The thermal infrared optical depth of mineral dust retrieved from integrated CALIOP and IIR observations

Abstract. This paper presents the reconstruction of a 73-year time series of the aerosol optical depth (AOD) at 500 nm at the subtropical high-mountain Izaña Atmospheric Observatory (IZO) located in Tenerife (Canary Islands, Spain). For this purpose, we have combined AOD estimates from artificial neural networks (ANNs) from 1941 to 2001 and AOD measurements directly obtained with a Precision Filter Radiometer (PFR) between 2003 and 2013. The analysis is limited to summer months (July–August–September), when the largest aerosol load is observed at IZO (Saharan mineral dust particles). The ANN AOD time series has been comprehensively validated against coincident AOD measurements performed with a solar spectrometer Mark-I (1984–2009) and AERONET (AErosol RObotic NETwork) CIMEL photometers (2004–2009) at IZO, obtaining a rather good agreement on a daily basis: Pearson coefficient, R, of 0.97 between AERONET and ANN AOD, and 0.93 between Mark-I and ANN AOD estimates. In addition, we have analysed the long-term consistency between ANN AOD time series and long-term meteorological records identifying Saharan mineral dust events at IZO (synoptical observations and local wind records). Both analyses provide consistent results, with correlations >  85 %. Therefore, we can conclude that the reconstructed AOD time series captures well the AOD variations and dust-laden Saharan air mass outbreaks on short-term and long-term timescales and, thus, it is suitable to be used in climate analysis.

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Volcanic ash detection and retrievals using SLSTR. Test case: 2019 Raikoke eruption

10.5194/egusphere-egu21-7363 ◽

2021 ◽

Author(s):

Ilaria Petracca ◽

Davide De Santis ◽

Stefano Corradini ◽

Lorenzo Guerrieri ◽

Matteo Picchiani ◽

...

Keyword(s):

Radiative Transfer ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Volcanic Ash ◽

Thermal Infrared ◽

Integrated Approach ◽

Effective Radius ◽

Volcanic Plume ◽

Transfer Model ◽

Volcanic Cloud

When an eruption event occurs it is necessary to accurately and rapidly determine the position and evolution during time of the volcanic cloud and its parameters (such as Aerosol Optical Depth-AOD, effective radius-Re and mass-Ma of the ash particles), in order to ensure the aviation security and the prompt management of the emergencies.Here we present different procedures for volcanic ash cloud detection and retrieval using S3 SLSTR (Sentinel-3 Sea and Land Surface Temperature Radiometer) data collected the 22 June at 00:07 UTC by the Sentinel-3A platform during the Raikoke (Kuril Islands) 2019 eruption.The volcanic ash detection is realized by applying an innovative machine learning based algorithm, which uses a MultiLayer Perceptron Neural Network (NN) to classify a SLSTR image in eight different surfaces/objects, distinguishing volcanic and weather clouds, and the underlying surfaces. The results obtained with the NN procedure have been compared with two consolidated approaches based on an RGB channels combination in the visible (VIS) spectral range and the Brightness Temperature Difference (BTD) procedure that exploits the thermal infrared (TIR) channels centred at 11 and 12 microns (S8 and S9 SLSTR channels respectively). The ash volcanic cloud is correctly identified by all the models and the results indicate a good agreement between the NN classification approach, the VIS-RGB and BTD procedures.The ash retrieval parameters (AOD, Re and Ma) are obtained by applying three different algorithms, all exploiting the volcanic cloud &#8220;mask&#8221; obtained from the NN detection approach. The first method is the Look Up Table (LUTp) procedure, which uses a Radiative Transfer Model (RTM) to simulate the Top Of Atmosphere (TOA) radiances in the SLSTR thermal infrared channels (S8, S9), by varying the aerosol optical depth and the effective radius. The second algorithm is the Volcanic Plume Retrieval (VPR), based on a linearization of the radiative transfer equation capable to retrieve, from multispectral satellite images, the abovementioned parameters. The third approach is a NN model, which is built on a training set composed by the inputs-outputs pairs TOA radiances vs. ash parameters. The results of the three retrieval methods have been compared, considering as reference the LUTp procedure, since that it is the most consolidated approach. The comparison shown promising agreement between the different methods, leading to the development of an integrated approach for the monitoring of volcanic ash clouds using SLSTR.The results presented in this work have been obtained in the sphere of the VISTA (Volcanic monItoring using SenTinel sensors by an integrated Approach) project, funded by ESA and developed within the EO Science for Society framework [https://eo4society.esa.int/projects/vista/].

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Longwave indirect effect of mineral dusts on ice clouds

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-7753-2010 ◽

2010 ◽

Vol 10 (16) ◽

pp. 7753-7761 ◽

Cited By ~ 11

Author(s):

Q. Min ◽

R. Li

Keyword(s):

Infrared Radiation ◽

Mineral Dust ◽

Dust Cloud ◽

Thermal Infrared ◽

Minor Role ◽

Ice Clouds ◽

Cloud Systems ◽

Ice Cloud ◽

Mineral Dusts ◽

Thermal Infrared Radiation

Abstract. In addition to microphysical changes in clouds, changes in nucleation processes of ice cloud due to aerosols would result in substantial changes in cloud top temperature as mildly supercooled clouds are glaciated through heterogenous nucleation processes. Measurements from multiple sensors on multiple observing platforms over the Atlantic Ocean show that the cloud effective temperature increases with mineral dust loading with a slope of +3.06 °C per unit aerosol optical depth. The macrophysical changes in ice cloud top distributions as a consequence of mineral dust-cloud interaction exert a strong cooling effect (up to 16 Wm−2) of thermal infrared radiation on cloud systems. Induced changes of ice particle size by mineral dusts influence cloud emissivity and play a minor role in modulating the outgoing longwave radiation for optically thin ice clouds. Such a strong cooling forcing of thermal infrared radiation would have significant impacts on cloud systems and subsequently on climate.

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Aerosol Radiative Forcing and Forcing Efficiency in the UVB for Regions Affected by Saharan and Asian Mineral Dust

Journal of the Atmospheric Sciences ◽

10.1175/2008jas2816.1 ◽

2009 ◽

Vol 66 (4) ◽

pp. 1033-1040 ◽

Cited By ~ 10

Author(s):

O. E. García ◽

A. M. Díaz ◽

F. J. Expósito ◽

J. P. Díaz ◽

A. Redondas ◽

...

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Radiative Forcing ◽

Climate Model ◽

Mineral Dust ◽

Global Climate ◽

Global Climate Model ◽

Aerosol Radiative Forcing ◽

Benchmark Database ◽

Aerosol Radiative

Abstract The influence of mineral dust on ultraviolet energy transfer is studied for two different mineralogical origins. The aerosol radiative forcing ΔF and the forcing efficiency at the surface ΔFeff in the range 290–325 nm were estimated in ground-based stations affected by the Saharan and Asian deserts during the dusty seasons. UVB solar measurements were taken from the World Ozone and Ultraviolet Data Center (WOUDC) for four Asian stations (2000–04) and from the Santa Cruz Observatory, Canary Islands (2002–03), under Gobi and Sahara Desert influences, respectively. The Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth at 550 nm was used to characterize the aerosol load τ, whereas the aerosol index provided by the Total Ozone Mapping Spectrometer (TOMS) sensor was employed to identify the mineral dust events. The ΔF is strongly affected by the aerosol load, the values found being comparable in both regions during the dusty seasons. Under those conditions, ΔF values as large as −1.29 ± 0.53 W m−2 (τ550 = 0.48 ± 0.24) and −1.43 ± 0.38 W m−2 (τ550 = 0.54 ± 0.26) were reached under Saharan and Asian dust conditions, respectively. Nevertheless, significant differences have been observed in the aerosol radiative forcing per unit of aerosol optical depth in the slant path, τS. The maximum ΔFeff values associated with dust influences were −1.55 ± 0.20 W m−2 τS550−1 for the Saharan region and −0.95 ± 0.11 W m−2 τS550−1 in the Asian area. These results may be used as a benchmark database for establishing aerosol corrections in UV satellite products or in global climate model estimations.

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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 ◽

10.5194/amt-4-757-2011 ◽

2011 ◽

Vol 4 (5) ◽

pp. 757-773 ◽

Cited By ~ 47

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=0.623. 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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Review of ‘Thin ice clouds in the Arctic: Cloud optical depth and particle size retrieved from ground-based thermal infrared radiometry’

10.5194/amt-2016-371-rc1 ◽

2016 ◽

Author(s):

Anonymous

Keyword(s):

Particle Size ◽

Optical Depth ◽

Thermal Infrared ◽

The Arctic ◽

Ice Clouds ◽

Cloud Optical Depth ◽

Infrared Radiometry

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Properties and challenges of mineral dust aerosol modelling in the latest Earth System Models

10.5194/egusphere-egu2020-9236 ◽

2020 ◽

Author(s):

Ramiro Checa-Garcia ◽

Yves Balkanski ◽

Tommi Bergman ◽

Ken Carslaw ◽

Mohit Dalvi ◽

...

Keyword(s):

Optical Depth ◽

Mineral Dust ◽

Regional Scale ◽

Climate System ◽

Deposition Flux ◽

Dust Aerosols ◽

Earth Systems ◽

Imperfect Knowledge ◽

Sahel Region ◽

Mineral Dust Aerosols

Mineral dust aerosols participate in the climate system and biogeochemistry processes due to its interactions with key components of Earth Systems: radiation, clouds, soil and chemical components. A central element to improve our understanding of mineral dust is through its modeling with Earth Systems Models where all these interactions are included. However, current simulations of dust variability exhibit important uncertainties and biases, which are model-dependent, whose cause is our imperfect knowledge about how to best represent the dust life cycle. For these reasons a continuous evaluation of the performance and properties of the different models compared against measurements is a crucial step to improve our knowledge of the dust cycle and its role in the climate system and biogeochemical cycles. Here we present an exhaustive evaluation of mineral dust aerosols in CRESCEND-ESMs over global, regional and local scales. We compare models against three networks of instruments for total dust deposition flux, yearly surface concentrations, and optical depths. Global and regional dust optical depths are compared with MODIS and MISR derived products. Specific analyses are done over the Sahel region where improved and compressive dust observational datasets are available. The results indicate that all the models capture the general properties of the global dust cycle, although the role of larger particles remains challenging. Differences are partially due to surface winds as nudged simulations improve the inter-model comparison and the performance in optical depth compared to MODIS. At the regional scale, there is an optical depth reasonable agreement over main source areas, but a joint inter-comparison including fluxes and concentration indicates larger differences. At the local scale, the uncertainties increase and current models are not able to reproduce together several observables at the same time.

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