قاعدة الرسائل الجامعية
أَثَرُ الذَّبْذَباتِ الضغْطيَّةِ في تغيّرِ أَنْمَاطِ الجوَّ العليا وعَلََْقَتِهُما بالجفافِ المُنَاخيَّ في العُرَاقِ )دراسةٌ في علم المُناخ الشِموليْ والارتباط عن ب عد(
عنوان الرسالة : أَثَرُ الذَّبْذَباتِ الضغْطيَّةِ في تغيّرِ أَنْمَاطِ الجوَّ العليا وعَلََْقَتِهُما بالجفافِ المُنَاخيَّ في العُرَاقِ )دراسةٌ في علم المُناخ الشِموليْ والارتباط عن ب عد(
عنوان الرسالة المترجم : The Effect Pressures Oscillation in Change Upper Atmospheric Patterns and Relationship Climatic Drought in Iraq (Study in Synoptic Climatology and Teleconnections)
اسم الباحث : عمر حمدان عبد الله ال شجيري
الدرجة : دكتوراه
الكلية - القسم : كلية التربية – ابن رشد للعلوم الانسانية
الجامعة : جامعة بغداد
التاريخ : 2019
الموضوع :
المشرف : يوسف محمد علي حاتم الهذال
الرابط :

This Research Aims to Assess the Role of Atmospheric Circulation in Pressure Variations at Upper Atmospheric Levels over Iraq and its Connection with Spatial and Temporal Characteristics of Climatic droughts. This aim extends further to suggest more “ robust” Scenarios for Adaptation with Drought Impacts on Different Disciplines (e.g. Water Resources, Crop Yield, Agriculture, etc.). This Research Employed data from Different Climatic Sources, Including Rainfall Data from 15 rain Gauges Distributed over Iraq and Represented the Different Climatic Regions in Iraq. Based on these data, we used Four Climatic Indices to characterize Meteorological Droughts, including SPI, PNI, SI and SDII. We also utilized Reanalysis data [NOAA: NCEP/ NCAR, ECMWF] of Pressure fields at different Geopotential Heights that Helped Detecting Pressure Anomalies and Polar Jetstream tracks. This Research also employed data of a wide range of Atmospheric Teleconnections, covering the last six decades (1952-2017). Overall, this investigation spanned three sub-periods within the Long-term period 1952- 2017, with Particular focus on three Seasons (Winter, Spring and Autumn). This Research employed different Parametric and non-parametric statistics, including- among others Pearson’s r Correlation, time series Analysis, Mann- Kendal test, Multiple Linear Regression, Factor Analysis and Cluster Analysis. We also used GIS techniques to map Spatial Patterns of Drought over Iraq. Our Results Demonstrate that there is a Statistically Significant Decrease in Rainfall Amounts during the rainy Season in Iraq, with a Clear Spatial Gradient from the North to the South. This Decrease is mainly reflected in the increase in the frequency and severity of Climatic Drought, especially during Winter and Spring. Albeit with their non-significant Trend, the M-K Statistic Reveals an opposite Trend, with a decrease in the frequency of dry years during autumn. Interestingly, we found that winter and spring showed the Highest frequency of Dry Years. Also, the stations with Highest Rainfall Amounts Exhibited more frequent and severe Drought Events, especially in the past two decades. This Research confirms the role of Atmospheric Circulation in Climatic Drought Evolution over Iraq. In specific, results suggest that the negative modes of AO, NAO, AMO, EA and SOI are mainly linked to the increase in Drought Frequency. On the other hand, the positive phases of EAWR, NCP, MOI, IOD, and ONI are associated with Drought severity. Importantly, the Association between Drought and Circulation Patterns seems to be seasonally Dependent, with ONI and IOD being the most leading patterns during Autumn, compared with AO NAO, EAWR, NCP, and SOI in Winter and AMO, EA, MOI during Springtime. To explain the role of these Circulation Patterns in temporal Variations of Drought in Iraq, we used Pearson’s R and coefficient of Determination to Characterize this Dependency for Different sub-periods. Results Indicate that the Atlantic Teleconnections (e.g. NAO, EA, AMO, and AO) can better explain the positive SPI values during the first sub-period and to some extent during the second sub-period. On the other hand, the Eurasian Teleconnections (SOI, ONI, IOD, EAWR, NCP, and MOI) Contributed More to the Evolution of Drought during the Second sub-period. The Atmospheric Processes Associated with these Temporal Patterns are also explained in this Work. In Particular, the Polar Advections are Mainly Associated with the Negative Phases of the Atlantic Oscillations and to a less extent with the Eurasian Indices. This Atmospheric Situation Corresponds to a Negative Pressure Anomaly with Axis Trough a NW-SE Extension over Iraq. On the other hand, the Positive Modes of the Eurasian Circulations are Characterized by Axis Trough a NE-SW Depression. These two Atmospheric Configurations are also Linked with the Extratropical Advections from Southwest, which Mostly Correspond to a Positive Pressure Anomaly at Upper Atmospheric Levels. Temporarily, the most humid sub-periods over Iraq occurred during 1952- 1973 and 1974-1995, with a clear southward advection of the jet stream. In contrast, the driest years are recorded in the last two decades (1996-2017), in which there is a shift of the jet stream to the northern latitudes. This explanation should also be seen in the context of the Expansion of Hadley Cell, which Explains the Relocation of the Polar Jet stream and Accordingly the northward shift of the Tropical and Extratropical Advections. To conclude, results of this work can contribute to better understanding of the spatial and temporal variability of Climatic Droughts over Iraq and its driving forces. This can improve current policies and future adaptation plans to cope with the Negative impacts of Drought on different disciplines in Iraq (e.g. water resources, agriculture).