From: David Schwab <schwab@zeus.glerl.noaa.gov>
Subject: Vertical segmentation for 2 km grid
To: eegle-mod@wings.glerl.noaa.gov
Date: Tue, 02 Jun 1998 10:35:33 EDT

As discussed at the 5/27/98 EEGLE modeling group meeting, we have developed
a vertical segmentation scheme for the Lake Michigan 2 km hydrodynamic
model simulations.  There are 40 sigma levels (39 layers) in the segmentation.
This top 20 layers cover the upper 25% of the water column with uniform
(delta sigma = 0.0125) vertical spacing.  Between the 20th layer and the
bottom, layer thicknesses increase and decrease geometrically so that the
lowest layer thickness is also 0.0125.  Here are the levels:

    i   sigma
   -- ---------  
    1  0.000000
    2 -0.012500
    3 -0.025000
    4 -0.037500
    5 -0.050000
    6 -0.062500
    7 -0.075000
    8 -0.087500
    9 -0.100000
   10 -0.112500
   11 -0.125000
   12 -0.137500
   13 -0.150000
   14 -0.162500
   15 -0.175000
   16 -0.187500
   17 -0.200000
   18 -0.212500
   19 -0.225000
   20 -0.237500
   21 -0.250000
   22 -0.265407
   23 -0.284398
   24 -0.307805
   25 -0.336656
   26 -0.372217
   27 -0.416049
   28 -0.470075
   29 -0.536667
   30 -0.618745
   31 -0.700824
   32 -0.767415
   33 -0.821441
   34 -0.865273
   35 -0.900835
   36 -0.929686
   37 -0.953093
   38 -0.972083
   39 -0.987500
   40 -1.000000

Here is an IDL program to plot the levels:

z=[0.00000, -0.012500, -0.025000, -0.037500, -0.050000, -0.062500, -0.075000,$
-0.087500, -0.100000, -0.112500, -0.125000, -0.137500, -0.150000, -0.162500,$
-0.175000, -0.187500, -0.200000, -0.212500, -0.225000, -0.237500, -0.250000,$
-0.265407, -0.284398, -0.307805, -0.336656, -0.372217, -0.416049, -0.470075,$
-0.536667, -0.618745, -0.700824, -0.767415, -0.821441, -0.865273, -0.900835,$
-0.929686, -0.953093, -0.972083, -0.987500, -1.000000]

n=n_elements(z)
print,n
plot,[0,1],[-1,0],/nodata
for i=0,n-1 do plots,[0.4,0.6],[z(i),z(i)]
a=findgen(16)*!pi/8.
usersym,cos(a),sin(a)
for i=0,n-2 do plots,0.5,0.5*(z(i)+z(i+1)),psym=8,symsize=0.3
end
------------------------------------------------------------------------------

Thank you all for attending the modeling group meeting.  I think it was very
productive.  Dmitry is writing up a brief report on the meeting and will post
it on the Web when it's complete.  Chen and Jiang are continuing their visit
here and are making considerable progress in developing the food web model. 
I'm scheduled to participate in another CoOP Scientific Steering Commitee
meeting on June 16.  I'll certainly keep them up to date on our activities. I
also look forward to occasional reports from all of you as your work
progresses.  

Best wishes,

... Dave Schwab