niamey, niger, 1 st june 2007 la prevision saisonniere avec l’outil cpt by: ousmane ndiaye
TRANSCRIPT
Niamey, Niger, 1st June 2007
La prevision saisonniere avec l’outil CPT
By:Ousmane NDIAYE
Les bases de la prevision saisonnieres?
Forcage de la SST sur le climat
Ocean 2/3 de la surface de la terre forte capacite thermique : source de vapeur d’eau precipitable Dynamique : circulation –El Nino
Rationale for seasonal prediction: slower evolution of the oceanic component of the climate sytem SST on tropical atmosphere
Comment cela marche alors ?
Atmospheric General Circulation Model
SEA SURFACETEMPERATURE
ATMOSPHERIC CONDITIONS
Coupled Ocean and Atmosphere GCM
AtmosphereOcean Atmospheric conditions
Ocean conditions
Model Output Statistics(Statistical Correction)
Observed : yield/rainfall
Ocean Atmosphere
SST AGCM
STATISTICAL RELATIONSHIPSEA SURFACE
TEMPERATURE
PREDICTION :Rainfall, humidity…
Observed Rainfall/crop yield
Modele de prevision statistique: regression
Comment ca fonctionne ?
Y Y50 Y51 Y52 Y99Y98Y97Y96Yk Yk+1Yk-1Y53
XX50 X51 X52 X99X98X97X96Xk Xk+1Xk-1X53
Y = a*X + b
timePredictand (rainfall)
Predictor(SST)
(a,b) ? a*X + b
observee prevue
Periode 1 Periode 2
Tres tres simple :
Ŷ + e
1951 Predict
1951 Training period
1952 Training period
Predict 1952
Training Period
1953 Training period
Predict 1953
Training period
1954 Training period
Predict 1954
Training Period
1955 Training period
Predict 1955
Training period
… après correle 1951–2000 observee vs prevue.
La Validation croisee sur une fenetre d’une annee
Prevision Retro-spective/active
1981 Training period
(1951-1980) Predict 1981
Omit 1982+
1982 Training period
(1951-1981) Predict 1982
Omit 1983+
1983 Training period
(1951-1982) Predict 1983
Omit 1984+
1984 Training period
(1951-1983) Predict 1984
Omit 1985+
1985 Training period
(1951-1984) Predict 1985
Climate Predictability Tool :CPT
The Climate Predictability Tool (CPT) provides a Windows package for :
seasonal climate forecasting model validation actual forecasts given updated data
Uses ASCII input files : GCM, Stations, Indices Options :
principal components regression (PCR) canonical correlation analysis (CCA)
Help Pages on a range of topics in HTML format Options to save outputs in ASCII format and graphics
as JPEG Program source code is now available for those using
other systems (e.g., UNIX)
OVERVIEW
1. STATION files:
This file-type contains :
Station_name (without spaces; 16 characters)
Latitude (in signed degrees)
Longitude (signed degrees)
Year (in the first column)
Data (missing values should be filled with the same value, -9999 for example)
Keywords:STN, LAT, LONG
CPT INPUT FILE FORMATS
• For further details, read the help page of each menu and option.
• Subscribe to the user-list to be advised of updates:http://iri.columbia.edu/outreach/software/
• We want to hear from you. Your comments and questions help us to improve the CPT so do not hesitate to write to us at:
CONCLUSIONS