All rural livelihood systems in Ethiopia are highly sensitive to climate. Rainfall is the primary climatic factor that directly affects Agriculture, hydrological dynamics and driver of food insecurity. It varies across space and time. The study aims to analyses spatial-temporal variability of rainfall and its association with SSTs by using statistical method over western Oromia, southwest Ethiopia. Annual and Kiremt rainfall distribution increases toward the central portion of the area from the east and west. Inter-annual and Kiremt rainfall variability varies from low to moderate (CV%=11 to 24%).
The MK-trend test show an increasing change in annual and seasons. Mean onset date is more variable than cessation and late one to two week from previous studies. This may be a signal of climate change impact on the region. Earliest onset in Jimma zone, mean date in the last decade of March and the latest onset in the first decade of May in west Wollega. Belg and kiremt precipitation to SSTs showed statically relationship over different parts of Oceans.
Central and tropical eastern Pacific is negatively correlated to kiremt (summer) rains over whole western Oromia zones and Spring (Belg) rainfall anomalies to SSTs in the region show a no significant spacial correlation relationship over most parts of oceans. The study revealed the climatology of rainfall and local variability which is necessary information for users to respond with local relevance in agriculture operation and hydrological management.
Table of Contents
1. Introduction
2. Materials and Methods
2.1 Descriptions of the study area
2.2 Methods of data analysis
3. Results and Discussions
3.1 The spatial and temporal distribution and pattern of rainfall climatology
3.2 Variability of Onset, cessation and Length of the Growing Period (LGP)
3.3 Number of rainy days
3.4 Trend Analysis of Annual and Seasonal Rainfall
3.5 Correlation of Rainfall to SST
4. Conclusions and Recommendations
5. References
Research Objectives and Key Topics
This study aims to examine the spatial-temporal variability of rainfall over western Oromia, Ethiopia, and to investigate the statistical relationship between local precipitation patterns and sea surface temperatures (SSTs) to better inform agricultural and hydrological management.
- Analysis of spatial and temporal rainfall distribution patterns.
- Assessment of rainfall onset, cessation, and length of the growing period (LGP).
- Investigation of rainfall trends using Mann-Kendall and Sen's slope estimator methods.
- Evaluation of correlation between seasonal rainfall and sea surface temperatures.
- Climatological characterization for enhanced agricultural decision-making.
Excerpt from the Book
3.1 The spatial and temporal distribution and pattern of rainfall climatology
Mean annual and kiremt rainfall distribution over Western Oromia increases toward the central portion of the area from the east and west because of the local topography. The annual rainfall climatology is characterized by large spatial variations which range from less than 1277mm/year over West Wollega to 2070mm/year over East Wollega zone. Seasonally, 291.8 to 532.9 mm, 729.3 to 1325.6 mm and 144.2 to 317.7 mm contribution come from Belg, kiremit and bega respectively (Table 3). During the Kiremt season (JJAS), the central parts of the study area received high rainfall up to 78% (Nekemt) of the annual rainfall and its distributions decreases to 53% southward both from the east and west (Illubabor & jimma zones. Inversely, Belg (FMAM) &Bega (ONDJ) seasonal rainfall increases southward from east and west (Illubabor&jimma zones) upto 30% and 17% of the annual rainfall respectively and this is due to ITCZ position. (Figures 2). The mean Belg and Bega rainfall varies from 320mm (at WW & EW) to 530mm (at Jimma & Illubabor) and from140mm to 317mm over the Wollega and Jimma and illubabor areas, respectively. The Belg and Bega rainfall over Jimma & Illubabor zones is higher than the main rainy season fall in the lowland areas of Ethiopia as studies by Wagesho (2013) and Misganaw (2014).
Summary of Chapters
1. Introduction: Discusses the significance of climate variability and its critical impact on agricultural productivity and food security in Ethiopia.
2. Materials and Methods: Describes the study area, the datasets used (gauge data and SSTs), and the statistical techniques for trend and correlation analysis.
3. Results and Discussions: Presents the findings regarding rainfall climatology, trends in seasonal precipitation, variability in growing periods, and associations with sea surface temperatures.
4. Conclusions and Recommendations: Synthesizes the core findings and suggests further research paths for climate-related studies in the region.
5. References: Provides a comprehensive list of literature and sources consulted for the study.
Keywords
SSTs, climate change, season, Onset, cessation, length of growing period, rainfall variability, western Oromia, Ethiopia, Mann-Kendall test, agriculture, hydrological management, ITCZ, precipitation, climatology.
Frequently Asked Questions
What is the core focus of this research?
The research focuses on analyzing the spatial and temporal variability of rainfall in western Oromia, Ethiopia, and determining how these patterns relate to global sea surface temperatures.
What are the primary thematic areas of the study?
The study covers rainfall climatology, seasonal trends, the onset and cessation of rain, the length of the growing period (LGP), and the statistical influence of SSTs on regional precipitation.
What is the main objective of the paper?
The primary goal is to provide reliable climate data to support agricultural planning, crop production management, and hydrological design in the study region.
Which scientific methods are employed?
The study utilizes the Inverse Distance Weighting (IDW) method, the Mann-Kendall trend test, Sen's slope estimator, and Pearson’s correlation coefficient for statistical evaluation.
What does the main body cover?
It details the geographical and climatic characteristics of the study area, provides statistical analysis of rainfall patterns from 1985 to 2016, and maps the correlations between rainfall anomalies and SSTs.
Which keywords define the work?
Key terms include SSTs, climate change, rainfall variability, onset, cessation, and length of growing period (LGP).
How is the rainy season onset defined in this study?
The onset is defined as a period receiving 20mm of rainfall over three consecutive days, without being followed by a dry spell of more than ten days within the next 30 days.
What is the significance of the relationship between SSTs and rainfall?
The study finds that sea surface temperatures in the central and tropical eastern Pacific have a negative correlation with Kiremt (summer) rainfall in western Oromia, suggesting a teleconnection that influences regional water availability.
- Citar trabajo
- Kefiyalew Alandu (Autor), 2019, Spatial-Temporal Rainfall Variability and Its Relationship With Sea Surface Temperature Over Western Oromia, Múnich, GRIN Verlag, https://www.grin.com/document/512109
