SHADOWING IN THE ATMOSPHERE
Ross Lieb-LappenChris Danforth
Forecasting Challenges
• Uncertainty in the initial state
• Chaos: sensitive dependence on initial conditions
• Model error
Trajectory of the System Truth
Forecast of the System Truth
Improving the Forecast
Our Model
Image: Nick Allgaier
Forecasting Methodology• Ensemble forecasting
• Lorenz ‘96 Model
• Define new ensemble members
• Inflation of forecast ellipsoid
FXXXXdtdX jj jjj 121 )(/
advection dissipation
external forcing
Controlled Inflation• Only in contracting directions • Within climatological span of particular variable
• Maintain appropriate ratio with neighboring values
Model Success
0 1 2 3 4 5 6 7 8 9 100
2
4
6
8
10
12
14
16
18
Time
Erro
rDifference between Truth and Forecast
Acknowledgments
Advisor:Chris Danforth
Nick Allgaier Kameron Harris
Singular Value Decomposition
-4 -3.5 -3 -2.5 -2
4
4.2
4.4
4.6
4.8
5
5.2
5.4
5.6
5.8
Variable 1
Var
iabl
e 2
Definition of new ensemble members