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Mapping without the sun
Zhang, Jixian

value of freezing bulge is 5 mm, and maximum value of
thawing subsidence is 25mm in this area during 2004 to 2006.
Figure 6. Distribution of PS candidates around Qinghai-Tibet
railway and highway overlaid on SAR image.
In this paper, we process 13 ASAR images and obtain 16
interfergrams with different temporal and spatial baseline. The
characteristics of coherence for different surface objects are
analyzed at Beiluhe area in the Qinghai-Tibetan plateau. Due to
the difference of their structure and dielectric properties, ground
objects show widely variety on their coherence coefficients.
The permafrost’s thawing and freezing influence the ground
objects’ pattern and structure, and lead to change of ground
objects’ coherence. Between the active periods of frozen ground,
coherence reduces obviously and is mush lower than in the
stable period. With temperature rising and beginning of process
of thawing, alpine aim’s coherence reduces quickly. The ground
objects’ coherence pass two active processes are lower than
after one active process, and are full decorrelation after whole
thawing/fazing circle procedure in the study area.
Figure 7. Deformation history of PS during 2004 to 2006
around Qinghai-Tibet railway. The master image is acquired in
Jan. 27, 2005
The Qinghai-Tibetan railway and highway keep high coherence
under the condition of long spatial. The image pixels,
representing the railway and highway, are coherent over almost
all the observation. So these pixels can be chosen as permanent
scatters for deformation sequence analyzing of frozen ground.
The deformation of railway roadbed, detected by Permanent
Scatters Interferometry, mainly appears in the way of thawing
subsidence from May to November every year with 25 mm
maximum subsidence in the two years.
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This work was supported by funds from NSFC and CAS under
grants 40671140 and kzcx2-yw-301. The EnviSat ASAR data
were provided by ESA through the Category-1 ID: 1406. The
authors wish to thank Dr. Bert Kampes for providing Doris