Articles | Volume 16, issue 7
https://doi.org/10.5194/tc-16-2859-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-16-2859-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
19 Jul 2022
Research article |
| 19 Jul 2022
| 19 Jul 2022
Coherent backscatter enhancement in bistatic Ku- and X-band radar observations of dry snow
Institute of Environmental Engineering, ETH Zurich, 8093 Zurich, Switzerland
Institute of Environmental Engineering, ETH Zurich, 8093 Zurich, Switzerland
LISTIC, Université Savoie Mont Blanc, 74000 Annecy, France
Gamma Remote Sensing, 3073 Gümligen, Switzerland
Othmar Frey
Institute of Environmental Engineering, ETH Zurich, 8093 Zurich, Switzerland
Gamma Remote Sensing, 3073 Gümligen, Switzerland
Irena Hajnsek
Institute of Environmental Engineering, ETH Zurich, 8093 Zurich, Switzerland
Microwaves and Radar Institute, German Aerospace Center, 82234 Weßling, Germany
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This preprint is open for discussion and under review for Natural Hazards and Earth System Sciences (NHESS).
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The latest satellite technology with longer wavelength radar improves our ability to detect and monitor large alpine rock slope instabilities. This approach works better than current satellite systems in forested areas and on fast-moving slopes, giving experts more reliable data to understand these major hazards. Our results from three locations in Italy and Switzerland also provide important recommendations for the preparation of future satellite radar missions.
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Synthetic Aperture Radar (SAR) revealed ice features of unknown glaciological origin in southwest Greenland’s ablation zone. Using SAR techniques, we identified low-backscatter areas with surface scattering, in contrast to surrounding high-backscatter areas with scattering from the subsurface. Our first theory relates the low backscatter to residual liquid water in a weathering crust and the surrounding to bare glacier ice. These findings may deepen our understanding of ablation zone properties.
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Avalanches are important for the mass balance of mountain glaciers, but few data exist on where and when they occur and which glaciers they affect the most. We developed an approach to map avalanches over large glaciated areas and long periods of time using satellite radar data. The application of this method to various regions in the Alps and High Mountain Asia reveals the variability of avalanches on these glaciers and provides key data to better represent these processes in glacier models.
Fanny Brun, Owen King, Marion Réveillet, Charles Amory, Anton Planchot, Etienne Berthier, Amaury Dehecq, Tobias Bolch, Kévin Fourteau, Julien Brondex, Marie Dumont, Christoph Mayer, Silvan Leinss, Romain Hugonnet, and Patrick Wagnon
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The South Col Glacier is a small body of ice and snow located on the southern ridge of Mt. Everest. A recent study proposed that South Col Glacier is rapidly losing mass. In this study, we examined the glacier thickness change for the period 1984–2017 and found no thickness change. To reconcile these results, we investigate wind erosion and surface energy and mass balance and find that melt is unlikely a dominant process, contrary to previous findings.
Jan Freihardt and Othmar Frey
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In Bangladesh, riverbank erosion occurs every year during the monsoon and affects thousands of households. Information on locations and extent of past erosion can help anticipate where erosion might occur in the upcoming monsoon season and to take preventive measures. In our study, we show how time series of radar satellite imagery can be used to retrieve information on past erosion events shortly after the monsoon season using a novel interactive online tool based on the Google Earth Engine.
Philipp Bernhard, Simon Zwieback, and Irena Hajnsek
The Cryosphere, 16, 2819–2835, https://doi.org/10.5194/tc-16-2819-2022, https://doi.org/10.5194/tc-16-2819-2022, 2022
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S. Kaushik, S. Leinss, L. Ravanel, E. Trouvé, Y. Yan, and F. Magnin
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Philipp Bernhard, Simon Zwieback, Nora Bergner, and Irena Hajnsek
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We present an investigation of retrogressive thaw slumps in 10 study sites across the Arctic. These slumps have major impacts on hydrology and ecosystems and can also reinforce climate change by the mobilization of carbon. Using time series of digital elevation models, we found that thaw slump change rates follow a specific type of distribution that is known from landslides in more temperate landscapes and that the 2D area change is strongly related to the 3D volumetric change.
Lanqing Huang, Georg Fischer, and Irena Hajnsek
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This study shows an elevation difference between the radar interferometric measurements and the optical measurements from a coordinated campaign over the snow-covered deformed sea ice in the western Weddell Sea, Antarctica. The objective is to correct the penetration bias of microwaves and to generate a precise sea ice topographic map, including the snow depth on top. Excellent performance for sea ice topographic retrieval is achieved with the proposed model and the developed retrieval scheme.
Silvan Leinss, Enrico Bernardini, Mylène Jacquemart, and Mikhail Dokukin
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A cluster of 13 large mass flow events including five detachments of entire valley glaciers was observed in the Petra Pervogo range, Tajikistan, in 1973–2019. The local clustering provides additional understanding of the influence of temperature, seismic activity, and geology. Most events occurred in summer of years with mean annual air temperatures higher than the past 46-year trend. The glaciers rest on weak bedrock and are rather short, making them sensitive to friction loss due to meltwater.
Andreas Kääb, Mylène Jacquemart, Adrien Gilbert, Silvan Leinss, Luc Girod, Christian Huggel, Daniel Falaschi, Felipe Ugalde, Dmitry Petrakov, Sergey Chernomorets, Mikhail Dokukin, Frank Paul, Simon Gascoin, Etienne Berthier, and Jeffrey S. Kargel
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Hardly recognized so far, giant catastrophic detachments of glaciers are a rare but great potential for loss of lives and massive damage in mountain regions. Several of the events compiled in our study involve volumes (up to 100 million m3 and more), avalanche speeds (up to 300 km/h), and reaches (tens of kilometres) that are hard to imagine. We show that current climate change is able to enhance associated hazards. For the first time, we elaborate a set of factors that could cause these events.
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Satellites prove to be very valuable for documentation of large-scale avalanche periods. To test reliability and completeness, which has not been satisfactorily verified before, we attempt a full validation of avalanches mapped from two optical sensors and one radar sensor. Our results demonstrate the reliability of high-spatial-resolution optical data for avalanche mapping, the suitability of radar for mapping of larger avalanches and the unsuitability of medium-spatial-resolution optical data.
Eef C. H. van Dongen, Guillaume Jouvet, Shin Sugiyama, Evgeny A. Podolskiy, Martin Funk, Douglas I. Benn, Fabian Lindner, Andreas Bauder, Julien Seguinot, Silvan Leinss, and Fabian Walter
The Cryosphere, 15, 485–500, https://doi.org/10.5194/tc-15-485-2021, https://doi.org/10.5194/tc-15-485-2021, 2021
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The dynamic mass loss of tidewater glaciers is strongly linked to glacier calving. We study calving mechanisms under a thinning regime, based on 5 years of field and remote-sensing data of Bowdoin Glacier. Our data suggest that Bowdoin Glacier ungrounded recently, and its calving behaviour changed from calving due to surface crevasses to buoyancy-induced calving resulting from basal crevasses. This change may be a precursor to glacier retreat.
Cited articles
Aegerter, C. M. and Maret, G.: Coherent Backscattering and Anderson
Localization of Light, Prog. Optics, 52, 1–62,
https://doi.org/10.1016/S0079-6638(08)00003-6, 2009. a
Akkermans, E. and Montambaux, G.: Mesoscopic physics of photons, J. Opt. Soc.
Am. B, 21, 101–112, https://doi.org/10.1364/JOSAB.21.000101, 2004. a
Akkermans, E., Wolf, P. E., and Maynard, R.: Coherent backscattering of light
by disordered media: Analysis of the peak line shape, Phys. Rev.
Lett., 56, 1471–1474, https://doi.org/10.1103/PhysRevLett.56.1471, 1986. a, b
Baffelli, S., Frey, O., Werner, C., and Hajnsek, I.: Polarimetric Calibration
of the Ku-Band Advanced Polarimetric Radar Interferometer, IEEE T. Geosci. Remote, 56, 2295–2311, 2017. a
Belward, A., Bourassa, M., Dowell, M., et al.: The global observing system for climate: implementation
needs, Tech. Rep., GCOS-200, World Meteorological Organization, https://gcos.wmo.int/en/gcos-implementation-plan (last access: 12 July 2022), 2016. a
Black, G. J., Campbell, D. B., and Nicholson, P. D.: Icy Galilean Satellites:
Modeling Radar Reflectivities as a Coherent Backscatter Effect, Icarus, 151,
167–180, https://doi.org/10.1006/icar.2001.6616, 2001. a
DLR: TanDEM-X Science Service System, DLR [data set], https://tandemx-science.dlr.de/, last access: 9 June 2022. a
Dubois-Fernandez, P., Cantalloube, H., Vaizan, B., Krieger, G., Horn, R.,
Wendler, M., and Giroux, V.: ONERA-DLR bistatic SAR campaign: Planning, data
acquisition, and first analysis of bistatic scattering behavior of natural
and urban targets, Radar, Sonar and Navigation, IEE P.-Radar Son. Nav., 153,
214–223, https://doi.org/10.1049/ip-rsn:20045117, 2006. a
Duque, S., Balss, U., Rossi, S., Fritz, T., and Balzer, W.: TanDEM-X
Payload Ground Segment CoSSC Generation and Interferometric Considerations,
TD-PGS-TN-3129, issue 1.0, Remote Sensing Technology Institute, DLR, https://tandemx-science.dlr.de/pdfs/TD-PGS-TN-3129_CoSSCGenerationInterferometricConsiderations_1.0.pdf (last access: 12 July 2022), 2012. a, b
Fierz, C., Armstrong, R. L., Durand, Y., Etchevers, P., Greene, E., McClung, D. M., Nishimura, K., Satyawali, P. K., and Sokratov, S. A.: The International Classification for Seasonal Snow on the Ground, IHP-VII Technical Documents in Hydrology No. 83, IACS Contribution No. 1, UNESCO-IHP, Paris, https://unesdoc.unesco.org/ark:/48223/pf0000186462 (last access: 12 July 2022), 2009. a
Fritz, T., Brautigam, B., Krieger, G., and Zink, M.: TanDEM-X Ground
Segment – TanDEM-X Experimental Product Description,
TD-GS-PS-3028, issue 1.2, DLR, 1.2 edn., https://tandemx-science.dlr.de/pdfs/TD-GS-PS-3028_TanDEM-X-Experimental-Product-Description_1.2.pdf (last access: 12 July 2022), 2012. a, b
Haeberli, W. and Alean, J.: Temperature and Accumulation of High Altitude Firn
in the Alps, Ann. Glaciol., 6, 161–163,
https://doi.org/10.3189/1985AoG6-1-161-163, 1985. a
Hajnsek, I., Busche, T., Krieger, G., Zink, M., Schulze, D., and Moreira, A.:
Announcement of opportunity: TanDEM-X science phase, Tech. Rep.
TD-PD-PL-0032, Microwave and Radar Institute (DLR-HR), https://tandemx-science.dlr.de/pdfs/TD-PD-PL_0032TanDEM-X_Science_Phase.pdf (last access: 12 July 2022), 2014. a
Hapke, B.: Bidirectional reflectance spectroscopy: 4. The extinction
coefficient and the opposition effect, Icarus, 67, 264–280,
https://doi.org/10.1016/0019-1035(86)90108-9, 1986. a, b
Hapke, B.: Coherent backscatter and the radar characteristics of outer planet
satellites, Icarus, 88, 407–417, https://doi.org/10.1016/0019-1035(90)90091-M, 1990. a
Hapke, B., DiMucci, D., Nelson, R., and Smythe, W.: The cause of the hot spot
in vegetation canopies and soils: Shadow-hiding versus coherent backscatter,
Remote Sens. Environ., 58, 63–68,
https://doi.org/10.1016/0034-4257(95)00257-X, 1996. a, b
Hapke, B., Nelson, R., and Smythe, W.: The Opposition Effect of the Moon:
Coherent Backscatter and Shadow Hiding, Icarus, 133, 89–97,
https://doi.org/10.1006/icar.1998.5907, 1998. a
Hapke, B. W., Nelson, R. M., and Smythe, W. D.: The Opposition Effect of the
Moon: The Contribution of Coherent Backscatter, Science, 260, 509–511,
https://doi.org/10.1126/science.260.5107.509, 1993. a
Ishimaru, A.: Wave propagation and scattering in random media, 1st edn., vol. 1–2,
Academic press New York, ISBN 978-0-12-374701-3, https://doi.org/10.1016/B978-0-12-374701-3.X5001-7, 1978. a
Jun, L., Wang, W., and Zwally, H. J.: Interannual variations of shallow firn
temperature at Greenland summit, Ann. Glaciol., 35, 368–370, 2002. a
Kaasalainen, S., Kaasalainen, M., Mielonen, T., Suomalainen, J., Peltoniemi,
J. I., and Näränen, J.: Optical properties of snow in
backscatter, J. Glaciol., 52, 574–584,
https://doi.org/10.3189/172756506781828421, 2006. a
Krieger, G., Moreira, A., Fiedler, H., Hajnsek, I., Werner, M., Younis, M., and
Zink, M.: TanDEM-X: A satellite formation for high-resolution SAR
interferometry, IEEE T. Geosci. Remote, 45,
3317–3341, 2007. a
Kuga, Y. and Ishimaru, A.: Retroreflectance from a dense distribution of
spherical particles, J. Opt. Soc. Am. A, 1, 831–835,
https://doi.org/10.1364/josaa.1.000831, 1984. a, b
Kuga, Y., Ulaby, F. T., Haddock, T. F., and DeRoo, R. D.: Millimeter‐wave
radar scattering from snow 1. Radiative transfer model, Radio Sci., 26,
329–341, https://doi.org/10.1029/90RS02560, 1991. a, b
Leinss, S. and Bernhard, P.: TanDEM-X:Deriving InSAR Height Changes and
Velocity Dynamics of Great Aletsch Glacier, IEEE J. Sel. Top.
Appl., 14, 4798–4815,
https://doi.org/10.1109/JSTARS.2021.3078084, 2021. a, b, c
Lemmetyinen, J., Kontu, A., Pulliainen, J., Vehviläinen, J., Rautiainen, K., Wiesmann, A., Mätzler, C., Werner, C., Rott, H., Nagler, T., Schneebeli, M., Proksch, M., Schüttemeyer, D., Kern, M., and Davidson, M. W. J.: Nordic Snow Radar Experiment, Geosci. Instrum. Method. Data Syst., 5, 403–415, https://doi.org/10.5194/gi-5-403-2016, 2016. a, b
Löwe, H. and Picard, G.: Microwave scattering coefficient of snow in MEMLS and DMRT-ML revisited: the relevance of sticky hard spheres and tomography-based estimates of stickiness, The Cryosphere, 9, 2101–2117, https://doi.org/10.5194/tc-9-2101-2015, 2015. a
Lucas, C., Leinss, S., Bühler, Y., Marino, A., and Hajnsek, I.:
Multipath interferences in ground-based radar data: A case study, Remote
Sensing, 9, 1260, https://doi.org/10.3390/rs9121260, 2017. a
Mätzler, C.: Improved Born approximation for scattering of radiation in a
granular medium, J. Appl. Phys., 83, 6111–6117,
https://doi.org/10.1063/1.367496, 1998. a, b
Mätzler, C. and Wegmüller, U.: Dielectric properties of freshwater ice at
microwave frequencies, J. Phys. D: Appl. Phys., 20, 1623–1630,
https://doi.org/10.1088/0022-3727/20/12/013, 1987. a
Mätzler, C. and Wegmüller, U.: Dielectric properties of freshwater ice at
microwave frequencies – Errata, J. Phys. D Appl. Phys., 21, 1660–1660,
https://doi.org/10.1088/0022-3727/21/11/522,
1988. a
Meta, A., Trampuz, C., Coccia, A., Placidi, S., Hendriks, L. I., Davidson, M.,
and Schuettemeyer, D.: Bistatic Airborne SAR Acquisitions at L-Band by
MetaSensing: First Results, in: EUSAR 2018; 12th European Conference on
Synthetic Aperture Radar, Aachen, Germany, 4–7 June 2018, 1368–1372, https://ieeexplore.ieee.org/document/8438240 (last access: 12 July 2022), 2018. a
Mishchenko, M. I.: The angular width of the coherent back-scatter opposition
effect: an application to icy outer planet satellites, Astrophys. Space
Sci., 194, 327–333, https://doi.org/10.1007/BF00644001, 1992a. a, b, c
Mishchenko, M. I.: Polarization characteristics of the coherent backscatter
opposition effect, Earth Moon Planets, 58, 127–144,
https://doi.org/10.1007/BF00054650, 1992b. a, b, c
Mishchenko, M. I.: Enhanced backscattering of polarized light from discrete
random media: calculations in exactly the backscattering direction, J. Opt.
Soc. Am. A, 9, 978–982, https://doi.org/10.1364/JOSAA.9.000978, 1992c. a, b
Mishchenko, M. I., Luck, J.-M., and Nieuwenhuizen, T. M.: Full angular profile
of the coherent polarization opposition effect, J. Opt.
Soc. Am. A, 17, 888–891, https://doi.org/10.1364/JOSAA.17.000888, 2000. a
Montgomery, W. W. and Kohl, R. H.: Opposition-effect experimentation, Opt.
Lett., 5, 546–548, https://doi.org/10.1364/OL.5.000546, 1980. a
Muhleman, D. O., Butler, B. J., Grossman, A. W., and Slade, M. A.: Radar
images of mars, Science, 253, 1508–1513,
https://doi.org/10.1126/science.253.5027.1508, 1991. a
Nelder, J. A. and Mead, R.: A simplex method for function minimization,
Comput. J., 7, 308–313, 1965. a
Nozette, S., Lichtenberg, C. L., Spudis, P., Bonner, R., Ort, W., Malaret, E.,
Robinson, M., and Shoemaker, E. M.: The Clementine bistatic radar
experiment, Science, 274, 1495–1498, https://doi.org/10.1126/science.274.5292.1495,
1996. a
Oliver, C. and Quegan, S.: Understanding synthetic aperture radar images,
SciTech Publishing, ISBN 1891121316, 2004. a
Palmer, E. M., Heggy, E., and Kofman, W.: Orbital bistatic radar observations
of asteroid Vesta by the Dawn mission, Nat. Commun., 8, 409,
https://doi.org/10.1038/s41467-017-00434-6, 2017. a
Patterson, G. W., Stickle, A. M., Turner, F. S., Jensen, J. R., Bussey, D. B.,
Spudis, P., Espiritu, R. C., Schulze, R. C., Yocky, D. A., Wahl, D. E.,
Zimmerman, M., Cahill, J. T., Nolan, M., Carter, L., Neish, C. D., Raney,
R. K., Thomson, B. J., Kirk, R., Thompson, T. W., Tise, B. L., Erteza, I. A.,
and Jakowatz, C. V.: Bistatic radar observations of the Moon using Mini-RF
on LRO and the Arecibo Observatory, Icarus, 283, 2–19,
https://doi.org/10.1016/j.icarus.2016.05.017, 2017. a
Pieraccini, M. and Miccinesi, L.: Bistatic GBSAR for detecting target
elevation, in: 2017 IEEE International Conference on Microwaves, Antennas,
Communications and Electronic Systems (COMCAS), Tel-Aviv, Israel, 13–15 November 2017, pp. 1–4, IEEE, https://doi.org/10.1109/COMCAS.2017.8244728, 2017. a
Proksch, M., Löwe, H., and Schneebeli, M.: Density, specific surface area, and
correlation length of snow measured by high-resolution penetrometry, J. Geophys. Res.-Earth Surf., 120, 346–362,
https://doi.org/10.1002/2014JF003266, 2015. a
Raney, R., Freeman, T., Hawkins, R., and Bamler, R.: A plea for radar
brightness, in: Proceedings of IGARSS '94 – 1994 IEEE International
Geoscience and Remote Sensing Symposium, Pasadena, CA, USA, 8–12 August 1994, vol. 2, pp. 1090–1092,
https://doi.org/10.1109/IGARSS.1994.399352, 1994. a
Rignot, E. J.: Backscatter model for the unusual radar properties of the
Greenland ice sheet, J. Geophys. Res., 100, 9389–9400,
https://doi.org/10.1029/95JE00485, 1995. a, b, c
Rignot, E. J., Ostro, S. J., van Zyl, J. J., and Jezek, K. C.: Unusual Radar
Echoes from the Greenland Ice Sheet, Science, 261, 1710–1713,
https://doi.org/10.1126/science.261.5129.1710, 1993. a
Sihvola, A.: Mixing rules with complex dielectric coefficients, Subsurface
Sensing Technologies and Applications, 1, 393–415,
https://doi.org/10.1023/A:1026511515005, 2000. a
Simpson, R. A.: Spacecraft Studies of Planetary Surfaces Using Bistatic
Radar, IEEE T. Geosci. Remote., 31, 465–482,
https://doi.org/10.1109/36.214923, 1993. a
Simpson, R. A. and Tyler, G. L.: Reanalysis of Clementine bistatic radar data
from the lunar South Pole, J. Geophys. Res.-Planet., 104,
3845–3862, https://doi.org/10.1029/1998JE900038, 1999. a
Stefko, M.: Coherent backscatter enhancement in bistatic Ku-/X-band radar observations of dry snow – dataset, ETH Zurich [data set], https://doi.org/10.3929/ethz-b-000516171, 2021. a
Stefko, M., Frey, O., Werner, C., and Hajnsek, I.: KAPRI: A Bistatic
Full-Polarimetric Interferometric Real-Aperture Radar System for Monitoring
of Natural Environments, in: 2021 IEEE International Geoscience and Remote
Sensing Symposium IGARSS, Brussels, Belgium, 11–16 July 2021, pp. 1950–1953,
https://doi.org/10.1109/IGARSS47720.2021.9553427, 2021. a
Stefko, M., Frey, O., Werner, C., and Hajnsek, I.: Calibration and Operation of
a Bistatic Real-Aperture Polarimetric-Interferometric Ku-Band Radar, IEEE
T. Geosci. Remote, 60, 1–19,
https://doi.org/10.1109/TGRS.2021.3121466, 2022. a, b
Suter, S. and Hoelzle, M.: Cold firn in the Mont Blanc and Monte Rosa areas,
European Alps: spatial distribution and statistical models, Ann.
Glaciol., 35, 9–18, https://doi.org/10.3189/172756402781817059, 2002. a
Suter, S., Laternser, M., Haeberli, W., Frauenfelder, R., and Hoelzle, M.: Cold
firn and ice of high-altitude glaciers in the Alps: measurements and
distribution modelling, J. Glaciol., 47, 85–96,
https://doi.org/10.3189/172756501781832566, 2001. a, b, c
Tan, S., Chang, W., Tsang, L., Lemmetyinen, J., and Proksch, M.: Modeling Both
Active and Passive Microwave Remote Sensing of Snow Using Dense Media
Radiative Transfer (DMRT) Theory with Multiple Scattering and Backscattering
Enhancement, IEEE J. Sel. Top. Appl., 8, 4418–4430, https://doi.org/10.1109/JSTARS.2015.2469290, 2015. a, b
Tsang, L. and Ishimaru, A.: Backscattering enhancement of random discrete
scatterers, J. Opt. Soc. Am. A, 1, 836–839,
https://doi.org/10.1364/josaa.1.000836, 1984. a, b, c, d
Tsang, L. and Ishimaru, A.: Theory of backscattering enhancement of random
discrete isotropic scatterers based on the summation of all ladder and
cyclical terms, J. Opt. Soc. Am. A, 2, 1331–1338,
https://doi.org/10.1364/JOSAA.2.001331, 1985. a, b, c, d
Tsang, L., Pan, J., Liang, D., Li, Z., Cline, D. W., and Tan, Y.: Modeling
Active Microwave Remote Sensing of Snow Using Dense Media Radiative Transfer
(DMRT) Theory With Multiple-Scattering Effects, IEEE T. Geosci.
Remote, 45, 990–1004, https://doi.org/10.1109/TGRS.2006.888854, 2007. a
Van Albada, M. P. and Lagendijk, A.: Observation of weak localization of light
in a random medium, Phys. Rev. Lett., 55, 2692–2695,
https://doi.org/10.1103/PhysRevLett.55.2692, 1985. a
van Albada, M. P., van der Mark, M. B., and Lagendijk, A.: Observation of weak
localization of light in a finite slab: Anisotropy effects and light path
classification, Phys. Rev. Lett., 58, 361–364,
https://doi.org/10.1103/PhysRevLett.58.361, 1987. a, b, c
Van Albada, M. P., Van Der Mark, M. B., and Lagendijk, A.: Polarisation
effects in weak localisation of light, J. Phys. D Appl.
Phys., 21, S28–S31, https://doi.org/10.1088/0022-3727/21/10S/009, 1988. a, b, c
Van Albada, M. P., Van der Mark, M. B., and Lagendijk, A.: Experiments on weak
localization of light and their interpretation, 1st edn., in: Scattering and
Localization of Classical Waves in Random Media, edited by: Sheng, P., pp. 97–136, World
Scientific, https://doi.org/10.1142/9789814340687_0002, 1990. a
Vargel, C., Royer, A., St-Jean-Rondeau, O., Picard, G., Roy, A., Sasseville,
V., and Langlois, A.: Arctic and subarctic snow microstructure analysis for
microwave brightness temperature simulations, Remote Sens. Environ.,
242, 111754, https://doi.org/10.1016/j.rse.2020.111754, 2020. a
Virtanen, P., Gommers, R., Oliphant, T. E., Haberland, M., Reddy, T.,
Cournapeau, D., Burovski, E., Peterson, P., Weckesser, W., Bright, J., van
der Walt, S. J., Brett, M., Wilson, J., Millman, K. J., Mayorov, N., Nelson,
A. R. J., Jones, E., Kern, R., Larson, E., Carey, C. J., Polat, İ., Feng,
Y., Moore, E. W., VanderPlas, J., Laxalde, D., Perktold, J., Cimrman, R.,
Henriksen, I., Quintero, E. A., Harris, C. R., Archibald, A. M., Ribeiro,
A. H., Pedregosa, F., van Mulbregt, P., and SciPy 1.0 Contributors:
SciPy 1.0: Fundamental Algorithms for Scientific Computing in Python,
Nat. Methods, 17, 261–272, https://doi.org/10.1038/s41592-019-0686-2, 2020. a
Wang, S., Feng, W., Kikuta, K., Chernyak, G., and Sato, M.: Ground-Based
Bistatic Polarimetric Interferometric Synthetic Aperture Radar System, in:
IGARSS 2019-2019 IEEE International Geoscience and Remote Sensing Symposium, Yokohama, Japan, 28 July–2 August 2019,
pp. 8558–8561, IEEE, https://doi.org/10.1109/IGARSS.2019.8900455, 2019. a
Warren, S. G. and Brandt, R. E.: Optical constants of ice from the
ultraviolet to the microwave: A revised compilation, J. Geophys.
Res.-Atmos., 113, D14220, https://doi.org/10.1029/2007JD009744, 2008. a, b
Werner, C., Wiesmann, A., Strozzi, T., Kos, A., Caduff, R., and Wegmuller, U.:
The GPRI multi-mode differential interferometric radar for ground-based
observations, in: EUSAR 2012; 9th European Conference on Synthetic Aperture
Radar, Nuremberg, Germany, 23–26 April 2012, pp. 304–307, VDE, https://ieeexplore.ieee.org/document/6217065 (last access: 12 July 2022), 2012. a
Wiesmann, A. and Mätzler, C.: Microwave Emission Model of Layered
Snowpacks, Remote Sens. Environ., 70, 307–316,
https://doi.org/10.1016/S0034-4257(99)00046-2, 1999. a, b
Wiesmann, A. and Werner, C.: SnowScat, X- to Ku-Band Scatterometer
Development: D13 SnowScat User Manual, Tech. Rep.
ESTEC/AO1-5311/06/NL/EL, ESA ESTEC/GAMMA, available from GAMMA Remote
Sensing on request, 2010. a
Wiesmann, A., Mätzler, C., and Weise, T.: Radiometric and structural
measurements of snow samples, Radio Sci., 33, 273–289,
https://doi.org/10.1029/97RS02746, 1998.
a, b
Wiesmann, A., Werner, C., Strozzi, T., Mätzler, C., Nagler, T., Rott, H.,
Schneebeli, M., and Wegmuller, U.: SnowScat, X-to Ku-band scatterometer
development, in: Proceedings of ESA Living Planet Symposium, Bergen, Norway, 28 June–2 July 2010, vol. 686, p. 160, https://ui.adsabs.harvard.edu/abs/2010ESASP.686E.160W (last access: 12 July 2022), 2010. a, b
Wolf, P., Maret, G., Akkermans, E., and Maynard, R.: Optical coherent
backscattering by random media : an experimental study, J. Phys. France,
49, 63–75, https://doi.org/10.1051/jphys:0198800490106300, 1988. a, b, c, d
Wolf, P. E. and Maret, G.: Weak localization and coherent backscattering of
photons in disordered media, Phys. Rev. Lett., 55, 2696–2699,
https://doi.org/10.1103/PhysRevLett.55.2696, 1985. a, b, c
Yushkova, O. V., Gavrik, A. L., Marchuk, V. N., Yushkov, V. V., Smirnov, V. M.,
Laptev, M. A., Chernyshev, B. V., Dutyshev, I. N., Lebedev, V. P., Medvedev,
A. V., and Petrukovich, A. A.: Bistatic Radar Detection in the Luna-Resurs
Mission, Solar Syst. Res., 52, 287–300,
https://doi.org/10.1134/S0038094618040081, 2018. a
Zemp, M., Hoelzle, M., and Haeberli, W.: Distributed modelling of the regional
climatic equilibrium line altitude of glaciers in the European Alps, Global
Planet. Change, 56, 83–100,
https://doi.org/10.1016/j.gloplacha.2006.07.002, 2007. a
Short summary
The coherent backscatter opposition effect can enhance the intensity of radar backscatter from dry snow by up to a factor of 2. Despite widespread use of radar backscatter data by snow scientists, this effect has received notably little attention. For the first time, we characterize this effect for the Earth's snow cover with bistatic radar experiments from ground and from space. We are also able to retrieve scattering and absorbing lengths of snow at Ku- and X-band frequencies.
The coherent backscatter opposition effect can enhance the intensity of radar backscatter from...
