MSCI3001 Physical Oceanography /
MSCI5004 Oceanographic Processes
Assignment 2 – Matlab Instructions
In this lab, you will be plotting the Southern Hemisphere u-component of the windstress data for 2 general circulation models (NASA and CSIRO) and observations
(NCEP). The data and plots from this Lab will be needed to answer Question 3 in
Assignment2. Within the Matlab_labs directory, create a directory called
Assignment2. For this lab, you will need to download the following files from the
course website (http://web.maths.unsw.edu.au/~lauraciasto/teaching/MSCI3001.html):
1. tauu_20thcentury.mat: This file contains the following variables:
lat, lon:
latitudes (from 0S to 80S in 3 increments) and longitudes (0360E in 3 increments) over which data is given
tauu_csiro20c: monthly values of the u-component of the wind stress as calculated
from the CSIRO model in the Southern Hemisphere for the period
1980-1999 (240 months)
tauu_nasa20c: monthly values of the u-component of the wind stress as calculated
from the NASA model in the Southern Hemisphere for the period
1980-1999 (240 months)
tauu_ncep20c: monthly values of the u-component of the wind stress as given by
the observations in the Southern Hemisphere for the period 19801999 (240 months)
2. tauu_21stcentury.mat: This file contains the following variables:
lat, lon:
latitudes (from 0S to 80S in 3 increments) and longitudes (0360E in 3 increments) over which data is given
tauu_csiro21c: projected monthly values of the u-component of the wind stress as
calculated from the CSIRO in the Southern Hemisphere for the
period 2080-2099 (240 months)
tauu_nasa21c: projected monthly values of the u-component of the wind stress as
calculated from the NASA model in the Southern Hemisphere for
the period 2080-2099 (240 months)
NB: For this analysis, values of wind stress over land have been set to 0.
Make sure these files are in your Assignment2 folder.
Note that the instructions below do not contain any specific Matlab commands. Use
the commands learned in previous classes to complete the lab.
1. Load the u-wind stress component for the NCEP observations. The dimensions of
this data are latitude x longitude x time (i.e., 28 x 120 x 240).
a. Calculate the mean u-wind stress over the 20-yr (1980-1999) period. Hint:
you should average over the time dimension and end up with a 28x120
matrix).
b. Plot a map of the 20-yr mean calculated in part a. It is up to you to decide
which commands you want to use to plot the mean wind stress (e.g., pcolor,
surf, contourf, etc).
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Note: In order to make the calculations required Assignment 2 (Question 3),
you will need the values of u-wind stress at the following regions: 1) 50S,
100E; 2) 60S, 100E; 3) 15S, 250E; and 4) 25S, 250E. I don’t expect
you to have the exact value at these points, but you should choose contour
intervals and labels that make it is easier to read the approximate values
from your plots. (Hint: If you use contourf command, clabel has a manual
function so that you can specify where you want to place the contour labels.
Type “help clabel” for more details.)
2. Load the 20th century model u-wind stress data from both the CSIRO and NASA
models. The dimensions of the data are the same as in Step 1.
a. Calculate the 20-yr mean u-wind stress component for each of the two
models (i.e., same as in Step 1a but now for CSIRO and NASA data).
b. Plot a map of the 20-yr mean for each model (i.e., you should have one plot
for each model).
Note: In Assignment 2, you will be comparing the 20-yr mean plots between
the observations and the models. Thus, you may want to use the same
contour intervals and caxis in both Steps 1 and 2. You will also need the uwind stress values at the same regions as in Step 1.
3. Load the 21st century model u-wind stress data from both the CSIRO and NASA
models. The dimensions of this data are the same as in Step 1.
a. Calculate the 20-year (2080-2099) mean u-wind stress component for each
of the two models (i.e., same as in Step 2a but now for the 21st century
data).
b. For the NASA and CSIRO models, calculate the difference between the 21st
century 20-yr (2080-2099) mean u-wind stress component (from Step 2a)
and the 20th century 20-yr (1980-1999) mean u-wind stress component (from
Step 3a).
c. Plot the difference maps calculated in Step 3b. You should have one
difference map for each model. (Hint: the magnitude of your contours and
caxis will be considerably smaller than in Steps 1 and 2).
These figures will be used in your discussions associated with Assignment 2.
Check the assignment for specific instructions. You must include all figures from
Steps 1-3. Make sure your figures are labeled, have a figure number and a figure caption.
These figures must be explicitly referenced in your discussion in your assignment. You
should also attach your m-file to the end of your assignment. This should be suitably
commented.
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