High Summertime Aerosol Loadings Over the Arabian Sea and Their Transport Pathways

Jin, Qinjian; Wei, Jiangfeng; Pu, Bing; Parajuli, Sagar

doi:10.1029/2018jd028588

Cited by 56 publications

(35 citation statements)

References 67 publications

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“…Recent studies have suggested potential impacts of Middle East desert aerosols in modulating the ISM dynamics and intraseasonal variability (Jin et al, ; Vinoj et al, ), and indeed, mineral dust was found to dominate over anthropogenic aerosols in total aerosol loading during the monsoon season over the Indian subcontinent (Dey & Di Girolamo, ). Jin et al () also found a major contribution of dust (~60–80%) in the total summer AOD over the Middle East and India using several sets of observation data.…”

Section: Resultsmentioning

confidence: 99%

Near‐Future Anthropogenic Aerosol Emission Scenarios and Their Direct Radiative Effects on the Present‐Day Characteristics of the Indian Summer Monsoon

et al. 2020

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Various air pollution mitigation scenarios have been proposed to improve the existing severe air quality problem over South Asia. Here we use a regional climate model to examine the response of the Indian summer monsoon (ISM) to two projected anthropogenic aerosol emission scenarios (a) short‐lived climate pollutant “mitigation” scenario (2020–2030) and (b) current legislation “baseline” scenario (2005–2015). In the mitigation scenario, carbonaceous aerosol (black carbon and organic carbon) emissions are projected to decrease while sulfate emissions are projected to increase. This is expected to result in a marginal increase in anthropogenic aerosol optical depth over India (by 0.04–0.08). The dominating effect of scattering aerosols over absorbing aerosols in the mitigation scenario is expected to enhance atmospheric cooling over the Indian landmass, which in turn dampens the latitudinal thermal gradient and leads to a weakening of the ISM. This effect also reduces dust emissions over the Arabian Peninsula and transport across the Arabian Sea, decreasing the influence of the dust radiative feedback on the ISM. In addition, the increased amounts of sulfate and decreased amounts of carbonaceous aerosols are expected to result in drier conditions over the central parts of India. We also show that changes in emissions of different types of anthropogenic aerosols induce a chain of feedbacks, which can modulate the space‐time variability of dust, thereby affecting the magnitude of dust radiative effects on the ISM dynamics. We conclude that it is critical from the policy point of view to implement strategies to cut the currently increasing sulfate emissions.

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Section: Resultsmentioning

confidence: 99%

Near‐Future Anthropogenic Aerosol Emission Scenarios and Their Direct Radiative Effects on the Present‐Day Characteristics of the Indian Summer Monsoon

et al. 2020

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“…During strong dust storms, the dust particles may reach up to 5 km in altitude [35,36,[55][56][57][58]. If an anthropogenic impact also exists, the war-related dust can easily reach high altitudes.…”

Section: Seasonal Pattern Of Aodmentioning

confidence: 99%

“…We would also expect a larger influence from local variable sources, which are likely attributed to military services and battles. These small particles emitted from these variable and additional sources can stay advective for several days or even longer (depending on meteorological conditions and particle size), and if moved above the boundary layer, they can be transported long distances [57,58]. Additionally, during the summer in the dust-belt region, the boundary layer becomes relatively deep, reaching 3-5 km [35], whereas in the winter it is shallow, reaching 1.5-2 km [58,59].…”

Section: Seasonal Pattern Of Aodmentioning

confidence: 99%

“…These small particles emitted from these variable and additional sources can stay advective for several days or even longer (depending on meteorological conditions and particle size), and if moved above the boundary layer, they can be transported long distances [57,58]. Additionally, during the summer in the dust-belt region, the boundary layer becomes relatively deep, reaching 3-5 km [35], whereas in the winter it is shallow, reaching 1.5-2 km [58,59]. In this regard, we can speculate that elevated AOD values during spring-summer are related to advected mixed pollution sources whereas during fall-winter, pollution is more concentrated near the ground (due to the low boundary layer).…”

Section: Seasonal Pattern Of Aodmentioning

confidence: 99%

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Secular Changes in Atmospheric Turbidity over Iraq and a Possible Link to Military Activity

Chudnovsky

Kostinski

2020

Remote Sensing

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We examine satellite-derived aerosol optical depth (AOD) data during the period 2000–2018 over the Middle East to evaluate the contribution of anthropogenic pollution. We focus on Iraq, where US troops were present for nearly nine years. We begin with a plausibility argument linking anthropogenic influence and AOD signature. We then calculate the percent change in AOD every two years. To pinpoint the causes for changes in AOD on a spatial basis, we distinguish between synoptically “calm” periods and those with vigorous synoptic activity. This was done on high-resolution 10 km AOD retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor (Terra satellite). We found spatiotemporal variability in the intensity of the AOD and its standard deviation along the dust-storm corridor during three studied periods: before Operation Iraqi Freedom (OIF) (1 March 2000–19 March 2003), during OIF (20 March 2003–1 September 2010), and Operation New Dawn (OND; 1 September 2010–18 December 2011), and after the US troops’ withdrawal (19 December 2011–31 December 2018). Pixels of military camps and bases, major roads and areas of conflict, and their corresponding AOD values, were selected to study possible effects. We found that winter, with its higher frequency of days with synoptically “calm” conditions compared to spring and summer, was the best season to quantitatively estimate the impact of these ground-based sources. Surprisingly, an anthropogenic impact on the AOD signature was also visible during vigorous synoptic activity. Meteorological conditions that favor detection of these effects using space imagery are discussed, where the effects are more salient than in surrounding regions with similar meteorological conditions. This exceeds expectations when considering synoptic variations alone.

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“…Apart from the Sahara, the Middle East and southwest Asia emit large quantities of dust mainly in summer [30], while some rare but intense dust storms may also occur during winter (e.g., [31,32]). Dust storms in the Middle East and southwest Asia are usually associated with enhanced pressure gradients initiating intense northerly winds able to emit and transport dust plumes hundreds of kilometers downwind [33][34][35][36]. The topography modulates the main flow via channeling effects [37,38] and by accelerating the downslope winds [39].…”

Section: Introductionmentioning

confidence: 99%

Atmospheric Dynamics from Synoptic to Local Scale During an Intense Frontal Dust Storm over the Sistan Basin in Winter 2019

et al. 2019

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The Sistan Basin has been recognized as one of the most active dust sources and windiest desert environments in the world. Although the dust activity in Sistan maximizes during the summer, rare but intense dust storms may also occur in the winter. This study aims to elucidate the atmospheric dynamics related to dust emission and transport, dust-plume characteristics, and impacts on aerosol properties and air quality during an intense dust storm over Sistan in February 2019. The dust storm was initiated by strong northerly winds (~20 ms−1) associated with the intrusion of a cold front from high latitudes. The upper-level potential vorticity (PV)-trough evolved into a cut-off low in the mid and upper troposphere and initiated unstable weather over Afghanistan and northern Pakistan. At the surface, density currents emanating from deep convective clouds and further strengthened by downslope winds from the mountains, caused massive soil erosion. The passage of the cold front reduced the temperature by ~10 °C and increased the atmospheric pressure by ~10 hPa, while the visibility was limited to less than 200 m. The rough topography played a major role in modulating the atmospheric dynamics, wind field, dust emissions, and transport pathways. Meso-NH model simulates large amounts of columnar mass dust loading (> 20 g m−2) over Sistan, while the intense dust plume was mainly traveling below 2 km and increased the particulate matter (PM10) concentrations up to 1800 µg m−3 at Zabol. The dust storm was initially moving in an arc-shaped pathway over the Sistan Basin and then it spread away. Plumes of dust covered a large area in southwest Asia, reaching the northern Arabian Sea, and the Thar desert one to two days later, while they strongly affected the aerosol properties at Karachi, Pakistan, by increasing the aerosol optical depth (AOD > 1.2) and the coarse-mode fraction at ~0.7.

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High Summertime Aerosol Loadings Over the Arabian Sea and Their Transport Pathways

Cited by 56 publications

References 67 publications

Near‐Future Anthropogenic Aerosol Emission Scenarios and Their Direct Radiative Effects on the Present‐Day Characteristics of the Indian Summer Monsoon

Near‐Future Anthropogenic Aerosol Emission Scenarios and Their Direct Radiative Effects on the Present‐Day Characteristics of the Indian Summer Monsoon

Secular Changes in Atmospheric Turbidity over Iraq and a Possible Link to Military Activity

Atmospheric Dynamics from Synoptic to Local Scale During an Intense Frontal Dust Storm over the Sistan Basin in Winter 2019

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