Temperature and rainfall changes over East Africa from multi-gcm forced RegCM projections

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1 Temperature and rainfall changes over East Africa from multi-gcm forced RegCM projections Gulilat Tefera Diro and Adrian Tompkins - Earth System Physics Section International Centre for Theoretical Physics (ICTP) Thanks to Healthy Future project, RegCM Team Duke University, March 3, 3

2 Motivation East African Climate exhibits high spatial and temporal variability The region has complex topography and the current GCMs have difficulty in capturing this heterogeneity due to their coarse resolution Most impact models runs at sub regional scale need climate information at higher resolution than what the current CGCM could provide For instance in the Healthy Future project, high resolution climate model output are needed to produce high resolution projection of vector borne disease for East Africa.

3 Model description and setup Domain size: -S to N in and E to 9E Hydrostatic dynamical core on Arakawa B horizontal grid Land surface model: Biosphere Atmosphere Transfer Scheme (BATS) Updated version of the radiation scheme of CCM3 modified Layer Scheme of Holtslag et al 99: Large scale precipitation of Pal et al Convection scheme: Grell over land and Emanuel over the ocean Resolution : km (x grid points) in the horizontal and sigma levels in the vertical

4 Model domain and topography HadGEM topography (m) 3 3 Surface representation in RegCM is more realistic

5 Design of experiment boundary runs RegCM is forced with ERA Interim as LBC and OI-SST for surface boundary condition This configuration is performed to assess the error arise due to the regional model The integrations starts from 9 to 9 Control (present day) Integration forced with CMIP GCMs (HadGEM-ES and EC-EARTH) Integration period is between --9 to -- Future Scenario runs use the same CMIP GCMs This simulation use emission scenario of RCP. The model is restarted from the last time step of the reference run i.e. from December, and run up to December 99

6 Outline Spatial variability Temporal variability Spatial variability Temporal variability 3 Future Changes [77-99] - [93-]

7 Spatial variability: JJAS rainfall climatology CRU mean JJAS rainfall [mm/day] 3 GPCP mean JJAS rainfall [mm/day] 3 Spatial variability Temporal variability ERA Interim mean JJAS rainfall [mm/day] RegCM mean JJAS rainfall [mm/day] 3 3 RegCM follows the topographic pattern

8 Spatial variability: OND rainfall Climatology CRU mean OND rainfall [mm/day] 3 GPCP mean OND rainfall [mm/day] 3 Spatial variability Temporal variability ERA Interim mean OND rainfall [mm/day] RegCM mean OND rainfall [mm/day] 3 3 which one is correct over lake Victoria?

9 Spatial variability: JJAS m temperature climatology CRU mean JJAS m temperature [ C] 3 ERA Interim mean JJAS m temperature [ C] 3 Spatial variability Temporal variability 3 3 RegCM mean JJAS m temperature [ C] 3 3

10 Outline Spatial variability Temporal variability Spatial variability Temporal variability 3 Future Changes [77-99] - [93-]

11 Temporal variability: Annual Cycle Rainfall (mm/day) Temperature ( C) 7 3 Precipitation for East Africa (E E and S N) RegCM RCA CRU ERA Int Month Temperature for East Africa (E E and S N) 9 RegCM RCA CRU 7 ERA Int 3 Spatial variability Temporal variability Month RegCM reproduced the annual cycle very well

12 Temporal variability: inter-annual variability Rainfall (mm/day) OND precipitation over East Africa (E E and S N) 7 RegCM RCA CRU ERA Int year OND temperature over East Africa (E E and S N) 7 RegCM RCA CRU ERA Int Spatial variability Temporal variability Temperature ( C) Year Extreme events associated with ENSO are captured by the model

13 Outline Spatial variability Temporal variability Future Changes [77-99] - [93-] 3 Future Changes [77-99] - [93-]

14 Reference Period: OND rainfall GPCP mean OND rainfall [mm/day] EC EARTH OND rainfall [mm/day] for REF HadGEM ES OND rainfall [mm/day] Future Changes [77-99] - [93-] CRU mean OND rainfall [mm/day] ECEARTH RegCM OND rainfall [mm/day] HadGEM RegCM OND rainfall [mm/day] 3 3 RegCM reduced the wet bias of HadGEM 3

15 Reference Period: JJAS temperature ERA Interim mean JJAS m temperature [ C] 3 EC EARTH JJAS m temperature [ C] for REF 3 HadGEM ES JJAS m temperature [ C] 3 Future Changes [77-99] - [93-] CRU mean JJAS m temperature [ C] ECEARTH RegCM JJAS m temperature [ C] HadGEM RegCM JJAS m temperature [ C] Note the differences among the models and observations

16 Outline Spatial variability Temporal variability Future Changes [77-99] - [93-] 3 Future Changes [77-99] - [93-]

17 [Far Future - Present] OND rainfall changes ECEARTH OND rainfall change [mm/day] RCP Ref HadGEM OND rainfall change [mm/day] RCP Ref 3 3 Future Changes [77-99] - [93-] RegCM especially when forced with HadGEM suggests Eastern Africa gets slightly drier

18 [Far Future - Present] OND temperature changes ECEARTH OND m temperature change [ C] RCP Ref HadGEM OND m temperature change [ C] RCP Ref 3 EC EARTH RegCM OND m temperature change [ C] RCP Ref HadGEM RegCM OND m temperature change [ C] RCP Ref Future Changes [77-99] - [93-] N.B. difference between HadGEM and EC-EARTH.

19 Far Future - Present JJAS rainfall changes ECEARTH JJAS rainfall change [mm/day] RCP Ref HadGEM JJAS rainfall change [mm/day] RCP Ref 3 3 EC EARTH RegCM JJAS rainfall change [mm/day] RCP Ref HadGEM RegCM JJAS rainfall change [mm/day] RCP Ref Future Changes [77-99] - [93-] 3 3 The change is smaller but the RegCM tends to get dry over large area

20 mean OND rainfall changes Rainfall anomaly (mm/day) Rainfall anomaly (mm/day) OND rainfall over East Africa (E E and S N) HadGEM ES REF 3 HadGEM ES RCP EC EARTH REF EC EARTH RCP 3 Month OND rainfall change over East Africa (E E and S N) RegCM Had REF 3 RegCM Had RCP RegCM EC REF RegCM EC RCP 3 Future Changes [77-99] - [93-] Year HadGEM forced RegCM shows a drying trend but not supported by the GCM s

21 mean OND temperature changes OND temperatureover East Africa (E E and S N) Temperature anonaly ( C) 3 HadGEM ES REF HadGEM ES RCP EC EARTH REF EC EARTH RCP Month OND temperaturechange over East Africa (E E and S N) Temperature anomaly (mm/day) 3 RegCM Had REF RegCM Had RCP RegCM EC REF RegCM EC RCP Future Changes [77-99] - [93-] Year HadGEM shows more warming than EC-Earth

22 JJAS temperature changes Temperature anomaly ( C) Temperature anomaly ( C) 3 3 Temperature over Ethiopia (33E E and 7N N) HadGEM ES REF HadGEM ES RCP EC EARTH REF EC EARTH RCP Year Temperature over Ethiopia (33E E and 7N N) RegCM Had REF RegCM Had RCP RegCM EC REF RegCM EC RCP Future Changes [77-99] - [93-] Year

23 RegCM reproduce the climate over East Africa reasonably well when forced with re-analysis data Errors could propagate from GCM to RegCM and affect the result of the simulation e.g. HadGEM over Indian Ocean HadGEM and RegCM forced with HadGEM is showing more warming than EC-EARTH and RegCM forced with EC-EARTH The above analysis is based on the seasonal mean but further analysis is need to assess on the extremes Future analysis with RCP. is needed to see the climate change signal associated to the relaxed emission scenario

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