Model Practicals -
Stochastic Climate Models

1. Students should first review the lecture notes for this subject which can be downloaded here.
2. The programs for this model all reside on the server woodend.cims.nyu.edu and students have a user id students. In order to login you need (for security reasons) to be within the CIMS network and you need to login using ssh. To do this issue ssh students@woodend.cims.nyu.edu from a cims machine. When prompted enter the password issued in class. Do not share this password.
3. The stochastic model codes may be found in /home/students/models/stochastic and students are asked to copy this sub-directory and its contents to their own subdirectory to avoid clashing with other students in the running of the model.
4. To invoke the model gui type matlab -nodesktop and then type stochint at the matlab prompt. The following display should appear:
   
   
   
   
5. The model parameters should be cleared by resetting values. 
6. The top panels are the time series for the real and imaginary components of the first mode and the real component of a second mode. The bottom panels shows the corresponding spectra. A spectral window is used as a smoother of the spectrum since the time series are relatively short.
7. The first mode is assumed to have period of 1 time unit. The parameters have the following meaning.  Ratio 1 :  Decay time of mode 1.  Ratio  2: ratio of the period of mode 2 to its decay time (second decay time =r2*t2). Dissipation ratio: Muliply the decay time of mode 1 by this to get the decay time of mode 2. Notice that the period of mode 2 is defined implicitly by these parameters. Corr 1: The correlation of stochastic forcing onto the real and imaginary and real parts of mode 1. Corr 2: Same as Corr 1 but for the second mode. Modal Forcing Correlation (MFC): A correlation parameter between the two normal modes. The four by four covariance matrix has the form
   
8. Students need to complete the assignment which was handed out in class. It can be download here.