TY - JOUR
T1 - Analysis of the sources of variation in L-band backscatter from terrains with permafrost
AU - Watanabe, Manabu
AU - Kadosaki, Gaku
AU - Kim, Yongwon
AU - Ishikawa, Mamoru
AU - Kushida, Keiji
AU - Sawada, Yuki
AU - Tadono, Takeo
AU - Fukuda, Masami
AU - Sato, Motoyuki
N1 - Funding Information:
Manuscript received March 31, 2010; revised January 26, 2011 and May 9, 2011; accepted May 29, 2011. Date of publication July 22, 2011; date of current version December 23, 2011. This work was supported by the Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research (S) 18106008, (B) 22404001, and (C) 21510004. M. Watanabe and M. Sato are with the Center for Northeast Asian Studies, Tohoku University, Sendai 980-8576, Japan (e-mail: mwatana@cneas. tohoku.ac.jp; sato@cneas.tohoku.ac.jp). G. Kadosaki and T. Tadono are with the Japan Aerospace Exploration Agency/Earth Observation Research Center, Tsukuba 305-8505, Japan (e-mail: kadosaki.gaku@jaxa.jp). Y. Kim is with the International Arctic Research Center, University of Alaska, Fairbanks, AK 99775-7340 USA (e-mail: kimyw@iarc.uaf.edu). M. Ishikawa is with the Graduate School of Environment Science, Hokkaido University, Sapporo 060-0819, Japan (e-mail: mishi@ees.hokudai.ac.jp). K. Kushida is with the Center for Far Eastern Studies, University of Toyama, Toyama 930-8555, Japan (e-mail: kkushida@sci.u-toyama.ac.jp). Y. Sawada and M. Fukuda are with the Fukuyama City University, Fukuyama 721-0964, Japan (e-mail: y-sawada@fcu.ac.jp; m-fukuda@fcu.ac.jp). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TGRS.2011.2159843
Funding Information:
The authors would like to thank the graduate and undergraduate students at Sato Laboratory in Tohoku University for their assistance with the field data collection. The field measurements in Alaska were funded by the Japan Aerospace Exploration Agency. The authors would also like to thank the reviewers for the helpful advises to improving this paper.
PY - 2012/1
Y1 - 2012/1
N2 - Simultaneous field data collections and Advanced Land Observing Satellite/Phased Array type L-band Synthetic Aperture Radar (PALSAR) full polarimetry observations were performed in Ulaanbaatar (Mongolia) and Alaska (USA). Permafrost is present at the Alaska test sites. Backscattering copolarization (σ co-pol 0) values derived from the PALSAR data were compared with those calculated using the integrated equation method (IEM) model, a popular theoretical model describing surface scattering. PALSAR data taken in Ulaanbaatar matched the IEM model results to within a few decibels, whereas data taken in Alaska were 5 to 7 dB lower than those calculated using the IEM model. On the other hand, the σ co-pol 0(σ VH 0) components estimated from the Oh model were well matched to the PALSAR data in both Ulaanbaatar and Alaska. Moisture levels of the sphagnum moss layer in Alaska were estimated to be about 10% while moisture levels of the underlying organic and mineral layers were 25% to 79%; the moisture values of the organic and mineral layers were factored into the IEM and Oh models. When surface moisture levels of 10% were assumed for Alaska ground conditions, the σ co-pol 0 values calculated using the IEM model and those derived from the PALSAR data were well matched. From these observations, we conclude that the sphagnum moss layer, which is a seasonally unfrozen layer that occurs above permafrost, plays an important role in radar backscattering processes in permafrost regions and is a main contributor to the σ co-pol 0 backscattering component; the underlying organic and mineral layers contribute mainly to the σ co-pol 0 backscattering component. A two-layer model was applied to the data from a test site in Alaska; the model described the co- and cross-polarization backscatter (σ 0) derived from PALSAR data with off-nadir angles of 21.5° and 34.3°.
AB - Simultaneous field data collections and Advanced Land Observing Satellite/Phased Array type L-band Synthetic Aperture Radar (PALSAR) full polarimetry observations were performed in Ulaanbaatar (Mongolia) and Alaska (USA). Permafrost is present at the Alaska test sites. Backscattering copolarization (σ co-pol 0) values derived from the PALSAR data were compared with those calculated using the integrated equation method (IEM) model, a popular theoretical model describing surface scattering. PALSAR data taken in Ulaanbaatar matched the IEM model results to within a few decibels, whereas data taken in Alaska were 5 to 7 dB lower than those calculated using the IEM model. On the other hand, the σ co-pol 0(σ VH 0) components estimated from the Oh model were well matched to the PALSAR data in both Ulaanbaatar and Alaska. Moisture levels of the sphagnum moss layer in Alaska were estimated to be about 10% while moisture levels of the underlying organic and mineral layers were 25% to 79%; the moisture values of the organic and mineral layers were factored into the IEM and Oh models. When surface moisture levels of 10% were assumed for Alaska ground conditions, the σ co-pol 0 values calculated using the IEM model and those derived from the PALSAR data were well matched. From these observations, we conclude that the sphagnum moss layer, which is a seasonally unfrozen layer that occurs above permafrost, plays an important role in radar backscattering processes in permafrost regions and is a main contributor to the σ co-pol 0 backscattering component; the underlying organic and mineral layers contribute mainly to the σ co-pol 0 backscattering component. A two-layer model was applied to the data from a test site in Alaska; the model described the co- and cross-polarization backscatter (σ 0) derived from PALSAR data with off-nadir angles of 21.5° and 34.3°.
KW - L-band synthetic aperture radar (SAR)
KW - soil moisture
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U2 - 10.1109/TGRS.2011.2159843
DO - 10.1109/TGRS.2011.2159843
M3 - Article
AN - SCOPUS:84855444493
VL - 50
SP - 44
EP - 54
JO - IEEE Transactions on Geoscience and Remote Sensing
JF - IEEE Transactions on Geoscience and Remote Sensing
SN - 0196-2892
IS - 1
M1 - 5959203
ER -