This directory contains WRF-STILT footprints for North American CO2 and CH4
monitoring locations from June-August 2010.  The footprints were produced as 
part of the CarbonTracker-Lagrange project with support from NOAA's Climate 
Program Office via the Atmospheric Chemistry, Carbon Cycle, and Climate (AC4) 
Program and from NASA's Carbon Monitoring System. Additional footprints are 
available upon request for the period 2007-2010, including for GOSAT and
TCCON measurement locations.

Discrete air samples ("flask") were simulated using instantaneous particle 
releases, corresponding to a measurement at origutctime.  

Continuous ("obspack") receptors were simulated using continuous particle
releases over a two-hour window. Time runs backward in these STILT simulations,
and the variable origutctime corresponds to the end of the two hour window in
a forward sense. Thus, if origutctime = 2010-02-28T23:00:00, the footprint 
represents the period 21:00 - 23:00 GMT on that date.

The receptor list files can serve as a lookup table for particular sites.
The dataid field (e.g. LEF_short-tower_NOAA::UWI) includes abbreviated site name,
site type, laboratories(s). Only a subset of available footprint files has been 
posted here, corrosponding to conditions when data from these sites are thought to
be most representative large-area conditions (e.g. mid-afternoon for
continental sites, nighttime for complex terrain, late afternoon for coastal 
sites).

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Point of contact:  

Arlyn Andrews
303-497-6773
Arlyn.Andrews@noaa.gov

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CarbonTracker-Lagrange is a multi-institutional effort. Footprint generation
was done by scientists at Atmospheric and Environmental Research in collaboration
with NOAA. If you use these footprints in a publication or presentation, please 
contact me for guidance about citations and acknowledgements that may be 
appropriate. This is a new product and more comprehensive documentation will follow.
We would be grateful for feedback, especially regarding suspected errors in the 
products or variable definitions that require additional explanation.
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