Cyclogenesis and density currents in the Middle East and the associated dust activity in September 2015

Abstract

<p>The first 10 days of September 2015 were marked by an intense dust activity over the Middle East and the Arabian Peninsula. This study examines the atmospheric conditions at the origin of the large dust storms during this period. We particularly investigate the atmospheric dynamics leading to the development of a large dry cyclone over Iraq on 31 August 2015 which in turn generated an intense dust storm that affected most of the countries around the Arabian Gulf and lasted for 5 days. We found that the cyclone developed over Northwest Iraq as a transfer to low levels of a cut-off low which had formed two days earlier at upper levels over Turkey. Large dust loads exceeding 250 tons were emitted and moved southeast in a cyclonic shape toward the Arabian sea. The second large dust storm on 6-8 September 2015 occurred over Syria and affected all the coastal countries on the eastern side of the Mediterranean Sea. It was associated with the occurrence of a series of density currents over northeast Syria emanating from deep convection over the mountainous border between Syria and Turkey. The unusual development of deep convection over this area was associated with a blocking high and interaction with orography. Both the cut-off high and the cut-off low occurred during a period characterized by a meandering polar jet and an enhanced subtropical jet causing unstable weather over mid-latitudes which in turn led to highly polluted atmosphere by natural dust in the affected countries.<br>Keywords: Cut-off low; cut-off high; upper-level trough; density current; cyclone; evaporation cooling; desert areas; dust storms; polar jet; subtropical jet.</p>

Climate Change and Weather Extremes in the Eastern Mediterranean and Middle East

“…The Middle East is a major contributor to global dust emissions (15%–20% of the total), affecting the regional climate, human health, terrestrial and marine ecosystems (Huneeus et al., 2011; Kok et al., 2021; Zender et al., 2003). Several active deserts are located in the region such as the Egyptian and Nubian deserts in the northeastern Sahara; the Rub‐Al Khali, An Nafud and Al Dahna deserts in the Arabian Peninsula; the Negev desert in Israel; the Syrian‐Iraqi desert; the alluvial flood plains in Mesopotamia; the Dasht‐e Kavir and Dasht‐e Lut deserts in Iran as well as the desiccated, ephemeral or dried‐up lakes like Urmia, Jazmurian and Hamouns in Iran (Cao et al., 2015; Francis, Alshamsi, et al., 2019; Francis, Chaboureau, et al., 2021; Francis, Eayrs, et al., 2019; Ginoux et al., 2012; Kaskaoutis et al., 2016). The regional dust activity is highly sensitive to weather conditions (Bodenheimer et al., 2018; Hermida et al., 2018; Nabavi et al., 2016; Shaheen et al., 2021) and climate perturbations (Hemming et al., 2010; Hoerling et al., 2012).…”

“…Despite the observed decrease in precipitation totals, for some Mediterranean regions, a paradoxical increase of extreme rainfall magnitude or in the number of heavy precipitation days is evident (Alpert et al., 2002; Founda et al., 2013). Particularly for the Middle East, extreme precipitation events can be the result of tropical‐extratropical interactions, for example, Active Red Sea Troughs (De Vries et al., 2013) and cut‐off lows and highs from mid‐latitudes (Francis, Alshamsi, et al., 2019) associated with changes in the polar jet circulation (Francis, Eayrs, et al., 2019; Francis & Vavrus, 2012; Francis et al., 2018; J. Liu et al., 2021). Stratospheric potential vorticity streamers, as indicators of Rossby wave breaking, combined with intense moisture transport, can contribute substantially to this type of extreme event in the region (De Vries, 2021; De Vries et al., 2018).…”

“…The region is located at an atmospheric crossroads, directly influenced by a variety of atmospheric circulation patterns and meteorological processes on different continents (Carmona & Alpert, 2009; Lelieveld et al., 2002). For example, winter precipitation, critical for replenishing water resources, is largely related to the southward movement of the polar front jet, that drives cyclonic disturbances across the region (Francis, Alshamsi, et al., 2019; Francis, Eayrs, et al., 2019; Krichak et al., 2000). The steep orography, the complex coastlines and the effects of large water bodies (e.g., the Mediterranean, Red, Arabian, and Black Seas) add important feedbacks that influence the regional peculiarities of global warming.…”

Three‐dimensional pathways of dust over the Sahara during summer 2011 as revealed by new Infrared Atmospheric Sounding Interferometer observations

“…AEROIASI uses the hyperspectral measurements of IASI to derive vertically resolved horizontal fields of the aerosol extinction coefficient at 10 μm for cloud-free conditions. Previous studies using AEROIASI observations of the 3D distribution of dust were focused on East Asia (Cuesta et al, 2015) and the Middle East (Francis et al, 2019). For these studies, remarkable agreement between AEROIASI and CALIOP was found for several transects of vertical profiles of the major dust plumes.…”

Key Factors Modulating the Threat of the Arabian Sea's Tropical Cyclones to the Gulf Countries

“…In order to visualize the spatial structure and evolution of the TCs, visible satellite images from the Moderate Resolution Imaging Spectroradiometer (MODIS; Kaufman et al., 1997, 2002) instrument onboard the National Aeronautic and Space Administration's (NASA's) Terra and Aqua satellites are extracted from NASA's WorldView website (https://worldview.earthdata.nasa.gov/). Insight into the vertical extent of the clouds and potential dust lifting triggered by the storms is gained through the inspection of false‐color red‐green‐blue (RGB; Banks et al., 2019; Francis et al., 2019; Francis, Fonseca, Nelli, et al., 2022) satellite images from the Spinning Enhanced Visible and Infrared Imager (SEVIRI; Schmetz et al., 2002) instrument onboard the Meteosat Second Generation spacecraft. RGB images are available every 15 min at a 0.05° × 0.05° (∼5.6 km) resolution over the domain 60°S–60°N and 60°W–60°E.…”