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README_HCOOH_SOIL.txt
Updated 05/26/2020
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This folder contains 1-minute averaged HCOOH soil chamber mixing
ratio measurements from the 2016 PROPHET-AMOS campaign archived in
association with the following manuscript:
Alwe, H.D., D.B. Millet, X. Chen, J.D. Raff, Z.C. Payne, and K. 
Fledderman (2019), Oxidation of volatile organic compounds as the 
major source of formic acid in a mixed forest canopy, Geophys. Res. 
Lett., 46, 2940-2948, doi:10.1029/2018GL081526.

Further details can be found in:
Millet, D.B., H.D. Alwe, X. Chen, M.J. Deventer, T.J. Griffis, R.
Holzinger, S.B. Bertman, P.S. Rickly, P.S. Stevens, T. Léonardis,
N. Locoge, S. Dusanter, G.S. Tyndall, S.L. Alvarez, M.H. Erickson,
and J.H. Flynn (2018), Bidirectional ecosystem-atmosphere fluxes of
volatile organic compounds across the mass spectrum: How many
matter?, ACS Earth Space Chem., 2, 764-777,
doi:10.1021/acsearthspacechem.8b00061

The R (www.r-project.org) datafile HCOOH_SOIL.RDS contains the
 following 2 data columns:
1) day_of_year_edt, decimal day of year (12:01am on Jan 1 = 1.0007)
 in local time (EDT)
2) hcooh_ppb, 1-minute average HCOOH mixing ratios (ppb)

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Description of sampling procedure
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Chamber A: closed off from soil (blank)
Chambers B-D: open on bottom to soil

The hourly schedule was as follows:
 0:00, Lid on Chamber A closes and ambient air is measured for 7
   min at inlet of chamber before it enters the chamber.
 0:00-0:04: measure PTR-MS blank (catalytic converter)
 0:07, Chamber A air is measured for 8 min.
 0:15, Chamber A lid opens; Chamber B lid closes and ambient air is
   measured for 7 min at inlet of chamber B before it enters the
   chamber.
 0:22, Chamber B air is measured for 8 min.
 0:30, Chamber B lid opens; Chamber C lid closes and ambient air is
   measuredfor 7 min at inlet of chamber C before it enters the
   chamber.
 0:37, Chamber C air is measured for 8 min.
 0:45, Chamber C lid opens; Chamber D lid closes and ambient air is
   measured
   for 7 min at inlet of chamber D before it enters the chamber.
 0:52, Chamber D air is measured for 8 min.
 0:60, Chamber D lid opens; Chamber A lid closes and the cycle
   starts anew.

The volume of each chamber is 17.0456 L
The surface area measures 1065.35 cm^2 for each chamber.
The average flows for chambers A, B, and D, were 26.91. The average
 flow for chamber c (xx:30 - xx.45) was 27.3 lpm.

Valve timing was delayed ~2 minutes for first 3 hours

Special case for chamber D in hour 14:
 valve timing changes during the course of this hour
 need to adjust time stamp for D to align with others

Concentration spike(s) of up to 10ppb during first 30 minutes
 result from flow tests and should be excluded.

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If you plan to use this data please contact us so that we can
 track usage and alert users of any updates.
Dylan Millet
University of Minnesota
dbm@umn.edu
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