Basal Ice Imaging using Radars (BIIR) Science: By measuring surface topography, ice thickness and interface reflectivity, create 3-dimensional image maps of Greenland and Antarctica as they would appear were the ice sheets stripped away. Use these first ever maps to constrain estimates of present ice sheet mass balance. Use the maps to feed numerical models that describe the past and predict the future behavior of the ice sheets and their contribution to global sea level rise. Instrument: GISMO 150 MHz Radar using multiple transmitter/receiver antenna WISE Radar 1-10 MHz large wavelength with dipole antennas WFF Airborne Topographic Mapper using an airborne laser system Implementation: Airborne measurements using three systems working together: GISMO (Glaciers and Ice Sheet Mapping Observatory) radar (150 MHz) to map both surface and bottom of 3D topography of ice sheets WISE (JPL radar 1 – 10 MHz) to provide nadir depth sounding measurements of ice thickness for warmer and fractured ice to provide complementary coverage to GISMO WFF Lidar to provide accurate surface profile for elevation change detection to complement ICEsat and to provide validation for WISE and GISMO Cost: 6/4/2018

Primary Science Questions What is the flux of ice from the polar ice sheets and what is required to reduce IPCC error bounds on the contribution of ice sheets to global sea level rise? BIIR will conduct the first circum-ice-sheet campaign to accurately measure ice thickness. BIIR ice thickness measurements and DESDYNI measurements of surface velocity will yield a precise and complete assessment of the mass fluxes from the ice sheets into the ocean to reduce error bounds on mass balance assessment. What causes observed, abrupt changes in ice sheet motion? Does a rapid change in a glacier always lead to a large change in the ice sheet volume? BIIR will accurately map the depth of glaciers below sea level, how far inland they remain below sea level, and the basal slopes. These data are critical for ice sheet models assessing areas capable of rapid contribution to sea level rise, These are the sectors that are at most risk, and the present, systematic coverage is very poor. Without these data, the scientific community will be fundamentally limited in its capability to predict ice sheet evolution. No demonstrated alternative to BIIR exists. How will the mass balance and dynamics of the ice sheets change in the future? BIIR will conduct the first 3-d mapping of the bedrock topography and the distribution of subglacial water close to the ice-ocean transition. The maps will constrain estimates of basal friction and identify natural pathways for basal water. High fidelity surface DEMS created by merging BIIR and ICEsat-1/2 data will refine estimates of the gravitational driving stress that pushes the glacier forward and also improve estimates of the subglacial hydrologic potential that determines the distribution of subglacial water. The surface and base digital elevation models will be a primary input for predictive ice sheet dynamics models. For discussion only in center 6/4/2018

Key Physical Process Questions To what extent does bed topography (valleys and roughness) control the present day locations of ice stream networks and do any such subglacial valleys anchor the ice streams in place, providing resistance to any flips in routing to the margin? Compare ice stream networks to BIIR subglacial topography, in trunk zones and upstream of onset zones. Compare known fluctuations of ice stream width and shutdowns to underlying topography. Does ice stream location and vigor depend on the ability of the upstream bed topography to capture and route meltwater? Given coincident BIIR data on bed and ice surfaces, compute hydropotential surfaces for basal meltwater to see where it should flow and the extent to which it feeds ice stream lubrication. Is there a history of ice stream network evolution recorded in the bed geomorphology, and how stable are the existing flow paths? Use BIIR data to investigate whether today’s ice stream configuration is just one of a possible set of network configurations. Learn about longer term variability in ice streams than current observations permit. Subglacial bedforms (drumlins etc) are the physical manifestation of processes operating at the ice-bed interface and which facilitate fast ice flow. Are the existing numerical models on the formation of these bedforms correct? Current work uses predictions from such models tested against the scale and shape properties of now-exposed landforms, but in the absence of the glaciological parameters to feed the model. Having BIIR data on bedforming in action along with ice thickness and slope data provide the first chance to make better constrained tests of these models. For discussion only in center 6/4/2018

Key Physical Process Questions How well matched is basal and ice surface roughness? BIIR will provide the first 3-d information to test transfer function models that describe the between surface and basal topography. BIIR information on the 3-d slope of internal layers can be incorporated into the models. Given that the ice sheets were slightly larger during Quaternary glacial episodes, and once much smaller during previous interglacials or even further back in time, can the landform record imprinted on the ice sheet bed, help constrain former ice divide positions, flow configurations and margin positions? If so, then with judicious modeling exercises we have informative analogues for the possible future configurations of these ice sheets. While the Quaternary ice sheets have now retreated, they leave behind a landform record of their retreat (drumlins, moraines, meltwater channels, eskers etc). It is well known that elements are preserved that record earlier episodes and even some build-up phases. Amazingly, landforms are not always erased or adjusted to the latest ice flow. This is especially the case for interior regions beneath ice divides (sluggish flow) and cold-based regions. Such locations provide ‘windows’ into the past. In the spirit of other projects that mapped for the first time the surface of the polar ice sheets, BIIR aims to conduct basic exploration of the polar regions that remain shrouded by an icy cover. For discussion only in center 6/4/2018

Relevance To NASA BIIR relevance to NASA objectives BIIR Science Context Understand ice sheets sufficiently to predict their response to changing global climate and their contribution to global sea level rise. BIIR goals are aligned with the objectives of NASA’s Cryospheric Sciences Program (http://ice.nasa.gov/) measuring and understanding the mass balance of land ice, and its implications for sea level rise monitoring and understanding important cryospheric processes and their relationships with other parts of the climate system improving the simulation of cryospheric processes in climate models BIIR primary science addresses the changing polar ice sheets BIIR ancillary science investigates mechanisms by which the ice sheets modify landforms BIIR conducts basic exploration of the ice covered regions of Antarctica and Greenland Potential contribution to NASA missions Together with surface motion data from DESDYNI interferometry, BIIR ice thickness, basal topography and basal water measurements constrain ice sheet dynamics models BIIR 3-d surface topography maps can supplement ICEsat-2 surface elevation profiles to create high fidelity digital elevation models required for ice sheet models. 6/4/2018

Relevance To NASA Unique and innovative methods, approaches 3-d swath information compared to nadir sounding profile data Multi-frequency sounding radar and a lidar system combined on a single platform Radar interferometry and tomography combined to provide 3-d information about ice sheet interfaces Complementary to InSAR measurements of surface motion, LIDAR measurement of ice sheet elevation, GRACE measurements of ice sheet mass change, and geomorphological data acquired on deglaciated terrain. Degree of improvement over the state-of-the-art (measured by science return per dollar) No equivalent satellite system exists for making the proposed measurements. No measurement campaign of this extent, observational scope, and accuracy has been yet attempted on the polar ice sheets 6/4/2018

Instrument Heritage BIIR heritage GISMO system funded as an ESTO IIP 150 MHz radar will be duplicated based on the successful GISMO instrument WISE radar was developed under partial funding from PIDDP and deployed under IPY funds. Since 2005 the system has accumulated ~200 flight hours with a variety of planes including Single Otter, Twin Otter and the smaller Piper Seneca. ATM and associated navigation equipment have a 20 + year legacy at WFF 5x20 Km 3-d image of the base of the ice sheet. Scene is an orthorectified mosaic located just south of the main Jacobshavn Drainage Channel (to be corrected for cross track bias between mosaic swaths) 6/4/2018

Science Team Members and their Roles Qualifications and Experience Kenneth Jezek Principal Investigator P.I. for GISMO IIP Project. Professor, Byrd Polar Research Center. The Ohio State University Christina Hulbe Numerical Ice Sheet Modeling Member, SCAR ISMASS Group, Assistant Prof., Portland State University Ernesto Rodriguez Radar interferometry GISMO Co-I, Jet Propulsion Laboratory Richard Hindmarsh Modeling ice dynamical processes Member SCAR ISMASS Group, Physical Science Division, British Antarctic Survey David Holland Ocean – ice sheet modeling Member SCAR ISMASS Group, Professor of Mathematics and Atmosphere/Ocean Science, Courant Institute of Mathematical Sciences Eric Rignot Ice sheet mass balance Significant experience with ice-modeling, Professor, University of California Joel Johnson Radar scattering modeling GISMO partner, Professor, Electro-Science Laboratory, The Ohio State University William Krabill Ice Sheet surface elevation change using airborne LIDAR ATM PI Chris Clark Paleoglaciology and glacial geomorphology Geomorphology of palaeo ice stream beds (whole of Canada, UK, Fennoscandia) at the kind of scale envisaged for this study, Professor, University of Sheffield Anthony Freeman Radar calibration GISMO co-I, Jet Propulsion Laboratory 6/4/2018

Science Measurements 20 m vertical ice sheet base height accuracy for all ice covered terrain (S1, S2, S3, P1,P2,P3,P4,P5,P6) 2 m vertical ice sheet surface height accuracy – across the radar swath (S2, S3, P2, P5) 10 cm vertical ice sheet surface height accuracy – along laser scan for radar calibration and comparison with ICEsat (S3) 20 m vertical accuracy on radar internal layers for ice dynamics (P5) 25 m geolocation accuracy (WGS 84/polar stereographic projections) (All) Relative radiometric accuracy sufficient to discriminate basal rock from basal water (S1, S2, S3, P2, P5) 50 m pixels (All) Continuous coverage with 100 km swath from grounding lines for both Greenland and Antarctica. (S1, S2, S3) Capability for 5-10 year repeat of integrated measurements for mapping redistribution of subglacial water (post Ventures addition to baseline measurement of topography) (S3, P2, S5) Data products to be suitable for possible integration with DESDynI surface velocities and ICEsat surface topography (All) 6/4/2018

Operations Concept Use off-the-shelf track planning tools that generate standard output for the aircraft navigation (i.e. GPS) units The first campaign will be to Greenland and will include 150 flight hours during a period of 5 weeks The two target regions are Greenland and Antarctica and we plan to visit both sites each year after initial campaign. Greenland will be visited in April/May time frame while Antarctica will be visited starting Nov. and lasting to early February The tracks are planned ahead of time and are executed on consecutive days (weather permitting) The data is quick-looked in real time A sample of data is processed on the ground with standard ground processing software to assure product meets expected quality Both quick-look and ground processing results will assist in detecting any potential anomaly in the instruments Maps of Greenland and Antarctica showing margins and possible basins for detailed coverage 6/4/2018

Data Processing Throughput, Data Volume and Archive Plans Raw data Archive (380 TB) Final product archive: Ice thickness maps Surface topo/intensity maps Base topo/intensity maps Water/rock classification maps Multilook azimuth compressed images Basal layer roughness and correlation length maps Internal layer images Google earth interface to final products, flight lines and raw data sets Intermediate products: (not archived) Range compressed data Single look azimuth compressed data General public Science community Only raw data and final products are archived. Raw data will be available to science community per request. Intermediate products including range compressed data and single look azimuth compressed data are not archived. But they will be available after reprocessing to science community per request. (500 GB) Conservative estimate of storage disk cost: $500K. Data distribution heritage from Radarsat Antarctic Mapping Mission: http://bprc.osu.edu/rsl/radarsat/data/ 6/4/2018

Management Plan and Organization Chart PI (Ken Jezek) LIDAR (B. Krabill) WISE (A. Safaeinili) Science team Ernesto Rodriguez - interferometry William Krabill - Surface elevation change David Holland - ocean-ice sheet modeling Christina Hulbe - numerical ice sheet modeling Richard Hindmarsh - ice dynamics modeling Joel Johnson – radar scattering modeling Eric Rignot – ice sheet mass balance Chris Clark – glacial geomorpholgy Anthony Freeman – Radar calibration Payload system engineering (G. Sadowy) Project management (JPL/TBD) GISMO (X. Wu) System operations (JPL) Product development (X. Wu, A. Safaeinili, J. Sonntag) Product validation & modeling (K. Jezek) Operations Management Product distribution (Byrd, OSU) Aircraft management (JPL) Radar (B. Heavy, JPL) VHF Antennae (Volakis & Chen, OSU) Low Frequency transmitter/Antenna (Kurth, Kirchner, Iowa) Digital subsystem (Carswell,Moller, RSS) 6/4/2018

External Partners and Contributions We are approaching international colleagues for support. We will request that: French provide the fuel at Dumont D’urvil in exchange for access to data Australians provide fuel at Casey in exchange for data British provide fuel at Rothera in exchange for data Germans provide fuel at Kohnen in exchange for data Japanese provide fuel at Shirase in exchange for data Danes to provide permissions to Greenland in exchange for data We have also alerted the US National Science Foundation to our plans and are soliciting their concurrence and support. The total fuel cost saving could be as much as $1M 6/4/2018

Plans for Producing the Proposal Freeze all system parameters, instruments and platform by May 15 Firm partnership commitments by June 1 Starting May 4th, assign leads for proposal sections and start writing the first draft of the proposal to be completed by June 15th Revisit cost as new information is revealed Hold a section/Div. review during last week of May Participate in the June 4-5 preliminary baseline review Participate in the June 25-26 proposal review Participate in the Aug. 3-5 final review Submit proposal to NASA by Sept. 1 6/4/2018