Aerosol Optical Thickness over Large Urban Environments of the Arabian Peninsula—Speciation, Variability, and Distributions

Roshan, Dillan Raymond; Кочкодан, Віктор; Isaifan, Rima J.; Shahid, Muhammad Zeeshaan; Fountoukis, C.

doi:10.3390/atmos10050228

Cited by 28 publications

(18 citation statements)

References 48 publications

(109 reference statements)

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“…So far, the available satellite-derived UV Index data are not representative of the region as they do not accurately model the effect of UV absorbing aerosols such as the mineral dust. Severe dust storms occur with a frequency of 10-20 per year in the Middle East while typical "dusty conditions" are even more frequent locally [21,47]. In this study, for the first time, a method for UVI forecasting has been developed for the dust-rich conditions of the Middle East that makes use of a three-dimensional regional meteorology-chemistry model combined with surface solar radiation measurements from monitoring stations in Doha, Qatar and NASA's OMI Aura satellite-retrieved data.…”

Section: Discussionmentioning

confidence: 99%

“…It is also within the global dust belt, and thus, its atmosphere constantly has a large proportion of mineral desert dust aerosol particles that mostly absorb UV radiation [25,27]. Most of its mineral dust concentrations come through two wind regimes-the summer and the winter Shamal winds that blow from the deserts of Iraq, Syria, and the Arabian Peninsula [21,24].…”

Section: The Region Of Interestmentioning

confidence: 99%

“…The UVI is calculated by National Aeronautics and Space Administration (NASA)'s Ozone Monitoring Instrument (OMI) on its Aura satellite that considers cloud-free, and snow-free conditions, and provides data for mean sea level with surface albedo of 3% and aerosol optical depth (AOD) at 550 nm for a particle diameter of 0.2 nm [20]. However, for countries located in the global dust belt (an area that extends from the west coast of North Africa, through the Middle East, into Central Asia) with high surface albedo (due to its desert landscape), and high AOD throughout the year [21], there is a need for a more representative UVI.…”

Section: Introductionmentioning

confidence: 99%

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UV Index Forecasting under the Influence of Desert Dust: Evaluation against Surface and Satellite-Retrieved Data

et al. 2020

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Human exposure to healthy doses of UV radiation is required for vitamin D synthesis, but exposure to excessive UV irradiance leads to several harmful impacts ranging from premature wrinkles to dangerous skin cancer. However, for countries located in the global dust belt, accurate estimation of the UV irradiance is challenging due to a strong impact of desert dust on incoming solar radiation. In this work, a UV Index forecasting capability is presented, specifically developed for dust-rich environments, that combines the use of ground-based measurements of broadband irradiances UVA (320-400 nm) and UVB (280-315 nm), NASA OMI Aura satellite-retrieved data and the meteorology-chemistry mesoscale model WRF-Chem. The forecasting ability of the model is evaluated for clear sky days as well as during the influence of dust storms in Doha, Qatar. The contribution of UV radiation to the total incoming global horizontal irradiance (GHI) ranges between 5% and 7% for UVA and 0.1% and 0.22% for UVB. The UVI forecasting performance of the model is quite encouraging with an absolute average error of less than 6% and a correlation coefficient of 0.93. In agreement with observations, the model predicts that the UV Index at local noontime can drop from 10-11 on clear sky days to approximately 6-7 during typical dusty conditions in the Arabian Peninsula-an effect similar to the presence of extensive cloud cover.Atmosphere 2020, 11, 96 2 of 17 photokeratitis (inflammation of the cornea), and suppression of the immune system [1,[3][4][5]. Thus, it is important for people to control their exposure to UV radiation [1,6].The UV radiation on the Earth's surface is largely determined by the solar zenith angle, clouds, total ozone column, surface albedo, aerosols, earth-sun distance, and altitude [7]. Clouds poorly absorb UV radiation and in general, scatter UV radiation into the atmosphere [8,9]. Stratospheric ozone (ozone layer) predominantly absorbs UV radiation at wavelengths below 320 nm [10]. The extent of reflectivity from a surface affects UV surface irradiance with higher surface albedo enhancing the net UV surface irradiance due to multiple scattering of the reflected irradiance with the atmosphere. For example, a surface covered by snow (with albedo of 0.8) will increase UV irradiance at 320 nm by 1.5 times compared to snow-free, low albedo conditions [11]. Aerosols also affect the incoming UV irradiance. They usually decrease UV irradiance reaching the surface by scattering and absorption. A measurement campaign in Greece showed that UV irradiance decreased by 5-35% due to aerosols [12], and similar numbers of annual average aerosol attenuation of UV irradiance were obtained around the globe [13]. Desert dust intrusions also affect UV irradiance with differences larger than 30% in cloudless conditions in Santiago de Chile [14,15]. These differences in UV irradiance highlight the need for ground-based measurements to account for the attenuation of UV radiation in the troposphere which are not accounted for in satellite derived es...

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Section: Discussionmentioning

confidence: 99%

Section: The Region Of Interestmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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UV Index Forecasting under the Influence of Desert Dust: Evaluation against Surface and Satellite-Retrieved Data

et al. 2020

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“…Anthropogenic pollution is also present in the greater area where oil and gas extraction activities add up to the man-made aerosol particulate burden from the cities. The Aerosol Optical Depth at 500 nm in the region varies between 0.4 and 0.5 (Eck et al, 2008) where the contribution of mineral dust particles can be 60 -70 % even in urban areas (Roshan et al, 2019). Figure 1b shows the air mass backward trajectory cluster analysis, computed with HySPLIT (Stein et al, 2015, see Section 2.3), and their frequency over the course of the campaign period.…”

Section: The Measurement Sitementioning

confidence: 99%

Optical and geometrical aerosol particle properties over the United Arab Emirates

Filioglou¹,

Giannakaki²,

Backman³

et al. 2020

Preprint

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Abstract. One-year of ground-based night-time Raman lidar observations have been analysed under the Optimization of Aerosol Seeding In rain enhancement Strategies (OASIS) project, in order to characterize the aerosol particle properties over a rural site in the United Arab Emirates. In total, 1130 aerosol particle layers were detected during the one-year measurement campaign which took place between March 2018 and February 2019. Several subsequent aerosol layers could be observed simultaneously in the atmosphere up to 11 km. The observations indicate that the measurement site is a receptor of frequent dust events but predominantly the dust is mixed with aerosols of anthropogenic and/or marine origin. The mean aerosol optical depth over the measurement site ranged at 0.37 ± 0.12 and 0.21 ± 0.11 for the 355 and 532 nm, respectively. Moreover, a mean lidar ratio of 43 ± 11 sr at a wavelength of 355 nm and 39 ± 10 sr at 532 nm was found. The average linear particle depolarization ratio measured over the course of the campaign was 15 ± 6 % and 19 ± 7 % at 355 nm and 532 nm wavelengths, respectively. Since the region is both a source and a receptor of mineral dust, we have also explored the properties of Arabian mineral dust of the greater area of United Arab of Emirates and the Arabian Peninsula. The observed Arabian dust particle properties were 45 ± 5 (42 ± 5) sr at 355 (532) nm for the lidar ratio, 25 ± 2 % (31 ± 2 %) for the linear particle depolarization ratio at 355 (532) nm, and 0.3 ± 0.2 (0.2 ± 0.2) for the extinction‑related Ångström exponent (backscatter‑related Ångström exponent) between 355 and 532 nm. This study is the first to report comprehensive optical properties of the Arabian dust particles based on long term observations, using at the fullest the capabilities of a multi wavelength Raman lidar instrument. The results suggest that the mineral dust properties over the Middle East and western Asia, including the observation site, are comparable to those of African mineral dust with regard to the particle depolarization ratios but not for lidar ratios. The smaller lidar ratio values in this study compared to the reference studies are attributed to the difference in the geochemical characteristics of the soil originating in the study region compared to Northern Africa.

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“…Recent developments in remote sensing and coordination of ground-based instruments as networks, such as Aerosol Robotics NETwork (AERONET), have allowed a better characterization of aerosols at a global scale. In this special issue, nine original articles show new recent developments in remote sensing techniques [1][2][3][4][5] and synergies derived from combined use of different techniques [6][7][8][9].…”

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confidence: 99%

Remote Sensing of Aerosols

Molero

2019

Atmosphere

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Aerosol Optical Thickness over Large Urban Environments of the Arabian Peninsula—Speciation, Variability, and Distributions

Cited by 28 publications

References 48 publications

UV Index Forecasting under the Influence of Desert Dust: Evaluation against Surface and Satellite-Retrieved Data

UV Index Forecasting under the Influence of Desert Dust: Evaluation against Surface and Satellite-Retrieved Data

Optical and geometrical aerosol particle properties over the United Arab Emirates

Remote Sensing of Aerosols

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