Validation, comparison, and integration of GOCI, AHI, MODIS, MISR, and VIIRS aerosol optical depth over East Asia during the 2016 KORUS-AQ campaign

Choi, Myungje; Lim, Ho Soo; Kim, Jhoon; Lee, Seo-Young; Eck, T. F.; Holben, B. N.; Garay, M. J.; Hyer, E. J.; Saide, Pablo E.; Liu, Hongqing

doi:10.5194/amt-12-4619-2019

Cited by 74 publications

(41 citation statements)

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“…At a boreal forest site in northern Europe (SMR), size distribution data suggest that seasonal variation of b and å sp was caused by a shift in the accumulation mode and not by changes in the coarse-mode fraction (Luoma et al, 2019). Trends towards smaller particle sizes might be due to an increase in near-anthropogenic sources of pollution, to an increase in new particle formation, to a decrease in long-range transport of anthropogenic pollution, to increased scavenging of larger particles due to changes in atmospheric conditions, to a modification of atmospheric chemistry (Banzhaf et al, 2015) or to a change in both primary and secondary natural aerosol (e.g., an increase in biogenic secondary aerosols and their precursors as demonstrated by Ciarelli et al, 2019). Trends towards bigger particles can relate to a decrease in near-anthropogenic emissions, to larger influence of mineral dust caused by variation in desert emissions or dust transport, to changes in agricultural activities or to an increase in humidity.…”

Section: Particle Size Trendsmentioning

confidence: 99%

Multidecadal trend analysis of in situ aerosol radiative properties around the world

et al. 2020

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Abstract. In order to assess the evolution of aerosol parameters affecting climate change, a long-term trend analysis of aerosol optical properties was performed on time series from 52 stations situated across five continents. The time series of measured scattering, backscattering and absorption coefficients as well as the derived single scattering albedo, backscattering fraction, scattering and absorption Ångström exponents covered at least 10 years and up to 40 years for some stations. The non-parametric seasonal Mann–Kendall (MK) statistical test associated with several pre-whitening methods and with Sen's slope was used as the main trend analysis method. Comparisons with general least mean square associated with autoregressive bootstrap (GLS/ARB) and with standard least mean square analysis (LMS) enabled confirmation of the detected MK statistically significant trends and the assessment of advantages and limitations of each method. Currently, scattering and backscattering coefficient trends are mostly decreasing in Europe and North America and are not statistically significant in Asia, while polar stations exhibit a mix of increasing and decreasing trends. A few increasing trends are also found at some stations in North America and Australia. Absorption coefficient time series also exhibit primarily decreasing trends. For single scattering albedo, 52 % of the sites exhibit statistically significant positive trends, mostly in Asia, eastern/northern Europe and the Arctic, 22 % of sites exhibit statistically significant negative trends, mostly in central Europe and central North America, while the remaining 26 % of sites have trends which are not statistically significant. In addition to evaluating trends for the overall time series, the evolution of the trends in sequential 10-year segments was also analyzed. For scattering and backscattering, statistically significant increasing 10-year trends are primarily found for earlier periods (10-year trends ending in 2010–2015) for polar stations and Mauna Loa. For most of the stations, the present-day statistically significant decreasing 10-year trends of the single scattering albedo were preceded by not statistically significant and statistically significant increasing 10-year trends. The effect of air pollution abatement policies in continental North America is very obvious in the 10-year trends of the scattering coefficient – there is a shift to statistically significant negative trends in 2009–2012 for all stations in the eastern and central USA. This long-term trend analysis of aerosol radiative properties with a broad spatial coverage provides insight into potential aerosol effects on climate changes.

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Section: Particle Size Trendsmentioning

confidence: 99%

Multidecadal trend analysis of in situ aerosol radiative properties around the world

et al. 2020

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“…This is an array of relatively short-term AERONET stations deployed across a region in a grid with spatial resolution of approximately 10 km [118]. The DRAGONs provide insight into aerosol gradients and the process at a mesoscale level, but they also allowed confirmation that the DT product was accurately representing those gradients [76,78,102]. Figure 6 shows the most recent validation of the MODIS DT C6.1 product against AERONET and MAN (unpublished).…”

Section: Present Day Validationmentioning

confidence: 99%

The Dark Target Algorithm for Observing the Global Aerosol System: Past, Present, and Future

et al. 2020

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The Dark Target aerosol algorithm was developed to exploit the information content available from the observations of Moderate-Resolution Imaging Spectroradiometers (MODIS), to better characterize the global aerosol system. The algorithm is based on measurements of the light scattered by aerosols toward a space-borne sensor against the backdrop of relatively dark Earth scenes, thus giving rise to the name “Dark Target”. Development required nearly a decade of research that included application of MODIS airborne simulators to provide test beds for proto-algorithms and analysis of existing data to form realistic assumptions to constrain surface reflectance and aerosol optical properties. This research in itself played a significant role in expanding our understanding of aerosol properties, even before Terra MODIS launch. Contributing to that understanding were the observations and retrievals of the growing Aerosol Robotic Network (AERONET) of sun-sky radiometers, which has walked hand-in-hand with MODIS and the development of other aerosol algorithms, providing validation of the satellite-retrieved products after launch. The MODIS Dark Target products prompted advances in Earth science and applications across subdisciplines such as climate, transport of aerosols, air quality, and data assimilation systems. Then, as the Terra and Aqua MODIS sensors aged, the challenge was to monitor the effects of calibration drifts on the aerosol products and to differentiate physical trends in the aerosol system from artefacts introduced by instrument characterization. Our intention is to continue to adapt and apply the well-vetted Dark Target algorithms to new instruments, including both polar-orbiting and geosynchronous sensors. The goal is to produce an uninterrupted time series of an aerosol climate data record that begins at the dawn of the 21st century and continues indefinitely into the future.

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“…These include the Japanese Meteorological Agency (JMA) for AHI on Himawari (Uesawa, 2016) and the National Oceanographic and Atmospheric Agency (NOAA) for ABI on the GOES-R se-ries. In addition to these official operational products, other algorithms have been developed that make use of the new generation of GEO observations for aerosol retrievals, especially for AHI data (Sekiyama et al, 2015;Yumimoto et al, 2016;Lim et al, 2016Lim et al, , 2018aZhang et al, 2018;Yoshida et al, 2018;Yang et al, 2018;Shi et al, 2018;Yan et al, 2018;Choi et al, 2019). Some of these alternative aerosol products are research algorithms for specific purposes, while others could be of general interest and could be made public.…”

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confidence: 99%

Applying the Dark Target aerosol algorithm with Advanced Himawari Imager observations during the KORUS-AQ field campaign

et al. 2019

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Abstract. For nearly 2 decades we have been quantitatively observing the Earth's aerosol system from space at one or two times of the day by applying the Dark Target family of algorithms to polar-orbiting satellite sensors, particularly MODIS and VIIRS. With the launch of the Advanced Himawari Imager (AHI) and the Advanced Baseline Imagers (ABIs) into geosynchronous orbits, we have the new ability to expand temporal coverage of the traditional aerosol optical depth (AOD) to resolve the diurnal signature of aerosol loading during daylight hours. The Korean–United States Air Quality (KORUS-AQ) campaign taking place in and around the Korean peninsula during May–June 2016 initiated a special processing of full-disk AHI observations that allowed us to make a preliminary adoption of Dark Target aerosol algorithms to the wavelengths and resolutions of AHI. Here, we describe the adaptation and show retrieval results from AHI for this 2-month period. The AHI-retrieved AOD is collocated in time and space with existing AErosol RObotic NETwork stations across Asia and with collocated Terra and Aqua MODIS retrievals. The new AHI AOD product matches AERONET, and the standard MODIS product does as well, and the agreement between AHI and MODIS retrieved AOD is excellent, as can be expected by maintaining consistency in algorithm architecture and most algorithm assumptions. Furthermore, we show that the new product approximates the AERONET-observed diurnal signature. Examining the diurnal patterns of the new AHI AOD product we find specific areas over land where the diurnal signal is spatially cohesive. For example, in Bangladesh the AOD increases by 0.50 from morning to evening, and in northeast China the AOD decreases by 0.25. However, over open ocean the observed diurnal cycle is driven by two artifacts, one associated with solar zenith angles greater than 70∘ that may be caused by a radiative transfer model that does not properly represent the spherical Earth and the other artifact associated with the fringes of the 40∘ glint angle mask. This opportunity during KORUS-AQ provides encouragement to move towards an operational Dark Target algorithm for AHI. Future work will need to re-examine masking including snow mask, re-evaluate assumed aerosol models for geosynchronous geometry, address the artifacts over the ocean, and investigate size parameter retrieval from the over-ocean algorithm.

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Validation, comparison, and integration of GOCI, AHI, MODIS, MISR, and VIIRS aerosol optical depth over East Asia during the 2016 KORUS-AQ campaign

Cited by 74 publications

References 74 publications

Multidecadal trend analysis of in situ aerosol radiative properties around the world

Multidecadal trend analysis of in situ aerosol radiative properties around the world

The Dark Target Algorithm for Observing the Global Aerosol System: Past, Present, and Future

Applying the Dark Target aerosol algorithm with Advanced Himawari Imager observations during the KORUS-AQ field campaign

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