Long-term fluxes of carbonyl sulfide and their seasonality and interannual variability in a boreal forest
<p>The seasonality and interannual variability of terrestrial carbonyl sulfide (COS) fluxes are poorly constrained. We present the first easy-to-use parameterization for the net COS forest sink based on the longest existing eddy covariance record from a boreal pine forest, covering 32 months o...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-02-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/22/2569/2022/acp-22-2569-2022.pdf |
| Summary: | <p>The seasonality and interannual variability of
terrestrial carbonyl sulfide (COS) fluxes are poorly constrained. We present
the first easy-to-use parameterization for the net COS forest sink based on the
longest existing eddy covariance record from a boreal pine forest, covering 32 months
over 5 years. Fluxes from hourly to yearly scales are reported, with the aim
of revealing controlling factors and the level of interannual variability.
The parameterization is based on the photosynthetically active radiation,
vapor pressure deficit, air temperature, and leaf area index. Wavelet
analysis of the ecosystem fluxes confirmed earlier findings from
branch-level fluxes at the same site and revealed a 3 h lag between COS
uptake and air temperature maxima at the daily scale, whereas no lag between
radiation and COS flux was found. The spring recovery of the flux after the
winter dormancy period was mostly governed by air temperature, and the onset
of the uptake varied by 2 weeks. For the first time, we report a significant
reduction in ecosystem-scale COS uptake under a large water vapor pressure
deficit in summer. The maximum monthly and weekly median COS uptake varied by
26 % and 20 % between years, respectively. The timing of the latter varied
by 6 weeks. The fraction of the nocturnal uptake remained below 21 % of
the total COS uptake. We observed the growing season (April–August) average
net flux of COS totaling <span class="inline-formula">−58.0</span> <span class="inline-formula">g S ha<sup>−1</sup></span> with 37 % interannual
variability. The long-term flux observations were scaled up to evergreen
needleleaf forests (ENFs) in the whole boreal region using the Simple Biosphere
Model Version 4 (SiB4). The observations were closely simulated using
SiB4 meteorological drivers and phenology. The total COS uptake by boreal
ENFs was in line with a missing COS sink at high latitudes pointed out in
earlier studies.</p> |
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| ISSN: | 1680-7316 1680-7324 |