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Regional drivers of weather and climate over the Middle East, adapted from Dezfuli et al. (2017) with modification (© American Meteorological Society, used with permission). The phenomena schematically shown include a typical mid‐latitude storm, low‐level jet (LLJ), summer Indian monsoon, Zagros barrier jet (ZBJ), Shamal winds and several geographical features such as the Zagros Mountains and the regional seas.
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The frequency and intensity of weather‐related extreme events, particularly floods, have increased in recent decades, both globally and in parts of the Middle East. Some floods are caused by heavy rains from the atmospheric rivers (AR), which are long, narrow, and transient corridors of strong horizontal water vapor transport...
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... While in monsoon and lower latitude regions they further exacerbate rainfall events (Liang & Yong, 2021;Park et al., 2021;Vallejo-Bernal et al., 2023;Yang et al., 2018), at high-latitudes and over the high-terrain, ARs can have a substantial effect on sea-/land-ice and snow cover (Box et al., 2023;Bozkurt et al., 2021;Fonseca et al., 2023;Francis et al., 2020Francis et al., , 2021aFrancis et al., , 2022aFrancis et al., , 2022bMeinander et al., 2023;Shields et al., 2022b;Wille et al., 2024aWille et al., , 2024bZhang et al., 2023). When they move over a dust source region, such as the Saharan and Arabian Deserts, the associated wind flow can trigger dust lifting and create hazardous conditions (Dezfuli, 2020;Dezfuli et al., 2021;Francis et al., 2023;Nelli et al., 2021a;Voss et al., 2021). Besides water vapor and dust, ARs can transport other aerosols such as black and organic carbon and sea salt (Chakraborty et al., 2021(Chakraborty et al., , 2022Lapere et al., 2024). ...
... ARs in the Middle East tend to be less intense, in terms of the associated IVT, compared to those in Europe and North America, owing to the aridity of the neighboring north Africa and Sahara (Bozkurt et al., 2021;Eiras-Barca et al., 2021;Esfandiari & Rezaei, 2022). However, their horizontal and vertical structures are similar to those of ARs elsewhere, despite regional variations in intensity and impact (e.g., Bozkurt et al., 2021;Dezfuli, 2020;Dezfuli et al., 2021;Payne et al., 2020). In terms of frequency of occurrence, ARs make landfall up to two to three times more frequently in the west coast of Europe and North America compared to the Middle East . ...
... The IVT exceeded 350 kg m 1 s 1 , with contributions from the tropical Atlantic, Arabian Sea and Mediterranean Sea, further enhanced as the AR moved over the Red Sea and Arabian Gulf. Dezfuli et al. (2021) and Francis et al. (2023) highlighted the role of ARs in triggering dust storms in the Middle East: in the former dust is lifted directly by the atmospheric circulation that promoted the development of the AR, while in the latter density currents emanated from deep convection fueled by the ARs promoted dust emission. ...
Plain Language Summary
Atmospheric Rivers (ARs) are narrow and long bands of high water vapor content, which largely originate in the tropics or subtropics and propagate into mid‐ and high‐latitudes. They can bring beneficial rain and snow but, in particular the most intense, can lead to catastrophic flooding and loss of life. One of such occurrences in the Middle East in mid‐April 2023 is investigated using model and observational data. The high‐resolution (2.5 km) simulation put in evidence narrow (5–15 km) and long (100–200 km) convective structures within the AR, known as AR rapids, which produced heavy precipitation (>4 mm hr⁻¹), further enhanced by gravity waves that developed over the high terrain in western Saudi Arabia, and propagated at high speeds (>30 m s⁻¹). ARs are occurring more frequently in the Middle East as they are globally, and with increased atmospheric water vapor in a warming climate, AR rapids may be even more destructive.
... Results obtained using this method are very similar to those obtained from large-sample back-trajectory studies (e.g., Fig. 9). These pathways are analogous to the atmospheric rivers that are responsible for winter precipitation and flooding to the west, in Iran (Dezfuli, 2020;Dezfuli et al., 2021;Esfandiari and Lashkari, 2021). Atmospheric rivers have also been explicitly linked to the majority of winter precipitation variability and extremes over the western and central Himalayas Thapa et al., 2018;Lyngwa et al., 2023), where composite analysis shows circulation that strongly resembles that of a WD. ...
Western disturbances (WDs) are synoptic-scale weather systems embedded within the subtropical westerly jet. Manifesting as upper-level troughs often associated with a lower-tropospheric low over Western India, they share some dynamical features with extratropical cyclones. WDs are most common during the boreal winter (December to March), during which they bring the majority of precipitation – both rain and snow – to the Western Himalaya, as well as to surrounding areas of north India, Pakistan and the Tibetan Plateau. WDs are also associated with weather hazards such as heavy snowfall, hailstorms, fog, cloudbursts, avalanches, frost, and coldwaves. In this paper, we review the recent understanding and development on WDs. Recent studies have collectively made use of novel data, novel analysis techniques, and the increasing availability of high-resolution weather and climate models. This review is separated into six main sections – structure and thermodynamics, precipitation and impacts, teleconnections, modelling experiments, forecasting at a range of scales, and paleoclimate and climate change – each motivated with a brief discussion of the accomplishments and limitations of previous research. A number of step changes in understanding are synthesised. Use of new modelling frameworks and tracking algorithms has significantly improved knowledge of WD structure and variability, and a more frequentist approach can now be taken. Improved observation systems have helped quantification of water security over the Western Himalaya. Convection-permitting models have improved our understanding of how WDs interact with the Himalayas to trigger natural hazards. Improvements in paleoclimate and future climate modelling experiments have helped to explain how WDs and their impacts over the Himalaya respond to large-scale natural and anthropogenic forcings. We end by summarising unresolved questions and outlining key future WD research topics.
... It enables proactive decision-making and facilitates the implementation of transformative measures that build resilience, mitigate risks, and enhance sustainability in the face of a changing climate. Understanding these impacts is vital for building adaptive capacity and enhancing climate resilience 23,24 . Despite the significance of climate change concerns, more studies should focus on this region. ...
... In addition, it cannot adequately capture extreme events like intensity, frequency, and spatial distribution 9,30 . In response to the demand for more precise regional climate projections, various dynamical and statistical downscaling techniques have emerged, offering higher-resolution data to enhance reliability 24,31 . Numerous researchers [32][33][34][35] have emphasized the importance of employing downscaling and bias correction techniques to obtain high-resolution datasets for generating accurate climate change projections at the regional scale. ...
Global warming can profoundly influence the mean climate over the Arabian Peninsula, which may significantly influence both natural and human systems. The present study aims to investigate the changes in the precipitation regime in response to climate change over the Arabian Peninsula, with special emphasis on the United Arab Emirates (UAE). This work is performed using a sub-set of high-resolution NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) data derived from Coupled Model Intercomparison Project Phase 6 (CMIP6) Global Climate Models under three different Shared Socioeconomic Pathway (SSP) scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5). The changes are analyzed in three phases such as 2021–2050 (near future), 2051–2080 (mid future) and 2080–2100 (far future), with the period of 1985–2014 as the baseline. This study represents the first attempt to utilize data from NEX-GDDP models to project the regional patterns of precipitation regime across the Arabian Peninsula. Results suggest that the annual precipitation is expected to increase over most of the UAE by up to 30%, particularly intense from the mid-future onwards in all scenarios. Specifically, the spatiotemporal distribution of precipitation extremes such as intensity, 1-day highest precipitation, and precipitation exceeding 10 mm days are increasing; in contrast, the consecutive dry days may decrease towards the end of the century. The results show that the changes in extreme precipitation under a warming scenario relative to the historical period indicate progressive wetting across UAE, accompanied by increased heavy precipitation events and reduced dry spell events, particularly under the high emission scenarios. A high-resolution dataset is essential for a better understanding of changes in precipitation patterns, especially in regions where more detailed information is needed on a local scale to achieve water, food security, and environmental sustainability to formulate effective adaptation strategies for mitigating the potential risks and consequences associated with variations in wet and dry conditions.
... The blocking ridge over northern Middle East and Caspian Basin facilitated westerly/southwesterly flow along the eastern flank of the cut-off low. Fig. 2c and d shows an anomalous narrow band of moisture from tropical Africa, known as atmospheric river (AR, Massoud et al., 2020;Dezfuli et al., 2021;Bozkurt et al., 2021), being advected into the Middle East along the eastern flank of the cut-off lows. This significant supply of moisture via the AR helps in fueling the cut-off low and maintaining it over time (e.g., Francis et al., 2020b). ...
... This circulation also advects the more moist tropical air from Africa into Iran and the Arabian Gulf. In fact, the presence of an atmospheric river likely aids in the transport of dust, as noted by Dezfuli et al. (2021). AODs in excess of 2.5 were observed by the MODIS instrument, with the measurements interpolated to a 1 • × 1 • grid and available daily, over western UAE and adjacent Saudi Arabia on 17 May (Fig. 5b) where the advancing dust front was located (Fig. 1c). ...
Dust events have occurred over the Urmia Lake Basin in northwestern Iran for many years. In this study, we identified the mechanism and source of dust events in the region and assessed the ability of the Regional Climate Model (RegCM) to simulate these events. The observation data includes horizontal visibility and present weather phenomena achieved in Tabriz, Urmia, and Saqez stations. The ERA5, MERRA-2, and CAMS data were prepared for this research. The long-term dusty day analysis was conducted from 2000 to 2019. The synoptic-dynamic analysis and RegCM simulations were done during dust events on 28-31 October 2017—the HYSPLIT model and MODIS image usage to consider more detail. The results show that the Urmia Basin experiences two peaks, dusty days in the May and autumn months, including September and October. The persistent and widespread dust event in Urmia resulted from the approaching trough at 500 hPa to the north of Saudi Arabia and Iraq, trigged low pressure and increasing wind speed over the area. Based on the synoptic-dynamic analysis, MODIS satellite images, and the outputs of HYSPLIT, Iraq deserts were the primary source of dust on 28-31 October 2017. The dust distribution in the RegCM model, MERRA-2 data, and MODIS image agree. The RegCM aerosol optical depth (AOD) output time series agreed with MERRA-2 data, with a correlation coefficient of 0.84 and an index of agreement (IOA) of 0.56 in Urmia stations. The local dust source detected by the surface emission flux in the eastern Lake Urmia close to Tabriz can be a reason for the dustiest day in Tabriz. The AOD diurnal variation obtained from RegCM, MERRA-2, and CAM are similar in Tabriz and Urmia. The AOD of RegCM is underestimated compared to MERRA-2 and CAM in three selected stations.
... At the synoptic scale, the eastern Mediterranean trough plays a critical role in precipitation patterns in the region (Charabi and Al-Hatrushi, 2010). Furthermore, extreme precipitation and flooding in AWA can be attributed to weather-scale phenomena such as the Red Sea Trough (De Vries et al., 2013 and atmospheric rivers (Dezfuli, 2020;Dezfuli et al., 2021). ...
This study examines the interdecadal variation of cold season precipitation in arid West Asia (AWA) from 1960 to 2019 and identifies the underlying physical mechanisms. The results indicate that the precipitation in this region has exhibited significant interdecadal variation over the past 60 years, which is closely related to Interdecadal Pacific Variability (IPV). During the positive IPV phase, which was associated with a warming equatorial Middle East Pacific Ocean, an eastward-propagating Rossby wave induced a negative geopotential height anomaly over AWA, providing the dynamic conditions for precipitation. Additionally, IPV caused the westerly jet to move southward and strengthen, providing rich water vapor. Moreover, a positive geopotential height anomaly over the Indo-West Pacific, caused by cold sea surface temperature, led to the upward transport of water vapor from the Northern Indian Ocean to AWA, further enhancing the water vapor conditions. These factors together resulted in excess precipitation in AWA during the positive IPV phase, with a 17.6 mm increase compared to the negative phase, accounting for approximately 12% of the cold season precipitation. These findings were also confirmed by the piControl simulation of CESM2.
... The blocking ridge over northern Middle East and Caspian Basin facilitated westerly/southwesterly flow along the eastern flank of the cut-off low. Fig. 2c and d shows an anomalous narrow band of moisture from tropical Africa, known as atmospheric river (AR, Massoud et al., 2020;Dezfuli et al., 2021;Bozkurt et al., 2021), being advected into the Middle East along the eastern flank of the cut-off lows. This significant supply of moisture via the AR helps in fueling the cut-off low and maintaining it over time (e.g., Francis et al., 2020b). ...
... This circulation also advects the more moist tropical air from Africa into Iran and the Arabian Gulf. In fact, the presence of an atmospheric river likely aids in the transport of dust, as noted by Dezfuli et al. (2021). AODs in excess of 2.5 were observed by the MODIS instrument, with the measurements interpolated to a 1 • × 1 • grid and available daily, over western UAE and adjacent Saudi Arabia on 17 May (Fig. 5b) where the advancing dust front was located (Fig. 1c). ...
Large amounts of dust in the air can disrupt daily activities and pose a threat to human health. In May 2022, consecutive major dust storms occurred over the Middle East resulting in severe environmental, social and health impacts. In this study, we investigate the exceptional factors driving these storms and the effects of the dust clouds. Using a combination of satellite, in-situ and reanalysis datasets, we identify the atmospheric triggers for the occurrence of these severe dust storms, characterize their three-dimensional structure and evaluate the dust radiative impact. The dust emission was promoted by density currents emanating from deep convection over Turkey. The convective systems were triggered by cut-off lows from mid-latitudes fed by moisture from African atmospheric rivers. The dust clouds were transported southward at 4 km in altitudes but sunk to ground levels when they reached the southern Arabian Peninsula due to strong subsidence. At a station in coastal UAE, the dust caused a 350 W m-2 drop in the surface downward shortwave flux and a 70W m-2 increase in the longwave one during the dust episodes. This contributed to a 9ºC increase in nighttime temperatures which exacerbated the effects of the heat for the population. The newly highlighted mechanism for dust emission in the Middle East, in which a cut-off low interacts with an atmospheric river, as well as direct observations of the dust impact on the radiative budget can contribute to reducing associated uncertainties in climate models.
... Dust may be transported as far as 4000 km from their origin (Kutiel and Furman, 2003). For example, dust is transported from Asia to the west coast of the United States (Creamean et al., 2014) and from Saharan Africa to Europe (Israelevich et al., 2012;Di Mauro et al., 2019).Consequently, the impacts of ARs are not limited to flooding; they also facilitate dust transport to the region (Dezfuli et al., 2021). According to new research by Francis et al. (2022) the ARs had a major role in driving extreme dust transfer from the Sahara toward Europe during February 2021. ...
... They tried to show how commonly dust and ARs occur together. Dezfuli et al. (2021) showed that a dusty atmospheric corridor brings floods to the Middle East during April 2017. ...
Dust aerosols can sometimes extend thousands of kilometers continuously in the atmosphere. In this study, we refer to these dust streams, as Atmospheric Dust Corridors (ADCs). This study aims to identify ADCs by an automated algorithm and investigate their temporal and spatial characteristics in the Middle East. In order to do this, the Aerosol Optical Depth (AOD) and Angstrom Exponent (AE) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) (Aqua) were obtained on a daily scale at a resolution of 1*1° between 2003 and 2020. In this study, observations with AOD above 0.3 and AE below 0.75 were considered as dust aerosols. After determining a set of conditions, an algorithm was developed to identify the ADCs automatically. In the first step, the dust masses were identified using the connected components labeling method, and the largest dust mass was selected from each day. Then, a set of conditions were examined such as geometric shape and motion of the dust mass (based on wind data). As a result, we identified 281 ADCs and classified them according to their direction of movement. We found 33% cases of ADCs that flow toward the west, 19% cases that flow toward the east, 36% cases that flow toward the south, and 12% cases that flow toward the north. All the directions had the highest frequency in September, April, and March, whereas February, November and December had the lowest frequency. Spatially, the highest frequency can be seen around 45°E over Saudi Arabia, Iraq, and Syria. Western and southern ADCs are primarily found in the Arabian Peninsula and in Iraq, Syria, southern Iran, southern Afghanistan, and northern Pakistan, while northern and eastern ADCs are primarily found in northern Africa (Sudan and Chad, Niger, and Libya). May is important for western ADCs, September for southern ADCs, and April for eastern and northern ADCs. According to the Mann-Kendal test, no significant trends were observed on a monthly or annual basis during the studied period.
Water storage plays a profound role in the lives of people across the Middle East and North Africa (MENA) as it is the most water-stressed region worldwide. The lands around the Caspian and Mediterranean seas are simulated to be very sensitive to future climate warming. Available water capacity depends on hydroclimate variables such as temperature and precipitation that will depend on socioeconomic pathways and changes in climate. This work explores changes in both the mean and extreme terrestrial water storage (TWS) under an unmitigated greenhouse gas (GHG) scenario (SSP5-8.5) and stratospheric aerosol intervention (SAI) designed to offset GHG-induced warming above 1.5 • C and compares both with historical period simulations. Both mean TWS and extreme TWS are projected to significantly decrease under SSP5-8.5 over the domain, except for the Arabian Peninsula, particularly in the wetter lands around the Caspian and Mediterranean seas. Relative to global warming, SAI partially ameliorates the decreased mean TWS in the wet regions, while it has no significant effect on the increased TWS in drier lands. In the entire domain studied, the mean TWS is larger under SAI than pure GHG forcing, mainly due to the significant cooling and, in turn, a substantial decrease in evapotranspiration under SAI relative to SSP5-8.5. Changes in extreme water storage excursions under global warming are reduced by SAI. Extreme TWS under both future climate scenarios is larger than throughout the historical period across Iran, Iraq, and the Arabian Peninsula, but the response of the more continental eastern North Africa hyper-arid climate is different from the neighboring dry lands. In the latter case, we note a reduction in the mean TWS trend under both GHG and SAI scenarios, with extreme TWS values also showing a decline compared to historical conditions.
Water storage plays a profound role in the lives of people across the Middle East and North Africa (MENA) as it is the most water stressed region worldwide. The lands around the Caspian and Mediterranean Seas are simulated to be very sensitive to future climate warming. Available water capacity depends on hydroclimate variables such as temperature and precipitation that will depend on socioeconomic pathways and changes in climate. This work explores changes in both the mean and extreme terrestrial water storage (TWS) under an unmitigated greenhouse gas (GHG) scenario (SSP5-8.5) and stratospheric aerosol intervention (SAI) designed to offset GHG-induced warming above 1.5 °C and compares both with historical period simulations. Both mean and extreme TWS are projected to significantly decrease under SSP5-8.5 over the domain, except for the Arabian Peninsula, particularly in the wetter lands around the Caspian and Mediterranean Seas. Relative to global warming, SAI partially ameliorates the decreased mean TWS in the wet regions while it has no significant effect on the increased TWS in drier lands. In the entire domain studied, the mean TWS is larger under SAI than pure greenhouse gas forcing, mainly due to the significant cooling, and in turn, a substantial decrease of evapotranspiration under SAI relative to SSP5-8.5. Changes in extreme water storage excursions under global warming are reduced by SAI. Extreme TWS under both future climate scenarios are larger than throughout the historical period across Iran, Iraq, and the Arabian Peninsula, but the response of the more continental eastern North Africa hyper-arid climate is different from the neighboring dry lands.
Mineral dust affects health, climate, and ecosystems in various ways. East Asia is one of the major sources of mineral dust in the world. This study examines the year-to-year variability of dust deposition over Japan in April from the perspective of large-scale atmospheric circulations using atmospheric and aerosol reanalysis datasets for the period from 2011 to 2017. The increased dust deposition in Japan is explained by the intensified dust transport from the Mongolian Plateau by the anomalous westerly winds associated with a deepened trough over the East Asian continent toward the northwest of the Japanese islands in the middle to lower troposphere. The enhanced dust emission over Gobi Desert and the intensified extratropical cyclone activity are consistent with the larger-than-normal amount of dust in East Asia. Comparing the dust depositions over western and northern Japan, it is suggested that the slightly different anomalous trough positions may determine whether or not a large amount of dust is carried. A further analysis using the long-term (1967-2022) observation data of dust in Japan supports the importance of the intensified trough over the East Asian continent. Dust flux decomposed into cyclonic and anticyclonic components showed that both vortices contribute to the eastward dust transport in East Asia. These results suggest that Japanese dust events and their variability are affected by the stationary circulation anomaly as well as the baroclinic instability waves including transient cyclones and anticyclones.
