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Sonnentag, Oliver

Professeur agrégé

  • Chaire de recherche du Canada en biogéosciences atmosphériques en hautes latitudes

Contact :

  • Téléphone 514-343-8032 Pav. PAV.520 CH.COTE STE-CATHERINE \ bur. 429-3

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Sonnentag, Oliver

Présentation

Ma formation initiale est en hydrogéologie (maîtrise de l'Université de Karlsruhe, Allemagne). Après l'obtention de ma maîtrise en 2001, j'ai travaillé pour une entreprise d'arpentage et j'ai étudié pour obtenir une deuxième maîtrise en systèmes et sciences d'information géographique (l'Université de Salzburg, Autriche, en 2003). En 2004, j'ai quitté l'Europe pour le Canada pour commencer un doctorat en géographie physique à l'Université de Toronto. Sous la direction du Dr Jing Chen, j'ai abordé les questions liées à l'influence de la topographie sur les échanges de gaz à effet de serre des tourbières boréales. Après l'obtention de mon doctorat en 2008, j'étais un postdoctorant à l'Université de Californie Berkeley (2008-2010) où j'ai travaillé sur une variété de questions liées à l'hydrologie, la biogéochimie et l'écophysiologie des écosystèmes méditerranéens. Avant de joindre le Département de géographie de l'Université de Montréal en septembre 2011, j'étais un postdoctorant avec Dr Andrew Richardson à l'Université de Harvard (2010-2011) où j'ai effectué des recherches sur la phénologie des forêts en Nouvelle-Angleterre, en utilisant des mesures de covariance des turbulences et de laps de temps en photographie. À l'Université de Montréal, mes recherches portent sur l'hydrologie, la biogéochimie et l'écophysiologie des tourbières dans des zones où le sol est gelé de façon permanente (pergélisol).

 

Expertises de recherche

Mes principaux intérêts scientifiques portent sur la compréhension des altérations dans les interactions entre la biosphère et l'atmosphère en réponse aux changements environnementaux mondiaux, utilisant des mesures par exemple : des mesures de covariance des turbulences), la télédétection (satellite et près de la surface) et les techniques de modélisation. Je suis également intéressé par la mesure locale et la cartographie (régionale, mondiale) des paramètres biophysiques pour étudier les changements dans la structure, le fonctionnement et la phénologie des écosystèmes terrestres.

Publications principales

*Membres de mon groupe de recherche.
  1. Peters, R., Patrick, F., Poyatas, R., *Pappas, C., et al. incl. Sonnentag, O. (submitted), Quantification of uncertainties in tree sapflow measured with the thermal dissipation method. 
  2. *Pappas, C., Matheny, A., Baltzer, J.L., Barr, A., et al. incl. Sonnentag, O. (submitted), Boreal tree hydrodynamics: asynchronous, diverging, yet complementary.
  3. Filippa, G., Cremonese, E., Migliavacca, M., Galvagno, M., Sonnentag, O., et al. (accepted), NDVI derived from near-infrared-enabled digital cameras: applicability across different plant functional types. Agricultural and Forest Meteorology.
  4. *Warren, R.K., *Pappas, C., *Helbig, M., Chasmer, L.E., Berg, A.A., Baltzer, J.L., Quinton, W. L., Sonnentag, O. (accepted), Minor contribution of overstory transpiration to landscape evapotranspiration in boreal forest peatlands. Ecohydrology.
  5. *Helbig, M., Quinton, W. L., Sonnentag, O. (in press), Warmer spring conditions increase annual methane emissions from a boreal peat landscape with sporadic permafrost. Environmental Research Letters.
  6. Rapinski, M., *Payette, F., Sonnentag, O., Herrmann, T.M., Royer, M.-J.S., Currier, A., Siegwart Collier, L., Hermanutz, L., Guanish, G. (2017), Listening to Inuit and Naskapi peoples in the eastern Canadian Subarctic: combining local observations with gridded climate data. Regional Environmental Change, https://doi.org/10.1007/s10113-017-1188-3.
  7. *Roy, A., Toose, P., Derksen, C., Rowlandson, T., Berg, A., Lemmetyinen, J., Royer, A., Tetlock, E., Helgason, W., Sonnentag, O. (2017), Spatial variability of L-band brightness temperature during freeze/thaw events over a prairie environment. Remote Sensing, 9, 894-910.
  8. *Helbig, M., Chasmer, L., Desai, A., Kljun, N., Quinton, W.L., Sonnentag, O. (2017), Direct and indirect climate change effects on carbon dioxide fluxes in a thawing boreal forest-wetland landscape. Global Change Biology, 23, 3231-3248.
  9. Pelletier, N., Talbot, J., Olefeldt, D., Turetsky, M., Blodau, C., Sonnentag, O., Quinton, W. L. (2017), Influence of Holocene permafrost aggradation and thaw on the paleoecology and carbon storage of a peatland complex in northwestern Canada. The Holocene, 27, 1391-1405.
  10. *Helbig, M., Chasmer, L., Kljun, N., Quinton, W.L., Treat, C.C., Sonnentag, O. (2017), The positive net radiative greenhouse gas forcing of increasing methane emissions from a thawing boreal forest-wetland landscape. Global Change Biology, 23, 2413-2427.
  11. *Roy, A., Toose, P., Derksen, C., Royer, A.,Makrovic, A., et al. incl. Sonnentag, O. (2016), Analysis of L-band brightness temperature response to freeze/thaw in two prairie environments from surface-based radiometer measurements. 36th IEEE International Geosciences and Remote Sensing Symposium (IGARSS), 1667-1670.
  12. *Helbig, M., *Wischnewski, K., Kljun, N., Chasmer, L., Quinton, W. L., Detto, M., Sonnentag, O. (2016), Regional cooling and wetting e ect of permafrost thaw-induced boreal forest loss in the sporadic permafrost zone. Global Change Biology, 22, 4048 4066.
  13. Moore, C., Brown, T., Keenan, T., Duursma, R., et al. incl. Sonnentag, O. (2016), Australian vegetation phenology: new insights from satellite remote sensing and digital repeat photography. Biogeosciences, 17, 5085-5102.
  14. *Roy, A., Royer, A., Derksen, C., Langlois, A., Sonnentag, O. (2016), Monitoring boreal and Arctic freeze/thaw with the first year of SMAP brightness temperatures. 14th Specialist Meeting on MICROwave RADiometry and Remote Sensing of the Environment (MICRORAD), 82-84.
  15. *Helbig, M., *Wischnewski, K., *Gosselin, G.H., Biraud, S.C., Bogoev, I., Chan, W.S., Euskirchen, E.S., Glenn, A.J., Marsh, P.M., Quinton, W.L., Sonnentag, O. (2016), Addressing a systematic bias in carbon dioxide flux measurements with the EC150 and the IRGASON open-path gas analyzers, Agricultural and Forest Meteorology, 228, 349-359.
  16. Hwang, Y., Ryu, Y., Kimm, H., Jiang, C. Lang, M. Sonnentag, O. (2016), Correction for light scattering combined with sub-pixel classification improves estimation of gap fraction from digital cover photography. Agricultural and Forest Meteorology, 222, 32-44. 
  17. *Helbig, M., *Pappas, C., Sonnentag, O. (2016), Permafrost thaw and wildfire: equally important drivers of boreal tree cover changes in the Taiga Plains, Canada. Geophysical Research Letters, 43, GL067193.
  18. Brown, T.B., Hultine, K., Steltzer, H. et al. incl. Sonnentag, O. (2016), Using phenocams to monitor our changing Earth: towards a global phenocam network. Frontiers in Ecology and the Environment, 14, 84-93. Featured on the cover of the March 2016 issue.
  19. *Garon-Labreque, M.-É., Léveillé-Bourret, É., *Higgins, K., Sonnentag, O. (2015), Additions to the Boreal flora of the Northwest Territories with a preliminary vascular flora of Scotty Creek. Canadian Field-Naturalist, 129, 349-367.
  20. Connon, R., Quinton, W., Craig, J., *Hanisch, J., Sonnentag, O. (2015), The hydrology of interconnected bog complexes in discontinuous permafrost regions. Hydrological Processes, 29, 3829-4174. 
  21. Matthes, J.H., Knox, S.H., Sturtevant, C., Sonnentag, O., Verfaillie, J., Baldocchi, D.D. (2015), Predicting landscape-scale CO2 flux at a pasture and rice paddy with long-term hyper spectral canopy reflectance measurements. Biogeosciences, 12, 4577-4595.
  22. Raabe, K., Pisek, J., Sonnentag, O., Annuk, K. (2015), Variations of leaf inclination angle distribution with height over the growing season and light exposure for eight broadleaf tree species. Agricultural and Forest Meteorology, 214-215, 2-11.
  23. Detto, M., Asner, G.P., Mueller-Landau, H.C., Sonnentag, O. (2015), Spatial variability in tropical forest leaf area density from multireturn LiDAR and modeling. Journal of Geophysical Research-Biogeosciences, 120, G002774.
  24. Toomey, M., Friedl, M.A., Frolking, S., Hufkens, K., Klosterman, S., Sonnentag, O., et al., (2015), Greenness indices from digital cameras predict the timing and seasonal dynamics of canopy-scale photosynthesis. Ecological Applications, 25, 99-115.  
  25. Peichl, M., Sonnentag, O., Nilsson, M.B. (2015), Bringing color into the picture - using digital repeat photography to investigate phenology controls of the carbon dioxide exchange in a boreal mire. Ecosystems, 18, 115-131.
  26. Talbot, J., Roulet, N.T., Sonnentag, O., Moore, T.R. (2014), Increases in aboveground biomass and leaf area 85  years after drainage in a bog. Botany, 92, 713-721.  
  27. Keenan, T.F., Darby, B., Felts, E., Sonnentag, O., Friedl, M.A,, Hufkens, K., O'Keefe, J., Klosterman, S., Munger, J.W., Toomey, M., Richardson, A.D. (2014), Tracking forest phenology and seasonal physiology using digital repeat photography. Ecological Applications, 24, 1478-1489.
  28. Macfarlane, C., Ryu, Y., Odgen, G.N., Sonnentag, O. (2014), Digital camera photography: exposed and in the raw. Agricultural and Forest Meteorology, 197, 244-253.
  29. Klosterman, S.T., Hufkens, K., Gray, J., Melaas, E., Sonnentag, O., Lavine, I., Mitchell, L., Norman, R., Friedl, M.A., Richardson, A.D. (2014), Evaluating remote sensing of deciduous forest phenology at multiple spatial scales using PhenoCam imagery. Biogeosciences, 11, 4305-4320.
  30. Kross, A., Seaquist, J.W., Roulet, N.T., Fernandes, R., Sonnentag, O. (2013), Estimating carbon dioxide exchange rates of contrasting northern peatlands using MODIS satellite data. Remote Sensing of Environment, 137, 234-243.
  31. Royer, M.-J.S., Herrmann, T.M., Sonnentag, O., Delusca, K., Fortier, D. (2013), Linking Cree hunters' and scientific observations of changing inland ice and meteorological conditions in the subarctic Eastern James Bay region, Canada. Climatic Change, 199, 719-732.
  32. Peichl, M., Sonnentag, O., Wohlfahrt, G., Baldocchi, D.D., Flanagan, L.B., Kiely, G., Galvagno, M., Gianelle, D., Marcolla, B., Pio, C., Migliavacca, M., Jones, M.B., Saunders, M. (2013), Convergence of potential net ecosystem production across contrasting C3 grasslands. Ecology Letters 16, 502-512.
  33. Vargas, R., Sonnentag, O., Abramowitz, G., Carrara, A., Correia, A., Kobayashi, D., Papale, D., Pearson, J., Pereira, S., Piao, S., Rambal, S., Baldocchi, D.D. (2013),  Drought influences the accuracy of simulated ecosystem fluxes: a model-data meta-analysis for Mediterranean oak woodlands. Ecosystems 16, 749-764.
  34. Pisek, J., Sonnentag, O., Richardson, A.D., Mottus, M. (2013), Is the spherical leaf inclination angle distribution a valid assumption for temperate and boreal tree species? Agricultural and Forest Meteorology, 169, 186-194. Shared lead authorship between J. Pisek and O. Sonnentag.
  35. Richardson, A.D., Keenan, T., Migliavacca, M., Ryu, Y., Sonnentag, O., Toomey, M. (2013), Climate change, phenology, and phenological control of vegetation feedbacks to the climate system. Agricultural and Forest Meteorology, 169, 156-173. Invited review.
  36. Ryu, Y., Verfaillie, J., MacFarlane, C., Kobayashi, H., Sonnentag, O., Vargas, R., Ma, S., Baldocchi, D.D. (2012), A new approach for continuous observation of leaf area index at ecosystem scale using upward-pointing digital cameras. Remote Sensing of Environment, 126, 116-125.
  37. Sonnentag, O., Hufkens, K., Teshera-Sterne, C., Young, A.M., Friedl, M.A., Braswell, B.H., Miliman, T., O'Keefe, J., Richardson, A.D. (2012), Digital repeat photography for phenological research in forest ecosystems. Agricultural and Forest Meteorology, 152, 159-177.
  38. Hufkens, K., Richardson, A.D., Friedl, M.A., Keenan, T.F., Sonnentag, O., Bailey, A., O'Keefe, J. (2012), Ecological impacts of a widespread frost event following early spring leaf-out. Global Change Biology, 18, 2365-2377.
  39. Migliavacca, M., Sonnentag, O., Keenan, T.F., Cescatti, A., O'Keefe, O., Richardson, A.D. (2012), On the uncertainty of phenological responses to climate change, and implications for a terrestrial biosphere model. Biogeosciences, 9, 2063-2083.
  40. Hatala, J.A., Detto, M., Sonnentag, O., Deverel, S.J., Verfaillie, J., Baldocchi, D.D. (2012), Greenhouse gas fluxes from drained and  flooded agricultural peatlands in the Sacramento-San Joaquin Delta. Agricultural, Ecosystems and Environment, 115, 1-18.
  41. Baldocchi, D.D., Detto, M., Sonnentag, O., Verfaillie, J., Teh, Y., Silver, W., Kelly, M. (2012), The challenges of measuring methane  fluxes and concentrations over a peatland pasture. Agricultural and Forest Meteorology, 153, 177-187.
  42. Hufkens, K., Richardson, A.D., Sonnentag, O., Braswell, B.H., Miliman, T., Friedl, M.A. (2012), Linking near-surface and satellite remote sensing measurements of deciduous broadleaf phenology. Remote Sensing of Environment, 117, 30-321.
  43. Migliavacca, M., Galvagno, M., Cremonese, E., Rossini, M., Meroni, M., Sonnentag, O., et al., (2011), Using digital repeat photography and eddy covariance data to model grassland phenology and photosynthetic CO2 uptake. Agricultural and Forest Meteorology, 151, 1325-1337.
  44. Sonnentag, O., Detto, M., Ryu, Y., Vargas, R., Runkle, B., Kelly, M., Baldocchi, D.D. (2011), Tracking the structural and functional development of a perennial pepperweed (Lepidium latifolium L.) infestation using a multi-year archive of webcam imagery and eddy covariance measurements. Agricultural and Forest Meteorology, 151, 916-926.
  45. Teh, Y., Silver, W., Sonnentag, O., Detto, M., Kelly, M.,Baldocchi, D.D. (2011), Large greenhouse gas emissions from a temperate peatland pasture. Ecosystems, 14, 311-325.
  46. Govind, A., Chen, J.M., McDonnell, J., Kumari, J., Sonnentag, O. (2011), Effects of lateral hydrological processes on photosynthesis and evapotranspiration in a boreal ecosystem. Ecohydrology, 4, 394-410.
  47. Sonnentag, O., Detto, M., Runkle, B., Teh, YA., Silver, W., Kelly, M., Baldocchi, D.D. (2011), Carbon dioxide exchange of a pepperweed (Lepidium latifolium L.) infestation: how do flowering and mowing aect canopy photosynthesis and autotrophic respiration? Journal of Geophysical Research-Biogeosciences, 113, G02005.
  48. Ryu, Y., Baldocchi, D.D., Verfaillie, J., Ma, S., Falk, M., Ruiz-Mercado, I., Hehn, T., Sonnentag, O., (2010), Testing the performance of a novel spectral reflectance sensor, built with light emitting diodes (LEDs), to monitor ecosystem metabolism, structure and function. Agricultural and Forest Meteorology, 150, 1597-1606.
  49. Sulman, B.N., Desai, A., Saliendra, N., Lafleur, P. Flanagan, L.B., Sonnentag, O., Mackay, D.S., Barr, A.G., van der Kamp, G. (2010), CO2 fluxes at northern fens and bogs have opposite responses to inter-annual fluctuations in water table. Geophysical Research Letters, 37, L19702.
  50. Sonnentag, O., van der Kamp, G., Barr, A.G., Chen, J.M. (2010), On the relationship between water table depth and water vapor and carbon dioxide fluxes in a minerotrophic fen. Global Change Biology, 16, 1762-1776.
  51. Ryu, Y., Nilson, T., Kobayashi, H., Sonnentag, O., Law, B., Baldocchi, D.D. (2010), On the correct estimation of effective leaf area index: does it reveal information on clumping effects? Agricultural and Forest Meteorology, 150, 463-472.
  52. Pisek, J., Chen, J.M., Lacaze, R., Sonnentag, O., Alikas, K. (2010), Refining global mapping of clumping index with multi-angular POLDER 3 measurements: topographic correction and evaluation. ISPRS Journal of Photogrammetry and Remote Sensing, 65, 341-345.
  53. Ryu, Y., Sonnentag, O., Nilson, T., Vargas, R., Kobayashi, H., Baldocchi, D.D. (2010), How to quantify tree leaf area index in savannas? A multi-instrument and multi-model approach. Agricultural and Forest Meteorology, 150, 63-76.
  54. El Maayar, M., Sonnentag, O. (2009), Crop model validation and sensitivity to climate change scenarios. Climate Research, 39, 47-59.
  55. Govind, A., Chen, J.M., Margolis, H., Ju, W., Sonnentag, O., Giasson, M.-A. (2009), A spatially explicit hydroecological-modeling framework (BEPS-TerrainLab v2.0): Model description and test in a boreal ecosystem in Eastern North America. Journal of Hydrology, 367, 200-216.
  56. Sonnentag, O., Chen, J.M., Roulet, N.T., Ju, W., Govind, A. (2008), Spatially explicit simulation of peatland hydrology and carbon dioxide exchange: Influence of mesoscale topography. Journal of Geophysical Research-Biogeosciences, 113, G02005.
  57. Sonnentag, O., Talbot, J., Chen, J.M., Roulet, T.N. (2007), Using direct and indirect measurements of leaf area index to characterize the shrub canopy of an ombrotrophic peatland. Agricultural and Forest Meteorology, 144, 200-212.
  58. Sonnentag, O., Chen, J.M., Roberts, D.A., Talbot, J., Govind, A., Halligan, K. (2007), Mapping tree and shrub leaf area indices in an ombrotrophic peatland using eld measurements and multiple endmember spectral mixture analysis. Remote Sensing of Environment, 109, 342-360.
  59. Chen, J.M., Govind, A., Sonnentag, O., Zhang, Y., Barr, A.G., Amiro, B. (2006), Leaf area index measurements at Fluxnet-Canada forest sites. Agricultural and Forest Meteorology, 140, 257-268.

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