Contents lists available at ScienceDirect Aeolian Research journal homepage: www.elsevier.com/locate/aeolia Effects of Monsoon, Shamal and Levar winds on dust accumulation over the Arabian Sea during summer – The July 2016 case A. Rashki a , D.G. Kaskaoutis b, ⁎ , A. Mofidi c , F. Minvielle d , I. Chiapello d , M. Legrand d , U.C. Dumka e , P. Francois d a Department of Desert and Arid Zones Management, Ferdowsi University of Mashhad, Mashhad 91735, Iran b Institute for Environmental Research and Sustainable Development, National Observatory of Athens, 11810 Athens, Greece c Department of Geography, Ferdowsi University of Mashhad, Mashhad 91735, Iran d LOA, University of Lille-1, 59655 Villeneuve d’Ascq, France e Aryabhatta Research Institute of Observational Sciences, Nainital 263 001, India ARTICLE INFO Keywords: Dust Monsoon Shamal Levar ITD Arabian Sea ABSTRACT This study examines the atmospheric circulation patterns that are associated with contrasting wind regimes, desert dust outflows and accumulation of dust over the Arabian Sea in the summer season. The examined period is 11–16 July 2016, when several dust plumes of various intensity and from different sources (Arabian Peninsula, Somalia and Iran), affected the Arabian Sea. During summer, south Asia is under the influence of the southwest monsoon, with main characteristics being the thermal low-pressure system centered over northwest India/ Pakistan with secondary lows over south Iran and southeast Arabian Peninsula, and the Arabian ridge combined with the Indian trough in the mid troposphere. Apart from the dominant southwest monsoon flow over the Arabian Sea, strong local winds are developed over the desert areas, such as the northwest Shamal along the east Arabian Peninsula and northern Levar in southeast Iran. These wind regimes initiate several dust outbreaks, while their convergence over the Arabian Sea results in accumulation of large amounts of dust aerosols (AOD > 2.0), as observed by satellite (MODIS, MISR, CALIPSO) observations and reanalysis (MERRA-2). The dust-accumulation area (central/north part of the Arabian Sea) is characterized by weak winds, while the po- sition of the Inter-Tropical Discontinuity (ITD) plays an important role in merging the contrasting dust plumes. The vertical profiles of the monsoon, Shamal and Levar winds are especially important for the dust accumula- tion, since the low-altitude dust plumes come from the southeastern Arabian Peninsula and Somalia, while those above 3000 m from northern directions (Iran, Pakistan). 1. Introduction The southwestern part of the Asian continent (Middle East, Arabian Peninsula and Iran-Pakistan-Afghanistan, IPA) contains several deserts (Syrian-Iraqi desert, Rub-Al-Khali, An-Nafud, Al-Dahna, Karakum, Margo, Registan) and semi-desert areas (Iranian Plateau, Sistan) re- sponsible for large emissions of dust aerosols that are usually accu- mulated over the Arabian Sea (e.g., Prijith et al., 2013; Hamidi et al., 2014; Kaskaoutis et al., 2014; Jin et al., 2016). This area is character- ized by a complex topography with mountains up to ∼5 km, extended plateau, deep valleys and drainage basins. The dust activity exhibits a distinct seasonality, maximizing during late winter and spring over the Israeli deserts, Syrian-Iraqi plains and northwest Saudi Arabia (Kutiel and Furman 2003; Yu et al., 2013; Notaro et al., 2015), and in June - August over the southeastern Arabian Peninsula and IPA (Rezazadeh et al., 2013; Mashat et al., 2017). Long-term satellite observations re- vealed large inter-annual and intra-seasonal heterogeneities in aerosol distribution over the Arabian Sea during the summer season, due to remarkable changes in dust lifecycle (i.e., emission, transport, accu- mulation and deposition), which are strongly related to certain me- teorological phenomena and yearly changes in the atmospheric circu- lation patterns (Kaskaoutis et al., 2012; Jin et al., 2018). Several studies have shown that the dust radiative heating may favor the low-level cyclogenesis over the south Arabian Peninsula, leading to further in- tensification in dust emissions, changes in atmospheric stability and modulation of the monsoon circulation and rainfall over India (Das et al., 2015; Jin et al., 2015, 2016; Solmon et al., 2015; Kaskaoutis et al., 2018a). https://doi.org/10.1016/j.aeolia.2018.11.002 Received 21 June 2018; Received in revised form 13 November 2018; Accepted 13 November 2018 ⁎ Corresponding author. E-mail address: dkask@meteo.noa.gr (D.G. Kaskaoutis). Aeolian Research 36 (2019) 27–44 1875-9637/ © 2018 Elsevier B.V. All rights reserved. T