Japan Geoscience Union Meeting 2022

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[J] Oral

S (Solid Earth Sciences ) » S-TT Technology & Techniques

[S-TT39] Synthetic Aperture Radar and its application

Wed. May 25, 2022 10:45 AM - 12:15 PM 101 (International Conference Hall, Makuhari Messe)

convener:Takahiro Abe(Graduate School of Bioresources, Mie University ), convener:Yohei Kinoshita(University of Tsukuba), Yuji Himematsu(National Research Institute for Earth Science and Disaster Resilience), convener:Haemi Park(Japan Aerospace Exploration Agency), Chairperson:Yuji Himematsu(National Research Institute for Earth Science and Disaster Resilience), Haemi Park(Japan Aerospace Exploration Agency)

11:00 AM - 11:15 AM

[STT39-02] Demonstration of seasonal fluctuations of bare land soil moisture using ALOS-2 PALSAR-2

*Haemi Park1, Takeo Tadono1 (1.Japan Aerospace Exploration Agency)

Keywords:Microwave, L-band, Dubois algorithm, Ibaraki

Needs of spatiotemporal soil water content are increasing in recent years for agricultural crop yield estimation, drought forecasting, and climatological studies. Relationships between soil moisture and methane has been reported as positively connected. Microwave imagery is suitable to represent water content of soil surface by detecting its dielectric constant. The Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) on the Advanced Land Observing Satellite-2 (ALOS-2) is a representative active microwave sensor that enables full polarization observation (HH, HV, VH, and VV) at 6.25 m of pixel spacing. Soil moisture estimation methods were proposed in previous studies using empirical models. In Dubois 1995, HH and VV backscattering coefficients of L-band microwave were successfully delineated by logarithmic relationship between surface roughness and incidence angle, combined with dielectric constant. In Hajnsek 2001, suggested the inversion model of Dubois (1995) equation to make the dielectric constant calculation straightforward. The objective of this study is to estimate soil moisture using L-band SAR of PALSAR-2 in Ibaraki, Japan, from Jan 2021 to Oct 2021. As the result, soil moisture of the paddy field in Koga, Ibaraki was estimated as 14.26% averagely, using Hajnsek-Dubois method with PALSAR-2 full polarization data. RMSE was 18.48% and r-square value was 0.11 when the result was compared with in-situ observation. The spatial distributions of soil moisture were represented well in detail, although 1km resolution of Today’s Earth soil moisture of JAXA could be found only one pixel value since the area of field is relatively small (about 40,000m2). Results in this study showed seasonal fluctuations clearly. Obstacles by vegetation cover around summer were happened also. We conclude the usefulness of PALSAR-2 L-band data for soil moisture estimation has been shown through this study. For the next step, further algorithms will be compared with Hajnsek-Dubois method.