Performance evaluation on Sub-Saharian Africa region from high resolution simulations with

COSMO-CLM

Cava dé Tirreni, 30 August -2 September 2011

Paola Mercogliano, CIRA and CMCCEdoardo Bucchignani, CIRA and CMCCMyriam Montesarchio, CMCCEnrico Scoccimarro, INGV and CMCC

1. Outlook

•The CLUVA project•The domains simulated•List of simulations and status•NIGERIA- World Bank: validation over Nigeria•The West domain: validation•The Lower East domain: validation•Conclusions

Project Co-ordinator: AMRA, Center of Competence in the field of Analysis and Monitoring of Environmental Risk, Italy The project objective is to develop methods and knowledge to be applied to African cities, to manage climate risks, to reduce vulnerabilities and to improve their coping capacity and resilience towards climate changes. The project will explore the issues of climate change vulnerability, resilience, risk management and adaptation in selected African cities with local partners.

Task 1.1: Model projection of climate change (Leader: CMCC)

The aim is to set up methods and work out probabilistic scenarios of climate change affected hazards having a resolution that fits for regional and urban systems (for the 5 selected cities) and related uncertainties. More detailed aims are:

• To produce downscaled regional climate scenarios (IPCC scenarios: RCP4.5 and RCP8.5) for selected African areas surrounding the African cities of interest, at high resolution (about 8 km). Boundary from CMCC-MED.

• To produce very high resolution projection (about 1-2 km) for the climate of some African cities using specific and accurate statistical techniques

2. CLUVA – Climate change and urban vulnerability in Africa

3. Areas of interest for CLUVA 1950-2050

WEST Domain: (18 W -15.17 E; 3.3 – 16.8 N)(18 W -15.17 E; 3.3 – 16.8 N)465 x 190 grid points465 x 190 grid points

Spatial Resolution: 8 kmEAST Domains: N (34.4 – 42.9 E; 6.1N – 12.5N)(34.4 – 42.9 E; 6.1N – 12.5N) 120 x 90 grid points120 x 90 grid points

S (34.5 – 41.3 E; 11.8S – 2.1S)(34.5 – 41.3 E; 11.8S – 2.1S) 95 x 135 grid points95 x 135 grid points

St.Louis (16.5 W, 16.03 N) Ougadougou (1.55 W, 12.37 N)Douala (9.71 E, 4.045 N)

Addis Abeba (38.75 E, 9.02 N)Dar es Salaam (39.27 E, 6.82 S)

4. West Domain : orography of the area

Area of interest: (18W-15.17 E ; 3.3–16.8 N)(18W-15.17 E ; 3.3–16.8 N)

Extension: 3491 x 1489 kmComputational grid: 465x190 grid points;

40 levels

5. Lower east domain

Area of interest: (34.54 - 41.26E ; 11.8 – 2.2 S)(34.54 - 41.26E ; 11.8 – 2.2 S) Extension: 747 x 1064 km Computational grid: 95x135 grid points;

40 levels

Orography of the area

6. Upper east domain

Area of interest: (34.45 - 43.03E ; 6.16 – 12.59 N)(34.45 - 43.03E ; 6.16 – 12.59 N) Extension: 952 x 714 km Computational grid :120x90 grid points;

40 levelsOrography of the area

7. Details of the Numerical simulations

8 km resolution

• Supercomputer used: Cluster of 30 IBM P575 nodes (32 cores per node) (peak power 18 TF)

• Driving data: CMCC-MED 80 km resolution • Time step: 40 sec.• Numerical scheme: Runge-Kutta 2-time level HE-VI integration• Simulated periods and domains :

1970-2065 (A1B scenario, only for west domain) 1950-2050 (RCP4.5 and RCP8.5 scenarios,

for west domain and east domains)

8. List of simulations

• Scenario A1B West domain 1970- 2065 (completed)

• Scenario RCP 4.5 Lower East domain 1950-2050 (completed) • Scenario RCP 4.5 Upper East domain 1950-2050 (completed)

• Scenario RCP 4.5 West domain to be completed within November 2011• Scenario RCP 8.5 Lower East domain to be completed within November 2011 • Scenario RCP 8.5 Upper East domain to be completed within January 2012 • Scenario RCP 8.5 West domain to be completed within January 2012

9. NIGERIA- World Bank

(from Climate Risk Analysis in Nigeria, Interim Report, June 2011)

Validation over Nigeria region: T2M (1976-2005)

T2m yearly averaged value history

10. NIGERIA- World Bank

Validation over Nigeria region: Total Precipitation

(from Climate Risk Analysis in Nigeria, Interim Report, June 2011)

Total precipitation yearly averaged value history

11. NIGERIA- World Bank

Climate projection over Nigeria region: T2M (up to 2065)

(from Climate Risk Analysis in Nigeria, Interim Report, June 2011)

12. NIGERIA- World Bank

Climate projection over Nigeria region: Total Precipitation (up to 2065)

(from Climate Risk Analysis in Nigeria, Interim Report, June 2011)

13. Mean temperature bias with CRU (COSMO-CRU)

DJF

JJA

Not well defined bias map. Bias is between -3 and +3 degrees

Hot bias of 3-4 degrees in the north part.In the south part, the bias is between -1 and +1 degrees.

14. Mean precipitation (mm/month) bias with CRU

DJF

JJA

Underestimation in the south coastal area.Quite good agreement in the other parts.

A strong bias is registered.

DJF

JJA

15. Temperature variation : future (2021-2050) minus past (1971-2000)

16. Precipitation variation (mm/month): future (2021-2050) minus past (1971-2000)

DJF

JJA

There is a big difference between winter and summer.In winter, there is a slight decrease of precipitation, while in summer there is a general increase with some exceptions.

17. Mean temperature bias with CRU (east lower domain)

DJF JJA

DJF JJA

18. Temperature variation:future (2021-2050) minus past (1971-2000)

19. Conclusions

• Good agreement with observed data over Nigeria•An increase of temperature is expected in the XXI century in Nigeria, while precipitations are substantially unchanged.

•Numerical results related to the simulation of the climate of the west and the east lower domain at high resolution have been shown.

•for the west domain: in winter, temperature bias is not well defined and the precipitation is underestimated in the south coastal area with a quite good agreement in the other parts, while in summer there is a strong bias;•for the east lower domain: the temperature is underestimated in winter and overestimated in summer;•for the west domain in the future, the temperature will increase, especially in winter; the precipitation will decrease slightly in winter and will greatly increase in summer;•for the east lower domain in the future, the temperature will increase, especially in winter.

Thanks