Instrument Summit Notes
June 15, 2011
Irvine CA
DRAFT
The instrument summit began with a welcome from the UC Irvine Dean. Wagner and Tagg summarized
their long term objectives for IceBridge and the need to identify some overlap between the end of
IceBridge and the start of ICESat-2 observations. Studinger then gave an overview of meeting objectives
as detailed in the instrument summit definition document. He also highlighted the goal that the
instrument suite should serve to provide a data stream that is more than the sum of the individual
instruments.
Krabill provided an overview of ATM developments, relying on the thorough document provided prior to
the meeting to flesh out instrument performance details. Sonntag summarized aircraft navigation
technology and aircraft navigation accuracy (which is now better than the wingspan of the aircraft).
During the questions session, Jezek asked about shot to shot accuracy. The consensus was that shot to
shot accuracy was at least 10 cm, which satisfies the science requirement. Jezek also asked about GPS
redundancy on board the aircraft. The instrument team recommended that the redundancy remain but
there was an action item (1) to investigate whether integrating/comparing GPS data streams and
derived trajectories would lead to improved results. There was interest in possibly incorporating
gravimeter trajectory into the analysis but discussion suggested that meter-shock mounting would
degrade the performance required by other instruments.
Blair presented analyses of LVIS performance and noted the successful flights and delivery of preliminary
data from the recent Greenland deployment. He pointed out that LVIS can track multiple echoes along a
single trace and that the science team could give guidance on the physical significance of same. Jezek
asked about vertical accuracy as a function of altitude. Blair responded that the vertical accuracy errors
due to pointing were tiny at any elevation because the pointing geometry is known to sub-arcsec. There
followed an extensive discussion of instrument precision accuracy and repeatability and some concern
as to whether all team members were using the same definitions.
Young gave an interesting summary of the photon counting lidar used on ICECAP. Accuracies are about
38 m which is less than that OIB science requirement. He believes that these errors are associated with
the GPS processing. An action item (2) is to request help from other laser operators with reprocessing
some of the UT data to determine if this is indeed the issue. There was also high interest in access to
the photon counting lidar data partly because of the high noise levels observed and the need to
stringently filter the data.
Studinger then gave a summary of the UAF laser system. Performance is very good near base station
but the degradation away from base stations is not well understood. An action item (3)was to
determine whether more base stations were needed for all OIB flights.
Tagg retiterated that one outcome of the meeting for his program was a table of high level instrument
performance specs. He suggested these could be outlined in a traceable fashion from ICESAT-2 to OIB
instruments and requirements. Luthcke suggested that this was possible but that as phrased the
icebridge requirements might not serve as a good basis for that tracability. An action item (4) is to
develop an appropriate set of questions to help fill in the Tagg matrix.
Jezek asked that, given 4 laser systems, are we using them in the optimal fashion. He noted that ATM is
key for repeatability of the longest records, LVIS is providing important coverage, the photon lidar is
providing insight into that technology and the UAF lidar is proven for its applications. However, could
they be deployed operated in other fashions that maximizes the potential?
Cochran summarized the gravity data and demonstrated that performance is meeting science
requirements. He reiterated that turns compromise the gravity data and it will be important to have
some criteria for turn radius against which planning can be refined. He noted that additional data are
required to invert the data into bathymetry or subglacial geology and had several examples of inversion
yielding uncertainties of about 50 m in bathymetry. He estimated that density uncertainties were about
15m/.1 g/cc. Jezek asked about delivery of the bathymetric products. Cochran replied that they are
available on request. An action item (5) is to determine whether these should be sent to NSIDC. Bell
noted that a key action for the science team was to prioritize the next sites for processing.
A brief summary of the magnetic data was provided and showed that the instrument was working well
and held promise for aiding the velocity inverstion. Accuracies are estimated at about 10 nT. An issue
for the magnetic as well as all of the instruments was how much time should be allocated to calibration.
An action (6) is to requests an assessment of calibration requirements measured against the
performance and science requirements.
Dominguez summarized processing of best effort DMS data. An action (7) is to use better DEMS in
future processing. Derived products were summarized Averson. He indicated that he could now
process selected DMS frames to DEMS. There was discussion about the application of these data. There
was high interest from the sea ice team as well as the ICESAT-2 science team members who could use
the data for surface scattering studies. The issue of calibration over control points was raised and
reinforced the need for a justified calibration plan for the instrument suite.
Leuschen gave an overview of the KU radars. Jezek asked about the fact that the accumulation radar
does not fliy on the DC-8 and whether that impacts accumulation rate experiments planned for this fall.
Koenig said that the snow radar will suffice. Jezek asked whether the two radars were still required.
Paden summarized MCORDS processing and performance. He noted that several approaches were
being used to correct for navigational biases. Jezek asked why this was still and issue but the discussion
was deferred. Paden also briefly described echo picking procedures and the details were deferred till
the evening and till Wednesday.
Wu summarized tomographic processing. There followed a discussion of tomographic processing of P-3
and DC-8 data. An action (8) is for to assess the potential of existing DC-8 data for tomography soon
as that can impact flight planning.
Ben reviewed the Ku-band and Snow radar performance. Jezek noted that the snow radar had better
performance than the ku-band radar and whether from a geophysical sense it was better to rely on the
snow radar. Ben suggested that the ku-band radar provides control for Cryosat.
Koenig briefly reviewed platforms and indicated that there was good progress being made towards
integrating instruments onto UAVs.
NSIDC summarized data management and demonstrated large volumes of data were being made
available at NSIDC. Kaminski gave an overview of several new tools NSIDC is developing to aid data
exploration.
The instrument summit was very successful. Presentations and discussion highlighted that the data
stream is rich, accurate and timely. A lingering concern was that the instrument operators generally
functioned independent of each other. While this is necessary and understandable to some degree, it
does raise issues about redundancy as well as specific application of some data stream to the science
problems outlined in the requirements document. It also raises the question of whether integration
across teams could lead to a better product or whether integration would require a lot of additional
work with minor improvement.