Influence of ionospheric electron density fluctuations on satellite radar interferometry

Gray, Alistair; Mattar, Karim E.; Sofko, G. J.

doi:10.1029/2000gl000016

Cited by 206 publications

(125 citation statements)

References 9 publications

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“…Because of the timing of acquisitions (between 2000 and 0200 local time, when ionospheric scintillation is most intense), the location within about 20°of the magnetic equator (where these scintillations are most intense outside of the polar regions), and the fact that the distortions are only associated with single SAR images, we suspect that the distortions are of ionospheric origin [e.g., Xu et al, 2004]. The characteristics seem to vary across the regions, with streaks of decorrelation and phase perturbation in the central and southern Andes (similar to those seen in polar regions [e.g., Gray et al, 2000]) and only long spatial wavelength phase perturbations observed in the northern Andes. No ionospheric artifacts have been observed in Central America or the Caribbean arcs.…”

Section: Discussionmentioning

confidence: 99%

Duration, magnitude, and frequency of subaerial volcano deformation events: New results from Latin America using InSAR and a global synthesis

Fournier

Pritchard

Riddick

2010

Geochem Geophys Geosyst

147

128

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[1] We combine new observations of volcano deformation in Latin America with more than 100 previous deformation studies in other areas of the world to constrain the frequency, magnitude, and duration of subaerial volcano deformation events. We discuss implications for eruptive hazards from a given deformation event and the optimum repeat interval for proposed InSAR satellite missions. We use L band (23.6 cm wavelength) satellite-based interferometric synthetic aperture radar (InSAR) to make the first systematic search for deformation in all volcanic arcs of Latin America (including Mexico, Central America, the Caribbean, and the northern and southern Andes), spanning 2006-2008. We combine L and C band (5.6 cm wavelength) InSAR observations over the southern Andes volcanoes to extend the time series from 2002 to 2008 and assess the capabilities of the different radars: L band gives superior results in highly vegetated areas. Our observations reveal 11 areas of volcano deformation, some of them in areas that were thought to be dormant. There is a lack of observed deformation at several erupting volcanoes, probably due to temporal aliasing. The total number of deforming volcanoes in the central and southern Andes now totals 15 (from observations between 1992 and 2008), comparable to the Alaska/Aleutian arc. Globally, volcanoes deform across a variety of time scales (from seconds to centuries) often without eruption and with no apparent critical observation time scale, although observations made every minute are sometimes necessary to see precursors to eruption.

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Section: Discussionmentioning

confidence: 99%

Duration, magnitude, and frequency of subaerial volcano deformation events: New results from Latin America using InSAR and a global synthesis

Fournier

Pritchard

Riddick

2010

Geochem Geophys Geosyst

147

128

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“…[10] In the CVZ, both descending and ascending interferograms regularly show correlated noise that varies with atmospheric water vapor concentrations [Fournier et al, 2011]. Ascending tracks, which are acquired at approximately 10 P.M. local time in the CVZ, can have additional large ionospheric signals that are related to variability in electron density [e.g., Gray et al, 2000;Xu et al, 2004]. Ionospheric signals are easily identified as SW-NE trending, high amplitude streaks that are roughly parallel to the Earth's magnetic field at this latitude [Loveless et al, 2010;Fournier et al, 2010].…”

Section: Sources Of Noisementioning

confidence: 99%

Decadal volcanic deformation in the Central Andes Volcanic Zone revealed by InSAR time series

Henderson

Pritchard

2013

Geochem Geophys Geosyst

116

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Decadal trends of volcanic deformation in the Central Andes Volcanic Zone (CVZ) are identified with Interferometric Synthetic Aperture Radar (InSAR) stacks and time series velocity maps covering an area 19°S–27°S and 66°W–69°W. We combine over 750 ERS and Envisat interferograms from two descending and three ascending tracks. These tracks cover 100,000 km 2 and span 1992–2011. Our analysis extends observations at Cerro Blanco, Uturuncu, and Lazufre volcanic centers and uncovers two previously undocumented deformation centers: Cerro Overo in Northern Chile and Putana Volcano in Southwest Bolivia. Cerro Overo exhibits a transition from steady −0.4 cm/yr deflation to 0.5 cm/yr inflation over several years. Putana Volcano underwent a short‐lived episode of uplift between 13 September 2009 and 31 January 2010, with a maximum uplift of 4.0 cm. Cerro Blanco continues −1.0 cm/yr deflation since 1995. Uplift at Lazufre began between 1997 and 2000 and has gradually accelerated to 3.5 cm/yr since 2005. Uturuncu volcano continues 1.0 cm/yr monotonic uplift since 1992 and shows evidence for a broad moat of subsidence surrounding the uplifting region. Four of the nine deformation events in the CVZ are not obviously associated with a particular volcanic edifice. Furthermore, there is significant spatial and temporal variability of these deformation events within a small geographic area.

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“…Ionospheric disturbances cause phase gradient resulting in azimuth shifts, called "azimuth streaks" [10]. Large scale variations of the total electron content of the ionosphere also yield slight range shifts between the SAR images [11].…”

Section: Calibrationmentioning

confidence: 99%

Mapping of Ice Motion in Antarctica Using Synthetic-Aperture Radar Data

2012

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Ice velocity is a fundamental parameter in studying the dynamics of ice sheets. Until recently, no complete mapping of Antarctic ice motion had been available due to calibration uncertainties and lack of basic data. Here, we present a method for calibrating and mosaicking an ensemble of InSAR satellite measurements of ice motion from six sensors: the Japanese ALOS PALSAR, the European Envisat ASAR, ERS-1 and ERS-2, and the Canadian RADARSAT-1 and RADARSAT-2. Ice motion calibration is made difficult by the sparsity of in-situ reference points and the shear size of the study area. A sensor-dependent data stacking scheme is applied to reduce measurement uncertainties. The resulting ice velocity mosaic has errors in magnitude ranging from 1 m/yr in the interior regions to 17 m/yr in coastal sectors and errors in flow direction ranging from less than 0.5• in areas of fast flow to unconstrained direction in sectors of slow motion. It is important to understand how these mosaics are calibrated to understand the inner characteristics of the velocity products as well as to plan future InSAR acquisitions in the Antarctic. As an example, we show that in broad sectors devoid of ice-motion control, it is critical to operate ice motion mapping on a large scale to avoid pitfalls of calibration uncertainties that would make it difficult to obtain quality products and especially construct reliable time series of ice motion needed to detect temporal changes.

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Influence of ionospheric electron density fluctuations on satellite radar interferometry

Cited by 206 publications

References 9 publications

Duration, magnitude, and frequency of subaerial volcano deformation events: New results from Latin America using InSAR and a global synthesis

Duration, magnitude, and frequency of subaerial volcano deformation events: New results from Latin America using InSAR and a global synthesis

Decadal volcanic deformation in the Central Andes Volcanic Zone revealed by InSAR time series

Mapping of Ice Motion in Antarctica Using Synthetic-Aperture Radar Data

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