This tour explores the Climatological Atlas of the World Ocean, compiled by Sydney Levitus. The data set contains the annual average value of ocean temperature, salinity and oxygen at 33 levels to 5500 meters, over the world ocean.
Advanced use of FERRET commands in the tour will give you a good idea how useful the program can be exploring data sets. Commands to FERRET below will be in capital letters. FERRET prompts for input with the word
"yes?".yes? SET DATA levitus-climatology yes? SHOW DATA levitus-climatology currently SET data sets: 1> ./levitus-climatology.des (default) name title I J K L TEMP TEMPERATURE 1:360 1:180 1:33 1:1 SALT SALINITY 1:360 1:180 1:33 1:1 O2 DISSOLVED OXYGEN 1:360 1:180 1:33 1:1 OSAT OXYGEN SATURATION 1:360 1:180 1:33 1:1
Note that 4 variables are available; we'll look at just temperature and salinity in this tour. The grid is 1x1 degree, and global. For information on FERRET's grid indices click here.
Let's first display the sea surface temperature over the globe.
yes? SHADE/K=1/LEV=(-2,32,1) TEMP
You can note --
Let's look now at the sea surface salinity over the globe.
yes? SHADE/K=1/LEV="()(0,49,3)(33,37,.4)" SALT
In surface salinity you can see --
Overlay the two fields and outline the land masses. The relationship between surface temperature and salinity is not simple.
yes? SHADE/K=1/LEV=(-2,32,2) TEMP yes? CONTOUR/OVER/K=1/LEV="()(0,49,3)(33,37,.4)" SALT yes? GO land
Let's look deeper. Note at 200 meters temperature and salinity are more closely related.
yes? SHADE/Z=200/LEV=(-2,32,2) TEMP yes? CONTOUR/OVER/Z=200/LEV="()(0,49,3)(33,37,.4)" SALT yes? GO land
And next view a meridional slice -- first in the Atlantic:
yes? SHADE/X=30W/LEV=(-2,32,2) TEMP yes? CONTOUR/OVER/X=30W/LEV="()(0,49,3)(33,37,.4)" SALT
And then in the Pacific
yes? SHADE/X=180W/LEV=(-2,32,2) TEMP yes? CONTOUR/OVER/X=180W/LEV="()(0,49,3)(33,37,.4)" SALT
Finally, T-S diagrams may be constructed with a single "sounding", illustrating the general monotonic decrease of temperature with depth. This is in general true of salinity too but note here around 10 degrees Celsius, salinity increases -- due to inflow at depth into the Atlantic of higher salinity Mediterranean water.
yes? PLOT/VS/X=20W/Y=35N SALT,TEMP