Climate Variability in the Levant Region

Abstract

Climate change is a topic of great interest around the world because it has serious environmental, agricultural, hydrological, and socio-economic consequences. The Levant region, as a part of the East Mediterranean, is considered a region particularly vulnerable to current and future climate change, which also occurs in the context of other developmental stresses, such as water scarcity, fatigue infrastructure, and frequent drought events. Furthermore, political and ethnic conflicts, population growth, and increasing demand for water, food, and energy all exacerbate the implications of climate change. Additionally, there is a lack of cooperation and sharing of climate data among the region's countries, as well as a lack of cooperation in dealing with potential climate changes in the region. There have been no previous studies or comparisons in the literature assessing changes and variability in maximum (Tmax) and minimum (Tmin) temperatures, diurnal temperature range (DTR), precipitation, extreme temperature and precipitation indices, and drought in the entire Levant region (Syria, Lebanon, Jordan, Palestine, and Israel), using climatic data from ground stations. The majority of climate studies in the Levant are limited to specific areas or countries, primarily over Israel. Most of them measured climate change in terms of mean values, with low spatial and temporal coverage. Thus, it is essential to study and investigate the climate variability in the Levant region at multiple time and space scales. The thesis aims to uncover and establish the relationships between climate variability and the most important climate indicators such as large-scale circulation patterns, Sea Surface Temperature (SST), and Sea Level Pressure (SLP) indicators in the Mediterranean Sea and North Atlantic Ocean in order to, better understand the causal mechanisms of such climate variability. Besides, it also aims to identify the regions that are most vulnerable to drought, and assess the dry spells that affected this area and the current trends on multiple drought time scales. This thesis fills a real gap in climatic studies in this critical region of the world. It is the first study of its kind to focus on the climate of the Levant as a whole, using the largest amount of climate data ever collected. It does not focus on a single climate variable, but rather analyzes a number of them. For the first time, data have been compiled and long, homogeneous and quality-controlled climatic time series have been obtained for temperatures and precipitation, covering as many meteorological stations as possible in the Levant. Finally, this thesis serves as the scientific foundation for any future joint efforts by Levantine countries to combat climate change through a unified scientific strategy. The following thesis is divided into ten chapters. The first three chapters discuss and present in detail the objectives, geographic and climatic features of the study area, the raw data, data quality control methods, handling missing values, outliers, homogenization of data sets, and methodology applied in this work. Temperature, extreme temperature indices, precipitation, and extreme precipitation indices as well as their relationships with the large-scale circulation patterns are examined at multiple time scales in Chapters 4-7, respectively. Chapter 8 has been devoted to covariability analysis between the seasonal temperature and precipitation in the Levant and the general patterns of the SST and SLP. In Chapter 9, droughts have been analyzed, studying their characteristics, and its relationship with large-scale circulation patterns, SST and SLP. Each chapter from 4 to 9 consists of three sections, introduction, results, conclusions and discussion. Finally, the main conclusions reached in this thesis are summarized in Chapter 10.