Browsing by Author "Abraha, Gebregiorgis"

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    Challenges to Regional Integration: The Case of Intergovernmental Authority on Development (IGAD)
    (Addis Ababa University, 2013-05) Abraha, Gebregiorgis; Hassen, Mohammed (PhD)
    This study explores and examines the challenges of regional integration in the sub region of Intergovernmental Authority on Development (IGAD). Political and Economic integration has been part of African strategy to overcome fragmentation and improve the continent‟s position in the global political economy. Regional Economic Communities have been part of this and there are more such efforts in Africa than other continents. One of these, Intergovernmental Authority on Development was initiated in 1986 to coordinate efforts at combating drought and desertification and Reorganized in 1996, it has since been more active in managing regional conflicts. The paper uses the IGAD region as a case study to argue that there are more political and economic integration. In continental and regional perspectives there seem to be strong evidence that political and economic integration are close related, these include Neo-functionalism, Intergovernmentalism,Custom Union theory, Optimal Currency theory, Fiscal federalism and International Political Economy respectively. The study also discusses pre-conditions that are necessary to regional integration such as diversity in production, adequate infrastructure, political will, domestic peace, robust and strong private sector, strong market pressure and mutual trust among member countries and challenges for regional integration, including lack of supra nationalism and political will, overlapping membership, distrust among membership, lack of complementarities and poor infrastructure. The appraisal of this study reveals the challenges of IGAD region. The major challenges are political and security (lack of supra nationalism, lack of political will, security), structural challenges (weak institution, over lapping membership, lack of a proper managing of relations among member states) economic and social challenges (poverty, lack of complementarities, inadequate infrastructure, fast growth of population, endemic diseases and HIV/AIDS), problems on human and resources (lack of enough man power and finance). In conclusion the regional integration process in the IGAD region is still at lower level. Thus, this study stresses that if actual and sustainable regional integration is to advance, IGAD needs further agreements to implement and achieve their goal, and it needs synchronization of national efforts to improve agricultural production, bring the region‟s conflicts under control and need to reduce it
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    Total Electron Content (TEC) Variability of Low Latitude Ionosphere and Role of Dynamical Coupling: Quiet and Storm-Time Characteristics
    (Addis Ababa University, 2014-01) Abraha, Gebregiorgis; Mengistu, Gizaw (PhD)
    The low latitude ionosphere and its coupling to lower atmosphere such as (mesosphere, stratosphere and thermosphere)and high latitude ionosphere are investigated using observational and model data. The dominant modes of variability of low latitude ionosphere are linked to Equatorial Electrojet (EEJ), Counter Electrojet(CEJ) and Prereversal Enhancement(PRE). These are investigated using magnetometer data and EEJ models. The results of the analysis reveal that EEJ undergoes day and seasonal variations. From the daily variation analysis, the EEJ value at Addis Ababa sharply increases to its peak value from 9.00-13.00 LT and dies out around 18.00 LT. EEJ versus time graphs shows that the H-components of the magnetic eld at Addis Ababa location varies by a factor of 2-4 times larger compared to Adigrat. Seasonally as both measurements and model data revealed, EEJ has signi cantly increased during E season compared to D and J seasons. Our observation also shows that counter CEJ are more frequent on solstices than equinoxes and on the contrary Morning Counter Electrojets (MCEJ) occurs more frequently on equinoxes than solstices. Apart from that the localized EEJ, CEJ and PRE, low latitude ionosphere is dynamically coupled to lower atmosphere and high latitude ionosphere that control both low latitude ionospheric dynamics and chemistry during both quiet and storm-time. In this regard, the storm-time low latitude ionospheric total electron content (TEC) variability and the in uences of lower and high latitude ionsophere are investigated. The TEC variation is characterized in relation to diurnal, seasonal, temporal, spatial and longitudinal behaviors. The diurnal characteristics of TEC can be explained in terms of the Diurnal, Semidiurnal,Terdiurnal and Quterdiurnal tides. The TEC vii viii climatology from NeQuick and ionosonde is also compared during both quiet and geomagnetically disturbed days. Day time enhanced TEC value followed by night time depilation is a typical behavior of the ionosphere. A geomagnetic storm occurred during January 22-25, 2012. The Disturbance storm time (Dst) values for the period shows that it is a moderate intensity geomagnetic storm. The geomagnetic storm is characterized by di erent indices and indicators. The Symmetric H component of ring current (SYM􀀀H) value on January 22 shows a sudden increase to more than 50 nT at the Sudden Storm Commencement (SSC) and followed by sharp decrease to a value of -100 nT after which a recovering started. A second SSC on January 24 followed by a shock on January 25. These SSCs before the main storms on January 22 and 25 are evidences for the occurrence of Coronal Mass Ejection (CME). Moreover, the short recovery period, unlike that of Co-rotating Interaction Regions (CIR) driven geomagnetic storms, implies the geomagnetic storm is a CME-driven. The sudden jump of the solar wind dynamic pressure and the The southward Interplanetary Magnetic Field (IMF Bz) are also consistent with occurrence of CME. Our observational evidences of Proton uxes of high energy ranges and increase in proton density are also other indicators for occurrence of CME. The high values Auroral Electrojet (AE) index on these dates implies ionospheric perturbation in response to the storm. This is also re ected in the Total Electron Content (TEC) change during the storm relative to quiet day TEC over the polar regions. The response of the ionospheric to geomagnetic storms is also investigated from amplitude modulation of wave components that account for the majority of TEC variance during the period. The diurnal and semidiurnal TEC variances account upto a maximum of 83% and 30% of the TEC variance over fairly exclusive ionospheric regions respectively. The diurnal variability dominates the subtropical latitude where the solar cycle is an important factor while the semidiurnal variance is limited to higher latitudes. The diurnal and semidiurnal TEC variances show hemispheric asymmetries. The stationary planetary waves also account for TEC variances that exceed semidiurnal TEC variance and exhibit hemispheric asymmetry ix of opposite sign to diurnal TEC variance. These features of TEC variance are climatology of TEC variability irrespective of the storms. However, the impact of the geomagnetic storms are distinctly marked in the daily time series of amplitudes of diurnal and semidiurnal migrating tides and stationary planetary waves. The abrupt changes in amplitudes of diurnal (upto 5 TECU) and semidiurnal (upto 2 TECU) migrating tides are observed within the 20oS-20oN latitude band and along 20oN respectively while that of stationary planetary wavenumber 1 is in the order of 3 TECU and is mainly localized along 20oS