ATMO 632: Week 6

Predictability and Forecasting

Course Home Page: http://www.cgd.ucar.edu/~svn/atmo632

Reading Material

1. Wilks: Section 6.5 (ensembles), 7.3 (forecast skill), 7.5 (forecast verification)

Concepts

Chaos

Lorenz system

“Butterfly effect”

Predictability limit

Forecasting

Deterministic vs. Probabilistic (ensemble) forecasts

Dynamical vs. Statistical Models

Chaotic vs. Stochastic Systems

Ensemble forecasting

Choosing ensemble members

Ensemble spread

Spread vs. skill

Forecasting an AR(1) process

Persistence forecast

Optimal forecast (“damped persistence”)

Forecast verification

Mean square error

Skill score

Anomaly correlation

Spectral peaks and predictability

Kinds of Predictability

First kind: initial condition dependence

Second kind: boundary condition dependence

Predictability of weather

Predictability of climate

Potential predictability (Signal-to-noise ratio)

Analysis of variance (ANOVA)