2010-2013

 
 

Forest - Atmosphere Exchange Homepage


OCS Flux Data Archive


Publications:

R. Commane, L. K. Meredith, I. T. Baker, J. A. Berry, J. W. Munger, S. Montzka, P. Templer, S. Juice, M. S. Zahniser and S. C. Wofsy:  Seasonal fluxes of carbonyl sulfide in a mid-latitude forest, Proceedings of the National Academy of Science, 112, 46, 14162-14167, doi:10.1073/pnas.1504131112, 2015 pdf


L. K. Meredith, R. Commane, J. W. Munger, A. Dunn, J. Tang, S. C. Wofsy, R. G. Prinn: Ecosystem fluxes of hydrogen: a comparison of flux-gradient methods, Atmos. Meas. Tech., 7, 2787-2805, doi:10.5194/amt-7-2787-2014, 2014 pdf

All photographs copyright of Roisin Commane

Understanding the role of Carbonyl Sulfide (OCS) in forest ecosystems:

It has been proposed that OCS can be used as a proxy to resolve CO2 photosynthetic uptake and respiration (Campbell et al 2008, Science). However, these studies assumed the role of soil uptake on the OCS budget is negligible, while laboratory studies have suggested greater uptake from soils than previously assumed.

During 2010 and 2011, I worked at Aerodyne Research Inc. on the development of a quantum cascade laser spectroscopy (QCLS) instrument for high frequency continuous measurements of carbonyl sulfide (OCS) at a precision of ~3pptv (1s). The project is funded by a US Dept. of Energy Small Business Innovation Research grant in collaboration with Aerodyne Research Inc., MA and successfully qualified for Phase II funding until October 2012 to develop a compact QCL instrument to measure OCS, although measurements continued into 2013.

The original prototype instrument measured fluxes of OCS above the forest canopy at Harvard Forest (HFM), MA during 2010 and 2012.

A compact version of the instrument was installed and measured fluxes of OCS and CO2 in 2012 and 2013.

The comprehensive suite of chemistry measurements made at the site, such as CO2, H2 and H2O gradients and fluxes, allows for interpretation of the OCS fluxes. OCS has been measured at HFM by weekly glass flask collection and subsequent analysis by GC-MS since 2002 (Montzka et al, JGR, 2007). Comparison of the QCL and GC-MS data collected so far, highlights the large short-term variability of OCS above the forest canopy.

Live Images of Harvard Forest EMS Tower:

   Canopy Top                                            Forest Floor

* This phenocam data is stored at UNH (PI: Andrew Richardson, Harvard) and has some restrictions attached to use. Please view them here!