Complex refractive index and single scattering albedo of Icelandic dust in the shortwave part of the spectrum

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F60460709%3A41330%2F23%3A97508" target="_blank" >RIV/60460709:41330/23:97508 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.5194/acp-23-7975-2023" target="_blank" >http://dx.doi.org/10.5194/acp-23-7975-2023</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.5194/acp-23-7975-2023" target="_blank" >10.5194/acp-23-7975-2023</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Complex refractive index and single scattering albedo of Icelandic dust in the shortwave part of the spectrum

Popis výsledku v původním jazyce

Icelandic dust can impact the radiative budget in high-latitude regions directly by affecting light absorption and scattering and indirectly by changing the surface albedo after dust deposition. This tends to produce a positive radiative forcing. However, the limited knowledge of the spectral optical properties of Icelandic dust prevents an accurate assessment of these radiative effects. Here, the spectral single scattering albedo (SSA) and the complex refractive index (m = n - ik) of Icelandic dust from five major emission hotspots were retrieved between 370-950 nm using online measurements of size distribution and spectral absorption (beta(abs)) and scattering (beta(sca)) coefficients of particles suspended in a large-scale atmospheric simulation chamber. The SSA(lambda) estimated from the measured beta(abs) and beta(sca) increased from 0.90-0.94 at 370 nm to 0.94-0.96 at 950 nm in Icelandic dust from the different hotspots, which falls within the range of mineral dust from northern Africa and eastern Asia. The spectral complex refractive index was retrieved by minimizing the differences between the measured beta(abs) and beta(sca) and those computed using the Mie theory for spherical and internally homogeneous particles, using the size distribution data as input. The real part of the complex refractive index (n(lambda)) was found to be 1.60-1.61 in the different samples and be independent of wavelength. The imaginary part (k(lambda)) was almost constant with wavelength and was found to be around 0.004 at 370 nm and 0.002-0.003 at 950 nm. The estimated complex refractive index was close to the initial estimates based on the mineralogical composition, also suggesting that the high magnetite content observed in Icelandic dust may contribute to its high absorption capacity in the shortwave part of the spectrum. The k(lambda) values retrieved for Icelandic dust are at the upper end of the reported range for low-latitude dust (e.g., from the Sahel). Furthermore, Icelandic dust tends to be more absorbing towards the near-infrared. In Icelandic dust, k(lambda) between 660-950 nm was 2-8 times higher than most of the dust samples sourced in northern Africa and eastern Asia. This suggests that Icelandic dust may have a stronger positive direct radiative forcing on climate that has not been accounted for in climate predictions.

Název v anglickém jazyce

Complex refractive index and single scattering albedo of Icelandic dust in the shortwave part of the spectrum

Popis výsledku anglicky

Icelandic dust can impact the radiative budget in high-latitude regions directly by affecting light absorption and scattering and indirectly by changing the surface albedo after dust deposition. This tends to produce a positive radiative forcing. However, the limited knowledge of the spectral optical properties of Icelandic dust prevents an accurate assessment of these radiative effects. Here, the spectral single scattering albedo (SSA) and the complex refractive index (m = n - ik) of Icelandic dust from five major emission hotspots were retrieved between 370-950 nm using online measurements of size distribution and spectral absorption (beta(abs)) and scattering (beta(sca)) coefficients of particles suspended in a large-scale atmospheric simulation chamber. The SSA(lambda) estimated from the measured beta(abs) and beta(sca) increased from 0.90-0.94 at 370 nm to 0.94-0.96 at 950 nm in Icelandic dust from the different hotspots, which falls within the range of mineral dust from northern Africa and eastern Asia. The spectral complex refractive index was retrieved by minimizing the differences between the measured beta(abs) and beta(sca) and those computed using the Mie theory for spherical and internally homogeneous particles, using the size distribution data as input. The real part of the complex refractive index (n(lambda)) was found to be 1.60-1.61 in the different samples and be independent of wavelength. The imaginary part (k(lambda)) was almost constant with wavelength and was found to be around 0.004 at 370 nm and 0.002-0.003 at 950 nm. The estimated complex refractive index was close to the initial estimates based on the mineralogical composition, also suggesting that the high magnetite content observed in Icelandic dust may contribute to its high absorption capacity in the shortwave part of the spectrum. The k(lambda) values retrieved for Icelandic dust are at the upper end of the reported range for low-latitude dust (e.g., from the Sahel). Furthermore, Icelandic dust tends to be more absorbing towards the near-infrared. In Icelandic dust, k(lambda) between 660-950 nm was 2-8 times higher than most of the dust samples sourced in northern Africa and eastern Asia. This suggests that Icelandic dust may have a stronger positive direct radiative forcing on climate that has not been accounted for in climate predictions.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10511 - Environmental sciences (social aspects to be 5.7)

Projekt

<a href="/cs/project/GJ20-06168Y" target="_blank" >GJ20-06168Y: Polární prach a jeho role při klimatických změnách</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2023

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

ATMOSPHERIC CHEMISTRY AND PHYSICS

ISSN

1680-7316

e-ISSN

1680-7316

Svazek periodika

23

Číslo periodika v rámci svazku

14

Stát vydavatele periodika

CZ - Česká republika

Počet stran výsledku

26

Strana od-do

7975-8000

Kód UT WoS článku

001031468200001

EID výsledku v databázi Scopus

2-s2.0-85169674271