The Annual Behavior of Backscattering And Coherence of PALSAR Data.ppt

IGARSS 2011, July 24-29, 2011, Vancouver, Canada

The Annual Behavior of Backscattering And Coherence of PALSAR Data

Wenjian Ni1,2, Zhifeng Guo1, Zhiyu Zhang3 , Guoqing Sun2

1Institute of Remote Sensing Applications of Chinese Academy of Sciences 2Department of Geography, University of Maryland, College Park

3Beijing Normal University

[email protected] / [email protected]


OutLine 1. Introduction

2.Test site and data

3. The annual behavior of Backscattering

4. The annual behavior of Coherence

5.Conclusion


• PALSAR Mosaic data provide a great chance to map biomass at regional scale;

• The data covered a year and several seasons.

• The seasonal effects on coherence have been investigated using ERS1/2 tandem (Koskinen, J.T. et. al., 2001), and JERS data (Eriksson, L.E. et al., 2003) ;

• How PALSAR data were affected by precipitation and temperature?

Introduction


The multi-temporal backscattering data (HV). Red: cycle 14, Green: Cycle 19, Blue Cycle 20;

The true color IKNOS image of study site (06/24/2002 )

missed

Test site and data


2007/07/10 2007/08/25 2007/10/10 2008/01/10

2008/02/25 2008/04/11 2008/05/27 2008/07/12

Backscattering over a year (HH)

There was no obvious change on spatial pattern


Precipitation: 2007/07/09: No record2007/07/10: No record2007/08/25: 4:00 (0.25 mm)

21:00 (1.52 mm) 23:00 (0.25 mm)No Precipitation on other dates of data acquisition.

Backscattering over a year Rain

Leaves fall

Frozen and snow

Frozen thawing and snow melting

sprout of vegetation

(HH)

2008/02/25 2008/04/11 2008/05/27 2008/07/12

2007/08/25 2007/10/10 2008/01/10IKNOS

Baseline length

Rows:horizontal baseline, Columns: vertical baseline

Coherence over a year

2007/07/10 vs. others

There were totally 28 interferometric pairs formed by the 8 scenes of PALSAR data.


2007/07/10 vs. others

Snow and frozen


2008/01/10-2008/02/25 2008/02/25-2008/04/11 2008/04/11-2008/05/27 2008/05/27-2008/07/12

2007/07/10-2007/08/25 2007/08/25-2007/10/10 2007/10/10-2008/01/10IKNOS

Successive interferometric pairs


•The interferometric pairs from summer was the best;

•that composed by summer and autumn or by spring and summer was the middle;

•that composed by winter data was the worst;

Nearly noise

Baseline 3992.907

m


(a) (b) (c) (d)

(a) H75 from LVIS Ground Elevation (lge) acquired on 2009; (b) SRTM minus DEM (2007/07/10~ 2007/08/25) (HV); (c) Coherence of 2007/07/10~2007/08/25 (HH); (d) Coherence of 2008/04/11~2008/05/27(HH);

Spatial pattern of coherence and SRTM minus PALSAR-DEM.

The spatial pattern of Figure a and b was consistent.

Figure d was obviously opposite to that of Figure 8-c. This may be attributed to the melt of snow which leads to the high soil moisture. The double bounce between canopy and ground at high biomass area was the dominant and stable scattering component.


Conclusion In terms of backscattering, Summer data was stable. Leaves falling,

frozen and Snow accumulation decrease the autumn and winter data. Thawing, melting of snow and vegetation sprout increase the spring data.

Interferometric pair from summer data has the best coherence; Snow and frozen hinder the interferometric process of winter data. Summer data is the best to be used to map biomass

The difference of SRTM and DEM from PALSAR InSAR data can provide forest height information.

Coherence from spring data was positively correlated with forest coverage. Why and How ?

Information lies in variations! How to use the data in other seasons?


Thank you for your attention

And

Have a nice time in Vancouver!

Technology

The Annual Behavior of Backscattering And Coherence of PALSAR Data.ppt