiative Forcing ◽

Radiative Effect ◽

Diurnal Variability ◽

Diurnal Cycles ◽

Moderate Resolution ◽

Resolution Imaging ◽

Moderate Resolution Imaging Spectroradiometer ◽

The Impact

Abstract. The diurnal variability of aerosol optical depth (AOD) can be significant, depending on location and dominant aerosol type. However, these diurnal cycles have rarely been taken into account in measurement-based estimates of aerosol direct radiative forcing (ADRF) or aerosol direct radiative effect (ADRE). The objective of our study was to estimate the influence of diurnal aerosol variability at the top of the atmosphere ADRE estimates. By including all the possible AERONET sites, we wanted to assess the influence on global ADRE estimates. While focusing also in more detail on some selected sites of strongest impact, our goal was to also see the possible impact regionally. We calculated ADRE with different assumptions about the daily AOD variability: taking the observed daily AOD cycle into account and assuming diurnally constant AOD. Moreover, we estimated the corresponding differences in ADREs, if the single AOD value for the daily mean was taken from the the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra or Aqua overpass times, instead of accounting for the true observed daily variability. The mean impact of diurnal AOD variability on 24 h ADRE estimates, averaged over all AERONET sites, was rather small and it was relatively small even for the cases when AOD was chosen to correspond to the Terra or Aqua overpass time. This was true on average over all AERONET sites, while clearly there can be much stronger impact in individual sites. Examples of some selected sites demonstrated that the strongest observed AOD variability (the strongest morning afternoon contrast) does not typically result in a significant impact on 24 h ADRE. In those cases, the morning and afternoon AOD patterns are opposite and thus the impact on 24 h ADRE, when integrated over all solar zenith angles, is reduced. The most significant effect on daily ADRE was induced by AOD cycles with either maximum or minimum AOD close to local noon. In these cases, the impact on 24 h ADRE was typically around 0.1–0.2 W m−2 (both positive and negative) in absolute values, 5–10% in relative ones.

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MODIS Retrieval of Aerosol Optical Depth over Turbid Coastal Water

10.20944/preprints201705.0157.v1 ◽

2017 ◽

Author(s):

Yi WANG ◽

Jun Wang ◽

Robert C Levy ◽

Xiaoguang Xu ◽

Jeffrey S Reid

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Coastal Water ◽

Visible Spectrum ◽

Single Scattering ◽

Retrieval Algorithm ◽

Modis Aod ◽

Moderate Resolution ◽

Moderate Resolution Imaging Spectroradiometer ◽

Large Water

We present a new approach to retrieve Aerosol Optical Depth (AOD) from Moderate Resolution Imaging Spectroradiometer (MODIS) over the turbid coastal water. This approach supplements the operational Dark Target (DT) aerosol retrieval algorithm that currently don’t conduct any AOD retrieval in the regions with large water-leaving radiances in the visible spectrum. Over the global coastal water regions in all cloud-free conditions, this unavailability of AOD retrievals due to the inherent limitation in existing DT algorithm is ~20%. Here, we refine the MODIS DT algorithm by considering that water-leaving radiance at 2.1 μm is negligible regardless of water turbidity. This refinement, with the assumption that the aerosol single scattering properties over coastal turbid water are similar to that over the adjacent open-ocean pixels, yields ~18% more of MODIS-AERONET collocated pairs for six AEROENT stations in the coastal water regions. Furthermore, comparison with these AERONET observations show that the new AOD retrievals are in either equivalent or better accuracy than those retrieved by the MODIS operational algorithm (over coastal land and non-turbid coastal water). Combining the new retrievals with the existing MODIS operational retrievals not only yield an overall improvement of AOD over those coastal water regions, but also successfully extend the spatial and temporal coverage of MODIS AOD retrievals over the coastal regions where 60% of human population resides, and thereby, aerosol impacts on regional air quality and climate are expected to be significant.

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INTER-COMPARISON BETWEEN MODIS SATELLITE-BASED AND AERONET GROUND-BASED AEROSOL OPTICAL DEPTH PRODUCTS IN VIETNAM

Vietnam Journal of Science and Technology ◽

10.15625/2525-2518/58/3a/14340 ◽

2020 ◽

Vol 58 (3A) ◽

pp. 124

Author(s):

DUC LUONG NGUYEN ◽

Thi Hieu Bui ◽

Hoang Hiep Nguyen ◽

Quang Trung Bui ◽

Hoang Duong Do

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Subtropical Climate ◽

Deep Blue ◽

Modis Aod ◽

Moderate Resolution ◽

Resolution Imaging ◽

Moderate Resolution Imaging Spectroradiometer ◽

First Time ◽

Climatic Characteristics

Although a number of studies have extensively inter-compared the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite-based aerosol optical depth (AOD) with the Aerosol Robotic Network (AERONET) ground-based AOD on both global and regional scales, almost no similar studies have been conducted for Vietnam - a humid subtropical climate region. For the first time, inter-comparison between the MODIS Terra and Aqua Collection 6.1 (C6.1) Dark Target (DT) 10 km, Deep Blue (DB) 10 km, and merged DT-DB 10 km with the AERONET AODs has been performed in different areas with different surface types and different climatic characteristics in Vietnam. Three investigated AERONET stations are Nghia Do (urban), Son La (mountainous rural), and Bac Lieu (coastal urban) with the studying periods of 2010 - 2016, 2012 - 2017, and 2010 - 2017, respectively. Our findings showed the better performances of DB algorithm than those of DT and DT-DB products in the urban area. Additionally, all MODIS AOD algorithm performed worse over the coastal area compared to those in the non-coastal areas. Generally, the ability of all the MODIS AODs to catch up the monthly-mean AERONET AODs has been expressed in this study.

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Influence of observed diurnal cycles of aerosol optical depth on aerosol direct radiative effect

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-10327-2013 ◽

2013 ◽

Vol 13 (4) ◽

pp. 10327-10344 ◽

Cited By ~ 3

Author(s):

A. Arola ◽

T. F. Eck ◽

J. Huttunen ◽

K. E. J. Lehtinen ◽

A. V. Lindfors ◽

...

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Radiative Forcing ◽

Radiative Effect ◽

Diurnal Variability ◽

Diurnal Cycles ◽

Moderate Resolution ◽

Resolution Imaging ◽

Moderate Resolution Imaging Spectroradiometer ◽

The Impact

Abstract. The diurnal variability of aerosol optical depth (AOD) can be significant, depending on location and dominant aerosol type. However, these diurnal cycles have rarely been taken into account in measurement-based estimates of aerosol direct radiative forcing (ADRF) or aerosol direct radiative effect (ADRE). The objective of our study was to estimate the influence of diurnal aerosol variability on the top of the atmosphere ADRE estimates. By including all the possible AERONET sites, we wanted to assess the influence on global ADRE estimates, while by focusing also in more detail on some selected sites of strongest impact, our goal was to also see the possible impact regionally. We calculated ADRE with different assumptions about the daily AOD variability: taking the observed daily AOD cycle into account and assuming diurnally constant AOD. Moreover, we estimated the corresponding differences in ADREs, if the single AOD value for the daily mean was taken from the the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra or Aqua overpass times, instead of accounting for the true observed daily variability. The mean impact of diurnal AOD variability on 24 h ADRE estimates, averaged over all AERONET sites, was rather small and it was relatively small even for the cases when AOD was chosen to correspond to the Terra or Aqua overpass time. This was true on average over all AERONET sites, while clearly there can be much stronger impact in individual sites. Examples of some selected sites demonstrated that the strongest observed AOD variability (the strongest morning afternoon contrast) does not typically result in a significant impact on 24 h ADRE. In those cases, the morning and afternoon AOD patterns are opposite and thus the impact on 24 h ADRE, when integrated over all solar zenith angles, is reduced. The most significant effect on daily ADRE was induced by AOD cycles with either maximum or minimum AOD close to local noon. In these cases, the impact on 24 h ADRE was typically around 0.1–0.2 W m−2 (both positive and negative).

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An analysis of the Collection 5 MODIS over-ocean aerosol optical depth product for its implication in aerosol assimilation

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-20239-2010 ◽

2010 ◽

Vol 10 (8) ◽

pp. 20239-20265 ◽

Cited By ~ 3

Author(s):

Y. Shi ◽

J. Zhang ◽

J. S. Reid ◽

B. Holben ◽

E. J. Hyer ◽

...

Keyword(s):

Quality Assurance ◽

Data Assimilation ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Surface Characteristics ◽

Water Aerosol ◽

Modis Aod ◽

Moderate Resolution ◽

Level 3 ◽

Moderate Resolution Imaging Spectroradiometer

Abstract. As an update to our previous use of the Collection 4 Moderate Resolution Imaging Spectroradiometer (MODIS) over-water aerosol optical depth (AOD, symbol as τ data, we examined ten years of Terra and eight years of Aqua data Collection 5 data for its potential usage in aerosol data assimilation. Uncertainties in the over-water MODIS AOD were studied as functions of observing conditions, such as surface characteristics, aerosol optical properties, and cloud artifacts. Empirical corrections and quality assurance procedures were developed and compared to Collection 4 data. After applying quality assurance and empirical correction procedures, the Root-Mean-Square-Error (RMSE) in the MODIS Terra and Aqua AOD are reduced by 30% and 10–20%, respectively. Ten years of Terra and eight years of Aqua quality-assured level 3 MODIS over-water aerosol products were produced. The newly developed MODIS over-water aerosol products will be used in operational aerosol data assimilation and aerosol climatology studies, and will also be useful to other researchers who are using the MODIS satellite products in their projects.

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PMCAMx-2015 evaluation over Europe against AERONET and MODIS aerosol optical depth measurements

10.5194/gmd-2015-225 ◽

2016 ◽

Cited By ~ 1

Author(s):

Antigoni Panagiotopoulou ◽

Panagiotis Charalambidis ◽

Christos Fountoukis ◽

Christodoulos Pilinis ◽

Spyros N. Pandis

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Transport Model ◽

Chemical Transport Model ◽

The Balkans ◽

Modis Aod ◽

Moderate Resolution ◽

Fractional Error ◽

Resolution Imaging ◽

Moderate Resolution Imaging Spectroradiometer

Abstract. The ability of the chemical transport model (CTM) PMCAMx to reproduce aerosol optical depth (AOD) measurements by the Aerosol Robotic Network (AERONET) and the Moderate Resolution Imaging Spectroradiometer (MODIS) over Europe during a photochemically active period is evaluated. Periods with high dust levels are excluded so the analysis focuses on the ability of the model to simulate the mostly secondary aerosol and its interactions with water. PMCAMx reproduces the monthly mean MODIS and AERONET AOD values over the Iberian Peninsula, the British Isles, central Europe, and Russia with fractional bias less than 15 % and fractional error less than 30 %. However, the model overestimates the AOD over northern Europe probably due to an overestimation of organic aerosol and sulfates. On the other end, PMCAMx underestimates the monthly mean MODIS AOD over the Balkans, the Mediterranean, and the South Atlantic. These errors are probably due to an underestimation of sulfates. Sensitivity tests indicate that the evaluation results of the monthly mean AODs are quite sensitive to the relative humidity (RH) fields used by PMCAMx, but are not sensitive to the simulated size distribution and the black carbon mixing state.

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An analysis of the collection 5 MODIS over-ocean aerosol optical depth product for its implication in aerosol assimilation

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-557-2011 ◽

2011 ◽

Vol 11 (2) ◽

pp. 557-565 ◽

Cited By ~ 116

Author(s):

Y. Shi ◽

J. Zhang ◽

J. S. Reid ◽

B. Holben ◽

E. J. Hyer ◽

...

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Surface Characteristics ◽

Mean Square ◽

Modis Aod ◽

Moderate Resolution ◽

Level 3 ◽

Resolution Imaging ◽

Moderate Resolution Imaging Spectroradiometer ◽

Empirical Corrections

Abstract. As an update to our previous use of the collection 4 Moderate Resolution Imaging Spectroradiometer (MODIS) over-ocean aerosol optical depth (AOD) data, we examined ten years of Terra and eight years of Aqua collection 5 data for its potential usage in aerosol assimilation. Uncertainties in the over-ocean MODIS AOD were studied as functions of observing conditions, such as surface characteristics, aerosol optical properties, and cloud artifacts. Empirical corrections and quality assurance procedures were developed and compared to collection 4 data. After applying these procedures, the Root-Mean-Square-Error (RMSE) in the MODIS Terra and Aqua AOD are reduced by 30% and 10–20%, respectively, with respect to AERONET data. Ten years of Terra and eight years of Aqua quality-assured level 3 MODIS over-ocean aerosol products were produced. The newly developed MODIS over-ocean aerosol products will be used in operational aerosol assimilation and aerosol climatology studies, as well as other research based on MODIS products.

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