Mon domaine d’intervention est orienté vers l’étude et le suivi de notre environnement entre autres au moyen d’outils de télédétection. Par ailleurs, je m’intéresse aux changements climatiques de la planète et indirectement aux phénomènes physiques qui interviennent dans l’atmosphère. Je développe aussi des méthodes d’estimation, par télédétection, de l’équivalent en eau de la neige, dans un contexte de production hydroélectrique.

• Formation
• Domaines d’enseignement
• Recherches actuelles
• Publications récentes

• B. Sc. (physique), Université de Grenoble 1- Joseph Fourier, France (1975)
• M. Sc. (physique), Université de Grenoble 1- Joseph Fourier, France (1977)
• Ph.D. (géo-physique), Université de Grenoble 1- Joseph Fourier, France (1981)

• Climatologie et changements globaux
• Physique de la télédétection
• Télédétection optique, thermique, radar et micro-ondes passives

• Suivi et estimation par satellite de la couverture de neige, de la réserve en eau de la neige et des températures du sol
• Fusion de données infrarouge thermique et micro-onde
• Développement de méthodes de suivi de l’environnement nordique dans un contexte de changements climatiques
• Détection de feux de forêts
• Étude des aérosols atmosphériques et suivi de la qualité de l’air par télédétection

• Royer A. (2020)  Crises économiques, CO₂ et Climat : gare à l’effet pendule.  Le Climatoscope, Université de Sherbrooke, 2, 21-26.
• Pomerleau P., A. Royer, A. Langlois, P. Cliche, B. Courtemanche, J.-B. Madore, G. Picard and E. Lefebvre (2020). Low cost and compact FMCW 24 GHz radar applications for snowpack and ice thickness measurements. Sensors (MDPI), 20(14), 3909.
• Vargel V., A. Royer, O. St-Jean-Rondeau, G. Picard, A. Roy, V. Sasseville and A. Langlois (2020) Arctic and Subarctic snow microstructure analysis for microwave brightness temperature simulations. Remote Sensing of Environment, 242, 111754.
• Mavrovic A., J.-B. Madore, A. Langlois, A. Royer, A. Roy (2020) Snow liquid water content measurement using an open-ended coaxial probe (OECP). Cold Regions Science and Technology, 171, 102958
• Langlois, A., A. Royer, B. Montpetit, A. Roy and M. Durocher (2020) Presenting Snow Grain Size and Shape Distributions in Northern Canada Using a New Photographic Device Allowing 2D and 3D Representation of Snow Grains. Frontiers Earth Science, 7:347.
• Roy A., P. Toose, A. Mavrovic, C. Pappas, A. Royer, C. Derksen, A. Berg, T. Rowlandson, M. El-Amine, A. Barr, A. Black, A. Langlois and O. Sonnentag (2020). L-Band response to freeze/thaw in a boreal forest stand from ground- and tower-based radiometer observations. Remote Sensing of Environment, 237, 111542.
• Meloche, J., Royer, A., Langlois, A., Rutter, N., & Sasseville, V. (2020). Improvement of microwave emissivity parameterization of frozen Arctic soils using roughness measurements derived from photogrammetry. International Journal of Digital Earth, 1-17.
• Mavrovic, A., Pardo Lara, R., Berg, A., Demontoux, F., Royer, A., & Roy, A. (2020). Soil dielectric characterization at L-band microwave frequencies during freeze-thaw transitions. Hydrology and Earth System Sciences Discussions, 1-22.
• Rutter, N., Sandells, M. J., Derksen, C., King, J., Toose, P., Wake, L., Watts, T., Essery, R., Roy, A., Royer, A., Marsh, P., Larsen, C. and M. Sturm (2019). Effect of snow microstructure variability on Ku-band radar snow water equivalent retrievals. The Cryosphere, 13, 3045–3059.
• Royer A. (2019).  Alerte dans les hautes latitudes nord : l’Arctique réagit au réchauffement climatique. Le Climatoscope, 1, 25-28.
• Prince, M., Roy, A., Royer, A., & Langlois, A. (2019). Timing and spatial variability of fall soil freezing in boreal forest and its effect on SMAP L-band radiometer measurements. Remote Sensing of Environment, 231, 111230.
• Prince, M., Roy, A., Brucker, L., Royer, A., Kim, Y., and Zhao, T. (2018) Northern Hemisphere surface freeze–thaw product from Aquarius L-band radiometers. Earth System Science Data, 10, 2055-2067.
• Larue, F., Royer, A., De Sève, D., Roy, A., and Cosme, E. (2018) Assimilation of passive microwave AMSR-2 satellite observations in a snowpack evolution model over northeastern Canada. Hydrology and Earth System Sciences, 22, 5711-5734.
• Marchand, N., Royer, A., Krinner, G., Roy, A., Langlois, A. and C. Vargel (2018). Snow-Covered Soil Temperature Retrieval in Canadian Arctic Permafrost Areas, Using a Land Surface Scheme Informed with Satellite Remote Sensing Data. Remote Sensing, 10(11), 1703.
• Larue F., A. Royer, D. DeSève, A. Roy, G. Picard, V. Vionnet (2018). Simulation and assimilation of passive microwave data using a snowpack model coupled to a calibrated radiative transfer model over North-Eastern Canada. Water Resources Research, 54 : 4823-4848. (PDF)
• Mavrovic A., A. Roy, A. Royer, B. Filali, F. Boone, C. Pappas and O. Sonnentag (2018). Dielectric characterization of vegetation in L-band using an open-ended coaxial probe. Geoscientific Instrumentation, Methods and Data Systems, 7 : 195-208.
• Dolant C., B. Montpetit, A. Langlois, L. Brucker, O. Zolina, C.A. Johnson, A. Royer and P. Smith (2018). Assessment of the Barren Ground Caribou die-off during winter 2015-2016 using passive microwave observations. Geophysical Research Letter, 45. (PDF)
• Lyu H, K. A. McColl, X. Li, C. Derksen, A. Berg, T. A. Black, E. Euskirchen, M. Loranty, J. Pulliainen, K. Rautiainen,
T. Rowlandson, A. Roy, A. Royer, A. Langlois, J. Stephens, Hui Lu and D. Entekhabi (2018). Validation of the SMAP freeze/thaw product using categorical triple collocation. Remote Sensing of Environment, 205 : 329-337. (PDF)
• Montpetit B., A. Royer, A. Roy and A. Langlois (2018). In-situ passive microwave parameterization of sub-arctic frozen organic soils. Remote Sensing of Environment, 205 : 112–118. (PDF)
• Dolant C., A. Langlois, L. Brucker, A. Royer, A. Roy and B. Montpetit (2017). Meteorological inventory of Rain-On-Snow events in the Canadian Arctic Archipelago and satellite detection assessment using passive microwave data. Physical Geography, 5, 39 : 428-444.
• Blanchard Y., A. Royer, N. O'Neill, D. Turner and E. Eloranta (2017). Thin ice clouds in the Arctic : Cloud optical depth and particle size retrieved from ground-based thermal infrared radiometry. Atmospheric Measurement Techniques, 10 : 2129-2147.
• Roy, A., P. Toose, C. Derksen, T. Rowlandson, A. Berg, J. Lemmetyinen,A. Royer, E. Tetlock, W. Helgason and O. Sonnentag (2017). Spatial Variability of L-Band Brightness Temperature during Freeze/Thaw Events over a Prairie Environment. Remote Sensing, 9 : 894.
• Larue F., A. Royer, D. De Sève, A. Langlois, A. Roy and L. Brucker (2017). Validation of GlobSnow-2 snow water equivalent over Eastern Canada. Remote Sensing of Environment, 194 : 264-277.
• Derksen C., X. Xu, R.S. Dunbar, A. Colliander, Y. Kim, J. Kimball, A. Black, E. Euskirchen, A. Langlois, M. Loranty, P. Marsh, K. Rautiainen, A. Roy,A. Royer and J. Stephens (2017). Retrieving landscape freeze/thaw state from Soil Moisture Active Passive (SMAP) radar and radiometer measurements. Remote Sensing of Environment, 194 : 48–62.
• Wigneron J.P., T.J. Jackson, P. O’Neill, G.J. De Lannoy, P. de Rosnay, J.P. Walker, P. Ferrazzoli, V. Mironov, S. Bircher, J.P. Grant, M. Kurum, M. Schwank, J. Munoz-Sabater, N. Das, A. Royer, A. Al-Yaari, A. Al Bitar, R. Fernandez-Moran, H. Lawrence, A. Mialon, M. Parrens, P. Richaume, S. Delwart and Y. Kerr (2017). Modelling the passive microwave signature from land surfaces : A review of recent results and application to the L-Band SMOS & SMAP soil moisture retrieval algorithms. Remote Sensing of Environment, Invited Review Paper, 192 : 238–262.
• Busseau B.C., A. Royer, A. Langlois and F. Domine (2017). Analysis of snow-vegetation interactions in the Low Arctic – Subarctic transition zone (north-eastern Canada). Physical Geography, DOI: 10.1080/02723646.2017.1283477
• Roy A., P. Toose, M. Williamson, T. Rowlandson, C. Derksen, A. Royer, A. Berg, J. Lemmetyinen and L. Arnold (2017). Response of L-Band brightness temperatures to freeze/thaw and snow dynamics in a prairie environment from ground-based radiometer measurements. Rem. Sens. of Enviro., 191 : 67-80.
• Toose P., A. Roy, F. Solheim, C. Derksen, T. Watts, A. Royer and A. Walker (2017). Radio-frequency interference mitigating hyperspectral L-band radiometer. Geosci. Instrum. Method. Data Syst., 6 : 39–51.  doi:10.5194/gi-6-39-2017.
• Royer A., A. Roy, B. Montpetit, O. Saint-Jean-Rondeau, G. Picard, L. Brucker and A. Langlois (2017). Comparison of commonly-used microwave radiative transfer models for snow remote sensing. Remote Sensing of Environment, 190 : 247–259.
• Roy A., A. Royer, O. St-Jean-Rondeau, B. Montpetit, G. Picard, A. Mavrovic, N. Marchand, and A. Langlois (2016) Microwave snow emission modeling uncertaintiesin boreal and subarctic environments. The Cryosphere, 10 : 623-638.
• Papasodoro C., A. Royer, A. Langlois and E. Berthier (2016) Potential of RADARSAT-2 stereo radargrammetryfor the generation of glacier digital elevation models. J. of Glaciology, 62(233) : 486-496.
• Roy A., A. Royer, C. Derksen, L. Brucker, A. Langlois, A. Mialon, and Y. Kerr (2015) Evaluation of Spaceborne L-band Radiometer Measurements for Terrestrial Freeze/Thaw Retrievals in Canada. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 8(9) : 4442-4459.
• Papasodoro C., E. Berthier, A. Royer, C. Zdanowicz, and A. Langlois (2015) Area, elevation and mass changes of the two southernmost icecaps of the Canadian Arctic Archipelago between 1952 and 2014. The Cryosphere, 9 : 1535-1550.
• André, C., Ottlé, C., Royer, A., Maignan, F. (2015). Land Surface Temperature Retrieval over circumpolar Arctic using SSM/I-SSMIS and MODIS Data.Rem. Sens. Enviro., 162 : 1-10.
• Montpetit, B., Royer, A., Wigneron., J.-P., Chanzy, A., and Mialon, A. (2015) Evaluation of multi-frequency bare soil microwave reflectivity models. Remote Sensing of Environment, 162 : 186-195.
• Courtemanche, B., Montpetit, B., Royer, A., and Roy, A. (2015). Creation of a Lambertian Microwave Surface for Retrieving the Downwelling. Contribution in Ground-Based Radiometric Measurements. IEEE Geoscience and Remote Sensing Letters, 12(3).
• Dupont F., G. Picard, A. Royer, M. Fily, A. Roy, A. Langlois and N. Champollion (2014). Modeling the microwave emission of bubbly ice : Applications to blue ice and superimposed ice in the Antarctic and Arctic. IEEE Transactions on Geoscience and Remote Sensing, 52(10) : 6639-6651.
• Langlois, A., Bergeron, J., Brown, R., Royer, A., Harvey, R., Roy, A., Wang, L. and Thériault, N. (2014). Evaluation of CLASS 2.7 and 3.5 simulations of snow properties from the Canadian Regional Climate Model (CRCM4) over Québec, Canada. J. of Hydrometeorology, 15 : 1325-1343.
• Picard, G., Royer, A., Arnaud, L., and Fily, M. (2014) Influence of meter-scale wind-formed features on the variability of the microwave brightness temperature around Dome C in Antarctica. The Cryosphere, 8 : 1105-1119.
• Roy, A., Royer, A. and Hall, R. (2014) Relationship between forest microwave transmissivity and structural parameters for the Canadian boreal forest. IEEE Geoscience and Remote Sensing Letters, 11(10) :  1802-1806.
• Rutter, N., M. Sandells, C. Derksen, P. Toose, A. Royer, B. Montpetit, A. Langlois, J. Lemmetyinen, and J. Pulliainen (2014). Snow stratigraphic heterogeneity within ground-based passive microwave radiometer footprints : Implications for emission modeling. J. Geophys. Res. Earth Surf., 119, doi:10.1002/2013JF003017.
• Bergeron J., A. Royer, R. Turcotte (2014). Snow cover estimation using blended MODIS and AMSR-E data for improved watershed-scale spring streamflow simulation in Quebec, Canada. Hydrological Processes, 28, 4626–4639, DOI: 10.1002/hyp.10123.
• Picard, G., Brucker, L., Roy, A., Dupont, F., Fily, M., Royer, A., and Harlow, C. (2013) Simulation of the microwave emission of multi-layered snowpacks using the Dense Media Radiative transfer theory: the DMRT-ML model, Geosci. Model Dev., 6, 1061-1078, doi:10.5194/gmd-6-1061-2013.
• Roy, A., Royer, A., Montpetit, B., Bartlett, P.A., and Langlois, A. (2013) Snow specific surface area simulation using the one-layer snow model in the Canadian LAnd Surface Scheme (CLASS). The Cryosphere, 7, 961-975, doi:10.5194/tc-7-961-2013
• Kohn, J. and A. Royer, (2012) Microwave brightness temperature as an indicator of near-surface air temperature over snow in Canadian northern regions. International Journal of Remote Sensing, 33:4, 1126-1138. http://dx.doi.org/10.1080/01431161.2010.550643.
• Derksen, C., Smith, S. L., Sharp, M., Brown, L., Howell, S., Copland, L., Muelle, D. R., Gauthier, Y., Fletcher, C., Tivy, A., Bernier, M., Bourgeois, J., Brown, R., Burn, C. R., Duguay, C., Kushner, P., Langlois, A., Lewkowicz, A. G., Royer, A. and Walker, A. (2012) Varianility and change in the canadian cryosphere, Climatic Change, DOI: 10.1007/s10584-012-0470-0.
• Dupont, F., Royer, A., Langlois, A., Gressent, A., Picard, G., Fily, M., Cliche, P. and Chum, M. (2012) Monitoring the melt season length of the Barnes Ice Cap over the 1979–2010 period using active and passive microwave remote sensing data. Hydrol. Process. doi: 10.1002/hyp.9382
• Dupont, F., Picard, G., Royer, A., Fily, M., Langlois, A., Roy, A., and Champollion, N. (2012) Modeling the microwave emission of bubbly ice; Applications to blue ice and superimposed ice in the Antarctic and Arctic, IEEE Transactions on Geosciences and Remote Sensing, Submitted, TGRS_2012-01104.
• Langlois, A., A. Royer, C. Derksen, B. Montpetit, F. Dupont, and K. Goïta (2012) Coupling the snow thermodynamic model SNOWPACK with the microwave emission model of layered snowpacks for subarctic and arctic snow water equivalent retrievals. Water Resour. Res., 48, W12524, doi:10.1029/2012WR012133.
• Montpetit B., Royer, A., Roy, A., Langlois, A. and Derksen, C. (2012) Snow microwave emission modeling of ice lenses within the snowpack using the Microwave Emission Model for Layered Snowpacks (MEMLS), Hydrological Processes.
• Montpetit B., Royer A., Langlois A., Cliche P., Roy A., Champollion N., Picard G., Domine F., Obbard R. (2012) New short wave infrared albedo measurements for snow specific surface area retrieval, Journal of Glaciology, vol. 58, no. 211, doi: 10.3189/2012JoG11j248.
• Roy, A., Picard, G., Royer, A., Montpetit, B., Dupont, F., Langlois, A., and Derksen, C. (2012) Snow brightness temperature simulations driven by measurements of the specific surface area of snow grains, IEEE Transactions on Geoscience and Remote Sensing, Accepted, TGRS-2012-00591.
• Roy, A., Royer, A., Wigneron, J.-P., Langlois, A., Bergeron, J., Cliche, P. (2012) A simple parameterization for a boreal forest radiative transfer model at microwave frequencies. Remote Sensing of Environment, 124, doi: 10.1016/j.rse.2012.05.020.
• Rutter, N., Sandells, M., Derksen, C., Royer, A., Lemmetyinen, J., Toose, P., Montpetit, B., Langlois, A., and Pulliainen, J. (2012) Snow stratigraphic heterogeneity within ground-based passive microwave radiometer footprints: implications for emission modelling. Journal of Geophysical Research.

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