Refractive Index for Asian Dust in the Ultraviolet‐Visible Region Determined From Compositional Analysis and Validated With OMI Observations

Lee, Kwang‐Mog; Choi, Haklim; Kim, Jhoon

doi:10.1029/2019jd030629

Cited by 6 publications

(3 citation statements)

References 77 publications

(206 reference statements)

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“…One of the reasons for the discrepancy is the uncertainty of dust absorbability (Wang et al, 2006, 2004). The most recent study by Lee et al (2020) shows that Asian dust aerosols have smaller absorbability compared to Saharan dust, which was validated by the Ozone Monitoring Instrument (OMI) observations.…”

Section: Introductionmentioning

confidence: 79%

Impact of Dust Shortwave Absorbability on the East Asian Summer Monsoon

Wang

Jia

et al. 2020

Geophysical Research Letters

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Dust shortwave absorbability suffers from significant uncertainties. We investigated the radiative effects of dust aerosols from the circum-Tibet region using four shortwave absorbability schemes and examined their impacts on the East Asian summer monsoon by using the Community Earth System Model (CESM). We adopted superspheroidal models to compute dust aerosol optical properties and found that more absorptive particles have larger asymmetry factor and lower single-scattering albedo. Meiyu precipitation, as a part of the East Asian summer monsoon, is weakened by dust aerosols, particularly for the convective precipitation. The mechanism is that dust aerosols transported mainly from the Gobi desert radiatively heat the lower atmosphere to the north of the Meiyu rainband and decrease the meridional temperature gradient, leading to the weakening of the midtropospheric westerly jet over the Meiyu rainband, which is important for convection. More absorptive dust aerosols with a stronger radiative heating effect inhibit more convective Meiyu precipitation. Plain Language Summary The circum-Tibet region including the Taklimakan and Gobi deserts is the major source region of dust aerosols in East Asia particularly during the spring and summer seasons. Meiyu, as a part of the East Asian summer monsoon, generally occurs from mid-June to mid-July and often shows a tilt rain band extending from southwest to east China. The Letter reports on our finding about the relationship between dust shortwave absorbability (the amount of solar radiation absorbed by dust) and Meiyu precipitation. For weakly absorptive dust aerosols, convective Meiyu precipitation is rarely changed by dust aerosols; however, for strongly absorptive dust aerosols, convective Meiyu precipitation is significantly decreased. The impact of dust absorbability on Meiyu precipitation is explained through atmospheric heating rate, temperature, and wind field changes. This Letter emphasizes the urgent need of a more accurate knowledge of dust shortwave absorbability for climate modeling since significant uncertainties of refractive indices exist and new evidences show that Asian dust could be less absorptive than previously believed.

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Section: Introductionmentioning

confidence: 79%

Impact of Dust Shortwave Absorbability on the East Asian Summer Monsoon

Wang

Jia

et al. 2020

Geophysical Research Letters

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“…Based on previous analyses on the measurements and classifications of dust mineralogy (Di Biagio et al., 2017; Kandler et al., 2007; Lee et al., 2020; Stegmann & Yang, 2017), we organized nine mineralogical groups for dust aerosols as shown in Table 1. Egan and Hilgeman (1979) found that illite has relatively lower values of the real part of the refractive index than those of the other clay minerals in the SW spectra.…”

Section: Methodsmentioning

confidence: 99%

Sensitivities of Spectral Optical Properties of Dust Aerosols to Their Mineralogical and Microphysical Properties

Zhang,

Saito,

Yang

et al. 2024

JGR Atmospheres

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Dust aerosol is a key component in global radiative forcing and climate modeling. We developed a mineralogy‐resolved spectral optical property model for dust aerosols. The model incorporates nine mineral groups and applies the effective medium methods to obtain the spectral complex refractive indices of inhomogeneous dust particles. This study considers 5,000 sets of dust mineral composition mixtures along with the use of the bimodal particle size distribution. We calculate the bulk properties of these samples in a wide spectral range from 0.2 to 50 μm using a comprehensive database of hexahedral dust single‐scattering properties. Through sensitivity analyses, this study reveals that the illite and hematite components substantially affect the optical properties of dust. Furthermore, the effective radii of both the fine‐mode and the coarse‐mode dust particles have significant impacts on the bulk optical properties, albeit to varying degrees.

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“…The dust CRI is primarily determined by its mineralogy (Lee et al., 2020; Moosmüller et al., 2012). Dust particles are composed of various minerals, including quartz, clay, feldspar, calcite, goethite, and hematite (Kandler et al., 2007).…”

Section: Introductionmentioning

confidence: 99%

Larger Dust Cooling Effect Estimated From Regionally Dependent Refractive Indices

Wang,

Liu,

et al. 2024

Geophysical Research Letters

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The dust direct radiative effect (DRE) depends strongly on the dust particle size distribution (PSD) and complex refractive index (CRI). Although recent studies constrained the dust PSD in the models, its CRI uncertainties are still large. As a result, whether dust warms or cools the climate system remains unclear. Here, we estimate the dust DRE by employing the regionally‐dependent dust CRI based on global measurements. We find that new dust CRI significantly enhances the scattering of dust in the shortwave while reduces its absorption in the longwave, which is opposite to that caused by increasing the coarse and giant dust fraction via constraining the PSD. Constraining both PSD and CRI ultimately leads to a net dust DRE of −0.68 W m−2, a cooling stronger than current model estimates.

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Refractive Index for Asian Dust in the Ultraviolet‐Visible Region Determined From Compositional Analysis and Validated With OMI Observations

Cited by 6 publications

References 77 publications

Impact of Dust Shortwave Absorbability on the East Asian Summer Monsoon

Impact of Dust Shortwave Absorbability on the East Asian Summer Monsoon

Sensitivities of Spectral Optical Properties of Dust Aerosols to Their Mineralogical and Microphysical Properties

Larger Dust Cooling Effect Estimated From Regionally Dependent Refractive Indices

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