Belg Rainfall Research Articles

Spatiotemporal climate variability and food security implications in the Central Ethiopia Region

Studies focusing on the spatiotemporal distribution of climatic parameters and meteorological drought are of paramount significance for countries like Ethiopia, where climate change and variability cause major losses to rain-dependent agriculture. In this study, the National Meteorology Institute of Ethiopia provided an Enhanced National Climate Services (ENACTS) dataset at a spatial resolution of approximately 4 km by 4 km over 38 years (1981–2018) was used to study climate trends, spatiotemporal variability, and meteorological drought in the Central Ethiopia Region. Coefficient of variation (CV), Standardized Rainfall Anomaly (SRA), Standardized Precipitation Index (SPI), Mann-Kendall trend test, and Sen's slope were used for the analysis. The findings suggest that Belg rainfall (also known as "small-rain") varied greatly in space and time over the study area, with area-averaged CV of 29 % and pixel-level CVs ranging from 63 to 93 %. The average precipitation during Belg experienced a 15 % decrease from 2000 to 2019 compared to the preceding two decades, from 1981 to 1999. The maximum temperature has increased significantly during the Annual, Belg, and Bega seasons. The SPI and SRA showed that there have been multiple drought episodes with rising negative rainfall anomalies, with a drought occurring every 2.9 years during the Kiremt (also called "big rain", spanning from June to September) and Belg seasons. The growing negative rainfall anomaly, high CV, and highly significant increase in mean maximum temperature during the Belg season is concerning for food security and poverty eradication. The notable rise in rainfall during the June (sowing period) and November (harvesting period) also hurts crop production during the main cropping season. Thus, developing appropriate adaptation strategies and policies oriented toward climate-resilient agriculture is crucial to meet the global sustainable development goals (SDGs) and Africa Union's Agenda 2063.

Spatiotemporal climate variability and trends in the Upper Gelana Watershed, northeastern highlands of Ethiopia

The aim of this study was to evaluate the performance of CHIRPS and TAMSAT satellite rainfall data over the Upper Gelana watershed, where gauged meteorological data to understand the nature of the climate are scarce. In addition, variability and trends in rainfall and temperature were examined from 1983 to 2021. To evaluate satellite rainfall, categorical and continuous validation statistics were used. Trends were analyzed using Mann-Kendall, Sen's Slope estimator, and innovative trend analysis (ITA) methods. The study also utilized time-series geostatistical analysis techniques. The validation statistics show that TAMSAT performs better on the daily timescale, while the two products have comparable performance on the monthly timescale. TAMSAT was chosen for rainfall analysis because of its higher resolution and performance. The results reveal high inter-annual spatiotemporal variability and strong irregularities in monthly rainfall. The Mann-Kendall test indicates statistically significant positive trends in kiremt and annual rainfall, but belg rainfall exhibits an insignificant negative trend. In the kiremt season, we found a 96.1, 101.6, and 104.8 mm decadal rate of rainfall increment in the lower weina dega (LWD), upper weina dega (UWD), and dega agroecological zones, respectively. In contrast, belg season rainfall declined by 16.4, 16.2, and 14.0 mm per decade in the LWD, UWD, and dega agroecology zones, respectively. The pixel-wise trend analysis also revealed trends and magnitudes of monthly, seasonal, and annual rainfall that vary across the study area. In both LWD and UWD annual minimum and maximum temperatures, respectively, showed significant decreasing and increasing trends, but in dega agroecology the trends were insignificant. The findings of rainfall and temperature trends using the ITA method demonstrated its ability to discover some hidden trends that were not detected by the MK test.

Temporal rainfall variability and drought characterization in Cheleka Watershed, Awash River Basin, Ethiopia

Study regionCheleka Watershed, lower Awash River Basin, Ethiopia. Study focusThe lower part of Awash River (Cheleka Watershed) with an area of 1744.48 km2 has limited rainfall temporal variability and drought incidence data. So, the study analyzed the temporal rainfall variability and drought incidence from five meteorological station starting from1988 up to 2017. Coefficient of variation, precipitation concentration index, mean and standard deviation were computed to analysis the temporal variations of rainfall; frequency and severity of droughts were characterized through rainfall anomalies indexes (RAI) and standardized precipitation indexes (SPI). New hydrological insights for the regionThe study found that, mean annual rainfall with a range value of 908.90 mm - 1181.48 mm in Batie and Majetie station respectively. Kiremt rainfall total with the highest coefficient of variation (22.93–29.12%) next to Belg rainfall total (39.31–52.43%) and the lowest variations of annual rainfall total (15–22.59%). Frequency of drought in 12 month’s interval indicates severely dry droughts, most frequently next to moderately dry drought. The maximum frequency for severely dry (8.61%) and moderately dry (11.39%) drought were occurred in Kemisse station. The longest duration and the highest magnitude drought were occurred in Kombolcha station next to Kemisse. As recommendation, since, this study was focused only temporal rainfall variability and drought characteristic, it is better that, future research will be conducted to evaluate the spatial rainfall variability and hydrological drought severity nature and its impact on socio-economic and human well-beings in the area.

Local and regional climate trends and variabilities in Ethiopia: Implications for climate change adaptations

Ethiopia is experiencing considerable impact of climate change and variability in the last five decades. Analyzing climate trends and variability is essential to develop effective adaptation strategies, particularly for countries vulnerable to climate change. This study analyzed trends and variabilities of climate (rainfall, maximum temperature (Tmax), and minimum temperature (Tmin)) at local and regional scales in Ethiopia. The local analysis was carried out considering each meteorological station, while the regional analyses were based on agro-ecological zones (AEZs). This study used observations from 47 rainfall and 37 temperature stations obtained from the Ethiopian Meteorological Institute (EMI) for the period of 1986 to 2020. The Modified Mann-Kendall (MMK) trend test and Theil Sen's slope estimator were used to analyze the trends and magnitudes of change, respectively, in rainfall as well as temperature. The coefficient of variation (CV) and standardized anomaly index (SAI) were also employed to evaluate rainfall and temperature variabilities. The local level analysis revealed that Bega (dry season), Kiremt (main rainy season), and annual rainfall showed increasing trend, albeit no significant, in most stations, but the rainfall in Belg (small rainy) season showed a non-significant decreasing trend. The regional levels analysis also indicated an increasing trend of Bega, Kiremt, and annual rainfall in most AEZs, while Belg rainfall showed a decreasing trend in the greater number of AEZs. The result of both local and regional levels of analysis discerned a spatially and temporally more homogeneous warming trend. Both Tmax and Tmin revealed an increasing trend in annual and seasonal scales at most meteorological stations. Likewise, an increase was recorded for mean Tmax and Tmin in entire/most AEZs. The observed trends and variabilities of rainfall and temperature have several implications for climate change adaptations. For example, the decrease in Belg rainfall in most AEZs would have a negative impact on areas that heavily depend on Belg season's rainfall for crop production. Some climate adaptation options include identifying short maturing crop varieties, soil moisture conservation, and supplemental irrigation of crops using harvested water during the main rainy season. Conversely, since the first three months of Bega season (October to December) are crop harvest season in most parts of Ethiopia, the increase in Bega rainfall would increase crop harvest loss, and hence, early planting date and identifying short maturing crops during the main rainy season are some climate adaptation strategies. Because of the increase in temperature, water demand for irrigation during Bega season will increase due to increased evapotranspiration. On the other hand, the increase in Kiremt rainfall can be harvested and used for supplemental irrigation during Bega as well as the small rainy season, particularly for early planting. In view of these findings, it is imperative to develop and implement effective climate-smart agricultural strategies specific to each agro-ecological zone (AEZ) to adapt to rainfall and temperature changes and variabilities.

Performance variations of global precipitation products in detecting drought episodes in three wet seasons in Ethiopia: Part II—statistical analysis

AbstractThe need to evaluate global climate data has increased in recent times. In this study, we evaluate the ability of global precipitation products to monitor drought during three wet seasons (Belg/March–May, Kiremt/June–September and Autumn/September–November) and associated rainfall regions in Ethiopia. We employed statistical methods to quantify and evaluate precipitation products based on probability of drought detection (POD), the extent of false alarms (FAR) and the critical success index (CSI) to see the overall performance of the studied precipitation products. The majority of the studied precipitation datasets were relatively better in capturing the Autumn drought in southern Ethiopia, and 18 out of 21 precipitation products captured accurately more than 50% of observed droughts. The CSI scores for this season are also above 0.5 for 14 precipitation products. On the other hand, 15 and 14 precipitation products accurately captured more than 50% of the seasonal drought in Kiremt and Belg rainfall seasons in north‐eastern Ethiopia. In contrast, most precipitation products do not clearly represent the drought conditions of the Kiremt season in north‐western Ethiopia. Only 8 of the 21 precipitation products accurately captured more than 50% of the observed drought in this region, and only 6 precipitation products had a CSI score greater than 0.5. The results can facilitate the selection of precipitation products for drought monitoring purposes, for use in specific wet seasons and regions of Ethiopia.

Impacts of climate change on crop growing season characteristics in Northern Ethiopia

Abstract Understanding the likely impact of climate change on crop growth is very important to identify possible areas of intervention and consider climate-related impacts. This study aimed to investigate the future impact of climate change on the crop growing season in the Tigray region. Five global climate models under two representative concentration paths were projected for future periods using a delta downscaling approach. Results indicate that projections of rainfall showed an increase in annual and summer (Kiremt) rainfall at most stations. However, the Belg rainfall season had a declining trend except under RCP4.5 in a mid-term period that showed positive changes at most stations. On the contrary, projections of maximum and minimum temperatures indicated a continuous increase. In line with the increase in temperatures, the reference evapotranspiration consistently increased at all stations. Cumulatively, late onset and early cessation of rainfall are observed, accompanied by a 5.5–19% reduction in the length of the growing period (LGP), exacerbating the current short LGP in the study area and affecting the proper growth and maturity of major crops. The findings of this study have global implications in that similar areas may be alarmed to get prepared ahead and develop adaptive and sustainable crop production strategies.

ASSESSING COMMUNITY PERCEPTION ON CLIMATE CHANGE AND VARIABILITY, ITS IMPACTS IN ANLEMO WOREDA, HADIYA ZONE SOUTHERN NATION NATIONALITIES AND PEOPLES

The study assessed the rural community's perception of climate change and variability, its impacts, and adaptation strategies in Anlemo woreda. The study used purposive sampling techniques to select woreda and both kebeles. The sizes of the sample household respondents were 191 each, and 30 participants were from female-headed households. Both qualitative and quantitative methods of data collection and analysis were used. A time-series analysis was used to show the trend of temperature and rainfall. The researcher used the Coefficient of variation and percent of deviation to discern rainfall variability. The findings of the study showed that both maximum and the average temperature had increased, belg rainfall had decreased, whereas annual and Meher rainfall had increased and showed inter-annual and seasonal variation. The researchers also showed that the district is experiencing increasing land degradation, spatially soil erosion, nutrient depilation, and deforestation are perceived as impacts of climate variability. The results revealed that most people perceived long-term variability in the pattern of rainfall amount and distribution and an increasing trend and variability of temperature. Therefore, farmers are undertaking different adaptation and coping mechanisms. Providing training, increasing accessibility to infrastructure, the credit services market, and introducing new technologies are forwarded as recommendations.

Impact of rainfall variability on crop yields and its relationship with sea surface temperature in northern Ethiopian Highlands

Knowing the spatial and temporal variation of rainfall is crucial for the management of agricultural productivity. This study aimed at evaluating rainfall variability impact on crop yields and its relationship with sea surface temperature using GIS and statistical techniques in North and South Wello zones, northern Ethiopian Highlands. In this study, 30 years (1984–2013) time series data of rainfall from National Centers for Environmental Prediction’s Climate Forecast System Reanalysis and National Meteorological Agency, sea surface temperature from National Oceanic and Atmospheric Administration, and crop data from Central Statistical Agency were used. With regard to spatial and temporal distribution of rainfall, the highest amount of mean total Kiremt/summer and annual rainfall was 993.71 mm and 1715.95 mm, respectively. The magnitude of mean total Kiremt and annual rainfall temporal and spatial variations, using percentage of coefficient variation, was ranging from 24.8 to 62% and from 23.13 to 57.86%, respectively. The correlation between total Kiremt and Belg rainfall with mean sea surface temperature was negative (r = −0.457) and positive (r = 0.385), respectively and statically significant at alpha 0.05 level. From the regression analysis, it was observed that the variation of crop production was explained by the variation of rainfall. For instance, the impact of mean Kiremt rainfall accounted for 47.5% (R2 = 0.475) of variations in sorghum. Generally, the analysis of this study revealed that rainfall variability is one of the major determinant factors for variation of major crop yields in the study area, and this information might be used as an input for decision-makers take appropriate adaptive measures in various agricultural and water resource sectors. For instance, this study recommends the expansion of irrigation and water management practice and promoting perennial trees like fruits and drought-resistant crops.

Seasonal rainfall variability and its correlation with potential drivers over Western Oromia

Characterizing seasonal rainfall and identifying its association with the climate drivers are important to produce reliable seasonal climate forecasts of a given area. This study examined the rainfall variability and its relationships with SST, SLP and sunspot indices by statistical methods over Western Oromia. The regional is characterized by monomodal pattern of 60% seasonal rainfall contribution in Kiremt season. High temporal anomaly rainfall but no extremes were observed from 1981-2017. An insignificant decreasing Kiremt and Belg but, an increasing Bega trend was observed. ENSO and PDO/ DMI and AMO showed negative/ positive correlation with kiremt rainfall. ENSO, DMI and AMO showed positive correlation for belg rainfall whereas, PDO showed associated negatively for the most parts of the region. PSI to kiremt/Belg rainfall correlation showed significant positive/Negative spatial association over the western part (West Wolega and Illubabor) / the East part (Jimma & East wollega) of the region. The results showed that there is decreasing trends in rainfall anomalies for main rainy seasons of region and good correlations these various indices. Therefore, it is suggested that seasonal climate predictions may consider these large-scale determinants oscillation indices like AMO and PDO in predicting climatic events. Â

Perception of Impacts of Climate Variability on Pastoralists and Their Adaptation/Coping Strategies in Fentale District of Oromia Region, Ethiopia

Climate change has been threatening pastoral communities in Ethiopia as their economy is mainly based on rain-fed agriculture. The study area is one of the climate change prone area affected by climate induced shocks. To reduce the adverse effects of climate change, pastoral households need to recognize the changes already happening in their climate and employ climate change adaptation measures. Therefore, the present study was conducted in Fentale district, Central Ethiopia to determine the perceived adverse impacts of climate change and variability, the perception of pastoral households on the patterns of climate change and variability, and identify the adaptation/coping strategies of pastoralists to climate change impacts. A household questionnaire survey and focus group discussion were employed to collect primary data at a household level. A total of 130 pastoral households were sampled using random sampling. The data collected from household survey were analyzed using SPSS (version 20). The rainfall and temperature trends of the study area were analysed using Mann–Kendall test. The findings indicated significant decreasing trend of Belg rainfall and increasing trend of Kiremt rainfall for the period 1983–2017. The perception of pastoral households on rainfall and temperature trends was in line with the results of the recorded meteorological data analysis of the present study except the Kiremt rainfall and the long-term annual rainfall trends. The results indicated that pasture and water availability became scarce and livestock assets and productivity were highly reduced, due to adverse impacts of climate change and variability. The most important strategies deployed by the local people included (i) integrating livestock with crop production, (ii) livestock mobility, (iii) livestock diversification and herd composition change, (iv) decreased consumption, (v) remittance, (vi) cash for work and (vii) food aid. Therefore, the government should support and enhance household’s indigenous adaptation strategies through the provision of market access, early warning information, affordable credit access, and development of water points.

Temporal variability and trend analysis of temperature and rainfall in the Northern highlands of Ethiopia

ABSTRACT This study investigates the temporal variability and trend of temperature and rainfall in Gelana sub-watershed, northern highlands of Ethiopia. The study employed a mixed methods approach, but overwhelmingly relied on gridded monthly rainfall and maximum and minimum temperature data at a resolution of 10 × 10 km. The quantitative data were analyzed using standardized rainfall anomaly, precipitation concentration index, coefficient of variation and Mann-Kendall (MK) trend analysis. The results indicated that rainfall over “Kiremit” and “Belg” seasons is found highly variable in the study area. The annual total rainfall has shown an increasing trend of 0.05 mm per year. The MK test results showed that “Kiremit” rainfall has a positive increasing trend, while Belg rainfall showed a statistically significant decreasing trend. A warming trend of annual maximum and minimum temperature has been observed over the study area. The study suggests strategies to enhance the adaptive capacity of agricultural systems and to reduce the likelihood of production risks.

Climate change and its implications for rainfed agriculture in Ethiopia

Abstract This study aims to investigate the spatio-temporal variability and trends in climate and its implications for rainfed agriculture in the Rib watershed, north-western highland Ethiopia from 1986 to 2050. The daily rainfall and temperature records for the period 1986–2017 were used to detect the variability and trends of the current climate using the coefficient of variation, precipitation concentration index, Mann–Kendall test, and Sen's slope estimator. On the other hand, future climate changes (2018–2050) were analyzed based on the Coupled Model Intercomparison Project version 5 (CMIP5) model outputs under under two representative concentration pathway (RCP) scenarios, RCP 4.5 and 8.5. The results showed high inter-seasonal and inter-annual variability of rainfall and temperature in the studied watershed over the last four decades. The annual and Kiremt (June–September) rainfall showed a generally increasing trend, while the Belg (March–May) rainfall exhibited a decreasing trend between 1986 and 2017. Conversely, the minimum, maximum and mean temperature demonstrated increasing trends over the study period although most of the detected trends were statistically insignificant at 5 and 10% level of significance. Future climate analysis results showed an increase in future temperature and annual and Kiremt rainfall while Belg rainfall declined.

Characterization of Past Seasonal Climate Variability in Oromia Special Zone, North Eastern Ethiopia

This study was undertaken in oromia special zone of Amhara National Regional State to analyze past climate variability. Gridded climate data were obtained from National Meteorology Agency of Ethiopia. Standard stastical descriptors and statistical software like Instat V3.37, MAKESENS, XLSTAT 2014 and Arc GIS 10.1 were employed for the analysis and interpretation for results. The results indicated that the OSZ experienced moderate rainfall variability in kiremt (JJAS) season and very high variability in belg (FMAM) season . Increasing trend in kiremt rainfall while decreasing trend in belg rainfall. Except belg minimum temperature, also temperature trend increased. The median of the start of belg season did not between March and May. The risk of getting 5,7,10 and 15 days of dry spells based on the fitted first order Markov chain probability values indicate in belg season the probability of dry spell occurrence of 10 days’ length was 60%. In kiremt season, the dry spell risk of being greater than10 day consecutive dry spells was less than 50%, and it is expected to occurred beteewen 178 DOY (June 26) to 262 DOY (Sept 18). District level of upcoming season climate information in terms of climate variability and encourage farmers to benefit from these services, apply adaptation and mitigation strategy are important for reduce the challenges of cropping practices in the study area. Keywords:- Belg, Kiremt, Oromia, special Variavility DOI : 10.7176/JBAH/10-1-06 Publication date: January 31 st 2020

Spatiotemporal variability and trends of rainfall and temperature in the Northeastern Highlands of Ethiopia

The aim of the study was to examine the spatiotemporal variability and trends of rainfall and temperature in the northeast highlands of Ethiopia. To achieve this objective, long-term historical monthly rainfall and temperature data were recorded and analyzed for more than 100 years (1900–2016). Gridded rainfall and temperature data were gathered from CenTrends Great Horn of Africa v1 and CRU_TS 4.01 with a resolution of 0.1° × 0.1° and 0.50 × 0.5°, respectively. The Mann–Kendall test was used to analyze the trends of rainfall data in different recording stations, and the Sen’s slope estimator was used to determine the magnitude of change. The Inverse Distance Weighted spatial analysis tool was used to illustrate the spatial trends of rainfall and temperature. The results of the coefficient of variation revealed that the decadal, annual and seasonal rainfall distributions were varied though belg rainfall found to be more variable than the others. The MK test result demonstrated that belg and annual rainfall exhibit a decreasing trend as compared to kiremt rainfall. The distribution of kiremt, belg and annual rainfall demonstrated decreasing trends at a rate of 0.432, 0.335 and 0.595 mm/year, respectively. The decadal rainfall also showed a decreasing trend at the rate of 6.537 mm/decade. On the other hand, the averages of annual, maximum and minimum temperature were increased at the rate of 0.0034, 0.0028 and 0.0095 °C/year, respectively. The decadal minimum, maximum and average temperature has shown increasing trend at the rate of 0.098 °C, 0.041 °C and 0.069 °C, respectively. An abrupt declined rainfall and increased temperature were observed since the 1970s. Climate variability strongly affects rain-fed agriculture more than any other activities. Hence, policymakers and stakeholders have to give top priority in the designing and introduction of appropriate area-specific adaptive strategies to reduce the impacts on crop production over livelihood zones. Rainwater harvesting and the development of small-scale irrigation schemes could be taken as viable options where rainfall is scarce and more variable.

Spatial and temporal climate variability and change in the bilate catchment, central Rift Valley lakes region, Ethiopia

ABSTRACT The paper explores spatial and temporal variability of rainfall and temperature in Bilate catchment based on monthly data of 11 meteorological stations. Precipitation Concentration Index (PCI) and Pearson product moment correlation were used to estimate monthly concentrations and associations between annual and seasonal rainfall. Similar methods were used to analyze the association of ENSO with rainfall variability using Eastern Equatorial Pacific (Niño 3.4) data, Sea Surface Temperature (SST), and Southern Oscillation Index (SOI). Rainfall and temperature series were tested for trends using the Mann–Kendall test. Rainfall in the catchment is highly seasonal and concentrated in Kiremt (June–September), followed by Belg (February–May). Belg rainfall was highly variable. Annual rainfall was relatively stable in the upper catchment and variable in the lower catchment. PCI values are expected to increase as annual and seasonal rainfall decrease. The middle catchment had significant negative trends in annual and Belg rainfall. November–March SST is strongly associated with Belg rainfall variations throughout the catchment, and ~49% of the variability can be explained by Equatorial Pacific SST. Annual and seasonal temperature significantly increased in middle and lower parts of the catchment in the past 30 years. Warming was ~0.05°C/yr to 0.17°C/yr.

Watershed-Based Rainfall variability and trends of extreme rainfall events in South East Awash Basin, Ethiopia

This study presents analysis of Rainfall variability and trends of extreme rainfall events in the Oda Gunufeta -Cherecha -Dechatu watershed, Awash Drainage Basin, Eastern Ethiopia. The study employed the coefficient of variation and the Precipitation Concentration Index (PCI) as statistical descriptors of rainfall variability. The indices at the five stations were subjected to non-parametric Mann-Kendall test to detect the trend over the period between 1985 to 2014. The results of the study revealed that, the watershed experiences moderate inter-annual rainfall variability. The Belg rainfall shows high variability than Kiremt rainfall. Highest Belg & Kiremt rainfall variability is observed in Dire Dawa with coefficient of variation of 46% and 40% respectively. The annual PCI for the watershed in all the stations under investigation during the record periods showed that 100% of the years for which the annual PCI was estimated fell within the irregular precipitation distribution range or high precipitation concentration. The irregular precipitation distribution also extended to all the stations in short rainy season (Belg rainfall) and in two stations in the main rainy season (Kiremt season). With regard to the rainfall trend, the annual rainfall has showed a negative trend in most of the stations for the period 1985-2014. The Mann–Kendall trend test during the Kiremt season shows a positive trend in Dengego, Dire Dawa, Combolcha and Haramaya and the increasing tendency is significant at p<0.1 in Degego, p<0.05 in Dire Dawa, p <0.05 in Combolcha and p <0.01 in Haramaya. The heavy rainfall events, the 90th & 95th percentiles, in all the five stations showed an increasing pattern but except in Combolcha the trends are not statistically significant. This implies that the watershed has been under increased rainfall intensity and this in turn has the potential cause for high risk of flood occurrences.

Local level rainfall and temperature variability in drought-prone districts of rural Sidama, central rift valley region of Ethiopia

ABSTRACTThe purpose of this study is to examine local level spatiotemporal rainfall and temperature variability in drought-prone districts of rural Sidama, Central Rift Valley region of Ethiopia. The study used 129 gridded monthly rainfall and temperature data of 32 years (1983–2014). The gridded rainfall and temperature records were encoded into GIS software and evaluated through different statistical and geospatial techniques. Mann-Kendal rank test and F distribution tests were used to test temporal and spatial statistical significance, respectively, of the data. The analysis revealed that Belg and Kiremt are the main rainfall seasons, constituting 81% of the annual rainfall. Although annual, Kiremt, and Belg rainfall amounts appear to have decreased over time, the decreasing trend is statistically significant only for Belg rainfall records. On the other hand, rainfall standard anomaly results indicated seven droughts of different magnitudes: one extreme, two severe, and four moderate. The study also revealed increasing temperature trends over the years under consideration that are statistically significant. The findings of this study on rainfall contradict other findings obtained around the study area. Thus, climate change adaptations need to focus on location-specific climate data analysis so that the intended adaptive interventions can be successful.

Developing a satellite-based combined drought indicator to monitor agricultural drought: a case study for Ethiopia

Developing a robust drought monitoring tool is vital to mitigate the adverse impacts of drought. A drought monitoring system that integrates multiple agrometeorological variables into a single drought indicator is lacking in areas such as Ethiopia, which is extremely susceptible to this natural hazard. The overarching goal of this study is to develop a combined drought indicator (CDI-E) to monitor the spatial and temporal extents of historic agricultural drought events in Ethiopia. The CDI-E was developed by combining four satellite-based agrometeorological input parameters – the Standardized Precipitation Index (SPI), Land Surface Temperature (LST) anomaly, Standardized Normalized Difference Vegetation Index (stdNDVI) and Soil Moisture (SM) anomaly – for the period from 2001 to 2015. The method used to combine these indices is based on a quantitative approach that assigns a weight to each input parameter using Principal Component Analysis (PCA). The CDI-E results were evaluated using satellite-based gridded rainfall (3-month SPI) and crop yield data for 36 intra-country crop growing zones for a 15-year period (2001 to 2015). The evaluation was carried out for the main rainfall season, Kiremt (June-September), and the short rainfall season, Belg (February-May). The results showed that moderate to severe droughts were detected by the CDI-E across the food insecure regions reported by FEWS NET during Kiremt and Belg rainfall seasons. Relatively higher correlation coefficient values (r > 0.65) were obtained when CDI-E was compared with the 3-month SPI across the majority of Ethiopia. The spatial correlation analyses of CDI-E and cereal crop yields showed relatively good correlations (r > 0.5) in some of the crop growing zones in the northern, eastern and southwestern parts of the country. The CDI-E generally mapped the spatial and temporal patterns of historic drought and non-drought years and hence the CDI-E could potentially be used to develop an agricultural drought monitoring and early warning system in Ethiopia. Moreover, decision makers and donors may potentially use CDI-E to more accurately monitor crop yields across the food-insecure regions in Ethiopia.

Sub‐seasonal variability of the Belg rains in Ethiopia

The February–May rainfall season, locally known as Belg, contributes up to 40% of the annual rainfall over northeastern, central and southwestern Ethiopia. Its contribution exceeds 50% over southern and southeastern Ethiopia. The Belg season is characterized by significant inter‐annual and intra‐seasonal variability. However, there are only a few studies addressing the characteristics of this season. Interactions between extratropical and tropical systems across the Red Sea region play a major role in modulating the rainfall pattern during this season. It is shown in this article that the North Atlantic Oscillation (NAO) seems to play a major role in the variability of the Belg rains on the sub‐seasonal time scale. The Belg rains are negatively correlated with the NAO index over much of the region, with southern and southeastern Ethiopia exhibiting relatively highest correlation values. NAO rainfall anomaly composites also indicate that the negative (positive) phase of the NAO tends to enhance (suppress) the Belg rains. Two modes of regional circulation patterns that modulate Belg rainfall variability have also been identified in this study. A ridge/trough pattern, featuring two anomalous mid‐ to upper‐level warm anticyclones and one cold cyclonic trough in the region between the northeast Atlantic and the Arabian Peninsula, tends to suppress the Belg rainfall due to reduced tropical–extratropical interactions. In contrast, a tripole structure with two anomalous mid‐ to upper‐level cold cyclonic troughs and one warm anticyclone tends to enhance rainfall during the Belg season of Ethiopia. It is further shown in this article that the Madden–Julian Oscillation (MJO) tends to modulate rainfall during the Belg season.

Trend analysis of temperature and rainfall in south gonder zone, anhara ethiopia

This study mainly focuses on exploring trend analysis of temperature and rainfall in the case of south Gonder zone. The analysis is based on the temperature and rainfall variation in south Gonder zone over three stations at Addis Zemen, Nefas Mewcha and Mekane Eyesus. The duration of the study period for temperature and rainfall data was chosen as 1996-2015 for Addis Zemen, 1986-2015 for Nefas Mewcha and 1996-2015 for Mekane Eyesus. The Belg rainfall have been found much more variable (>30%) than the Kiremet rainfall in which the coefficient of variation is greater than 30% over the study area. The findings of the non-parametric Mann-Kendall test revealed that there was no significant trend in the annual and seasonal rainfall data whereas monthly rainfall of April and November shown statistically significant increasing trendover the study area. However, the trend was not significant, the annual, the Kiremet and monthly rainfall during June, August and November shows an increasing particularly November was also statically significant as the computed p-value is less than the significance level α = 0.05.On the other hand, the Belg rainfall and monthly rainfall of March and April shows a decreasing trend. Statistically significant increases of mean annual temperature have been found in Addis Zemen and Nefas Mocha whereas statistically insignificant decrease of mean annual temperature has found in Mekane Eyesus. On the other hand, statistically significant increase of annual maximum temperature has been found in Addis Zemen while statistically insignificant increase of annual maximum temperature have been found for Nefas Mewcha and Mekane Eyesus station. Besides, statistically significant increase of annual minimum temperature has been found in Nefas Mewcha whereas statistically insignificant increase of annual minimum temperature has been found in Addis Zemen and Mekane Eyesus. The rates of change in mean annual temperature for Addis Zemen 1.698 0 c per 20 years and Nefas Mocha 0.813 0 c per 30 years have been found greater than the rate of change which was found at national and global level. Therefore, it is recommended that small scale study should be undertaken to clearly detect the rate of climate change and to develop appropriate adaptation strategies for the given agricultural system with the prevailing climatic conditions.