Analysis of Climate Trends and Leading Modes of Climate Variability for MENA Region

Abstract

The Middle East and North Africa (MENA), primarily the Arabian Peninsula (AP), is a region where the rate of mean surface temperature rise per decade is among the highest globally known during the recent past. Moreover, MENA regional climate is very sensitive to internal and external climate drivers. Therefore, it is of significant practical importance to analyze MENA sensitivity to climate trends as well as leading variability modes such as El Niño Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), and Indian summer monsoon (ISM). Using multiple regression technique on observations and the high-resolution atmospheric model output, this study investigates the role of climate trends and leading circulation modes such as NAO, ENSO, and ISM in inducing temperature and precipitation variability in MENA region for the period 1979-2008. Our results show substantial regional temperature and precipitation responses of ENSO, NAO, and ISM over MENA. Both the model and the observations indicate that positive phase of NAO and ENSO significantly cools central parts of MENA, in particular, the AP in winter. However, in boreal summer, the warm ENSO phase produces significant warming and drying over the tropical region. The strengthening (weakening) of ISM suggests cooling (warming) and wetting (drying) over MENA rain-belt region. Moreover, ISM induces a dipole precipitation structure over the tropics caused by Intertropical Convergence Zone shift and associated cloud distribution. High-resolution atmospheric model slightly underestimates NAO and ENSO winter cooling over the AP; however, overall patterns are well reproduced. The conducted analysis sheds light on the internal mechanisms of MENA climate variability.

Hydrogeology of a Complex Aquifer System in Semi-Arid Mountainous Region: The Eastern Upper Guir Basin in the High Atlas (Morocco)

“…The concentration of each element globally shows a W-E oriented gradient, except for the bicarbonates. Such trends are well observed in sub-basins C1 and C4, with very high concentrations of Ca 2+ (>400 mg L −1 ), Mg 2+ (>240 mg L −1 ), Na + (>400 mg L −1 ), SO 4 2− (>800 mg L −1 ) and Cl − (>800 mg L −1 ). In sub-basins C2 and C3, the maximum concentrations reached by these same elements are halved.…”

“…Table 6 shows that groundwater in the C1 and C4 sub-basins is the least suitable for drinking. In sub-basin C1, only 34% of the samples are below the maximum threshold for TH, 60% for Mg and 60% for SO 4 . In sub-basin C4, the groundwater quality is more degraded since only 56% of the samples are below the maximum threshold for TH, 56% for Na, 78% for Mg and 56% for SO 4 .…”

“…Nowadays, this situation is exacerbated by global warming issues [2] affecting the whole MENA area. During the last few decades, this region has undergone one of the highest rates of mean surface temperature rise in the world [3], with the temperature increase reaching between 0.5 and 1.0 °C per decade [4]. Climatic evolution has affected the availability and quality of water resources in MENA, with a strong impact on populations [5] and human activities [6][7][8].…”

Regional Climate Response of Middle Eastern, African, and South Asian Monsoon Regions to Explosive Volcanism and ENSO Forcing

“…Initially, we showed combined/total anomalous signal that contains both postvolcanic direct radiative and indirect dynamic circulation impacts, and afterward, we analyzed posteruption circulation impacts and volcanic direct radiative impacts separately that are computed using multiple regression technique (section ). Multiple regression technique has been widely used to separate the volcanic signal and other major variability modes (see, e.g., Randel, ; Fujiwara et al, ; Dogar & Sato, ; Gu & Adler, 2010; Gu & Adler, ). Nonetheless, some shortcomings of using regression are possible as the climate system is complex (Mitchell et al, ).…”

“…Recent studies further emphasized that the regional convective structure and precipitation change are very sensitive to the model horizontal resolution (Bui et al, ; Liu, Yu, & Chen, ). HIRAM model has been previously used effectively to simulate aerosol's direct radiative and circulation impacts (Bangalath & Stenchikov, ; Dogar, ; Dogar & Sato, ; Dogar & Shahid, ; Dogar, Stenchikov, et al, ; Osipov et al, ). The idea of choosing two different HIRAM resolutions is to see if there could be any improvement in the simulations of volcanic impacts with improved resolution.…”