Middle East Climate Research Articles

Unraveling sub-seasonal precipitation variability in the Middle East via Indian Ocean sea surface temperature

This study examines sub-seasonal precipitation anomalies, challenging to predict yet vital for society and the environment. Focusing on October, we investigate correlations between the Indian Ocean Dipole Mode Index (DMI), West Tropical Indian Ocean Index (WTIO), and Middle Eastern precipitation. We find robust correlations (~ 0.7), up to a two-month lag, demonstrating strong links between these climate indices and rainfall patterns, potentially suggesting sub-seasonal precipitation predictability. Over the past four decades, DMI and WTIO have shown a significant upward trend of ~ 0.4 °C, intensifying their impact on precipitation dynamics. This trend signifies evolving Indian Ocean climate patterns with potential regional consequences and is projected to continue in the twenty-first century. Significant correlations also emerge between DMI, WTIO, and maximum daily precipitation, highlighting their role in extreme rainfall events. Finally, our study attributes most of October’s precipitation variability to Indian Ocean sea surface temperature variations. These temperature anomalies influence the Indian Ocean’s Walker circulation, affecting water vapor flux to the Middle East and shaping regional precipitation. Our findings underscore the importance of these indices in understanding and predicting Middle East climate variability, revealing intricate ocean–atmosphere interactions.

Ocean-atmosphere circulation controls on integrated meteorological and agricultural drought over Iran

Drought may affect more people than any other climate extremes worldwide, especially in (semi)arid climates such as Iran. In this paper, the empirical Multivariate Standardized Drought Index (MSDI) that incorporates the meteorological and agricultural drought conditions is first computed. The wavelet analysis is then used to identify teleconnections between ocean–atmosphere oscillations from Atlantic (AMO, AO, and NAO) and Pacific (ENSO, PDO, and PNA) oceans and Iran’s drought at a highly dense network of regularly gridded points (2485) during 1979–2016. It is found that among the droughts of 1980, 1985–86, 1990–91, 1998–99, 2000, 2007–08, and 2010–11, both the 2007–08 and 2000 are the broadest and strongest across the country. Overall, those droughts that occurred in the 2000–2016 period (average MSDI = -1.14) were, on the whole, stronger than those happened over the latest 20 years of the 20th century (average MSDI = -0.77), reflecting the strengthening of the influence that ENSO has on the Middle East climate in the most recent decades. According to the wavelet coherence results, unlike the Atlantic-based oscillations that almost have an anti-correlation with droughts, there is a positive correlation between Pacific-based oscillations and Iran’s drought. It is also identified that the severe historical droughts across the country were usually associated with a strong La Niña coupled with cold PDO and positive NAO phases in the latest 30 years. Overall, droughts in Iran tend to be substantially controlled by multiple interacting of climate indices since three-coupled indices have stronger coherence with drought than either two-coupled indices or single ones. A combination of the three indices of ENSO, PDO, and NAO has the strongest coherence with Iran’s drought compared to all the other three- and two-coupled, and all single indices, indicating that integrated impact of climate indices can better capture hydroclimate teleconnections. These multiple interacting impacts from the different large-scale climate circulation patterns mark a significant step towards an improved prediction of severe droughts across Iran and can also be used for other parts of the world.

EFdeN Signature - a case study of a zero-energy house prototype optimized for Middle East climate

When talking about the urban challenges we face today at a global level, population growth and urbanization ranks high in the charts. Both challenges can be found in the Middle East and especially in Dubai, one of the fastest growing cities in the world - a rapidly developing urban settlement supporting an ever-increasing human population. With a very warm climate, the United Arab Emirates are struggling to develop strategies and solutions to decrease energy consumption. Among the major consumers in Middle East are the building therefore an integrated approach using renewable sources is mandatory. Within the Solar Decathlon competition the Romanian team of students proposed a house prototype to answer Middle East challenges. In this paper we present the developed model, its structure, systems and we demonstrate its potential as a positive energy balance building using numerical simulations.

Middle East Climate Response to the Saharan Vegetation Collapse during the Mid-Holocene

AbstractUnderstanding climate change in the Middle East (ME) is crucial because people’s living environment depends on rain-fed crop systems. It remains unclear whether the ME climate would be affected by the Saharan vegetation collapse at the end of the mid-Holocene (MH). Proxy data suggest a transition from humid to more arid ME conditions during the period of 6.5–5 kyr BP. Using a set of idealized sensitivity experiments with an Earth system model (EC-Earth), we infer that the shift of Saharan vegetation plays a role in this wet-to-dry transition over the ME. The experimental results show that the Saharan greening can significantly increase the late winter and early spring precipitation over the ME. The reason is that the vegetation decreases the surface albedo, which induces a warming in North Africa and generation of an anomalous low-level cyclonic flow, which transports moisture from tropical North Africa and the Red Sea to the ME. The moisture also flows from the Mediterranean Sea region to the ME through the enhanced mid- to upper-level westerlies. The enhanced moisture carried by westerly and southwesterly flows is lifted upon reaching Mesopotamia and the Zagros Mountains, substantially increasing the precipitation there. When the Sahara greening is removed, a drier condition happens in the ME. The crop model simulation further shows a substantial decrease in wheat yield in Mesopotamia with the reduction of Saharan vegetation, which is consistent with paleoclimatic reconstructions. These results imply that future changes in Saharan land cover may have climatic and agricultural impacts in the Middle East.

Impact of sowing date on bread wheat kernel quantitative and qualitative traits under Middle East climate conditions

Impact of sowing date on bread wheat kernel quantitative and qualitative traits under Middle East climate conditions

A positive energy building for the Middle East climate: ReStart4Smart Solar House at Solar Decathlon Middle East 2018

Abstract The city of Dubai (UAE), in accordance with its program of transformation into one of the most smart and sustainable cities, hosted the 2018 edition of Solar Decathlon, the first in the Middle East (SDME 2018). The harsh climate of UAE, along with the booming construction industry and energy consumptions and CO2 emissions among the world’s highest, tasked participating university teams to find innovative solutions able to drive the region building sector towards a more sustainable future. Sapienza University of Rome participated, representing Italy, to SDME 2018 with the project ReStart4Smart, a full scale prototype of a single family energy positive smart home specifically designed for the Middle East climate and fully consistent with the Arab culture. This article examines the ReStart4Smart project in terms of energy strategies, architectural concept and technological solutions adopted, in order to verify, through a detailed analysis of energy simulations and monitoring carried out on the prototype built in Dubai, the expected performance levels. Results achieved demonstrate how the Restart4 Smart project represents, consistently with the Arab tradition, a valid proposal for zero-energy intelligent housing, perfectly responsive to the social demand emerging from the populations of the Middle East.

Constructed Wetlands for Sustainable Wastewater Treatment in Hot and Arid Climates: Opportunities, Challenges and Case Studies in the Middle East

Many countries and regions around the world are facing a continuously growing pressure on their limited freshwater resources, particularly those under hot and arid climates. Higher water demand than availability led to over-abstraction and deterioration of the available freshwater resources’ quality. In this context, wastewater, if properly treated, can represent a new water source added in the local water balance, particularly in regions of Colorado, California, Australia, China and in the wide region of the Middle East, which is characterized as one of most water-stressed regions in the world. This article summarizes the status of wastewater treatment and management in the Middle East and discusses the challenges, the various barriers and also the opportunities that arise by introducing the sustainable technology of Constructed Wetlands in the region. Furthermore, the aim of the article is to provide a better insight into the possibility and feasibility of a wider implementation of this green technology under the hot and arid climate of Middle East by presenting several successful case studies of operating Constructed Wetlands facilities in the region for the treatment of various wastewater sources.

Drying in the Middle East During Northern Hemisphere Cold Events of the Early Glacial Period

AbstractFew paleoclimate records exist to assess the central Middle East's response to natural forcing beyond the instrumental record. Here, we present a multiproxy stalagmite‐based climate reconstruction from Iran's semiarid northeast that spans 100–70,000 years before present. During severe cold (stadial) events in the North Atlantic at ≈88, 77, and 73 ka, stalagmite trace‐element data indicate anomalously dry periods at this location. Stadial event increases in the stalagmite oxygen isotopes mirror those in a published Iranian stalagmite 800 km to the west. A global climate model simulates drying across the Middle East region in response to stadial event forcing, in agreement with oxygen isotope enrichments in both Iranian records, caused by a smaller fractional loss of moisture on the trajectory upstream. The paleoproxies and model experiments are consistent in indicating a drier Middle East climate during the cold North Atlantic stadials.

Performance prediction of a solar district cooling system in Riyadh, Saudi Arabia – A case study

The present paper aims to evaluate the performance of a solar district cooling system in typical Middle East climate conditions. A centralized cooling station is supposed to distribute chilled water for a residential compound through a piping network. Two different solar cooling technologies are compared: two-stage lithium-bromide absorption chiller (2sABS) driven by Parabolic Trough Collectors (PTCs) vs. single-stage lithium-bromide absorption chiller (1sABS) fed by Evacuated Tube Collectors (ETCs). A computer code has been developed in Trnsys® (the transient simulation software developed by the University of Wisconsin) to simulate on hourly basis the annual operation of the solar cooling system, including building thermal load calculation, thermal losses in pipes and control strategy of the energy storage. A solar fraction of 70% was considered to size the solar field aperture area and the chiller capacity, within a multi-variable optimization process. An auxiliary compression chiller is supposed to cover the peak loads and to be used as backup unit. The two different solar cooling plants exhibit strongly different performance. For each plant configuration, the model determined the optimal size of every component leading to the primary cost minimization. The solar district cooling configuration based on 2sABS and PTCs shows higher performance at Riyadh (KSA) climate conditions and the overall cost is 30% lower than the one of the single-stage absorption chiller plant.

Simulating the Regional Impact of Dust on the Middle East Climate and the Red Sea

AbstractThe Red Sea is located between North Africa and the Arabian Peninsula, the largest sources of dust in the world. Satellite retrievals show very high aerosol optical depth in the region, which increases during the summer season, especially over the southern Red Sea. Previously estimated and validated radiative effect from dust is expected to have a profound thermal and dynamic impact on the Red Sea, but that impact has not yet been studied or evaluated. Due to the strong dust radiative effect at the sea surface, uncoupled ocean modeling approaches with prescribed atmospheric boundary conditions result in an unrealistic ocean response. Therefore, to study the impact of dust on the regional climate of the Middle East and the Red Sea, we employed the Regional Ocean Modeling System fully coupled with the Weather Research and Forecasting model. We modified the atmospheric model to account for the radiative effect of dust. The simulations show that, in the equilibrium response, dust cools the Red Sea, reduces the surface wind speed, and weakens both the exchange at the Bab‐el‐Mandeb strait and the overturning circulation. The salinity distribution, freshwater, and heat budgets are significantly altered. A validation of the simulations against satellite products indicates that accounting for radiative effect from dust almost completely removes the bias and reduces errors in the top of the atmosphere fluxes and sea surface temperature. Our results suggest that dust plays an important role in the energy balance, thermal, and circulation regimes in the Red Sea.

Foreign aid’s impact on domestic business climates

Purpose Existing literature has expressed significant pessimism about the outcomes of foreign aid received by developing nations. Foreign aid can lead to negative outcomes by generating greater rent-seeking opportunities and creating aid dependence. While aid’s negative impact has been explored in the context of growth, political institutions, and economic institutions, the literature has not investigated the effect of aid on business climate of recipient nations. The purpose of this paper is to explore foreign aid’s impact on government regulations on the business climate in Sub-Saharan African (SSA) and Middle East and North American countries. Design/methodology/approach The authors consider a panel of 64 countries over six years. Since foreign aid is most likely to be endogenous, as identified in most studies, the identification strategy follows two methodologies – system GMM estimator, that creates its own instruments via moment generating conditions and instrumental variable approach that relies on an external instrument. Findings The authors find that aid worsens the business climate by increasing government restrictions. Foreign aid provides the recipient governments and the political elite resources to strengthen their power and reinforce predatory policies that are harmful for the business climate. The results further show that in the presence of long-lasting and sustainable democratic regimes, the negative impact of foreign aid on business climate mitigates to a certain extent. Originality/value While aid’s negative impact has been explored in the context of growth, political institutions, and economic institutions, the literature has not investigated the effect of aid on business climate of recipient nations. The authors explore the impact of foreign aid on government regulations on the business climate in SSA and Middle East and North American countries.

Nonuniform Flow Distribution Analysis of Air-Cooled Heat Exchanger

The header and the multiple microchannel tubes connected to the header compose a complicated fluid network with several circuits, and the refrigerant flow into the header and is distributed to the microchannels in parallel by the refrigerant pressure driving in the inlet. So all changed details of geometry, operating conditions and thermophysical properties of the fluids lead to nonuniform refrigerant flow distribution in the microchannels. In the present work, one 6-pass 40-tube microchannel condenser as the research objective was equipped in a window type air conditioner prototype with the cooling capacity 5200W for Middle East T3 climate. A mathematical model based on fluid network theory was developed to predict flow distribution and phase separation in 9 flat tubes and their connecting headers on the second pass of the microchannel condenser. In the assumption of homogeneous flow, the mesh current analysis was employed to solve the mass flow of the loopi+1 by that of the loopi upon two phase pressure drop. The simulated mass flow rate distribution in 9 tubes is parabolic and approaches to uniform distribution when inlet quality comes to the median 0.45 from both directions.

Role of soil moisture in the amplification of climate warming in the eastern Mediterranean and the Middle East

Projections for the 21st century suggest that climate change will be associated with changes in the frequency and intensity of weather and climate extremes (e.g. heat waves, droughts, heavy precipitation events). In the already warm summertime eastern Mediterranean and Middle East (EMME) climate change may involve mechanisms and feedbacks that cause or intensify hot weather events. A potentially important feedback mechanism involves soil moisture� atmosphere interactions. When the soil water content and evapotranspiration are decreased, near- surface air temperatures are enhanced due to reduced evaporative cooling. Here we show the importance of this mechanism, especially in the northern part of the EMME, using the output of a regional climate model (HadRM3P). We applied the classical hydrology framework to define evapotranspiration regimes as a function of soil moisture and latent heat fluxes. Further, we used the correlation of summer maximum temperature and evapotranspiration as a diagnostic of this coupling, and we performed a composite analysis of maximum temperature for the dry and wet years of our dataset. Since temperature and precipitation regimes are expected to change in the EMME, we considered alterations of the relationship between soil moisture and the maximum temperature throughout the 21st century.

Phase Change Materials as a Modifier of Ageing Cement Concrete in Hot and Dry Climate

This paper is devoted to the use of Phase Change Materials as a cement concrete modifier in Middle East climate. Due to large amplitude of daily air temperature in these conditions, Phase Change Materials can be used to reduce the dynamic of thermal peak in an ageing concrete. Partial results of studies to determine the influence of various factors on the effects of modifications are presented

Integrated multi-site U–Th chronology of the last glacial Lake Lisan

We present a new integrated multi-site chronology for Lake Lisan, which occupied the Dead Sea basin and Jordan Valley during the last glacial period (70–14kka, Marine Isotope Stages 4,3,2). The Dead Sea basin lacustrine deposits are unique among closed basin sediments in that they formed in a deep, hypersaline water body that precipitated primary aragonite which is amenable to radiometric dating by U-series, providing a solid basis for studies of the relationship of Middle East climate to other changes in the high latitudes or the tropics.The application of U–Th dating for lacustrine carbonates requires corrections for detrital U and Th and hydrogenous (“initial”) 230Th. Here we followed an iterative approach, in which we evaluate the composition of the detrital contamination independently for every set of coeval samples to determine the corrected ages. These were further filtered and combined with lithological–limnological considerations, which were used to construct age–height models for all studied stratigraphic sections. Finally, the ages of stratigraphic tie-points were used to integrate the individual age–height models into a unified chronology. The resulting chronological framework indicates that the ages of several primary gypsum units associated with catastrophic lake level drops correspond with the timing of Heinrich events in the North Atlantic. Thus, a final iterative step involves refining the ages of “Lisan-gypsum events” based on the ages of Heinrich events 6, 5, 5a, 4, and 1. This approach yields an unprecedented basin-wide, unified, event-anchored chronology for the Lisan Formation, with typical age uncertainties ca. 1000–2000years (95% confidence limit) across the entire last glacial, well below those typically related to individual U–Th and radiocarbon dating of “dirty” carbonates from similar time intervals. The results can be further extrapolated to new sites and serve as a geochronometric reference for the reconstruction of the limnological history of Lake Lisan.

ROLE ASSESSMENT OF GIS ANALYSIS AND ITS RELIABILITY WHILE RANKING URBAN SUSTAINABILITY USING SCENARIOS SPECIFIC TO REGIONAL CLIMATE, COMMUNITY AND CULTURE

Abstract. Urban Sustainability expresses the level of conservation of a city while living a town or consuming its urban resources, but the measurement of urban sustainability depends on what are considered important indicators of conservation besides the permitted levels of consumption in accordance with adopted criteria. This criterion should have common factors that are shared for all the members tested or cities to be evaluated as in this particular case for Abu Dhabi, but also have specific factors that are related to the geographic place, community and culture, that is the measures of urban sustainability specific to a middle east climate, community and culture where GIS Vector and Raster analysis have a role or add a value in urban sustainability measurements or grading are considered herein. Scenarios were tested using various GIS data types to replicate urban history (ten years period), current status and expected future of Abu Dhabi City setting factors to climate, community needs and culture. The useful Vector or Raster GIS data sets that are related to every scenario where selected and analysed in the sense of how and how much it can benefit the urban sustainability ranking in quantity and quality tests, this besides assessing the suitable data nature, type and format, the important topology rules to be considered, the useful attributes to be added, the relationships which should be maintained between data types of a geo- database, and specify its usage in a specific scenario test, then setting weights to each and every data type representing some elements of a phenomenon related to urban suitability factor. The results of assessing the role of GIS analysis provided data collection specifications such as the measures of accuracy reliable to a certain type of GIS functional analysis used in an urban sustainability ranking scenario tests. This paper reflects the prior results of the research that is conducted to test the multidiscipline evaluation of urban sustainability using different indicator metrics, that implement vector GIS Analysis and Raster GIS analysis as basic tools to assist the evaluation and increase of its reliability besides assessing and decomposing it, after which a hypothetical implementation of the chosen evaluation model represented by various scenarios was implemented on the planned urban sustainability factors for a certain period of time to appraise the expected future grade of urban sustainability and come out with advises associated with scenarios for assuring gap filling and relative high urban future sustainability. The results this paper is reflecting are concentrating on the elements of vector and raster GIS analysis that assists the proper urban sustainability grading within the chosen model, the reliability of spatial data collected; analysis selected and resulted spatial information. Starting from selecting some important indicators to comprise the model which include regional culture, climate and community needs an example of what was used is Energy Demand & Consumption (Cooling systems). Thus, this factor is related to the climate and it's regional specific as the temperature varies around 30–45 degrees centigrade in city areas, GIS 3D Polygons of building data used to analyse the volume of buildings, attributes "building heights", estimate the number of floors from the equation, following energy demand was calculated and consumption for the unit volume, and compared it in scenario with possible sustainable energy supply or using different environmental friendly cooling systems this is followed by calculating the cooling system effects on an area unit selected to be 1 sq. km, combined with the level of greenery area, and open space, as represented by parks polygons, trees polygons, empty areas, pedestrian polygons and road surface area polygons. (initial measures showed that cooling system consumption can be reduced by around 15–20% with a well-planned building distributions, proper spaces and with using environmental friendly products and building material, temperature levels were also combined in the scenario extracted from satellite images as interpreted from thermal bands 3 times during the period of assessment. Other examples of the assessment of GIS analysis to urban sustainability took place included Waste Productivity, some effects of greenhouse gases measured by the intensity of road polygons and closeness to dwelling areas, industry areas as defined from land use land cover thematic maps produced from classified satellite images then vectors were created to take part in defining their role within the scenarios. City Noise and light intensity assessment was also investigated, as the region experiences rapid development and noise is magnified due to construction activities, closeness of the airports, and highways. The assessment investigated the measures taken by urban planners to reduce degradation or properly manage it. Finally as a conclusion tables were presented to reflect the scenario results in combination with GIS data types, analysis types, and the level of GIS data reliability to measure the sustainability level of a city related to cultural and regional demands.

Application of the Global Bioclimatic Classification to Iran: implications for understanding the modern vegetation and biogeography

This study aims at proposing a new bioclimatic zonation for Iran based on the recently developed Global Bioclimatic Classification System (GBC) and tries to re-appraise this classification system by checking the degree of correspondence between its bioclimatic zones and the distribution of major phytogeographical regions, biomes, and a selection of plant and insect taxa of Iran. After application of the GBC to Iranian meteorological data, three macrobioclimates, ten bioclimates, and three bioclimatic variants were distinguished. The Mediterranean macrobioclimate is the dominant macrobioclimate and correlates with the Irano-Turanian biogeographical region, the Tropical macrobioclimate in southern Iran correlates with the Saharo-Sindian region and finally a small Temperate macrobioclimatic zone in northern Iran correlates with the Euro-Siberian region. Mediterranean macrobioclimate of Iran displays a wide range of bioclimates including Mediterranean pluviseasonal-oceanic, Mediterranean xeric-oceanic, Mediterranean pluviseasonal-continental, Mediterranean xeric-continental, Mediterranean desertic-oceanic, and Mediterranean desertic-continental. Tropical macrobioclimate also shows a range of bioclimates including Tropical xeric, Tropical desertic, and Tropical hyperdesertic. Finally, Temperate macrobioclimate has only one bioclimate i. e. Temperate oceanic. In conclusion, bioclimatic zones identified using the GBC system correlate well with the main phytogeographical regions of Iran at macrobioclimatic level and with major biomes at bioclimatic level. An advantage of the GBC over other bioclimatic classification systems is the inclusion of both seasonal and annual variations in those climatic parameters which are significant for the growth and development of plant populations and communities. GBC distinguishes several types of Mediterranean climate regimes for Iran and helps to differentiate between two different desert climate types i. e. Mediterranean and Tropical deserts in arid parts of the country. Because the climate in the Irano-Turanian region clearly differs from the Mediterranean region in its degree of continentality and seasonality, we propose the term ‘ xero-estival-continental’ or ‘Irano-Turanian’ instead of ‘Mediterranean’ bioclimate when describing the climate of continental Middle East and Central Asia.

How uncertain are climate model projections of water availability indicators across the Middle East?

The projection of robust regional climate changes over the next 50 years presents a considerable challenge for the current generation of climate models. Water cycle changes are particularly difficult to model in this area because major uncertainties exist in the representation of processes such as large-scale and convective rainfall and their feedback with surface conditions. We present climate model projections and uncertainties in water availability indicators (precipitation, run-off and drought index) for the 1961-1990 and 2021-2050 periods. Ensembles from two global climate models (GCMs) and one regional climate model (RCM) are used to examine different elements of uncertainty. Although all three ensembles capture the general distribution of observed annual precipitation across the Middle East, the RCM is consistently wetter than observations, especially over themountainous areas. All future projections show decreasing precipitation (ensemble median between -5 and -25%) in coastal Turkey and parts of Lebanon, Syria and Israel and consistent run-off and drought index changes. The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) GCM ensemble exhibits drying across the north of the region, whereas the Met Office Hadley Centre work Quantifying Uncertainties in Model ProjectionsAtmospheric (QUMP-A) GCM and RCM ensembles show slight drying in the north and significant wetting in the south. RCM projections also show greater sensitivity (both wetter and drier) and a wider uncertainty range than QUMP-A. The nature of these uncertainties suggests that both large-scale circulation patterns, which influence region-wide drying/wetting patterns, and regional-scale processes, which affect localized water availability, are important sources of uncertainty in these projections. To reduce large uncertainties in water availability projections, it is suggested that efforts would be well placed to focus on the understanding and modelling of both large-scale processes and their teleconnections with Middle East climate and localized processes involved in orographic precipitation.

Middle to late Miocene Middle Eastern climate from stable oxygen and carbon isotope data, southern Alborz mountains, N Iran

The Alborz mountains of northern Iran intercept and divert the northern hemisphere westerlies carrying moisture from the Mediterranean and Black Sea, and form an orographic barrier to moisture sourced to the north in the Caspian Sea. This implies that terrestrial deposits along the southern Alborz mountains (leeward side of northerly winds and windward side of westerlies with the respect to Tibet and other mountainous terrain in the Himalayan–Karakoram realm) potentially track changes in past moisture and erosional regimes and mirror rainfall patterns. Here, we present results of a stable isotope analysis and clay mineral study of the Miocene (ca. 17.5–7.6 Ma) Upper Red Formation in the foreland of the southern Alborz mountains. The changes recorded by stable oxygen and carbon isotope data from pedogenic and lacustrine/palustrine carbonate in the southern Alborz mountains suggest: 1) an increase in aridity possibly related to the evolution of the Alborz orographic rain shadow, which became more efficient between 17.5 and 13.2 Ma; 2) a steady increase in precipitation between 13.2 and 10.3 Ma with a significant increase in rainout along the southern slope of the Alborz mountains between 11 and 10.3 Ma, possibly related to perturbations in atmospheric circulation pattern in the northern hemisphere as suggested by coeval wetter phases in southern Europe; and 3) a decrease in aridity from ca. 9.6 to 7.6 Ma, possibly reflecting an increase in the seasonality of precipitation. Based on environmental and climatic changes observed across southern Asia and India starting from ca. 10 Ma, we speculate that the topographic evolution of the Himalayan–Tibetan system might have affected the late Miocene climate in Middle East.

Trends in Middle East climate extreme indices from 1950 to 2003

A climate change workshop for the Middle East brought together scientists and data for the region to produce the first area‐wide analysis of climate extremes for the region. This paper reports trends in extreme precipitation and temperature indices that were computed during the workshop and additional indices data that became available after the workshop. Trends in these indices were examined for 1950–2003 at 52 stations covering 15 countries, including Armenia, Azerbaijan, Bahrain, Cyprus, Georgia, Iran, Iraq, Israel, Jordan, Kuwait, Oman, Qatar, Saudi Arabia, Syria, and Turkey. Results indicate that there have been statistically significant, spatially coherent trends in temperature indices that are related to temperature increases in the region. Significant, increasing trends have been found in the annual maximum of daily maximum and minimum temperature, the annual minimum of daily maximum and minimum temperature, the number of summer nights, and the number of days where daily temperature has exceeded its 90th percentile. Significant negative trends have been found in the number of days when daily temperature is below its 10th percentile and daily temperature range. Trends in precipitation indices, including the number of days with precipitation, the average precipitation intensity, and maximum daily precipitation events, are weak in general and do not show spatial coherence. The workshop attendees have generously made the indices data available for the international research community.