Demonstrating Effects of Current and Projected Rainfall Characteristics on Wheat yield has been investigated in Sinana district for the period 1995-2016. Data on rainfall and crop yield for the period 1995-2016 were o...Demonstrating Effects of Current and Projected Rainfall Characteristics on Wheat yield has been investigated in Sinana district for the period 1995-2016. Data on rainfall and crop yield for the period 1995-2016 were obtained from National Meteorological Agency and Sinana District Agricultural Offices, respectively. Following data quality checking, rainfall data (current and future), correlation and regression studies were analyzed using Statistical software like Instat V3.36 and SPSS V20. Downscaling the output of CSIRO-Mk3.6.0 GCM model (daily rainfall data) for RCP8.5 emission scenario using a web based software tool (Marksim GCM) for the period 2020-2049 were used to determine seasonal total rainfall and ascertain its impact on yield. This study used mean, coefficient of variation, correlation and regression analysis to ascertain the relation, cause and effect relationship between rainfall characteristics and wheat yields. The results indicated that the mean onset date of the main rainy season (JJAS) for Robe and Sinana station was June 30 and July 3. Furthermore, the results of Pearson Correlation Coefficients indicated that kiremt rainfall total (JJAS) had moderate positive relationship (r = 0.499) with wheat yield in the study area. It was also observed that nearly fifty percent of total variance of crop yield is explained jointly by kiremt rainfall total and rainy day (R2 value was 47.9%). The result of projected wheat yield indicated that there will be a slight decrease in wheat yield (qt/ha) after 2030 years due to the impact of expected weakening of kiremt rainfall total. Taking in to account the above findings, it could be suggested that the farmers’ community will be encouraged encouraged to utilize timely climate information issued from National Meteorological Agency of Ethiopia (NMA) and other centers for farm level decision to enhance their crop production.展开更多
In this study, we unveil atmospheric circulation anomalies associated with the large-scale tropical teleconnections using National Center for Environmental Prediction (NCEP) reanalysis dataset. Composite analyses have...In this study, we unveil atmospheric circulation anomalies associated with the large-scale tropical teleconnections using National Center for Environmental Prediction (NCEP) reanalysis dataset. Composite analyses have been performed to know the impact of large-scale tropical circulations on the Horn of Africa. The composite analysis performed at the geopotential height of 850 Mb and 200 Mb, and precipitation rate (mm/day) during six strong El Niño and La Niña episodes revealed that the large-scale tropical variability induced climate anomalies in space and time. A substantial decrease in upper-level height (200 Mb) has been observed in the study area during El Niño composite years as compared to the La Niña years. During El Niño conditions, the upper-level divergence initiates low-level vertical motion, thereby enhancing convection, however, during La Niña composite years, nearly contrasting situations are noticed in Belg (February to May) season in Ethiopia. However, geopotential height anomalies at 850 Mb are above-normal during the strong El Niño years, suggesting suppressed convection due to vertical shrinking and enhancement of divergence at the lower level. Compared to the Belg (February to May), geopotential anomalies were generally positive during the Kiremt (June to September) season, thereby suppressing the rainfall, particularly in Southern Ethiopia and Northern Part of Kenya. In contrast, an increase in rainfall was observed during the Belg season (February to May).展开更多
文摘Demonstrating Effects of Current and Projected Rainfall Characteristics on Wheat yield has been investigated in Sinana district for the period 1995-2016. Data on rainfall and crop yield for the period 1995-2016 were obtained from National Meteorological Agency and Sinana District Agricultural Offices, respectively. Following data quality checking, rainfall data (current and future), correlation and regression studies were analyzed using Statistical software like Instat V3.36 and SPSS V20. Downscaling the output of CSIRO-Mk3.6.0 GCM model (daily rainfall data) for RCP8.5 emission scenario using a web based software tool (Marksim GCM) for the period 2020-2049 were used to determine seasonal total rainfall and ascertain its impact on yield. This study used mean, coefficient of variation, correlation and regression analysis to ascertain the relation, cause and effect relationship between rainfall characteristics and wheat yields. The results indicated that the mean onset date of the main rainy season (JJAS) for Robe and Sinana station was June 30 and July 3. Furthermore, the results of Pearson Correlation Coefficients indicated that kiremt rainfall total (JJAS) had moderate positive relationship (r = 0.499) with wheat yield in the study area. It was also observed that nearly fifty percent of total variance of crop yield is explained jointly by kiremt rainfall total and rainy day (R2 value was 47.9%). The result of projected wheat yield indicated that there will be a slight decrease in wheat yield (qt/ha) after 2030 years due to the impact of expected weakening of kiremt rainfall total. Taking in to account the above findings, it could be suggested that the farmers’ community will be encouraged encouraged to utilize timely climate information issued from National Meteorological Agency of Ethiopia (NMA) and other centers for farm level decision to enhance their crop production.
文摘In this study, we unveil atmospheric circulation anomalies associated with the large-scale tropical teleconnections using National Center for Environmental Prediction (NCEP) reanalysis dataset. Composite analyses have been performed to know the impact of large-scale tropical circulations on the Horn of Africa. The composite analysis performed at the geopotential height of 850 Mb and 200 Mb, and precipitation rate (mm/day) during six strong El Niño and La Niña episodes revealed that the large-scale tropical variability induced climate anomalies in space and time. A substantial decrease in upper-level height (200 Mb) has been observed in the study area during El Niño composite years as compared to the La Niña years. During El Niño conditions, the upper-level divergence initiates low-level vertical motion, thereby enhancing convection, however, during La Niña composite years, nearly contrasting situations are noticed in Belg (February to May) season in Ethiopia. However, geopotential height anomalies at 850 Mb are above-normal during the strong El Niño years, suggesting suppressed convection due to vertical shrinking and enhancement of divergence at the lower level. Compared to the Belg (February to May), geopotential anomalies were generally positive during the Kiremt (June to September) season, thereby suppressing the rainfall, particularly in Southern Ethiopia and Northern Part of Kenya. In contrast, an increase in rainfall was observed during the Belg season (February to May).
