A"
step'by'step"recipe"of"band'spli3ng"technique"for"isola8on"of"ionospheric"signal"in"L'band"InSAR"data"
Masato&Furuya
1$,&Takato&Suzuki
1,&and&Dominique&Derauw
2&
1:&Dept.&Earth&and&Planetary&Sciences,&Hokkaido&University,&Sapporo,&2:&Universite&de&Liege,&Belgium&& $&furuya@sci.hokudai.ac.jp&
Acknowledgement: This work is supported by the 2016 Researcher’s Community Support Project of Japan Arctic Research Network Center. PALSAR&level&1.0&and&PALSAR2&level&1.1&data&in&this&study&shared&among&the&
PALSAR&Interferometry&ConsorQum&to&Study&our&Evolving&Land&Surface&(PIXEL),&and&provided&from&JAXA&under&a&cooperaQve&research&contract&with&ERI,&University&of&Tokyo.&A&part&of&the&PALSAR&data&are&also&provided&by&the&ALOS&3rd&PI& cooperaQve&research&contract&with&the&Japan&Aerospace&ExploraQon&Agency&(JAXA).&The&ownership&of&PALSAR&data&belongs&to&JAXA&and&the&Ministry&of&Economy,&Trade&and&Industry.&The&ownership&of&PALSAR2&data&belongs&to&JAXA.
G43A-1044
Introduc8on
Theory"and"Processing"Steps
Ionospheric&signals&are&widely®arded&as&nuisance&in&lowZ frequency&InSAR&data,&and&thus&a&variety&of&correcQon& techniques&have&been&proposed.&Although&bandZspli[ng&of& range&spectrum&has&been&shown&to&be&effecQve&(Brcic&et&al.,& 2010;&Rosen&et&al.,&2010;&Gomba&et&al.,&2015),&the&bandZ spli[ng&technique&seems&to&have¬&been&widely&used.& Whereas&this&would&be&partly&because&the&impacts&of& ionosphere&on&InSAR&data&are¬&necessarily&serious,&we& consider&that&this&could&be&also&because&the&details&of&the& technique&have¬&been&reproducibly&shown.& &Here&we&show&our&stepZbyZstep&recipe&of&the&bandZspli[ng& technique,&and&demonstrate&two&case&studies&that&reveal& the&effecQveness&of&the&technique.& Master&SLC Generate&subbands&(bpf&&&SLC_demod) Slave&SLC Generate&subbands&(bpf&&&SLC_demod)Master&SLCZHigh Slave&SLCZHigh Master&SLCZLow Slave&SLCZLow Slave&RSLCZHigh SLC_interp_map Slave&RSLCZLow
SLC_interp_map
InterferogramZHigh InterferogramZLow
UnwrappingZHigh UnwrappingZLow
View&the&two&results& Using&“dis2mph”
f f0 f0+Bw /2 f0-Bw /2 Spectrum f1 f2 f f0 f0+Bw /2 f0-Bw /2 Spectrum f2 f f2 f2+B’w /2 f2-B’w /2 Spectrum f f0 f0+Bw /2 f0-Bw /2 Spectrum ΔφH = 4π fH
c (Δrtopo + Δrdef + Δrtropo)−
4πK
cfH ΔTEC ΔφL =
4π fL
c (Δrtopo + Δrdef + Δrtropo)−
4πK cfL ΔTEC Δφiono = fL fH f0 ( fH2 − fL2 )
(
ΔφL fH − ΔφH fL)
, Δφnondisp = f0 ( fH2 − fL2 )(
ΔφH fH − ΔφL fL)
ΔφH ΔφL Δφion Δφnondisp ΔφH ΔφL Δφion ΔφNondisp ALOS1:&2007/07/14_2007/10/14 Bperp=&973.0&meter,&Bw=4.6&MHz ΔφH ΔφL ALOS1:2009/03/28_2009/06/28& Δφion ΔφNondisp Bperp=&154.6&meter,&Bw=8.4&MHzStrong"Ionospheric"Signal"in"Polar"Region"
Mid'la8tude"Sporadic'E"Episodes"Detected"by"SB'InSAR
ΔφH ΔφL Δφion ΔφNondisp (a) (b) (c) (d) (a)&Original&range&spectrum&with&bandwidth,&Bw,&around&the&carrier&frequency&f0,&but&it6is&basebandZed.&(b)&We&split&the&original&Bw6into&two&new&narrower& bands&with&newer¢er&frequencies,&f1&and&f2.&Besides&the&band&pass&
filtering&in&(c),&we&need&to&further&demodulate&so&it&is&basebandZed&(d).& s(t) = T π e − j 2π f0τ ⋅ sin c[π Bw(t − τ )] sibb(t) = Ti π e − j 2π fiτ ⋅ sin c[π Bwi(t − τ )] Gamma&commands:& bpf,6SLC_interp_map6 dis2mph,6float_math6 Original&command:& SLC_demod Δφ’ion Δφ’Nondisp
<&ALOS'2&>&
2016/05/25&&03:10&UT& Path:&22,&Frame:&2920& Mode:&SM1"(Bw"79MHz)" Descending
Using&ALOS1&data,&Maeda&et&al&(2016)&
first&reported&the&sporadic&E&(Es)&phases&in& InSAR&with&the&aid&of&GNSS&TEC,&but&the&
InSAR&phases&were¬&decomposed&into& the&dispersive&and&nonZdispersive&signals.& Suzuki&et&al&(2016)&reported&the&2nd&
successful&detecQon&of&Es,&using&ALOS2.& Comparing&the&TEC&(Δφion)&and&nonZ
dispersive&effect&(Δφnondisp),&we&realize&the& similarity&in&the&phase&anomaly&shape.&
We&may&associate&the&Δφnondisp66with&the& phase&delay&due&to&the&presence&of&
posiQve&charges&around&the&Es&signals.&
ALOS2:&2016/02/17_2009/05/25 Bperp=&Z63.4&meter,&Bw=11.9&MHz float_math 37&m ΔφH ΔφL Δφion ΔφNondisp &&&&&&&&&&&&&&&&&&&&&Yamal&Peninsula,&NW&Siberia,&includes& &&&&&&&&&&&&&&&&&&&&&numerous&thermokarst&lakes&and& &&&&&&&&&&&&&&&&&&&&&characterisQc&landforms&related&to& &&&&&&&&&&&&&&&&&&&&&permafrost&processes.&In&2014,&several& holes&with&its&diameter&of&~40&m&were&idenQfied.& Examining&any&related&surface&displacements,& however,&we&encountered&many&& anomalous&phases&that&were&unlikely& due&to&the&deformaQon&but&presumably& due&to&the&ionosphere.&This&will&be&the& case&at&nearly&all&the&LZband&InSAR&& studies&at&polar®ion,&and&the&SBZ& InSAR&is&indispensable.&We&show&two&& successful&“clean”&and&one&noisy&result.&&&& ALOS2:&2015/08/17_2015/09/14 Bperp=&Z102.2&meter,&Bw=8.0&MHz ALOS2:&2015/08/27_2015/09/24 Bperp=&103.8&meter,&Bw=8.3&MHz IniQal&interferograms& with&(les)&and&without& (right)&consideraQon& of&image&offsets&in&the& coZregistraQon.&Strong& ionosphere&can&cause& errors&in®istraQons.& The&noisy&result&below&is&presumably&due&to&both&the&long&baseline&and&the&narrow& bandwidth.&& si(t) = Ti π e − j 2π fiτ ⋅ e j 2π ( fi− f0)τ ⋅ sin c[π B w i (t −τ )] (0).&Original&point&target&response&with& the&delay&τ&(=2R/c) (1).&BandZpassed&point&target&response& includes&modulated&phases.& (2).&BasebandZed&point&target&response&& with&the&new&frequency6fi6and&Bwi.&6
