Ice cover monitoring on Lake Saroma Using ERS-1 SAR

Hiroyuki Wakabayashi
NASDA
1-29-6 Hamamatsu-cho, Minato-ku, Tokyo 105, Japan
hiro@eos.nasda.go.jp

Fumihiko Nishio
Hokkaido University of Education, Kushiro
1-15-55 Shiroyama, Kushiro, Hokkaido 085, Japan
fnishio@earth.kus.hokkyodai.ac.jp


Abstract

In order to confirm an effectiveness for SAR to monitor sea ice in the Sea
of Okhotsk, the ground truth data associated with SAR data onboard the
ERS-1 and the JERS-1 were acquired for four consecutive years (1993-1996).
Lake Saroma had been chosen as a test site for this field observation,
because this lake is a salt water lake connected to the Sea of Okhotsk, and
the ice cover on this lake is considered to be first-year ice with the same
salinity as the sea ice in the open sea. The ice cover on the lake was
thick and stable enough to collect ground truth data. The ground truth data
from sampling sites, where were chosen to cover various ice thickness with
the same surface conditions, have been acquired during observations.
By comparing the backscattering coefficient derived from SAR data with the
ice physical data, the following interesting results were obtained: (1) The
ice layer structure, the salinity profiles, and the ice surface conditions
of the ice cover on Lake Saroma were found to be similar to those of thin
first-year ice observed in the Arctic region; (2)  The observed backscatter
of ERS-1 was about 7 dB higher than that of JERS-1 and the backscatter
range of ERS-1 was about three times as large as that of J-SAR; (3) The
backscatter values observed by ERS-1 and JERS-1 were correlated to the ice
thickness. It is assumed that the backscatter from the ice cover is mainly
dominated by the ice surface scattering.

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry