Precipitation Data from CMIP5-ESMs-RCPs Experiment: in Weyib River Basin, Southeastern Ethiopia
C. Mean Annual and Monthly Precipitation Scenarios
3.3.6. Scenarios developed for future temperatures and precipitation (2006-2100) for three averaged arbitrary spatial weather stations
A. Mean Annual and Monthly Maximum Temperature Scenarios
The predicted absolute change in monthly mean daily maximum temperature has larger extent of increase for the month of Apr 2080s 2.07°C (RCP8.5) and 1.29°C (RCP4.5) at the end of the century but for the month of Apr in 2050s time slice by 0.91°C in case of RCP2.6 scenario then decline at the end of the century in all month and time slice because of history line of RCP2.6. Opposing, the larger decrease in Sep 2080s 1.16°C and 0.67°C occurred for RCP8.5 and RCP4.5 at the end of the century and greater decrease on the month of Sep in 2050s time slice by 0.46°C in case of RCP2.6 scenario (Fig 3.16a, b, and c).
Characteristically, the absolute change in monthly mean daily maximum temperature for RCP8.5 scenario ranges -0.41 to +0.76°C in the 2020s, -0.79 to +1.41°C in 2050s and -1.16 to +2.07°C in 2080s. In case of RCP4.5 scenario, ranges -0.38 to +0.72°C in 2020s, -0.57 to +1.12°C in 2050s and -0.67 to +1.29°C in 2080s. The absolute change in monthly mean daily maximum temperature under RCP2.6 scenario ranges -0.40 to +0.70°C in the 2020s, -0.50 to +0.92°C in 2050s and -0.46 to +0.91°C in 2080s. A very slight increase of mean annual maximum temperature was in the ranges 0.03-0.06°C (RCP8.5), 0.04-0.07°C (RCP4.5) and 0.02-0.05°C (RCP2.6) (Table 3.11). The inconsistency of maximum temperature is almost same for RCP8.5 and RCP4.5 scenarios but a slight variation on the RCP2.6 scenario (Fig 3.16d).
B. Mean Annual and Monthly Minimum Temperature Scenarios
The future predicted absolute change in monthly mean daily minimum temperature has larger extent of increase on May 2080s 5.50°C (RCP8.5) and 3.24°C (RCP4.5) at the end of the century but on May in 2050s time slice 2.26°C in case of RCP2.6 scenario then decline at the end of the century in all month and time slice. Contrariwise, the larger decrease in Feb 2080s 1.77°C and 1.05°C ensued for RCP8.5 and RCP4.5 at the end of the century and larger decrease on the month of Feb in 2050s time slice by 0.79°C in case of RCP2.6 scenario (Fig 3.17a, b, and c).
Commonly, the absolute change in monthly mean daily minimum temperature for RCP8.5 scenario ranges -0.69 to +2.01°C in the 2020s, -1.17 to +3.62°C in 2050s and -1.77 to +5.50°C in 2080s. In case of an intermediate emission scenario, ranges -0.65 to +1.89°C in
2020s, -0.94 to +2.81°C in 2050s and -1.05 to +3.24°C in 2080s. The absolute change in monthly mean daily minimum temperature under RCP2.6 scenario ranges -0.60 to +1.79°C in the 2020s, -0.82 to +2.43°C in 2050s and -0.79 to +2.26°C in 2080s. An increase of mean annual minimum temperature (Table 3.12) might vary 0.78-2.15°C (RCP8.5), 0.74-1.28°C (RCP4.5) and 0.71-0.88°C (RCP2.6). Like in maximum temperature scenario, the deviation of minimum temperature is greater under RCP8.5 scenario than RCP4.5 and RCP2.6 scenarios (Fig 3.17d). Reasonably, RCP8.5 depicted the higher change in minimum temperature trend at the end of the century than the RCP4.5 and RCP2.6 scenarios.
C. Mean Annual and Monthly Precipitation Scenarios
The predicted percentage change in monthly mean daily precipitation has larger extent of increase on Sep 2080s 88.26% (RCP8.5) and 52.14% (RCP4.5) at the end of the century, but on Sep in 2050s time slice 45.26% in case of RCP2.6 scenario then decline at the end of the century in all month and time slice. In opposition, the larger decrease on Dec 2080s 36.22%
and 13.47% resulted for RCP8.5 and RCP4.5 at the end of the century and larger decrease on Feb in 2050s time slice by 12.82% in case of RCP2.6 scenario (Fig 3.18a, b, and c).
Mostly, the percentage change in monthly mean daily precipitation for RCP8.5 scenario ranges -10.77 to +36.02% in 2020s, -29.31 to +62.46% in 2050s and -36.22 to +88.26% in 2080s. In case of RCP4.5 scenario, Varies -11.43 to +32.66% in 2020s, -12.82 to +50.68% in 2050s and -10.28 to +52.14% in 2080s. The percentage change in monthly mean daily precipitation under RCP2.6 scenario ranges -7.85 to +39.96% in 2020s, -13.47 to +45.26% in 2050s and -7.74 to +40.70% in 2080s. A sizeable increase of mean annual precipitation (Table 3.13) was found to be in the ranges 15.59-24.00% (RCP8.5), 11.04-15.16% (RCP4.5) and 9.84-13.32% (RCP2.6). As shown in Fig 3.18d the unevenness of precipitation is greater under RCP8.5 scenario than RCP4.5 and RCP2.6 scenarios. An interesting point here is that the variation of precipitation under RCP2.6 is higher than that of RCP4.5 at the end of the century. Accordingly, RCP8.5 shows a higher change in precipitation trend at the end of the century than the RCP4.5 and RCP2.6 scenarios.
Figure 3.16a (top left): Monthly mean daily absolute change in maximum temperature from base period in three future time slice under RCP2.6 scenario for three averaged spatial stations, b (top right): same as fig 3.16a but for RCP4.5, c (bottom left): same as fig 3.16a but for RCP8.5, d (bottom right): future trend of mean annual maximum temperature for three averaged spatial stations
Figure 3.17a (top left): Monthly mean daily absolute change in minimum temperature from base period in three future time slice under RCP2.6 scenario for three averaged spatial stations, b (top right): same as fig 3.17a but for RCP4.5, c (bottom left): same as fig 3.17a but for RCP8.5, d (bottom right): future trend of mean annual minimum temperature for three averaged spatial stations
Figure 3.18a (top left): Monthly mean daily percentage change in precipitation from base period in three future time slice under RCP2.6 scenario for three averaged spatial stations, b (top right): same as fig 3.18a but for RCP4.5, c (bottom left): same as fig 3.18a but for RCP8.5, d (bottom right): future trend of mean annual precipitation for three averaged spatial stations
3.3.7. Scenarios developed for future temperatures and precipitation (2006-2100) for a