Source
Area Modeling
for Measurements of Turbulent Fluxes and Concentrations
| H.P.
Schmid
Dept. of Geography
Climate & Meteorology Program
Indiana University
Bloomington, IN 47405, USA |
 |
This document and the Flux Source Area
Model is primarily directed at members of FLUXNET. However, other
interested parties are welcome to browse and request specific model runs.
These will be attended to at slightly lower priority.
This site and the Source Area Modeling
service is under construction and its current status is very much preliminary.
Please don't hesitate to relay your remarks or suggestions to me! (hschmid@indiana.edu)
(last update: March. 13, 2001)
Footprints and Source Areas 
Numerous versions of footprint models are
described in the literature (see e.g. the references in Schmid, 1994, Boundary-Layer
Meteorol.,
67, 293-318), based on Lagrangian trajectory models
or analytical solutions of the advection-diffusion equation in a Eulerian
reference frame. The models used here are of the latter kind and are thus
very simple.
While their simplicity makes these models
very easy to use, they of course have their limits. Some cautionary
remarks are thus a-propos, before you delve into using them:
-
they can only handle surface layer situations.
-
they assume that the wind-flow conditions
are not disturbed by obstacles or topography.
-
they assume that the surface is of a very
simple kind: it can be a rough surface, but any three dimensional source/sink
distributions or sub-canopy flow is ignored. For a forest situation these
models thus assume that the (closed) canopy top is the surface.
Incidentely, most currently available source
area or footprint models have these limitations inherent in them - even
if the authors do not say so explicitly. Clearly, most situations where
a source area estimate is desirable, do not conform to the restrictions
listed above. Thus, any source area modeling result should be taken with
a grain of salt, and interpretations of measurements based on source area
model results should be closely examined for plausibility.
Nevertheless, a simple source area /footprint
model is often the best we can do, so: let's get on with it!
Before you go on I suggest that you familiarize
yourself with these models, how they are used, and what kind of input
information is needed.
| Press
here: |
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You can download compiled
versions of my models here. You are welcome to use these models, but
I ask you to observe the usual fair
use policy as stated in the AmeriFlux web page. At any rate, I
would appreciate a short note that indicates that you are planning to use
SAM or FSAM. If you are ready to download one of the models (executable
files for Windows9x/NT4),
| Press
here: |
|
If you would like to use the model in non-interactive
mode, send me an e-mail (hschmid@indiana.edu),
and I'll send you the code.
More questions? remarks? complaints? praises?
Please contact me: hschmid@indiana.edu