Dust Constraints from joint Observational-Modelling-experiMental analysis (DustCOMM): Comparison with measurements and model simulations

Abstract. Mineral dust is the most abundant aerosol specie by mass in the atmosphere, and it impacts global climate, biogeochemistry, and human health. Understanding these varied impacts on the Earth system requires accurate knowledge of dust abundance, size, and optical properties, and how they vary in space and time. However, current global models show substantial biases against measurements of these dust properties. For instance, recent studies suggest that atmospheric dust is substantially coarser and more aspherical than accounted for in models, leading to persistent biases in modelled impacts of dust on the Earth system. Here, we facilitate more accurate constraints on dust impacts by developing a new dataset: Dust Constraints from joint Observational-Modelling-experiMental analysis (DustCOMM). This dataset leverages observational and experimental constraints on dust size distribution and shape to obtain more accurate constraints on three-dimensional (3-D) atmospheric dust properties than is possible from global model simulations alone. Specifically, we present annual and seasonal climatologies of the 3-D dust size distribution, 3-D dust mass extinction efficiency at 550 nm, and two-dimensional atmospheric dust loading. Comparisons with independent measurements taken over several locations, heights, and seasons show that DustCOMM estimates consistently outperform conventional global model simulations. In particular, DustCOMM achieves a substantial reduction in the bias relative to measured dust size distributions in the 0.5–20 µm diameter range. Furthermore, DustCOMM reproduces measurements of dust mass extinction efficiency to almost within the experimental uncertainties, whereas global models generally overestimate the mass extinction efficiency. DustCOMM thus provides more accurate constraints on 3-D dust properties, and as such can be used to improve global models or serve as an alternative to global model simulations in constraining dust impacts on the Earth system.

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Dust Constraints from joint Observational-Modelling-experiMental analysis (DustCOMM): comparison with measurements and model simulations

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-829-2020 ◽

2020 ◽

Vol 20 (2) ◽

pp. 829-863 ◽

Cited By ~ 2

Author(s):

Adeyemi A. Adebiyi ◽

Jasper F. Kok ◽

Yang Wang ◽

Akinori Ito ◽

David A. Ridley ◽

...

Keyword(s):

Mass Extinction ◽

Global Model ◽

Earth System ◽

Atmospheric Dust ◽

Global Models ◽

Model Simulations ◽

Extinction Efficiency ◽

Dust Size Distribution ◽

The Earth ◽

Mass Extinction Efficiency

Abstract. Mineral dust is the most abundant aerosol species by mass in the atmosphere, and it impacts global climate, biogeochemistry, and human health. Understanding these varied impacts on the Earth system requires accurate knowledge of dust abundance, size, and optical properties, and how they vary in space and time. However, current global models show substantial biases against measurements of these dust properties. For instance, recent studies suggest that atmospheric dust is substantially coarser and more aspherical than accounted for in models, leading to persistent biases in modelled impacts of dust on the Earth system. Here, we facilitate more accurate constraints on dust impacts by developing a new dataset: Dust Constraints from joint Observational-Modelling-experiMental analysis (DustCOMM). This dataset combines an ensemble of global model simulations with observational and experimental constraints on dust size distribution and shape to obtain more accurate constraints on three-dimensional (3-D) atmospheric dust properties than is possible from global model simulations alone. Specifically, we present annual and seasonal climatologies of the 3-D dust size distribution, 3-D dust mass extinction efficiency at 550 nm, and two-dimensional (2-D) atmospheric dust loading. Comparisons with independent measurements taken over several locations, heights, and seasons show that DustCOMM estimates consistently outperform conventional global model simulations. In particular, DustCOMM achieves a substantial reduction in the bias relative to measured dust size distributions in the 0.5–20 µm diameter range. Furthermore, DustCOMM reproduces measurements of dust mass extinction efficiency to almost within the experimental uncertainties, whereas global models generally overestimate the mass extinction efficiency. DustCOMM thus provides more accurate constraints on 3-D dust properties, and as such can be used to improve global models or serve as an alternative to global model simulations in constraining dust impacts on the Earth system.

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Mass Extinction Efficiency Approximation for Polydispersed Aerosol Using Harmonic Mean-Type Approximation

Applied Sciences ◽

10.3390/app10238637 ◽

2020 ◽

Vol 10 (23) ◽

pp. 8637

Author(s):

Junshik Um ◽

Seonghyeon Jang ◽

Young Jun Yoon ◽

Seoung Soo Lee ◽

Ji Yi Lee ◽

...

Keyword(s):

Optical Properties ◽

Chemical Composition ◽

Extinction Coefficient ◽

Mass Extinction ◽

Aerosol Particles ◽

Size Distributions ◽

Extinction Efficiency ◽

Type Approximation ◽

Aerosol Mass ◽

Mass Extinction Efficiency

Among many parameters characterizing atmospheric aerosols, aerosol mass extinction efficiency (MEE) is important for understanding the optical properties of aerosols. MEE is expressed as a function of the refractive indices (i.e., composition) and size distributions of aerosol particles. Aerosol MEE is often considered as a size-independent constant that depends only on the chemical composition of aerosol particles. The famous Malm’s reconstruction equation and subsequent revised methods express the extinction coefficient as a function of aerosol mass concentration and MEE. However, the used constant MEE does not take into account the effect of the size distribution of polydispersed chemical composition. Thus, a simplified expression of size-dependent MEE is required for accurate and conventional calculations of the aerosol extinction coefficient and also other optical properties. In this study, a simple parameterization of MEE of polydispersed aerosol particles was developed. The geometric volume–mean diameters of up to 10 µm with lognormal size distributions and varying geometric standard deviations were used to represent the sizes of various aerosol particles (i.e., ammonium sulfate and nitrate, elemental carbon, and sea salt). Integrating representations of separate small mode and large mode particles using a harmonic mean-type approximation generated the flexible and convenient parameterizations of MEE that can be readily used to process in situ observations and adopted in large-scale numerical models. The calculated MEE and the simple forcing efficiency using the method developed in this study showed high correlations with those calculated using the Mie theory without losing accuracy.

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Development of Observation-based Global Multi-layer Soil Moisture Products for 1970 to 2016

10.5194/essd-2021-84 ◽

2021 ◽

Author(s):

Yaoping Wang ◽

Jiafu Mao ◽

Mingzhou Jin ◽

Forrest M. Hoffman ◽

Xiaoying Shi ◽

...

Keyword(s):

Soil Moisture ◽

Earth System Model ◽

System Model ◽

Surface Model ◽

Earth System ◽

Model Simulations ◽

The Earth ◽

Wide Range ◽

In Situ Observations

Abstract. Soil moisture (SM) datasets are critical to understanding the global water, energy, and biogeochemical cycles and benefit extensive societal applications. However, individual sources of SM data (e.g., in situ and satellite observations, reanalysis, offline land surface model simulations, Earth system model simulations) have source-specific limitations and biases related to the spatiotemporal continuity, resolutions, and modeling/retrieval assumptions. Here, we developed seven global, gap-free, long-term (1970–2016), multi-layer (0–10, 10–30, 30–50, and 50–100 cm) SM products at monthly 0.5° resolution (available at https://doi.org/10.6084/m9.figshare.13661312.v1) by synthesizing a wide range of SM datasets using three statistical methods (unweighted averaging, optimal linear combination, and emergent constraint). The merged products outperformed their source datasets when evaluated with in situ observations and the latest gridded datasets that did not enter merging because of insufficient spatial, temporal, or soil layer coverage. Assessed against in situ observations, the global mean bias of the synthesized SM data ranged from −0.044 to 0.033 m3/m3, root mean squared error from 0.076 to 0.104 m3/m3, and Pearson correlation from 0.35 to 0.67. The merged SM datasets also showed the ability to capture historical large-scale drought events and physically plausible global sensitivities to observed meteorological factors. Three of the new SM products, produced by applying any of the three merging methods onto the source datasets excluding the Earth system models, were finally recommended for future applications because of their better performances than the Earth system model–dependent merged estimates. Despite uncertainties in the raw SM datasets and fusion methods, these hybrid products create added value over existing SM datasets because of the performance improvement and harmonized spatial, temporal, and vertical coverages, and they provide a new foundation for scientific investigation and resource management.

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Understanding and improving model representation of aerosol optical properties for a Chinese haze event measured during KORUS-AQ

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-6455-2020 ◽

2020 ◽

Vol 20 (11) ◽

pp. 6455-6478 ◽

Cited By ~ 1

Author(s):

Pablo E. Saide ◽

Meng Gao ◽

Zifeng Lu ◽

Daniel L. Goldberg ◽

David G. Streets ◽

...

Keyword(s):

Optical Properties ◽

Air Quality ◽

Data Assimilation ◽

South Korea ◽

Mass Extinction ◽

Model Representation ◽

Climate Projections ◽

Extinction Efficiency ◽

Aerosol Mass ◽

Mass Extinction Efficiency

Abstract. KORUS-AQ was an international cooperative air quality field study in South Korea that measured local and remote sources of air pollution affecting the Korean Peninsula during May–June 2016. Some of the largest aerosol mass concentrations were measured during a Chinese haze transport event (24 May). Air quality forecasts using the WRF-Chem model with aerosol optical depth (AOD) data assimilation captured AOD during this pollution episode but overpredicted surface particulate matter concentrations in South Korea, especially PM2.5, often by a factor of 2 or larger. Analysis revealed multiple sources of model deficiency related to the calculation of optical properties from aerosol mass that explain these discrepancies. Using in situ observations of aerosol size and composition as inputs to the optical properties calculations showed that using a low-resolution size bin representation (four bins) underestimates the efficiency with which aerosols scatter and absorb light (mass extinction efficiency). Besides using finer-resolution size bins (8–16 bins), it was also necessary to increase the refractive indices and hygroscopicity of select aerosol species within the range of values reported in the literature to achieve better consistency with measured values of the mass extinction efficiency (6.7 m2 g−1 observed average) and light-scattering enhancement factor (f(RH)) due to aerosol hygroscopic growth (2.2 observed average). Furthermore, an evaluation of the optical properties obtained using modeled aerosol properties revealed the inability of sectional and modal aerosol representations in WRF-Chem to properly reproduce the observed size distribution, with the models displaying a much wider accumulation mode. Other model deficiencies included an underestimate of organic aerosol density (1.0 g cm−3 in the model vs. observed average of 1.5 g cm−3) and an overprediction of the fractional contribution of submicron inorganic aerosols other than sulfate, ammonium, nitrate, chloride, and sodium corresponding to mostly dust (17 %–28 % modeled vs. 12 % estimated from observations). These results illustrate the complexity of achieving an accurate model representation of optical properties and provide potential solutions that are relevant to multiple disciplines and applications such as air quality forecasts, health impact assessments, climate projections, solar power forecasts, and aerosol data assimilation.

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Mass extinction efficiency and extinction hygroscopicity of ambient PM2.5 in urban China

Environmental Research ◽

10.1016/j.envres.2017.03.022 ◽

2017 ◽

Vol 156 ◽

pp. 239-246 ◽

Cited By ~ 11

Author(s):

Zhen Cheng ◽

Xin Ma ◽

Yujie He ◽

Jingkun Jiang ◽

Xiaoliang Wang ◽

...

Keyword(s):

Mass Extinction ◽

Urban China ◽

Extinction Efficiency ◽

Mass Extinction Efficiency

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Mixing of dust and NH<sub>3</sub> observed globally over anthropogenic dust sources

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-12503-2012 ◽

2012 ◽

Vol 12 (5) ◽

pp. 12503-12530

Author(s):

P. Ginoux ◽

L. Clarisse ◽

C. Clerbaux ◽

P.-F. Coheur ◽

O. Dubovik ◽

...

Keyword(s):

Mass Extinction ◽

Indian Subcontinent ◽

Monsoon Season ◽

Coastal Region ◽

Mineralogical Composition ◽

Extinction Efficiency ◽

Deep Blue ◽

Cloud Properties ◽

Fine Mode ◽

Mass Extinction Efficiency

Abstract. The global distribution of dust column burden derived from MODIS Deep Blue aerosol products is compared to NH3 column burden retrieved from IASI infrared spectra. We found similarities in their spatial distributions, in particular their hot spots are often collocated over croplands and to a lesser extent pastures. Globally, we found 22% of dust burden collocated with NH3. This confirms the importance of anthropogenic dust from agriculture. Regionally, the Indian subcontinent has the highest amount of dust mixed with NH3 (26%), mostly over cropland and during the pre-monsoon season. North Africa represents 50% of total dust burden but accounts for only 4% of mixed dust, which is found over croplands and pastures in Sahel and the coastal region of the Mediterranean. In order to evaluate the radiative effect of this mixing on dust optical properties, we derive the mass extinction efficiency for various mixtures of dust and NH3, using AERONET sunphotometers data. We found that for dusty days the coarse mode mass extinction efficiency decreases from 0.62 to 0.48 m2 g−1 as NH3 burden increases from 0 to 40 mg m−2. The fine mode extinction efficiency, ranging from 4 to 16 m2 g−1, does not appear to depend on NH3 concentration or relative humidity but rather on mineralogical composition and mixing with other aerosols. Our results imply that a significant amount of dust is already mixed with ammonium salt before its long range transport. This in turn will affect dust lifetime, and its interactions with radiation and cloud properties.

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The Boltysh impact structure: An early Danian impact event during recovery from the K-Pg mass extinction

Science Advances ◽

10.1126/sciadv.abe6530 ◽

2021 ◽

Vol 7 (25) ◽

pp. eabe6530

Author(s):

Annemarie E. Pickersgill ◽

Darren F. Mark ◽

Martin R. Lee ◽

Simon P. Kelley ◽

David W. Jolley

Keyword(s):

Mass Extinction ◽

Crater Lake ◽

Temporal Association ◽

Earth System ◽

Impact Event ◽

The Earth ◽

Relationship Of ◽

Chicxulub Impact ◽

The Impact ◽

Impact Events

Both the Chicxulub and Boltysh impact events are associated with the K-Pg boundary. While Chicxulub is firmly linked to the end-Cretaceous mass extinction, the temporal relationship of the ~24-km-diameter Boltysh impact to these events is uncertain, although it is thought to have occurred 2 to 5 ka before the mass extinction. Here, we conduct the first direct geochronological comparison of Boltysh to the K-Pg boundary. Our 40Ar/39Ar age of 65.39 ± 0.14/0.16 Ma shows that the impact occurred ~0.65 Ma after the mass extinction. At that time, the climate was recovering from the effects of the Chicxulub impact and Deccan trap flood volcanism. This age shows that Boltysh has a close temporal association with the Lower C29n hyperthermal recorded by global sediment archives and in the Boltysh crater lake sediments. The temporal coincidence raises the possibility that even a small impact event could disrupt recovery of the Earth system from catastrophic events.

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Mixing of dust and NH<sub>3</sub> observed globally over anthropogenic dust sources

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-7351-2012 ◽

2012 ◽

Vol 12 (16) ◽

pp. 7351-7363 ◽

Cited By ~ 26

Author(s):

P. Ginoux ◽

L. Clarisse ◽

C. Clerbaux ◽

P.-F. Coheur ◽

O. Dubovik ◽

...

Keyword(s):

Mass Extinction ◽

Indian Subcontinent ◽

Monsoon Season ◽

Coastal Region ◽

Mineralogical Composition ◽

Extinction Efficiency ◽

Deep Blue ◽

Cloud Properties ◽

Fine Mode ◽

Mass Extinction Efficiency

Abstract. The global distribution of dust column burden derived from MODIS Deep Blue aerosol products is compared to NH3 column burden retrieved from IASI infrared spectra. We found similarities in their spatial distributions, in particular their hot spots are often collocated over croplands and to a lesser extent pastures. Globally, we found 22% of dust burden collocated with NH3, with only 1% difference between land-use databases. This confirms the importance of anthropogenic dust from agriculture. Regionally, the Indian subcontinent has the highest amount of dust mixed with NH3 (26%), mostly over cropland and during the pre-monsoon season. North Africa represents 50% of total dust burden but accounts for only 4% of mixed dust, which is found over croplands and pastures in Sahel and the coastal region of the Mediterranean. In order to evaluate the radiative effect of this mixing on dust optical properties, we derive the mass extinction efficiency for various mixtures of dust and NH3, using AERONET sunphotometers data. We found that for dusty days the coarse mode mass extinction efficiency decreases from 0.62 to 0.48 m2 g−1 as NH3 burden increases from 0 to 40 mg m−2. The fine mode extinction efficiency, ranging from 4 to 16 m2 g−1, does not appear to depend on NH3 concentration or relative humidity but rather on mineralogical composition and mixing with other aerosols. Our results imply that a significant amount of dust is already mixed with ammonium salt before its long range transport. This in turn will affect dust lifetime, and its interactions with radiation and cloud properties.

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Climate models miss most of the coarse dust in the atmosphere

Science Advances ◽

10.1126/sciadv.aaz9507 ◽

2020 ◽

Vol 6 (15) ◽

pp. eaaz9507 ◽

Cited By ~ 9

Author(s):

Adeyemi A. Adebiyi ◽

Jasper F. Kok

Keyword(s):

Climate Models ◽

Mineral Dust ◽

Climate System ◽

Size Distributions ◽

Earth System ◽

Atmospheric Dust ◽

The Earth ◽

Current Climate ◽

Accurate Treatment ◽

The Impact

Coarse mineral dust (diameter, ≥5 μm) is an important component of the Earth system that affects clouds, ocean ecosystems, and climate. Despite their significance, climate models consistently underestimate the amount of coarse dust in the atmosphere when compared to measurements. Here, we estimate the global load of coarse dust using a framework that leverages dozens of measurements of atmospheric dust size distributions. We find that the atmosphere contains 17 Tg of coarse dust, which is four times more than current climate models simulate. Our findings indicate that models deposit coarse dust out of the atmosphere too quickly. Accounting for this missing coarse dust adds a warming effect of 0.15 W·m−2 and increases the likelihood that dust net warms the climate system. We conclude that to properly represent the impact of dust on the Earth system, climate models must include an accurate treatment of coarse dust in the atmosphere.

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