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Sand and Dust storms are considered a major natural disaster that cause many damages to society and environment in Iraq and surrounded deserted regions. Two spring sand/dust storms on May in two different years were synoptically analyzed. These sand/dust storms were compared in terms of dust surface concentration from NMMB/BSC-Dust model, sea level pressure, surface wind vector, satellite vegetation index and stations rainfall. The findings of this sand/dust storms comparison indicate that Iraq in spring may be affected by two types of wind one dust storm initiated by Shamal which have long occurred in this region and caused frequent dust storms in spring and second by Al-Khamsian. Dust storm in 2012 is massive than sand/dust storm in 2018 where the highest dust surface concentration is reached to (7700 μg/m3) in 22 May 2012 and about (3100 μg/m3) in 11 May 2018. Increase in vegetation cover over Iraq in 2018 was about 23% more than in 2012. Rainfall level in season (2017-2018) was higher than in rainfall season (2011-2012) in Iraqi dust sources regions. Low pressure gradient, less strong wind, rise in rainfall level and enhancement in vegetation cover are contributed to decrease the storm concentration of 2018 roughly by half.

Al-Shamal train pathway, which is extended between Saudi Arabia and Jordan, is prone to geo-hazards due to the geological features, proximity to faults, earthquake epicenter, and the human activities along the pathway. The objectives of this study are to shed light on the ground subsidence susceptibility along Al-Shamal train pathway in Qarrayat city in Saudi Arabia and develop a ground subsidence susceptibility model to determine the prone areas to the impacts of ground subsidence to mitigate and avoid the loss of life and property. This study integrated the various data types to map the subsidence susceptibility along Al-Shamal train pathway. Nine ground subsidence causative parameters were selected as subsidence controlling factors in the study area including lithology, land cover/land use, elevation, slope, aspect, annual average rainfall, distance to faults, distance to earthquake epicenter, and distance to streams. The analytical hierarchy process is applied to obtain accurate weight to each criterion through the distribution of online Google form questionnaire to experts in different expertise and get their judgments on the weights of ground subsidence causative parameters in the study area. A subsidence susceptibility index was derived by classifying susceptible maps into five classes, namely, very low, low, moderate, high, and very high using the statistical distribution analysis. The results revealed that the study area is subjected to moderate susceptibility with about 32.56. A total of 29.8 and 11.52% of the study area had very low and low susceptibilities, respectively, and 8.44 and 17.68% had very high and high susceptibilities, respectively. The results were validated using the receiver operating characteristic using previous ground subsidence locations. The area under the curve showed 0.971, which is equivalent to 97.1%. Consequently, the findings of the study are thought to be beneficial to managers and decision makers for future planning, mitigating, and preventing subsidence in the study area.

This study evaluates the performance of a dynamically downscaled Weather Research and Forecasting (WRF) model by capturing the characteristics of the interseasonal variability in terms of active and break spells of the Indian summer monsoon during the period 1980–2014. We identify the active and break days based on the standard criteria of previous studies. Further, the composite means in the rainfall and different rainfall events, along with the thermal and dynamical features associated with active and break spells, are analyzed and discussed. Our results clearly show that the WRF model reproduces the observed features of monsoon circulation in active spells such as the wider and intensified lower tropospheric winds, the presence of mid-tropospheric cyclonic circulation, and the dominance of strong upper-level tropical easterlies along with the high influx of moisture towards the Indian subcontinent. Even in the break spells, the WRF model effectively simulates the observed features of the ERA, such as weaker monsoon winds at both low and upper levels and decreased strength of northwesterly winds of Shamal, the presence of a strong thermal inversion over the northwestern part of the Arabian Sea, and a significant increase in the African easterly jet. Moreover, our rainfall analysis during active and break spells reveals that the WRF model accurately reproduces the observed characteristics of the regional-scale precipitation. The results also reveal that the spatial distributions of moderate, heavy, and very heavy rainfall events over the monsoon core region are well captured by the WRF model, with only slight intensity variations compared to the observed distributions.

The synoptic and dynamic characteristics of dust storm events over northern Saudi Arabia were studied during the spring season from 1978 to 2008 using surface dust storm observations from 11 stations and meteorological data from the NCEP/NCAR reanalysis dataset. Two-day dust-free periods were selected before and after each event to represent the pre- and post-event stages, respectively. The synoptic study identified two synoptic systems associated with dust events, i.e., frontal systems and shamal systems, and these systems were associated with increases in the pressure and temperature gradient over the northern Arabian Peninsula (AP) and an eastward shift in the maximum wind as a dust storm event progressed from the pre- to post-event stages. The dynamic study also showed that during the pre-event stage, the atmosphere was baroclinic and featured dynamic disturbances by frontal systems. Additionally, frontal systems resulted in slightly greater intensification than the shamal systems. Moreover, the dynamic study demonstrated that the kinetic energy (KE) shifted eastward and the available potential energy (APE) shifted northward through a series of regions importing and exporting KE and APE. The vertical profile of the average energy area indicated that the main layer in which sensible heat was converted into KE was located above the dust cloud.

Background:The mesoscale circulation over Kuwait is an important influence on changes in surface temperatures and soil temperatures.Introduction:This paper presents two common summertime atmospheric features over Kuwait linking wind circulation to soil temperatures.Methods:In this study, we use the European Centre for Medium-range Weather Forecasts ECMWF reanalysis ERA-Interim dataset to investigate effects of the synoptic scale and mesoscale circulations.Results:The results show that a large-scale pressure gradient in summer typically leads to northerly winds over Kuwait, while a weak synoptic-scale pressure gradient leads to light easterly humid winds from the Persian Gulf, consistent with a mesoscale circulation.Conclusions:The results demonstrate the significance of wind circulations in driving the Soil Temperature (SOILT). Using the Era-Interim/Land reanalysis dataset for August 2015 over Kuwait, the average SOILT on days of sea breeze is higher than the average SOILT on days dominated by a synoptic-scale pressure gradient.

The Akkadian Empire was the first united empire in Mesopotamia and was established at 4.6 kyr B.P. (where present is A.D. 1950). The empire abruptly collapsed in 4.2 ± 0.2 kyr B.P. Seasonal-scale climatic dynamics behind this collapse have not yet been resolved. Here, we present monthly climatic parameters (temperature and hydrology) inferred from fossil Omani corals that lived between 4.5 and 2.9 kyr B.P. Winter temperatures derived from a modern Omani coral correlate with winter shamal (western Asian dust storm) frequency. A fossil coral from 4.1 kyr B.P. shows a prolonged winter shamal season with frequent shamal days. This likely caused agricultural failures in Mesopotamia and contributed to the Akkadian Empire collapse, as this region depends on winter rainfall.

International audience; 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 position 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 accumulation, since the low-altitude dust plumes come from the southeastern Arabian Peninsula and Somalia, while those above 3000 m from northern directions (Iran, Pakistan).

This study aims to assess the wind and wave spatio-temporal variability in the Persian Gulf using localized ECMWF wind data and numerically modeled wave characteristics in a 31-yearly period. The results represented that the highest values occur mainly in the middle part of the domain, especially during the winter, and the seasonal variation of the wind and wave climate is mostly affected by Shamal wind phenomena while the winter and summer-time Shamal winds affect the middle and northwestern parts of the Persian Gulf, respectively. For quantitative assessment, twenty stations were selected and the results indicated that the highest mean significant wave height (SWH) occurs in the central strip of the middle parts of the Persian Gulf during both February and June, while the monthly variations of wind and wave characteristics are different in the stations located near the Strait-of-Hormuz. In addition, the temporal stability of both wind speed (WS) and SWH is more in the eastern part of the domain, while the stability of wave dominant direction is more than that of wind. Based on the similarity between the temporal variations of wind and wave characteristics, the domain was divided into three sub-regions as representatives of different wind/wave climates.

Aerosol index (AI) is qualitatively indicating the presence of suspended aerosol particles in the air. The major sources of these particles are desert dust, biomass burning, and volcanic ash plumes. The AI observations derived from the ozone monitoring instrument (OMI) on Aura satellite were analyzed over Iraq for the period 2005–2018. The results showed that the long-term spatiotemporal distribution of AI was significantly variable, with lower values ( 2 may reach more than 140 days in Basra and more than 90 in Anah and Baghdad. Comparisons of Moderate Resolution Imaging Spectroradiometer (MODIS) true color images and AI for five different types of dust storms occurred over Iraq showed that AI is maximum at the core of the storm and the gradation of decreasing AI was consistent with the spread of dust out of the core. Maximum AI was > 5.5 during summer Shamal storm, > 3.0 during winter Shamal and frontal cases, and > 2.0 for the Haboob case. The HYSPLIT trajectories calculations showed that the dust plume in the MODIS image was significantly similar to the computed trajectories and the majority of air masses were coming from north and northwest.

Daily aerosol optical depth (AOD) and meteorological fields obtained from Monitoring Atmospheric Composition and Climate (MACC) and ERA-Interim reanalysis, respectively are used to analyze spatial patterns of AOD in the west part of Iran during the period 2003–2012. The areas affected by high daily AODs in southwest and west/northwest parts of Iran are identified using principal component analysis (PCA) and the atmospheric circulation patterns for these high AODs are classified in six clusters for each region, with larger frequencies in spring and summer. Despite their between differences, the weather clusters are mostly associated with a strong westerly/northwesterly flow (Shamal wind) across the Iraqi plains and southwest Iran from May to September, which is triggered by the pressure gradient between the North Africa/Mediterranean high and the monsoon low over southeast Iran. In the cold season, the pressure gradient between the Kurdi cut-off low and the high pressure over North Africa facilitates frontal dust storms that enhance the dust AOD over the west parts of Iran. The Caspian Sea high-pressure system during summer intensifies the easterly-northeasterly winds from the Karakum Desert to northwest Iran, while in winter, the strengthening of the Siberian High and its expansion over the Caspian Sea trigger strong cold northerlies over central/northwest Iran. In addition, the convergence of south/southwesterly winds, as a result of the surface low-pressure in the southern Arabian Peninsula, facilitates pre-frontal dust storms toward southwestern Iran, mostly during March–April. In summer, the gradient zone between the Iraq low-pressure and the Zagros high-pressure enables transport of dust aerosols toward west-northwest Iran. Identification of the weather clusters associated with intense dust storms over the west part of Iran is critical for the prevention of the deleterious effects of dust on climate, ecosystems and human health.

Waves in the Arabian Gulf are primarily controlled by the regional winds, for example, shamal winds during winter and early summer. Though Gulf wave characteristics have been heavily utilized for the design of offshore platforms and structures, wave features associated with various wind systems are not explicitly covered scientifically, say, for the Exclusive Economic Zone (EEZ) of Qatar. Therefore, we made an attempt to identify the features associated with different wind systems by analyzing the measured waves off Fuwairit, north coast of Qatar during 29 Oct - 26 Nov 2019. The analyses have been further extended to the Gulf using the reanalysis waves obtained from the COPERNICUS Marine Environment Monitoring Services (CMEMS) to describe the monthly, seasonal and annual characteristics. The results indicate that the easterly waves generated due to Nashi winds influence the east and northeast coasts of Qatar and shamal waves show clear dominance in the northern and northeastern offshore boundaries of the EEZ of Qatar. We find exceptional easterly (Nashi) waves during March 2019 contributing to the highest monthly mean significant wave height, which is a deviation from the known long-term wave climate of the Gulf.

International audience; Historical texts and archaeological studies attest to the maritime and trade importance of the Persian Gulf since the Sassanid Empires. Nonetheless, there is a paucity of data regarding ancient navigation and the reasons for a shift in m aritim e trade from the western (e.g. Shatt-al-Arab) to eastern (Siraf) Persian Gulf by the Abbasid dynasty. For som e scholars, Siraf was occupied between 360 and 977 CE, after which tim e an earthquake en-trained the dem ise of the city. However, it is unclear when Siraf was founded and how natural navigation conditions changed for ocean-going vessels in harbours of the NW Persian Gulf. To address this knowledge gap, we here present new geoarchaeological data from Siraf. Two anthropogenic facies were detected in drilled cores. They suggest that Siraf dates back to 2 BC-317 CE. After a hiatus, a second occupation phase began during the reign of Shapur II. Relative Sea-Level (RSL) fluctuations, climate change and Persian Gulf bathymetry all affected the possible nautical accessibility of this ancient Persian harbour. A fall in RSL, leading to a shortening of navigable water columns and amplified summertime Shamal wind from 550 CE onwards possibly led to a loss in the im portance of Shatt-al-Arab and other ports in the western Persian Gulf. It appears to have m ade Siraf the best alternative for seafarers. According to the wind regimes, the best time for arrival and departure from Siraf was August and October, respectively. RSL rise and increasing coastal erosion during the winter-tim e Shamal winds led to the degradation of harbour potentialities and was possibly at the origin of econom ic decline and poorly adapted harbour works at Siraf during a 150-year period between 850 and 1000 CE.

Coniatoids and the more extensive coniatolites were originally described, respectively, as rough surfaced, aragonite coated grains and rough surfaced, aragonite encrusted beachrocks near Jebel Dhanna, Abu Dhabi. At that time, a microbial involvement in their origins was rejected in favour of supratidal physico-chemical precipitation and this study investigates the validity of those conclusions. Vadose aragonite cementation has certainly occurred but new evidence of microbial involvement is presented and an intertidal influence is suggested with due consideration given to Holocene eustatic sea levels. The surface roughness of particularly the coniatolites is largely due to wick-like movement of surface marine waters under the influence of prevailing northwesterly winds, including the Shamal. Leewards growth extensions of the microbial communities in the direction of aeolian-driven, marine surface water drainage were rapidly cemented by micritic aragonite which also engulfed carbonate grains. A similar aeolian wick-like precipitation process is illustrated in a halite deposit of an Abu Dhabi sabkha salina.

Glacially driven eustatic sea-level fluctuations have left a clear signature only along the coastal regions and barrier islands of the Abu Dhabi Emirate. Four marine sequences are identifiable although others are known to exist offshore. The stratigraphy is complicated by aeolian processes associated especially with the Shamal winds which have blown from the northwest to create dune fields that dominate the Quaternary sedimentation. Whilst aeolian facies can clearly be identified separating marine incursions along the coastal regions, aeolian deflation has complicated the stratigraphy by recycling sediment partly in response to loss of windward sediment sources during marine transgressions and partly in response to glacially driven climatic changes. Unravelling the sequence stratigraphy of the desert dunes inland, especially beyond the coastal sabkhas, is therefore extremely difficult. The late Quaternary aeolian dunes and their veneer of mobile aeolian sands are grouped into a single poorly defined formation which spans the entire timescale of the sequences identified along the coast.

The mean annual temperature is 25 °C, with slightly cooler temperatures in the eastern mountains. The mean monthly relative humidity over UAE is around 60% during winter and around 50% during summer, varying between 46% in May to 64% in December. The two wind systems affecting the UAE are the winter “Shamal” winds, which affect the western coast, and the summer monsoon, which affects the Gulf of Oman and eastern mountain areas. The average annual evaporation is 3322 mm, while the mean annual rainfall is 100 mm for the period 1976–2015.

Excess evaporation within the Persian (also referred as the Arabian) Gulf induces an inverse-estuary circulation. Surface waters are imported, via the Strait of Hormuz, while saltier waters are exported in the deeper layers. Using output of a 1/12-Degree horizontal resolution ocean general circulation model, the spatial structure and time variability of the circulation and the exchanges of volume and salt through the Strait of Hormuz are investigated in detail. The model’s circulation pattern in the Gulf is found to be in good agreement with observations and other studies based on numerical models. The mean export of salty waters in the bottom layer is of 0.26±0.05Sv (Sverdrup = 1.0 × 106 m3 s−1). The net freshwater import, the equivalent of the salt export divided by a reference salinity, done by the baroclinic circulation across that vertical section is decomposed in an overturning and a horizontal components, with mean values of 7.2±2.1 × 10−3 Sv and 5.0±1.7 × 10−3 Sv respectively. An important, novel finding of this work is that the horizontal component is confined to the deeper layers, mainly in the winter. It is also described for the first time that both components are correlated at the same level with the basin averaged evaporation minus precipitation (E-P) over the Persian Gulf. The highest correlation (r2 = 0.59) of the total freshwater transport across 26°N with E-P over the Gulf is found with a one-month time lag, with E-P leading. The time series of freshwater import does not show any significant trend in the period from 1980 to 2015. Power spectra analysis shows that most of the energy is concentrated in the seasonal cycle. Some intraseasonal variability, likely related to the Shamal wind phenomenon, and possible impacts of El-Nino are also detected. These results suggest that the overturning and the horizontal components of freshwater exchange across the Strait of Hormuz are both driven by dynamic and thermodynamic processes inside the Persian Gulf.

Recent studies point out the importance of northerly winds and waves in the Arabian Sea, especially those due to shamal and makran events in addition to the northeast monsoon system. We have analyzed climatology and trends of northerly maximum wind speed and significant wave height (Hs) in the Arabian Sea and the connected marginal seas, Arabian/Persian Gulf and the Red Sea, during non-monsoon season derived from 40 years of ERA5 wind and wave data, and estimated monthly, annual and decadal extreme climate and their trends. The study brings out an increasing trend in the northerly maximum wind speed (0.8–1.2 cm/s/year) and Hs (0.42–0.88 cm/year) in the southern and central Arabian Sea, which is consistent with the global trend in extreme wind speed and Hs. The northern Arabian Sea including the Sea of Oman exhibits significant decreasing trend in northerly maximum wind speed (− 1.4 cm/s/year) and Hs (− 0.67 cm/year), while the Gulf and the Red Sea exhibit sectorial contrasting trend, indicating the dominance of localized effects in modifying the regional climate. Distinct features identified in the climate and trends of northerly winds and waves are further discussed. The project is funded under the IRCC International Research Co-Fund Collaboration Program of QU and NIO, executed through ORS, QU (IRCC-2019-002).

Middle East Area and especially the central part is a dust dominated domain and therefore estimation of natural dust emissions is critical. Aim of this study is to assess the sensitivity of state-of-the art dust modules, utilized in multiple modelling schemes, and especially of their three main components; namely the horizontal mass flux, the drag partition and the sandblasting efficiency. To accomplish this, several simulations with the Natural Emission MOdel (NEMO), driven by the Weather Research and Forecasting (WRF) model, were made for the period April–June 2015 focusing in the central Middle East (CME). First, the meteorological model was evaluated over the study period, as well as during a Shamal event, showing a satisfactory performance on wind speed which is the most important meteorological variable inserted in the dust modules. Second, dust emissions were found to be a few tenths of μg/m2s on average, while the daily amount exceeds 1000 mg/m2day. Over the studied period, the fluxes range from 15 to 750 g/m2. The total emissions in CME were estimated with the NEMO's basic configuration at 139 Tg. The most active areas are associated with clay content ranging between 17 and 25%, highlighting the importance of soil texture on the definition of the dust sources. During a Shamal event in the second half of June 2015, the mean dust emission fluxes reached up to several hundreds of μg/m2s, contributing 21 Tg in CME. Few such events could cover a large portion of the dust emissions. Finally, concerning the sensitivity of the total emissions, the drag partition scheme has the largest effect, followed by sandblasting efficiency and horizontal mass flux. The total dust emissions budget, among the 16 simulations was found to be in the range of 21–139 Tg, with the choice of the drag partition scheme to be mandatory for the narrowing of the total emissions in CME.

Marine areas are affected by different atmospheric phenomena such as wind and storm. In this research the effect of a large scale atmospheric phenomenon, known as Winter Shamal Wind, is investigated on the regime of currents and waves in the northwest part of the Persian Gulf. This wind normally occurs for the period of three to seven days, during December to early March. MIKE21 Coupled Model FM was applied to study the pattern of current and waves for this period. To provide the hydrodynamic data for the model and validate the simulated results, the wind data of ECMWF and mast meteorology of coastal synoptic station of Bushehr and wave data of buoy located offshore of Bushehr was used. The results indicated only a slight increase in current speed with no significant change in current direction during Winter Shamal Wind, showing a stable current pattern in northwest of the Persian Gulf. The significant wave height and wave propagation speed for the period of Winter Shamal Wind in comparison with the days prior to the wind show significant changes. The maximum wave speed in the area under investigation reaches up to 1 m/s and the significant wave height is almost 1 meter higher than that of normal situation.

The lithogenic fraction of carbonate drift sediments from IODP Exp. 359 Site U1467 (Maldives) provides a unique record of atmospheric dust transport over the northern Indian Ocean during the past 4 Myr. Grain-size data provide proxies for dust flux (controlled by source area aridity) as well as wind transport capacity (wind speed). Entrainment and long-range transport of dust in the medium to coarse silt size range is linked to the strength of the Arabian Shamal winds and the occurrence of convective storms which prolong dust transport. Dust flux and the size of dust particles increased between 4.0 and 3.3 Ma, corresponding to the closure of the Indonesian seaway and the intensification of the South Asian Monsoon. There is no clear trend in dust flux between 3.3 and 1.6 Ma, whereas wind transport capacity decreased. Between 1.6 Ma and the Recent, dust flux increased and shows higher variability, especially during the last 500 kyr. Transport capacity increased between 1.2 and 0.5 Ma and slightly decreased since then. Frequency analysis shows that dust transport varies on orbital timescales, with eccentricity control being the most prominent (400 kyr throughout the record, 100 kyr between 2.0 and 1.3 Ma, and since 1.0 Ma). Higher frequency cycles (obliquity and precession) are more pronounced in wind transport capacity than in the amount of dust. This indicates that the amount of coarse dust in sediments from the Maldives as a far-field site is more prone to changes in transport mechanisms than to changes in dust source-area aridity.

This study investigates the influence of the Indian Summer Monsoon (ISM) on the atmospheric circulation over the Arabian Peninsula (AP) using the European Centre for Medium Range Weather Forecasts’ twentieth century reanalysis (ERA-20C) for the period 1901–2010. After describing the summer climate of the AP using various dynamic and thermodynamic parameters, we investigate the link between extreme ISMs and atmospheric circulation over the AP on inter-annual time scale. Analysis of composites of different parameters during extreme monsoon (strong and weak) years reveals that the ISM plays an important role in the summer circulation over the AP and adjoining regions. The major noticeable changes in modulating circulation during extreme monsoons are: (1) a strengthening of lower tropospheric northerly winds, westerly winds passing through the Tokar Gap, Shamal winds, and the upper tropospheric easterly jet stream during strong ISM; (2) a northward (southward) shift of the subtropical westerly jet stream during strong (weak) monsoon years; (3) the development of strong upper level ridge above the surface thermal low during strong ISM years, which result in a baroclinic structure over the AP and adjoining regions; (4) an increase in adiabatic warming, and hence aridity, over the AP during strong monsoon years, caused by intense subsidence of the middle to upper troposphere due to zonal overturning circulation; and (5) convective instability during strong monsoon years caused by an intensification of the upward motion over the southern AP. Furthermore, during strong monsoons, the availability of excess moisture leads to atmospheric instability, which in turn triggers the formation of clouds that lead to more rainfall over the southwestern AP. Finally, the westward propagation of a Gill-type Rossby waves induced by the ISM play an important role in the variations of the AP summer climate by enhancing the warm core structure over the AP and through their interaction with the midlatitude westerlies during strong monsoons.

Profiles of periodic GPS Radiosonde ascends collected from a station at the west coast of India (Goa) during summer monsoon months (June to September) of 2009 and 2013 have been used to analyze the thermal inversion statistics at various heights and their repercussions on the regional weather is studied. The interaction of contrasting air masses over the northern Arabian Sea often produces a two layer structure in the lower 5000 m close to the coastal station with warm and dusty air (Summer Shamal) occupying the space above the cool and moist Low Level Jet (LLJ) by virtue of their density differences. The warm air intrusion creates low lapse rate pockets above LLJ and modifies the gravitational stability strong enough to inhibit convection. It is observed that the inversion occurring in the lower 3000 m layer with an optimum layer thickness of 100–200 m has profound influence on the weather beneath it. We demonstrated the validity of the proposed hypothesis by analyzing the collocated data from radiosonde, lidar and the rain gauge during 16th July 2013 as a case study. The lidar depolarization ratio provides evidence to support the two layer structure in the lidar backscatter image. The presence of dust noticed in the two layer interface hints the intrusion of warm air that makes the atmosphere stable enough to suppress convection. The daily rainfall record of 2013 surprisingly coincides with the patterns of a regional break like situation centered at 16th July 2013 in Goa.

The speech of characters is one of the important elements of story as it defines the thoughts of the story and it can promote the events of story. A narrator transfers the speech from the author to the reader and it is manifested as “The narration methods of story speeches”. The story speeches are dived into five groups as direct, indirect, free direct and free indirect and narrative report. In the famous novel “Mawsim al-Hijraila alShamal” by “Tayeb Salih”, contemporary Sudani author, the mentioned methods are manifested based on narrative situation of story. The story is started with the first-person view and the narrator presents the report and other methods are dominant as the characters are increased. The present study is a descriptive-analytic design showing that the direct speech is highly frequent in the novel.

Dust storms are among the most severe environmental problems in arid and semi-arid regions of the world. The predictability of seven dust events, viz. D1: April 2–4, 2014; D2: February 23–24, 2015; D3: April 1–3, 2015; D4: March 26–28, 2016; D5: August 3–5, 2016; D6: March 13–14, 2017 and D7:March 19–21, 2017, are investigated over the Arabian Peninsula using a regionally adapted chemistry transport model CHIMERE coupled with the Weather Research and Forecast (WRF) model. The hourly forecast products of particulate matter concentrations (PM 10 ) and aerosol optical depths (AOD) are compared against both satellite-based (MSG/SEVRI RGB dust, MODIS Deep Blue Aerosol Optical Depth: DB-AOD, Ozone Monitoring Instrument observed UV Aerosol Absorption Index: OMI-AI) and ground-based (AERONET AOD) remote sensing products. The spatial pattern and the time series of the simulations show good agreement with the observations in terms of the dust intensity as well as the spatiotemporal distribution. The causative mechanisms of these dust events are identified by the concurrent analyses of the meteorological data. From these seven storms, five are associated with synoptic scale meteorological processes, such as prefrontal storms (D1 and D7), postfrontal storms of short (D2), and long (D3) duration types, and a summer shamal storm (D6). However, the storms D4 and D6 are partly associated with mesoscale convective type dust episodes known as haboobs. The socio-economic impacts of the dust events have been assessed by estimating the horizontal visibility, air quality index (AQI), and the dust deposition flux (DDF) from the forecasted dust concentrations. During the extreme dust events, the horizontal visibility drops to near-zero values co-occurred with hazardous levels of AQI and extremely high dust deposition flux (250 μg cm − 2 day − 1 ).

This study investigates four types of synoptic dust events in the Middle East region, including cyclonic, pre-frontal, post-frontal and Shamal dust storms. For each of these types, three intense and pervasive dust events are analyzed from a synoptic meteorological and numerical simulation perspective. The performance of 9 operational dust models in forecasting these dust events in the Middle East is qualitatively and quantitatively evaluated against Terra-MODIS observations and AERONET measurements during the dust events. The comparison of model AOD outputs with Terra-MODIS retrievals reveals that despite the significant discrepancies, all models have a relatively acceptable performance in forecasting the AOD patterns in the Middle East. The models enable to represent the high AODs along the dust plumes, although they underestimate them, especially for cyclonic dust storms. In general, the outputs of the NASA-GEOS and DREAM8-MACC models present greater similarity with the satellite and AERONET observations in most of the cases, also exhibiting the highest correlation coefficient, although it is difficult to introduce a single model as the best for all cases. Model AOD predictions over the AERONET stations showed that DREAM8-MACC exhibited the highest R2 of 0.78, followed by NASA_GEOS model (R2 = 0.74), which both initially use MODIS data assimilation. Although the outputs of all models correspond to valid time more than 24 h after the initial time, the effect of data assimilation on increasing the accuracy is important. The different dust emission schemes, soil and vegetation mapping, initial and boundary meteorological conditions and spatial resolution between the models, are the main factors influencing the differences in forecasting the dust AODs in the Middle East.

Waves in the Arabian Gulf (Gulf) are dominated by shamal winds during winter and early summer. Although wave characteristics in the Gulf are broadly studied, features associated with various wind systems are not explicitly covered, especially in the Exclusive Economic Zone (EEZ) of Qatar. In this study, we analyzed the wave parameters measured off Fuwairit, north coast of Qatar during 29 October – 26 November 2019 to identify the features associated with different wind systems. The analyses have been further extended to the Gulf using the reanalysis waves obtained from the COPERNICUS Marine Environment Monitoring Services (CMEMS) to describe the monthly, seasonal and annual characteristics. Results indicate that Nashi winds influence the east and northeast coasts of Qatar with higher waves than those generated by shamal winds. We find exceptional easterly (Nashi) waves during March 2019 contributing to the highest monthly mean Hs, which is a deviation from the known long-term wave climate of the Gulf. This work was jointly carried out under the IRCC International Research Co-Fund Collaboration Program of QU and CSIR-NIO, executed through Office of Research Support (ORS), QU (IRCC-2019-002).

We present a field survey and a number of simulations of the local Persian Gulf tsunami of 19 March 2017 at Bandar Dayyer, Iran, which resulted in one death, five persons missing and significant damage to the port. The field survey defined the inundated area as extending $$\sim\, 40$$ km along the coast, with major effects concentrated on an $$\sim\, 8$$ km stretch immediately west of Dayyer, a maximum run-up of 3 m and maximum inundation reaching 600 m. In the absence of significant earthquakes on that day, we first test the possibility of generation of a landslide; however, our simulations for legitimate sources fail to reproduce the distribution of run-up along the coast. We prefer the model of a meteorological tsunami, triggered by Proudman resonance with a hypothetical weather front moving at 10 m/s in a NNW azimuth, which could be an ancillary phenomenon to a major shamal wind system present over the Persian Gulf on that day. More detailed simulations of the Dayyer tsunami would require an improved bathymetric grid in the vicinity of the relevant coastal segment.

The importance of mineral dust and aerosols in the transfer of bio-essential elements to terrestrial and marine ecosystems far removed from the source region is well known. Aerosol concentrations measured at the surface over the west coast of India during the SW monsoon period (June to September) are usually very low as pristine maritime air from the Southern Indian Ocean blows over this region. However, we find very high levels of mineral dust and dust derived nutrients in rainwater collected during the SW monsoon period. We show that the dry, warm and dusty Red Sea Wind and Shamal Wind from the Middle-East override the moist oceanic Low-Level Jet (Findlater Jet) of the SW monsoon and transport large quantities of dust at heights between 2 km and 5 km over the Indian Peninsula. A substantial portion is the desert dust is scavenged and wet-deposited over the Western Ghats of India where it neutralizes the acidity of rainwater and provides substantial amounts of nutrients that have the potential to impact sensitive ecosystems in this region. After the Red Sea and Shamal Winds subside in September, the alkaline rainwater reverts to the acidic range due to soluble ions derived from local carbonaceous aerosols.

In this paper, a quantitative evaluation of the severe dust storm which occurred in the Middle East during 3–8 July 2009 is presented. The quantification is based on the numerical simulation using the WRF/Chem-D model which has been verified and calibrated for the Middle East region. It is found that, during the 3–8 July 2009 event, more than 9.67 Tg dust were emitted from the study area and the maximum simulated dust emission rate is 540 (μg m −2 s −1 ). The west of Iraq, east of Syria and northwest of Jordan (Al-Nafud desert and western Euphrates alluvial plain) are found to be the most active areas of dust emission, contributing much to the dust emission from the Middle East region. In this study, more that 60% of dust particles were emitted from these areas and less than 10% were emitted from Iran dust sources. About 21% of the deposited dust was deposited in Iran land, while 79% in other parts of the study area. The dust load in the study area was estimated to be more than 0.3 g m −2 . The residence time of dust in the atmosphere was 6.2 days over the study area, 7.8 days over Iran and 6 days over other parts. The simulation results exhibit that Iran contribution in emission rate in the study area is much lower than its contribution in dust deposition and residence time and the conclusion of this study can demonstrate the necessity of forming cooperation for suppressing the severe dust events.

Corals in the Persian/Arabian Gulf are the most thermally tolerant in the world, but live very near the thresholds of their thermal tolerance. Warming sea temperatures associated with climate change have resulted in numerous coral bleaching events regionally since the mid-1990s, but it has been unclear why unusually warm sea temperatures occur some years but not others. Using a combination of 5 years of observed sea-bottom temperatures at three reef sites and a meteorologically linked hydrodynamic model that extends through the past decade, we show that summer sea-bottom temperatures are tightly linked to regional wind regimes, and that strong ‘shamal’ wind events control the occurrence and severity of bleaching. Sea bottom temperatures were primarily controlled by latent heat flux from wind-driven surface evaporation which exceeded 300 W m-2 during shamal winds, double that of typical breeze conditions. Daily temperature change was highly correlated with wind speed, with breeze winds (5 weeks, while the cooler intervening years (2013–2016) had summers with more frequent and/or strong shamal events which repeatedly cooled temperatures below bleaching thresholds for days to weeks, providing corals temporary respite from thermal stress. Using observed data from 2012 onward and simulated data from 2008 to 2011, we show that the severity of bleaching events over the past decade was linked to both the number of cumulative days above bleaching thresholds (rather than total days, which obfuscates the cooling effects of occasional brief shamal events), as well as to maxima. We show that winds of 4 m s-1 represents a critical threshold for whether or not corals cross bleaching threshold temperatures, and provide simulations to forecast sea-bottom temperature change and recovery times under a range of wind conditions. The role that wind-driven cooling may play on coral reefs globally is discussed.

This study investigates the underlying atmospheric dynamics associated with intense dust storms in summer 2018 over the Arabian Peninsula (AP); a major dust source at global scale. It reports, for the first time, on the formation of cyclone over the Empty Quarter Desert as important mechanism for intense dust storms over this source region. The dust direct and semi-direct radiative forcings are observed, for the first time over this source region, using high-resolution in-situ and CERES-SYN satellite observational data. The three-dimensional structure and evolution of the dust storms are inferred from state-of-the-art satellite products such as SEVIRI, AEROIASI and CALIPSO. The dynamics and thermodynamics of the boundary layer during this event are thoroughly analyzed using ERA5 reanalysis and ground based observations. We found that a large dust storm by Shamal winds led up, through radiative forcing, to cyclone development over the Empty Quarter Desert, subsequent dust emissions, development of convective clouds and rain. The cyclogenesis over this region initiated a second intense dust storm which developed and impacted the AP for 3 consecutive days. The uplifted dust by the cyclone reached 5 km in altitude and altered the radiative budget at the surface, inducing both significant warming during night and cooling during day. The dust load uplifted by the cyclone was estimated by the mesoscale model Meso-NH to be in the order of 20 Tg, and the associated aerosol optical depth was higher than 3. The model simulates reasonably the radiative impact of the dust in the shortwave but highly underestimated its impact in the LW. Our study stresses the importance of the dust radiative forcing in the longwave and that it should be accurately accounted for in models to properly represent the impact of dust on the Earth system especially near source areas. Missing the warming effect of dust aerosols would impact both the weather and air quality forecast, and the regional climate projections.

Synthetic Aperture Radar (SAR) in wave mode is a powerful sensor for monitoring the swells propagating across ocean basins. Here, we investigate crossing swells in the Indian Ocean using 10-years Envisat SAR wave mode archive spanning from December 2003 to April 2012. Taking the benefit of the unique “fireworks” analysis on SAR observations, we reconstruct the origins and propagating routes that are associated with crossing swell pools in the Indian Ocean. Besides, three different crossing swell mechanisms are discriminated from space by the comparative analysis between results from “fireworks” and original SAR data: (1) in the mid-ocean basin of the Indian Ocean, two remote southern swells form the crossing swell; (2) wave-current interaction; and, (3) co-existence of remote Southern swell and shamal swell contribute to the crossing swells in the Agulhas Current region and the Arabian Sea.

The occurrence of dust storms in Iran has been a source of interest for centuries, but their study has increased dramatically over the last two decades. This paper reviews recent work on the distribution of dust storms in Iran. We show that the dust events that affect Iran come from sources within the country and also from outside Iran's boundaries. The location of major sources within Iran are identified in high-resolution maps and satellite images. Many of these sources have not been previously identified. This paper discusses the transport pathways of this material, the synoptic conditions associated with dust storms and dust haze, recent changes in dust storm frequencies and their causes, and the consequences of dust storms, particularly with respect to health, for Iranian society. Economic consequences include adverse impacts on solar power generation, crops, productivity of the manufacturing industry, and damage to agricultural land, buildings and infrastructure.

The Middle Eastern Shamal is a strong north-northwesterly wind, capable of lifting dust from the Tigris-Euphrates basin and transporting it to the Persian Gulf and Arabian Peninsula. The present study explores the poorly understood spatial and temporal variability of summer Shamal on the diurnal, seasonal, and interannual time scales, along with its influence on dust storm activity and sensitivity to global patterns of sea surface temperature using a comprehensive set of observational data. Statistics of the summer Shamal season are quantified for the first time, including its onset, termination, duration, and the occurrence of distinct break periods. Based on a multistation criteria, the mean onset and termination of the Shamal season occur on 30 May ± 16 days (1 standard deviation) and 16 August ± 22 days, respectively. Anomalously early (late) onset and termination of the Shamal season are typically associated with La Nina (El Nino) conditions, which favor (inhibit) the development of the Iranian heat low in spring and inhibit (favor) its persistence into late summer. Dust source regions in the Tigris-Euphrates basin and Kuwait, as well as southeastward dust transport during the summer Shamal, which cannot be detected by satellite aerosol products alone, are identified, for the first time, from the Multiangle Imaging Spectroradiometer plume motion vector products and confirmed by surface observations and lidar data. A close interrelationship has been revealed among summertime dust activity across the eastern Arabian Peninsula, frequency of Shamal days, and duration of the Shamal season on the interannual time scales.

Dust and impurity accumulation has a significant effect on the efficiency and performance of PV panel output power. It influences the transmittance of solar radiation from the PV panels surface. Scheduling weekly or monthly cleaning periods requires complete knowledge of area’s weather and environmental condition. In this study, an experimental-based investigation is conducted aiming for a proper scheduling cleaning periods by comparing the output power efficiency of two identical PV panels, the first being cleaned daily and the other cleaned monthly. Both are exposed to unstable weather condition with Sarayat season in April and May, winter and summer Shamal of Kuwait for one year. The results indicated a significant degradation of PV panel output power in April, May, October and December. A need for frequent weekly water washing is a necessity to maintain the power efficiency loss of 15.07%, 13.74%, 10.685% and 8.742% respectively, and frequent monthly water washing for the remaining months of the year.

Ahvaz is among the most polluted cities in the world in terms of particulate matter (PM) concentration. It is a prevailingly vulnerable city to the dust storms intrusion experiencing nearly 98 dusty days per year. The main aim of this study is to determine the transport pathways of dust particles reaching Ahvaz and investigate the dust sources that potentially contribute to dust loading over this city. To this end, temporal and spatial characteristics of Ahvaz dusty days, with a focus on associated air parcel trajectories are investigated in tandem with station observation, potential source contribution function (PSCF) and aerosol optical depth (AOD). Four main dust corridors were identified, based on the trajectory results; one northwesterly and two westerly routes, passing mainly over Tigris Euphrates Plain and Mesopotamian marshlands before hitting Ahvaz. These transport routes are associated with Shamal winds and are active all year long, especially in the summer. Another dust corridor influencing Ahvaz is a southerly route related to the prefrontal dust-storm mechanism. This corridor is active mainly in spring and winter and lifts the dust from Zubair Desert, Ad Dahna Desert and arid land of southern Khuzestan Plain. The forward calculation, PSCF and AOD analysis are consistent with backward air masses trajectory results and showed that eastern Syria, central and southeastern Iraq, and northwest of Ahvaz are the primary sources for dust affecting Ahvaz. Other intense dust sources are located in the south of Ahvaz including the eastern coastal zone of the Arabian Peninsula, southern Iraq, and southeast of Ahvaz.

Anoop, T.R.; Sheela Nair, L.; Prasad, R.; Reji, S.; Ramachandran, K.K.; Prakash, T.N., and Balakrishnan Nair, T.M., 2020. Locally and remotely generated wind waves in the southwestern shelf sea of India. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 77-83. Coconut Creek (Florida), ISSN 0749-0208.The Southwestern Shelf Sea (SWSS) of India has a distinct wave pattern, which makes it different as compared to the adjoining regions. Wave directional spectra during the monsoon season are comparatively broader and double peaked in contrast to that of the western shelf sea. The well-defined directional bi-modality is observed during the south west monsoon which is attributed to the coexistence of the south Indian Ocean swells and the southwest monsoon swells. The shamal swells generated by the shamal wind blowing from the Arabian Peninsula are found to have a significant influence on the wave pattern of the SWSS. In addition, the local sea breeze/land breeze also contributes significantly to the observed changes, particularly to the diurnal variation. A distinct phase lag in occurrence of the maximum significant wave height for the wind sea component is also observed in the northern region of the SWSS during the fair seasons.