Thermal infrared remote sensing of mineral dust over land and ocean: a spectral SVD based retrieval approach for IASI

Abstract. From the high spectral resolution thermal infrared observations of the Infrared Atmospheric Sounding Interferometer (IASI) mineral dust AOD (transferred from thermal infrared to 0.5 μm) is retrieved using a Singular Vector Decomposition of brightness temperature spectra. As infrared retrieval based on 8–12 μm observations, dust observation with IASI is independent from solar illumination. Through the linear combinations of suitable independent singular vectors weighted by their contribution to the observed signal, and a projection of different a-priori dust spectra on the resulting signal the dust can be well distinguished from the influence of surface emissivity and gas absorption. In contrast to lookup-table based single-channel retrievals this method takes advantage of the spectral shape of dust extinction and surface and atmosphere influence over the total 8–12 μm window band. Using different a-priori spectra for dust extinction allows also for an estimation of dust particle size in terms of effective radius based on the respective dust model size distributions. These dust models are also used for the transfer of infrared AOD to 0.5 μm. Four months of IASI observations covering Northern Africa and Arabia are used for evaluation. Two large scale dust events, one covering the Arabian Peninsula and adjacent parts of the Indian Ocean, the other over the Atlantic Ocean off the coast of West-Africa, are analysed and compared with other satellite images. They also show the good suitability of IASI data for dust observation at day and night. Monthly means derived from IASI observations represent well the known seasonal cycles of dust activity over Northern Africa and Arabia. IASI Dust AOD0.5 μm and AERONET coarse mode AOD0.5 μm are reasonably well (linearly) correlated with ρ=0.623. Moreover, comparison of time series of AERONET and IASI observations shows that the evolution of dust events is very well covered by the IASI observations. Rank correlation between dust effective radius and AERONET Ångström exponent is −0.557 indicating the general capability of (qualitative) dust particle size information being provided by this method.

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Thermal infrared remote sensing of mineral dust over land and ocean: a spectral SVD based retrieval approach for IASI

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-4-461-2011 ◽

2011 ◽

Vol 4 (1) ◽

pp. 461-509 ◽

Cited By ~ 1

Author(s):

L. Klüser ◽

D. Martynenko ◽

T. Holzer-Popp

Keyword(s):

Particle Size ◽

Dust Particle ◽

Mineral Dust ◽

A Priori ◽

Thermal Infrared ◽

Effective Radius ◽

Northern Africa ◽

Lookup Table ◽

Dust Extinction ◽

Dust Events

Abstract. From the high spectral resolution thermal infrared observations of the Infrared Atmospheric Sounding Interferometer (IASI) mineral dust AOD (transferred from thermal infrared to 0.5 μm) is retrieved using a Singular Vector Decomposition of brightness temperature spectra. As infrared retrieval based on 8–12 μm observations, dust observation with IASI is independent from solar illumination. Through the linear combinations of suitable independent singular vectors weighted by their contribution to the observed signal, and a projection of different a-priori dust spectra on the resulting signal the dust can be well distinguished from the influence of surface emissivity and gas absorption. In contrast to lookup-table based single-channel retrievals this method takes advantage of the spectral shape of dust extinction and surface and atmosphere influence over the total 8–12 μm window band. Using different a-priori spectra for dust extinction allows also for an estimation of dust particle size in terms of effective radius based on the respective dust model size distributions. These dust models are also used for the transfer of infrared AOD to 0.5 μm. Four months of IASI observations covering Northern Africa and Arabia are used for evaluation. Two large scale dust events, one covering the Arabian Peninsula and adjacent parts of the Indian Ocean, the other over the Atlantic Ocean off the coast of West-Africa, are analysed and compared with other satellite images. They also show the good suitability of IASI data for dust observation at day and night. Monthly means derived from IASI observations represent well the known seasonal cycles of dust activity over Northern Africa and Arabia. IASI Dust AOD0.5 μm and AERONET coarse mode AOD0.5 μm are reasonably well (linearly) correlated with ρ = 0.655. Moreover, comparison of time series of AERONET and IASI observations shows that the evolution of dust events is very well covered by the IASI observations. Rank correlation between dust effective radius and AERONET Ångström exponent is –0.614 indicating the general capability of (qualitative) dust particle size information being provided by this method.

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Size-resolved atmospheric ice-nucleating particles during East Asian dust events

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-3491-2021 ◽

2021 ◽

Vol 21 (5) ◽

pp. 3491-3506

Author(s):

Jingchuan Chen ◽

Zhijun Wu ◽

Jie Chen ◽

Naama Reicher ◽

Xin Fang ◽

...

Keyword(s):

Particle Size ◽

Mineral Dust ◽

East Asian ◽

Substantial Effect ◽

Ice Nucleation ◽

Asian Dust ◽

Dust Particles ◽

Significant Difference ◽

Dust Events ◽

Surface Ice

Abstract. Asian dust is an important source of atmospheric ice-nucleating particles (INPs). However, the freezing activity of airborne Asian dust, especially its sensitivity to particle size, is poorly understood. In this study we report the first INP measurement of size-resolved airborne mineral dust collected during East Asian dust events. The measured total INP concentrations in the immersion mode ranged from 10−2 to 102 L−1 in dust events at temperatures between −25 and −5 ∘C. The average contributions of heat-sensitive INPs at three temperatures, −10, −15, and −20 ∘C, were 81±12 %, 70±15 %, and 38±21 %, respectively, suggesting that proteinaceous biological materials have a substantial effect on the ice nucleation properties of Asian airborne mineral dust at high temperatures. The dust particles which originated from China's northwest deserts are more efficient INPs compared to those from northern regions. In general, there was no significant difference in the ice nucleation properties between East Asian dust particles and other regions in the world. An explicit size dependence of both INP concentration and surface ice-active-site density was observed. The nucleation efficiency of dust particles increased with increasing particle size, while the INP concentration first increased rapidly and then leveled, due to the significant decrease in the number concentration of larger particles. A new set of parameterizations for INP activity based on size-resolved nucleation properties of Asian mineral dust particles were developed over an extended temperature range (−35 to −6 ∘C). These size-dependent parameterizations require only particle size distribution as input and can be easily applied in models.

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Size-Resolved Atmospheric Ice Nucleating Particles during East Asian Dust Events

10.5194/acp-2020-678 ◽

2020 ◽

Author(s):

Jingchuan Chen ◽

Zhijun Wu ◽

Jie Chen ◽

Naama Reicher ◽

Xin Fang ◽

...

Keyword(s):

Particle Size ◽

Mineral Dust ◽

East Asian ◽

Substantial Effect ◽

Ice Nucleation ◽

Asian Dust ◽

Dust Particles ◽

Significant Difference ◽

Dust Events ◽

Surface Ice

Abstract. Asian dust is an important source of atmospheric ice nucleating particles (INPs). However, the freezing activity of airborne Asian dust, especially its sensitivity to particle size, is poorly understood. In this study we report the first INP measurement of size-resolved airborne mineral dust collected during East Asian dust events. The measured total INP concentrations in the immersion mode ranged from 10−2 to 102 L−1 in dust events at temperatures between −25 and −5 °C. The average contributions of heat-sensitive INPs at three temperatures, −10, −15, and −20 °C, were 81 ± 12 %, 70 ± 15 %, and 38 ± 21 %, respectively, suggesting that proteinaceous biological materials have a substantial effect on the ice nucleation properties of Asian atmospheric mineral dust at warm temperatures. The dust particles which originated from China's northwest deserts are more efficient INPs compared to those from northern regions. There was no significant difference in the ice nucleation properties between East Asian dust particles and other regions in the world. An explicit size dependence of both INP concentration and surface ice active density was observed. The nucleation efficiency of dust particles increased with increasing particle size, while the INP concentration first increased rapidly and then levelled, due to the significant decrease in the number concentration of larger particles. A new set of parameterizations for INP activity based on size-resolved nucleation properties of Asian mineral dust particles were developed over an extended temperature range (−35 ~ −6 °C). These size-dependent parameterizations require only particle size distributions as input, and can be easily applied in models.

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Size-dependent ice nucleation by airborne particles during dust events in the eastern Mediterranean

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-11143-2019 ◽

2019 ◽

Vol 19 (17) ◽

pp. 11143-11158 ◽

Cited By ~ 7

Author(s):

Naama Reicher ◽

Carsten Budke ◽

Lukas Eickhoff ◽

Shira Raveh-Rubin ◽

Ifat Kaplan-Ashiri ◽

...

Keyword(s):

Particle Size ◽

Active Sites ◽

Mineral Dust ◽

Eastern Mediterranean ◽

Sampling Site ◽

Ice Nucleation ◽

Airborne Particles ◽

Ice Formation ◽

Airborne Dust ◽

Dust Events

Abstract. The prediction of cloud ice formation in climate models remains a challenge, partly due to the complexity of ice-related processes. Mineral dust is a prominent aerosol in the troposphere and is an important contributor to ice nucleation in mixed-phase clouds, as dust can initiate ice heterogeneously at relatively low supercooling conditions. We characterized the ice nucleation properties of size-segregated mineral dust sampled during dust events in the eastern Mediterranean. The sampling site allowed us to compare the properties of airborne dust from several sources with diverse mineralogy that passed over different atmospheric paths. We focused on particles with six size classes determined by the Micro-Orifice Uniform Deposit Impactor (MOUDI) cutoff sizes: 5.6, 3.2, 1.8, 1.0, 0.6 and 0.3 µm. Ice nucleation experiments were conducted in the Weizmann Supercooled Droplets Observation on a Microarray (WISDOM) setup, whereby the particles are immersed in nanoliter droplets using a microfluidics technique. We observed that the activity of airborne particles depended on their size class; supermicron and submicron particles had different activities, possibly due to different composition. The concentrations of ice-nucleating particles and the density of active sites (ns) increased with the particle size and particle concentration. The supermicron particles in different dust events showed similar activity, which may indicate that freezing was dominated by common mineralogical components. Combining recent data of airborne mineral dust, we show that current predictions, which are based on surface-sampled natural dust or standard mineral dust, overestimate the activity of airborne dust, especially for the submicron class. Therefore, we suggest including information on particle size in order to increase the accuracy of ice formation modeling and thus weather and climate predictions.

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North African mineral dust across the tropical Atlantic Ocean: Insights from dust particle size, radiogenic Sr-Nd-Hf isotopes and rare earth elements (REE)

Aeolian Research ◽

10.1016/j.aeolia.2018.06.001 ◽

2018 ◽

Vol 33 ◽

pp. 106-116 ◽

Cited By ~ 7

Author(s):

Michèlle van der Does ◽

Ali Pourmand ◽

Arash Sharifi ◽

Jan-Berend W. Stuut

Keyword(s):

Particle Size ◽

Rare Earth ◽

Atlantic Ocean ◽

Rare Earth Elements ◽

Dust Particle ◽

Mineral Dust ◽

Hf Isotopes ◽

Tropical Atlantic ◽

North African ◽

Tropical Atlantic Ocean

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Size-dependent ice nucleation by airborne particles during dust events in the Eastern Mediterranean

10.5194/acp-2019-511 ◽

2019 ◽

Author(s):

Naama Reicher ◽

Carsten Budke ◽

Lukas Eickhoff ◽

Shira Raveh-Rubin ◽

Ifat Kaplan-Ashiri ◽

...

Keyword(s):

Particle Size ◽

Active Sites ◽

Mineral Dust ◽

Eastern Mediterranean ◽

Sampling Site ◽

Ice Nucleation ◽

Airborne Particles ◽

Ice Formation ◽

Airborne Dust ◽

Dust Events

Abstract. Predictions of cloud ice formation in climate models remain a challenge, partly due to the complexity of ice-related processes. Mineral dust is a prominent aerosol in the troposphere and is known to be an important contributor to ice nucleation in mixed phase clouds, as dust can initiate ice heterogeneously at relatively low supercooling conditions. We characterized the ice nucleation properties of size-segregated mineral dust sampled during dust events in the Eastern Mediterranean. The sampling site allowed us to compare between the properties of airborne dust from several sources with diverse mineralogy that passed over different atmospheric paths. We focused on particles with six size-classes, determined by the Micro-Orifice Uniform Deposit Impactor (MOUDI) cut-off sizes: 5.6, 3.2, 1.8, 1.0, 0.6 and 0.3 µm. Ice nucleation experiments were conducted in the WeIzmann Supercooled Droplets Observation on Microarray (WISDOM) setup, where the particles are immersed in nanoliter droplets using a microfluidics technique. We observed that the activity of airborne particles depended on their size-class, where supermicron and submicron particles had different activities, possibly due to different composition. The concentrations of ice nucleating particles and the density of active sites (ns) increased with the particle size and particle concentration. The supermicron particles in different dust events showed similar activity, which may indicate that freezing was dominated by common mineralogical components. Combining recent data of airborne mineral dust, we show that current predictions, which are based on natural dust or standard mineral dust, overestimate the activity of airborne dust, especially for the submicron class, and therefore we suggest to include information of particle size in order to increase the accuracy of ice formation and, thus, weather and climate predictions.

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Evaluation of natural aerosols in CRESCENDO-ESMs: Mineral Dust

10.5194/acp-2020-1147 ◽

2020 ◽

Author(s):

Ramiro Checa-Garcia ◽

Yves Balkanski ◽

Samuel Albani ◽

Tommi Bergman ◽

Ken Carslaw ◽

...

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Dust Particle ◽

Mineral Dust ◽

Radiative Effects ◽

Dust Emissions ◽

Dust Sources ◽

Global Consistency ◽

The Difference

Abstract. This paper presents an analysis of the mineral dust aerosol modelled by five Earth System Models (ESM) within the Coordinated Research in Earth Systems and Climate: Experiments, kNowledge, Dissemination and Outreach (CRESCENDO) project. We quantify the global dust cycle described by each model in terms of global emissions together with dry and wet depositions, reporting large differences in ratio of dry over wet deposition across the models not directly correlated with the range of particle sizes emitted. The multi-model mean dust emissions was 2954 Tg yr−1 but with a large uncertainty due mainly to the difference in maximum dust particle size emitted. For the subset of ESMs without particles larger than 10 μm we obtained 1664 (σ = 650) Tg yr−1. Total dust emissions with identical nudged winds from reanalysis give us better consistency between models with 1530 (σ = 282) Tg yr−1. Significant discrepancies in the globally averaged dust mass extinction efficiency explain why even models with relatively similar dust load global budgets can display strong differences in dust optical depths. The comparison against observations has been done in terms of dust optical depths based on MODIS satellite products, showing a global consistency in terms of preferential dust sources and transport across the Atlantic. However, we found regional and seasonal differences between models and observations when we quantified the cross-correlation of time-series over dust emitting regions. To faithfully compare local emissions between models we introduce a re-gridded normalization method, that also can be compared with satellite products derived from dust events frequencies. Dust total depositions are compared with instrumental network to assess global and regional differences. We found that models agree with observations distant from dust sources within a factor 10, but the approximations of dust particle size distribution at emission contributed to a misrepresentation of the actual range of deposition values when instruments are close to dust emitting regions. The observational dust surface concentrations also are reproduced within a factor 10. The comparison of total aerosol optical depths with AERONETv3 stations where dust is dominant shows large differences between models, however with an increase of the inter-model consistency when the simulations are conducted with nudged-winds. The increase of the model ensemble consistency also means a better agreement with observations, which we have ascertained for dust total deposition, surface concentrations and optical depths (against both AERONETv3 and MODIS-DOD retrievals). We estimated the direct radiative effects of a multi-modal representation of the dust particle size distribution that includes the largest particles measured at FENNEC experiment. We introduced a method to ascertain the contributions per mode consistent with the multimodal direct radiative effects.

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Observations of Saharan dust microphysical and optical properties from the Eastern Atlantic during NAMMA airborne field campaign

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-723-2011 ◽

2011 ◽

Vol 11 (2) ◽

pp. 723-740 ◽

Cited By ~ 57

Author(s):

G. Chen ◽

L. D. Ziemba ◽

D. A. Chu ◽

K. L. Thornhill ◽

G. L. Schuster ◽

...

Keyword(s):

Particle Size ◽

Optical Properties ◽

Dust Particle ◽

Saharan Dust ◽

Dust Particles ◽

Small Range ◽

Size Distributions ◽

Particle Size Distributions ◽

Field Campaign ◽

Sahara Dust

Abstract. As part of the international project entitled "African Monsoon Multidisciplinary Analysis (AMMA)", NAMMA (NASA AMMA) aimed to gain a better understanding of the relationship between the African Easterly Waves (AEWs), the Sahara Air Layer (SAL), and tropical cyclogenesis. The NAMMA airborne field campaign was based out of the Cape Verde Islands during the peak of the hurricane season, i.e., August and September 2006. Multiple Sahara dust layers were sampled during 62 encounters in the eastern portion of the hurricane main development region, covering both the eastern North Atlantic Ocean and the western Saharan desert (i.e., 5–22° N and 10–35° W). The centers of these layers were located at altitudes between 1.5 and 3.3 km and the layer thickness ranged from 0.5 to 3 km. Detailed dust microphysical and optical properties were characterized using a suite of in-situ instruments aboard the NASA DC-8 that included a particle counter, an Ultra-High Sensitivity Aerosol Spectrometer, an Aerodynamic Particle Sizer, a nephelometer, and a Particle Soot Absorption Photometer. The NAAMA sampling inlet has a size cut (i.e., 50% transmission efficiency size) of approximately 4 μm in diameter for dust particles, which limits the representativeness of the NAMMA observational findings. The NAMMA dust observations showed relatively low particle number densities, ranging from 268 to 461 cm−3, but highly elevated volume density with an average at 45 μm3 cm−3. NAMMA dust particle size distributions can be well represented by tri-modal lognormal regressions. The estimated volume median diameter (VMD) is averaged at 2.1 μm with a small range of variation regardless of the vertical and geographical sampling locations. The Ångström Exponent assessments exhibited strong wavelength dependence for absorption but a weak one for scattering. The single scattering albedo was estimated at 0.97 ± 0.02. The imaginary part of the refractive index for Sahara dust was estimated at 0.0022, with a range from 0.0015 to 0.0044. Closure analysis showed that observed scattering coefficients are highly correlated with those calculated from spherical Mie-Theory and observed dust particle size distributions. These values are generally consistent with literature values reported from studies with similar particle sampling size range.

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