The Simulation and Analysis of Temperature and Precipitation

of CAM on Sahel Drought

Yi-Chih Huang

Sahel Drought (I)

Nicholson et al. 2000

Dai et al. 2004

Sahel Drought (II)

Todd Mitchell’s web page

GPCP• Global Precipitation climatology Project • Data

– 2.5 x 2.5 degree grid from Jan 1979 to Sep 2009– 1 x 1 degree grid from Oct 1996 to Jun 2009

• Created by merging – rain gauge data– Infrared estimates of precipitation– microwave satellite estimates of precipitation

• Scattering : Wilheit et al. (1991) histogram approach• Emission : Grody (1991) scattering index

CMAP• The CPC (Climate Prediction Center) Merged

Analysis of Precipitation• Data

– on 2.5 x 2.5 degree grid from 1979 to 2008– pentad and monthly analysis

• Sources– gauge observations– five kinds satellite estimates (IR-based GPI, OLR-

based OPI, MSU, microwave scattering and microwave emission)

– NCEP/NCAR reanalysis

Hydrological Onset and Withdrawal Index

Dalu, et al., 2009

Precipitation in August 2000 (I)

Precipitation in August 2000 (II)

Precipitation in August 2000 (III)

African Surface Temperature CAM v CRU

African Surface Temperature DeparturesCAM v CRU

Histogram of African Surface Temperature Departures for CAM v CRU

African Surface Temperature Departures with Least/Largest RMSE for CAM v CRU

African Surface Temperature CAM v NCEP

African Surface Temperature Departures CAM v NCEP

Histogram of African Surface Temperature Departures for CAM v NCEP

African Surface Temperature Departures with Least/Largest RMSE for CAM v NCEP

Sahelian Surface Temperature Departures CAM v CRU

Sahelian Surface Temperature Departures with Least/Largest RMSE for CAM v CRU

Sahelian Surface Temperature Departures CAM v NCEP

Sahelian Surface Temperature Departures with Least/Largest RMSE for CAM v NCEP

African Precipitation CAM v CRU

African Precipitation Departures CAM v CRU

RMS Histograms of African Precipitation Departures for CAM v CRU

African Precipitation Departures with Least/Largest RMSE for CAM v CRU

African Precipitation CAM v NCEP

African Precipitation Departures CAM v NCEP

RMS Histograms of African Precipitation Departures for CAM v NCEP

African Precipitation Departures with Least/Largest RMSE for CAM v NCEP

Sahelian Precipitation Departures CAM v CRU

Sahelian Precipitation Departures with Least/Largest RMSE for CAM v CRU

Sahelian Precipitation Departures CAM v NCEP

Sahelian Precipitation Departures with Least/Largest RMSE for CAM v NCEP

CAM Ensemble Tables6 15 20 23 31 35 40 45 least RMSE largest RMSE

st ΔCAM-ΔCRU 14 22 32 39 43 54 56 62

2 5 6 15 20 28 57 63

st ΔCAM-ΔNCEP 13 14 32 39 43 56 60 62

5 6 15 20 23 28 51 53

pcp ΔCAM-ΔCRU 4 12 13 34 36 37 43 61

2 15 20 23 31 33 35 45

pcp ΔCAM-ΔNCEP 4 34 36 37 41 43 60 61

6 15 20 23 31 35 40 45Sahel least RMSE largest RMSE

st ΔCAM-ΔCRU 9 12 14 22 26 34 41 60

6 15 20 23 31 33 45 58

st ΔCAM-ΔNCEP 9 12 14 22 26 34 41 44

6 15 19 20 23 31 33 45

pcp ΔCAM-ΔCRU 4 19 36 37 38 42 48 61

3 6 7 20 31 33 50 53

pcp ΔCAM-ΔNCEP 4 13 14 19 37 42 43 61

3 6 7 31 33 45 50 53

Summary• Since late 1960’s precipitation in Sahelian region is

almost persistently below the longterm mean• The patterns of mean CAM ensemble precipitation

in August 2000 are very different from CRU, GPCP, CMAP and NCEP

• CAM is Compared with CRU and NCEP– No ensemble run is in the groups with the least RMSE’s

in both temperature and precipitation– Several runs are in groups with the largest RMSE’s in

both temperature and precipitation in African and Sahelian domains