FRINGE Seed Questions
- InSAR techniques provide a wealth of data on tectonic events
that cannot be feasibly obtained through traditional measurements; is it
possible to quantify the benefit, in human or financial terms, of the resulting
improved knowledge of underlying geophysical mechanisms?
- What are the smallest tectonic signals that can be measured reliably,
co-seismic, interseismic, and aseismic?
- Can measurements of atmospheric water vapor variations, such as by
MERIS, accurately correct for the path delay in interferograms of areas
with great topographic relief?
- How can non-tectonic deformation effects, such as ground subsidence,
be separated from tectonic deformation?
- What improvements on tectonic measurements can be made with multiple
incidence angles and both ascending and descending tracks?
Session: Land Motion
- Do the available InSAR products on land motion fulfill the
needs of the hazard protection and geotechnical engineering communities?
- What is the status of methods for InSAR motion mapping and which
methodological developments would help to improve land motion products?
- How better merge INSAR products with ground based observations (GPS,
leveling, tacheometry etc.), and other spatial products (optical correlation
- Which measures can be taken to foster the utilization of Envisat
ASAR for land motion monitoring?
- What is the preferred sensor configuration for land motion services
(SAR frequency, repeat cycle, spatial resolution, look angle, polarization
- Which actions are needed to guarantee long-term continuity for InSAR
monitoring of landslides and seismic deformation?
Session: Methodology and Techniques:ERS/Envisat Interferometry
- Are there techniques / experiments to predict/model the
atmospheric phase screen by means of different sensors (Meris, etc.)?
- Can the tropospheric water vapor contribution to interferograms be
reliably corrected and what are the best methods?
- How should we model uncorrected errors in InSAR data?
- What is the best method for constructing a deformation time series
- What's the contribution of Envisat polarimetry in interferometry,
DEM generation etc.?
- Can the persistent scatterers technique be used to detect small deformation
signals, such as interseismic strain across active faults, in remote parts
of the world where there few man-made structures to act as corner reflectors?
- How do public domain and/or open source InSAR tools compare to commercial
- Which surface is represented by a microwave DEM?
- Temporal decorrelation in the repeat-pass case and volume decorrelation in the single-pass case are limiting factors in high-resolution DEM generation. What would be the optimum system parameters (frequency, polarization, resolution, orbit etc.) for DEM generation in the:
- single-pass case?
- repeat-pass case?
- Has INSAR DEM generation reached operational status? For which type
of applications microwaves DEMs are preferable/comparable to those generated
with other techniques (e.g. flooding, telecommunications, military, urban,
road and pipelines track planning etc.)?
- A DEM generated from multi-pass satellite SAR interferometry is affected
by atmospheric artifacts and low wavenumber errors induced by orbital inaccuracies:
they can be partially compensated in many ways (Permanent Scatterers, Corner
Reflectors, CATs, reference DEM, GPS etc.). What is the current state of
- A way to cope with atmospheric artifacts is to try avoiding them
by appropriate data selection.
What kind of sensor should be added to future SAR missions in order
to get the required information for proper SAR data selection?
Which is the best strategy to gain coherence with single antenna
satellite SAR systems (e.g. lower frequencies, multiple polarizations,
shorter revisiting times etc.)?
Which part of the ERS tandem archives has been exploited
to generate/refine DEMs? Which is the average cost per square kilometer?
How frequently should a DEM be updated? Is ENVISAT suitable for DEM
updating (35 days revisiting time)?
- What are the main ancillary data to be taken into account to perform
SAR scene selection?
- Are these ancillary information adequately and easily available?
- Should these data be added to information systems like the
Session: Longterm DINSAR
- What are the current and future most frequent and most promising
What are the major current deficits of the two methods mentioned before
and how should they be remedied?
Which other data types (meteorological, land cover, etc.) are required
routinely to support long-term differential interferometry and to increase
its rage of applicability and its accuracy?
Different types of surfaces (water, snow, ice, fields, forests,
sandy or rocky deserts, towns) have different dynamics and roughness: -
Which tools are best for a meaningful description of their motion (microwave
or lidar altimetry, SAR interferometry, GPS, optical levelling, etc.)?
- Peristent Scatterer DInSAR
- "classical" long-term DInSAR?
Do we know the long-term behavior of artificial scatterers like CR's or CAT's?
Is it possible to combine and use scatterers that are not coherent
for the long term?
We could in principle temporally combine data from multiple platforms:
where would this be an advantage?
What would an optimum SAR system for long-term differential
interferometry look like?
- Is there any use for more accurate, sub-millimetric measurements?
- Should we push for higher frequencies?
- Is there optimum polarizarion?
- Lower frequencies will better penetrate vegetation reducing motion
accuracy; where do we need that?
- What is the reasonable revisiting rate we should ask for? (daily, biweekly, weekly, bimonthly, etc.)
Session: Thematic Mapping
- What are the most promising thematic mapping applications
Which are the primary obstacles for InSAR to become an operationally
applied tool for thematic mapping?
Is temporal decorrelation understood sufficiently to be interpreted
- C-band InSAR?
- L-band InSAR?
- X-band InSAR?
Which radar wavelength provides the best overall compromise for different
applications of InSAR?
Do current InSAR applications fully exploit the information content
in the data?
What future mission extensions (multi-frequency, multi-incidence
angles, multi-polarization) would be most useful for thematic mapping?
- How can present limitations due to temporal decorrelation be overcome?
- What would be the optimal revisit time (temporal baseline)?
- Inversions of InSAR-measured deformation at many volcanoes
have relied heavily on Mogi models. Does this reflect on the quality of
the data, the nature of the volcanic pressure sources or some other factor?
- To what extent is the increasingly complex picture emerging from
the InSAR-measured deformation at Etna - reservoir pressurisation, shallow
gravity spreading, tectonic coupling - likely to be found elsewhere?
- What are the temporal samplings that are needed by InSAR missions
to adequately address issues related to volcano deformation?
How much do we need the full 3D motion vectors from volcano InSAR
in any future radar system? Will one ascending plus one descending pass
Are classical DInSAR and peristent scatterer DInSAR techniques complementary
If we had to choose either C-band or L-band for operational InSAR
monitoring of volcanoes, which would it be?
Can general recommendations be given about how to combine InSAR and
conventional observations on volcanic areas?
- what is required based on volcanic processes themselves?
- what is required as a means of reducing effects such as atmospheric
Session: Ice Motion
- Can ice velocity snapshots illuminate glaciological processes?
- For users of InSAR data it is important to know the accuracy of the
measurements. Which qualitative error characteristics are needed?
What are your experiences with longer than 1- or 3-days datasets?
They have the potential to improve accuracy, but can they be used
- what can InSAR presently provide?
interferometrically and under what conditions?
Is operational monitoring of small ice bodies viable?
How might other missions benefit ERS InSAR glaciology - e.g. ENVISAT,
SRTM, PALSAR, CryoSat?
ERS and ENVISAT were not designed specifically for repeat pass interferometry.
How shall key design parameters be optimized to ice flow applications if
a future dedicated interferometric SAR mission is decided? Key parameters
include: frequency, repeat cycle, look angle, swath-width, resolution,
polarization, auxiliary instruments etc.
How mature is the use of interferometric data for snow accumulation mapping?
Is interannual variability in snow conditions being correctly addressed as a source of error in repeat pass inteferometry of dynamic ice streams and margins.
Is the ScanSAR mode of interferometry appropriate for ice sheet velocity mapping on a broad scale on a regular basis? What are the limitations?.
How might the InSAR community grow?
- in which areas are ENVISAT InSAR expected to work?