Thursday, August 12, 2010


So a few years ago Dr. Bill Sacks (clever man that he is) incorporated a spatial component to SIPNET. The implementation for the user is pretty straight forward.

Assuming that you can run SIPNET for a single site all you need to do is to create a climate file and if needed a parameter file for each location you need to run the model for.

The first field in the climate file is 'loc' usually this is set to zero - however you can tell SIPNET to run at many locations.

I put together a tutorial with Bill Sacks on how to do this for the NCAR ASP conference in 2008.

You can view the tutorial here (Regional Biogeochemica Cycling)

You need to create the spatial inputs either manually based on some input data you already have or you can use some sort of automated procedured based on climate re-analysis data or perhaps MTCLIM.

You also need to edit the "dot.param-spatial" file to tell SIPNET how many locations to expect.

The controls to switch on the spatial version are in

Open the file using your text editot
* Set RUNTYPE = standard
* Set FILENAME = NEW_Spatial_Files (to use the newly-created spatially-varying climate and parameter files)
* Set LOCATION = -1 (to run at all locations)

Below is just the graphic from the regional tutorial - it gives an idea of how the spatial data might look on a very regular grid.

Have fun,

Parameterization of the SIPNET model for your site

If you have a forested eddy covariance site, it should be possible to parameterize the model using previous studies at the site and by assimilating the data from the site.
You will need to assemble the appropriate climate divers and you will also need to estimate the parameters used to drive model

You can find a description of the model drivers and parameters on this website:

Figure shows the layout of a small portion of a parameter file used by SIPNET - click on the image for a more detailed view.

Not all of the parameters in the default 'dot.param' file are used. The parameters which are required depend on the model options that you employ. I recommend that you look carefully at the model options at the start of the code in the file "sipnet.c". We hope to create an improved interface for changing SIPNET options but for now we need to manually change the options in the sipnet.c code (... and remember to recompile!).

The options include options to vary how respiration or little is treated, whether growing degree days are calculated etc. written by Bill Sacks and Rob Braswell (see Braswell et al 2005, Sacks et al 2006, 2007). They also include options written by John Zobitz to include various soil pools (see Zobitz et al 2008).

You might also want to check out the previous blog post (from March).

Please speak to one of the SIPNET team before you use SIPNET for publication so that you have access to the most up to date version of the code. The code is hosted at the University of Wisc and will be moved during the fall of 2010.

Dave Moore (King’s College London), John Zobitz (Augsburg College), Bill Sacks (NCAR/NEON), Ankur Desai (Univ Wisc)