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ORCHIDEE-PEAT (revision 4596), a model for northern peatland CO2, water, and energy fluxes on daily to annual scales

Qiu, Chunjing; Zhu, Dan; Ciais, Philippe; Guenet, Bertrand; Krinner, Gerhard; Peng, Shushi; Aurela, Mika; Bernhofer, Christian; Brümmer, Christian and Bret-Harte, Syndonia, et al. (2018) In Geoscientific Model Development 11(2). p.497-519
Abstract

Peatlands store substantial amounts of carbon and are vulnerable to climate change. We present a modified version of the Organising Carbon and Hydrology In Dynamic Ecosystems (ORCHIDEE) land surface model for simulating the hydrology, surface energy, and CO2 fluxes of peatlands on daily to annual timescales. The model includes a separate soil tile in each 0.5° grid cell, defined from a global peatland map and identified with peat-specific soil hydraulic properties. Runoff from non-peat vegetation within a grid cell containing a fraction of peat is routed to this peat soil tile, which maintains shallow water tables. The water table position separates oxic from anoxic decomposition. The model was evaluated against eddy-covariance (EC)... (More)

Peatlands store substantial amounts of carbon and are vulnerable to climate change. We present a modified version of the Organising Carbon and Hydrology In Dynamic Ecosystems (ORCHIDEE) land surface model for simulating the hydrology, surface energy, and CO2 fluxes of peatlands on daily to annual timescales. The model includes a separate soil tile in each 0.5° grid cell, defined from a global peatland map and identified with peat-specific soil hydraulic properties. Runoff from non-peat vegetation within a grid cell containing a fraction of peat is routed to this peat soil tile, which maintains shallow water tables. The water table position separates oxic from anoxic decomposition. The model was evaluated against eddy-covariance (EC) observations from 30 northern peatland sites, with the maximum rate of carboxylation (Vcmax) being optimized at each site. Regarding short-term day-to-day variations, the model performance was good for gross primary production (GPP) (r2 Combining double low line 0.76; Nash-Sutcliffe modeling efficiency, MEF Combining double low line 0.76) and ecosystem respiration (ER, r2 Combining double low line 0.78, MEF Combining double low line 0.75), with lesser accuracy for latent heat fluxes (LE, r2 Combining double low line 0.42, MEF Combining double low line 0.14) and and net ecosystem CO2 exchange (NEE, r2 Combining double low line 0.38, MEF Combining double low line 0.26). Seasonal variations in GPP, ER, NEE, and energy fluxes on monthly scales showed moderate to high r2 values (0.57-0.86). For spatial across-site gradients of annual mean GPP, ER, NEE, and LE, r2 values of 0.93, 0.89, 0.27, and 0.71 were achieved, respectively. Water table (WT) variation was not well predicted (r2<0.1), likely due to the uncertain water input to the peat from surrounding areas. However, the poor performance of WT simulation did not greatly affect predictions of ER and NEE. We found a significant relationship between optimized Vcmax and latitude (temperature), which better reflects the spatial gradients of annual NEE than using an average Vcmax value.

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Geoscientific Model Development
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11
issue
2
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23 pages
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Copernicus Gesellschaft Mbh
external identifiers
  • scopus:85041718396
ISSN
1991-959X
DOI
10.5194/gmd-11-497-2018
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English
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1a394e38-c103-48e2-ad98-809669f2c101
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2018-02-21 09:16:59
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2018-07-15 04:47:35
@article{1a394e38-c103-48e2-ad98-809669f2c101,
  abstract     = {<p>Peatlands store substantial amounts of carbon and are vulnerable to climate change. We present a modified version of the Organising Carbon and Hydrology In Dynamic Ecosystems (ORCHIDEE) land surface model for simulating the hydrology, surface energy, and CO2 fluxes of peatlands on daily to annual timescales. The model includes a separate soil tile in each 0.5° grid cell, defined from a global peatland map and identified with peat-specific soil hydraulic properties. Runoff from non-peat vegetation within a grid cell containing a fraction of peat is routed to this peat soil tile, which maintains shallow water tables. The water table position separates oxic from anoxic decomposition. The model was evaluated against eddy-covariance (EC) observations from 30 northern peatland sites, with the maximum rate of carboxylation (Vcmax) being optimized at each site. Regarding short-term day-to-day variations, the model performance was good for gross primary production (GPP) (r2 Combining double low line 0.76; Nash-Sutcliffe modeling efficiency, MEF Combining double low line 0.76) and ecosystem respiration (ER, r2 Combining double low line 0.78, MEF Combining double low line 0.75), with lesser accuracy for latent heat fluxes (LE, r2 Combining double low line 0.42, MEF Combining double low line 0.14) and and net ecosystem CO2 exchange (NEE, r2 Combining double low line 0.38, MEF Combining double low line 0.26). Seasonal variations in GPP, ER, NEE, and energy fluxes on monthly scales showed moderate to high r2 values (0.57-0.86). For spatial across-site gradients of annual mean GPP, ER, NEE, and LE, r2 values of 0.93, 0.89, 0.27, and 0.71 were achieved, respectively. Water table (WT) variation was not well predicted (r2&amp;lt;0.1), likely due to the uncertain water input to the peat from surrounding areas. However, the poor performance of WT simulation did not greatly affect predictions of ER and NEE. We found a significant relationship between optimized Vcmax and latitude (temperature), which better reflects the spatial gradients of annual NEE than using an average Vcmax value.</p>},
  author       = {Qiu, Chunjing and Zhu, Dan and Ciais, Philippe and Guenet, Bertrand and Krinner, Gerhard and Peng, Shushi and Aurela, Mika and Bernhofer, Christian and Brümmer, Christian and Bret-Harte, Syndonia and Chu, Housen and Chen, Jiquan and Desai, Ankur R. and Dušek, Jǐrí and Euskirchen, Eugénie S. and Fortuniak, Krzysztof and Flanagan, Lawrence B. and Friborg, Thomas and Grygoruk, Mateusz and Gogo, Sébastien and Grünwald, Thomas and Hansen, Birger U. and Holl, David and Humphreys, Elyn and Hurkuck, Miriam and Kiely, Gerard and Klatt, Janina and Kutzbach, Lars and Largeron, Chloé and Laggoun-Défarge, Fatima and Lund, Magnus and Lafleur, Peter M. and Li, Xuefei and Mammarella, Ivan and Merbold, Lutz and Nilsson, Mats B. and Olejnik, Janusz and Ottosson-Löfvenius, Mikaell and Oechel, Walter and Parmentier, Frans Jan W. and Peichl, Matthias and Pirk, Norbert and Peltola, Olli and Pawlak, Włodzimierz and Rasse, Daniel and Rinne, Janne and Shaver, Gaius and Peter Schmid, Hans and Sottocornola, Matteo and Steinbrecher, Rainer and Sachs, Torsten and Urbaniak, Marek and Zona, Donatella and Ziemblinska, Klaudia},
  issn         = {1991-959X},
  language     = {eng},
  month        = {02},
  number       = {2},
  pages        = {497--519},
  publisher    = {Copernicus Gesellschaft Mbh},
  series       = {Geoscientific Model Development},
  title        = {ORCHIDEE-PEAT (revision 4596), a model for northern peatland CO2, water, and energy fluxes on daily to annual scales},
  url          = {http://dx.doi.org/10.5194/gmd-11-497-2018},
  volume       = {11},
  year         = {2018},
}