% notes for the june 20 meeting.

Purpose:  CO2 instrument calibration

Attendees: Jielun Sun, Britt Stephens, Steve Oncley, Karl Schwenz (ATD
 Machinist), Alex Guenther, Andrew Turnipseed, Sean Burns, Tony
 Delany, and Don Lenschow.

Some Items:
------------

 * The Ameriflux tower is actually sampled with TWO CO2 systems (one
   by CU (LiCor 6251 which is on the tower) and one by USGS (LiCor
   7000 which is about 75m from the tower)

 * Tony Delany wants to keep the IHOP CO2 system as it is--needs to
   contact Scott Richardson at Penn State to confirm that he doesn't
   need it for anything.

 * There are 4 issues to consider for comparing the CO2 data:
   1. Some LiCors are drying the air prior to measuring the CO_2
      and some are not.
   2. Using synthetic air vs real air to do the in-field calibrations.
      (argon in real air is important?)
   3. Self calibration of the LiCor vs using the standard LiCor calibration.
   4. Some LiCors are pressurized and some are not.

 * Things for the calibration:
   1. Get a standard tank (andrew already has one up at the trailer?)
   2. Use 4 tanks at different C02 concentrations and calibrate each LiCor   
      at a different time of the day.  these concentrations were
      decided...it was something like:  350, 375, 400, and 450 ppm.
   3. Use synthetic air -- try to assign some numbers.
   4. ATD already has many cylinders...some partially full some full (all
      synthetic air?).
   
 * suggestion to use smaller tanks which would be easier to move
   around to do the cals.

 * Balloons will have 3 of the small russian CO2 sensors (these have
   not been thoroughly tested yet).

 * LiCor Inventory:
   1. LiCor 6251 on Ameriflux Tower
   2. LiCor 7000 in the center of the 4 towers
   3. MMM LiCor 7000 (part of the "spider" or on ATD 10-tower)
   4. ATD LiCor 6251 (to go on the 10-m ATD tower)
   5. ATD LiCor 7000 (part of the "spider"...not bought yet??)
   6. LiCor 7500 (open path) on a tripod near the USGS 33m tower
      (this is managed by someone at CU...perhaps it is not being
       used much right now...)