Model Practicals -
El Nino Model
- Students should first review the lecture notes for this subject which can be downloaded here.
- 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.
- The El Nino codes may be found in
/home/students/models/couple1
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. - To invoke the model gui type
matlab -nodesktop and then type elninogui at the matlab prompt. The following display should appear:
- The
model parameters should be cleared by resetting values. Note the model
runs forward from initial conditions in which variables are set to a
warm event. The only external forcing is stochastic which resembles
weather systems not simulated by the model atmosphere.
- The parameters have the following meaning. wbound:
Western boundary reflection efficiency coefficient. A value of 1.0
means perfect reflection of Rossby waves into Kelvin waves. Values less
than unity imply some absorption or transmission of the Rossby waves at
the boundary. ebound: Eastern boundary reflection
efficiency coefficient. Same as wbound but the reflection coefficient
of Kelvin waves into Rossby waves at the eastern boundary. cuple:
Atmosphere Ocean coupling coefficient. The greater this parameter the
greater the feedback between the media. A value of unity corresponds
approximately with observed conditions in the Pacific. stochstr:
Stochastic forcing with spatial patterns of the large scale tropical
weather have been added to the model. A value of 1.0-3.0 corresponds
approximately with observations. nnyears: Number of years to integrate model forward. Note: only 20 years are shown in the Longitude-Time plots of the gui display. Speed: Factor to multiply the shallow water/Kelvin wave speed. A value of 1.0 corresponds to a speed of 2.3 m/s.
- Students need to complete the assignment which was handed out in class. It can be download here.