Icebergs float from the calving Mendenhall glacier, which originates in Alaska's Coast Range. The glacier velocity dataset reveals that about 40 percent (approximately 20 cubic km) of ice lost annually in Alaska is due to calving alone, mostly from a few coastal glaciers. © UAF

Glacier Power

Glacier Power started as a 1997 middle-school curriculum supplement produced by the Alaska Satellite Facility (ASF) in collaboration with glaciologists, local scientists, teachers, students, and artists. Although parts of the supplement have become outdated, several components of Glacier Power are still user favorites and rank among ASF’s most-visited pages.

ASF has updated Glacier Power content in the form of Q&A pages and lesson plans for teachers. Many of the Q&A pages contain vocabulary lists, review questions, or exercises.

A crane assists with finishing touches on the newly installed 9.1-meter antenna on top of UAF's Elvey Building. © PWP Photography

A New Antenna for ASF Ground Station

After many weeks of meticulous planning, local and visiting engineers and contractors first worked in subzero temperatures (down to minus 30°F) to dislodge the original, 40,000-pound, 10-meter system….

International Polar Year – GIIPSY – Space Task Group Meetings


Briefing to WMO, GEO and IPY JCOMM SCOBS, Oct. 12 (Drinkwater)
Briefing to IGOS Cryosphere Team, Oct. 16, ESTEC
Briefing at NSIDC, Oct. 25, Boulder
Presentation at IGS Nordic Branch, Tromso, Oct. 2006 (Lytle)
GIIPSY participation in CSA Radarsat-1 Archive Processing Meeting, Nov. 8, Ottawa
GIIPSY Team meeting, Dec 12 
Briefing to WCRP CLiC, Boulder, Colorado, Dec. 6 (Drinkwater)

Tuesday December 12, 2006, 6:00PM-8:30PM
AGU Fall Meeting, San Francisco
Marriott Convention Center, Room Sierra K

PERSPECTIVES (~45-60min)

10 min GIIPSY Overview and Meeting Objectives (K. Jezek)
~5 min discussion on how GIIPSY fits into IPY (D. Carlson)
~5 min IGOS and GIIPSY (V. Ryabinin)
~5 min ESA presentation on ESA IPY AO proposals (Einar-Arne Herland, ESA)
~5 min CSA perspective on GIIPSY and Radarsat-1 Archive (P. Briand)
~5 min Japanese perspective on GIIPSY (J. Ukita)
~5 min NASA perspective on GIIPSY (S. Martin)
~5 min Ground Station perspective on processing large volumes of data (N. La Belle-Hamer)
~5 min DLR perspective on GIIPSY (K. Jezek for I. Hajnsek)

TOPICS FOR DISCUSSION (K. Farness) (1-1.5 hour)

1) Community input to flight agencies on archival data processing and new data acquisitions

2) Identify key IPY legacy data set(s)
  When? (for example: during windows of seasonal melt or alternatively during cycles of ICESAT data acquisitions?)

3) Related issues and potential additional resources
  Sensors and Spacecraft
  Acquisition Planning
  Receiving Ground Stations
  Processing Facilities
  Calibration and Validation

4) Data management issues
  Processing and product distribution
  Product format
  Metadata tagging for data explicitly collected for IPY including:
    Insitu data
    GIIPSY pull from the CSA archive



Space Task Group meeting in Geneva, January 17-19, 2007
IPY Launch Event, Paris, March 1, 2007
Space Task Group telecom, June 15, 2007 – (ESA Data Portfolio)
Space Task Group Telecon, August 8, 2007 – (ASAP (RADARSAT-1) Portfolio)
IICWG, October 2007, ESRIN, Frascatti
Space Task Group Meeting, November 26-27, 2007, Darmstadt (Agenda, Presentation, and Background Material)

Geneva, WMO Headquarters

Day 1

Day 2
  • Leaving an IPY legacy
  • “The Polar Snapshot” K. JezekExample Acquisitions
  • Geo Contribution (M. Rast and E. Sarukhanian)
  • Mechanisms for collecting IPY data requirements
  • SCOBS survey of IPY sat. data needs (E. Sarukhanian)
  • Other Agency IPY AOs (All)
  • Establishing the priorities for near-term/medium-term/long-term actions
  • Acquisition planning/Tasking satellites (All)
  • Data Management/Metadata standards (All)
  • Archiving and Data Distribution (All)
  • Data Policy (All)
  • Discussion on Agency Commitments
  • Baseline plans for data acquisitions
  • Archiving and distribution

Day 3 (half-day)
  • Missing Agencies
  • Consolidation of Action Items
  • Time and place of next Meeting
  • Meeting Closure

Summary Documents

Report to CM-7
Slides presented by T. Mohr to CM-7
STG1 Summary


STG SAR Workshop, March 2008, St. Hubert (Agenda, Presentations, and Background Material)
Space Task Group Meeting, May 5-6, 2008, ESRIN Frascati, Italy (Details and Summary Reports)
STG IPY Session, SCAR, July 2008, St. Petersburg, Russia
STG SAR Workshop 2, Sept. 30-Oct. 1, 2008, DLR Oberpfaffenhovfen, Germany (Details)

Canadian Space Agency, St. Hubert, Canada

As part of ongoing IPY Space Task Group activities, the Canadian Space Agency hosted an IPY SAR/InSAR workshop in response to an action item from STG-1.

The goal of the meeting was to develop an acquisition strategy for SAR and InSAR data that achieves the maximum number of IPY science objectives in such a way as to distribute the acquisition load across the different agencies – understanding that no single agency can accommodate all of the tasks. This will require a level of coordination between the space agencies that has not yet been attempted. The workshop focused on data acquisition requirements, as outlined by the scientific community, based on Agency strategic plans for IPY and unique capabilities of their systems. Data processing and distribution issues were briefly addressed but the primary objective was to populate the archive given the unique opportunity of IPY.

The workshop main tasks were:

1) To review existing GIIPSY science requirements as outlined in the Global Inter-agency IPY Polar Snapshot Year (GIISPY) Strategy Document.

2) To present the Agencies strategic priorities in line with IPY science activities.

3) To present and review SAR data which are being collected, and are planned for collection during the IPY.

4) To present the satellite and ground segment operators system capabilities and constraints related to the acquisition of data in support to IPY.

5) To attempt to forge a coordinated / multi-agency SAR acquisition plan for the remainder of IPY acquisitions.

In order to meet these ambitious objectives, invited attendees, which include members of the science and operational communities, space agencies operating SAR satellite; space agencies with data transmission, ground segment and processing capabilities, and ground segment operators, were requested to actively contribute to the achievement of the workshop objectives.

Logistical Information

Map to CSA


Meeting Introduction (YC)
STG Background (YC)
GIIPSY Background (KJ)
ESA Portfolio (HL)
ESA and IPY (YD)
ESA Constraints (HL)
DLR Strategic Objectives (ED)
DLR IPY Data Constraints (ED)
TerraSAR Capabilities (DF)
TerraSAR Data Access (DF)
CSA Strategic Objectives (YC)
R1 Constraints (RSJ)
R2 Allocation (DdL)
Ice Services (DL)
CNES Complementary Optical Studies (ET)
Summary and Action Items (YC and KJ)
Meeting Minutes
Participants List

Data Acquisition Plans

Strawman Acquisition Strategy Spreadsheet
Antarctic Acquisition Template
Sea Ice Acquisition Template
Arctic Land Ice Acquisition template

DLR, Oberpfaffenhofen, Germany

As a follow up to the STG action to enhance the coordination among the SAR Space Agencies in response to the IPY scientific objectives, a SAR/InSAR coordination workshop was held on 5/6 March 2008 at the Canadian Space Agency. As a result of this meeting, the SAR operating Agencies agreed on the strategic guidelines for imaging activities and for thematic priorities as outlined by the science community. Despite the significant way forward and considerable efforts we are putting to fulfill our commitments, there is still a need to develop a SAR Acquisition Consolidated Plan and discuss the way forward for a SAR processing strategy and data dissemination plan.

As part of the SAR coordination process, the German Aerospace Center (DLR) is organising a second meeting to address the harmonisation and coordination of the acquisition plans. The objectives of this meeting are:

* Consolidate the current SAR planning and imaging activities occurring under the auspices of IPY/STG in order to avoid gaps and overlaps and optimize resources (i.e. thematic / instrument matrix, common planning tool, etc.)
* Distribute imaging load according to Agencies’ capacities and priorities, and develop acquisition plans
* Look at a short/med/long term planning approach to continue the acquisitions (if at all possible)

The meeting will be held at the DLR facilities in Oberpfaffenhofen (Germany).
We now established the date of the workshop on 30 Sept./1 Oct.2008.

Logistical Information

Directions to DLR
Hotels close to DLR
Hotels in Munich
DRAFT Agenda

GIIPSY Draft Acquisition Plan Recommendation for TSX.

These plans were prepared to provide DLR with an estimate of SAR loading for Antarctic regions south of about –80°. Comments welcome. These are in addition to any individual proposals and to several super-site areas that the STG is considering in Greenland and Antarctica.

Filchner Ascending
Filchner Descending
TAM Ascending
TAM Descending

JAXA IPY Web Site (Comments welcomed by Dr. Masanobu Shimada)

Japanese: JAXA website | JAXA IPY Dataset page

English: JAXA website | JAXA IPY Dataset page

PALSAR Animations. Antarctic: /A/B/C

ESA/ESRIN Acquisitions and Plans

Information on upcoming ERS-2 acquisition from O’Higgins Station
Acquisition map for O’Higgins Station
Animation of ESA SAR data over Lincoln Sea. Courtesy Ron Kwok

Participants List


1) Buckreuss and Roth, DLR
2) Crevier, CSA
3) Jezek, OSU
4) Del Rio Vera, Drinkwater and Laur, ESA
5) Saint-Jean, CSA
6) Rigby, MDA
7) Hajnsek, DLR
8) Floricioiu, DLR
9) Braun, U Bonn
10) Helm and Miller, AWI
11) Hall, KSAT

TSX Subgroup meeting (Thursday, Oct 2)
SAR Subgroup meeting Summary
Meeting Minutes
Followup Telecon Minutes


STG Meeting, February 2009, Geneva (Agenda, Presentations, and Background Material)
3rd SAR Workshop, June 2009, Frascatti (Agenda, Presentations, and Background Material)
STG Meeting, December 2009, Geneva (Agenda, Presentations, and Background Material)


Oslo IPY Meeting and STG Meeting (June) (Agenda, Presentations, and Background Material)


Polar Gateways Meeting, Barrow, Alaska, January 2008
SCAR/IASC IPY Open Science Conference, July 2008 St. Petersburg, Russia
IPY STG SAR Workshop, March 5, 6 Canadian Space Agency, Montreal, Canada
2nd SAR Workshop Sept 30-Oct. 1 DLR Wessling Germany
2008 AGU Fall Meeting (Presentations and informal get together)
2008 AGU FALL MEETING TASK FORCE FOR REMOTE SENSING OF PERMAFROST. G. Grosse and C. Duguay. Monday, 15 December 2008, 5:00-6:30 pm in the San Francisco Marriott Pacific Room A (Agenda)
STG-4, Feb. 3-4, 2009, WMO, Geneva

Sea Ice MEaSUREs — Documents and Tools


Methodology: Sea Ice Dynamics

An understanding of Arctic and Antarctic sea ice dynamics is accomplished by monitoring sea ice movement with SAR imagery throughout the year. The convergence of satellite orbits at high latitudes means that repeat coverage tends to improve near the North and South Poles. This permits complete coverage of the entire Arctic basin and Southern Ocean every three days. These three-day composite mosaics serve as a “snaphot” in time and are compared to similar snapshots in a temporal series.

With the onset of each summer or winter season, a regular grid is superposed across the first snapshot of the seasonal series. The grid spacing is 10 km at high latitudes and 20 km near the Arctic and Antarctic perimeter. Monitoring sea ice movement consists of tracking the sea ice under each vertex in the regular grid. Sea ice exhibits structural characteristics based on its composition of first year and multi-year ice. The key to studying ice dynamics is tracking these characteristic features as the season evolves; allowing the regular grid to warp as the ice beneath each vertex moves.

The tracking is an automated process that relies on feature extraction to find the common points in subsequent snapshots. However, the automated process is not perfect, necessitating human intervention for quality control. Operators correct the vertices when locations are misidentified and remove points from consideration when ice begins to break-up or the grid polygons lose their physical meaning.

For the sake of product nomenclature, it should be noted that we have adopted the Lagrangian frame of reference (as compared to the Eulerian). Instead of studying sea ice motion at a particular location over time, we follow individual ice parcels as they move through space and time. Lagrangian tracking is better-suited for the time evolving Arctic and Antarctic ice motion and can be readily manipulated to generate a number of sea ice products that will be described in the Products and Tools Section.

References Citing Sea Ice SAR Data

Global satellite observation requirements for floating ice: Focusing on synthetic aperture radar – J.C. Falkingham, Environment Canada, World Meteorological Organization meeting (March 2014).

A KPCA texture feature model for efficient segmentation of RADARSAT-2 SAR sea ice imagery – L. Xua, J. Liab, A. Wong, Cheng Wang. International Journal of Remote Sensing 35:13 (2014), 5053-5072, DOI: OI:10.1080/01431161.2014.933279.

Landfast sea ice extent in the Chukchi and Beaufort Seas: The annual cycle and decadal variability – A. R. Mahoney, H. Eicken, A. G. Gaylord, R. Gens. Cold Regions Science and Technology 103 (2014) 41-56 DOI:

The newest oldest data from Seasat’s synthetic aperture radar – T. Logan, B. Holt, L. Drew. Eos, Transactions American Geophysical Union, 95:11, 93–94, (18 March 2014), DOI: 10.1002/2014EO110001.

Swell and sea in the emerging Arctic Ocean – J. Thomson, W. E. Rogers. Geophysical Research Letters 41, 3136–3140 (2014), DOI: 10.1002/2014GL059983.

Arctic sea ice circulation and drift speed: Decadal trends and ocean currents – R. Kwok, G. Spreen, S. Pang. Journal of Geophysical Research: Oceans 118, 2408-2425 (2013), DOI: 10.1002/jgrc.20191.

Sea ice monitoring by synthetic aperture radar – W. Dierking. Oceanography 26(2):100-111 (2013).

Unsupervised classification of sea ice and water using synthetic aperture radar via an adaptive texture sparsifying transform  – R. Amelard, A. Wong, D. A. Clausi, F. Li. IEEE International Geoscience and Remote Sensing Symposium, March 2013.

Waveform classification of airborne synthetic aperture radar altimeter over Arctic sea ice – M. Zygmuntowska, K. Khvorostovsky, V. Helm, S. Sandven1. The Cryosphere 7(4) 1315­-1324 (2013), DOI: 10.5194/tc-7-1315-2013

Wind-driven trends in Antarctic sea ice drift – P. R. Holland, R. Kwok. Nat Geosci.(2012), DOI: 10.1038/NGEO1627.

Source and pathway of the Western Arctic upper halocline in a data-constrained coupled ocean and sea ice model – A. Nguyen, R. Kwok, D. Menemenlis, J. Phys. Oceanog. 42 (2012), DOI: 10.1175/JPO-D-11-040.1

Changing Arctic Ocean freshwater pathways – J. Morison, R. Kwok, C. Peralta-Ferriz, M. Alkier, I. Rigor, R. Anderson, and M. Steele, (2012), Nature, 481, 66-70, DOI:10.1038/nature10705.

Arctic sea ice freeboard from IceBridge acquisitions in 2009: Estimates and comparisons with ICESat – R. Kwok, G. F. Cunningham, S. S. Manizade, W. B. Krabill (2012), J. Geophys. Res., 117, C02018, DOI:10.1029/2011JC007654.

Deformation of the Arctic Ocean ice cover after the 2007 record minimum in summer ice extent – R. Kwok, G. F. Cunningham (2012), CRST, 76-77, DOI: 10.1016/j.coldregions.2011.04.003.

Recent changes of arctic multiyear sea-ice coverage and the likely causes – I. V. Polyakov, J. Walsh, R. Kwok (2012), BAMS, DOI: 10.1175/BAMS-D-11-00070.1.

Evaluation of Arctic sea ice thickness simulated by Arctic Ocean Model Intercomparison Project models – M. Johnson, A. Proshutinsky, Y. Aksenov, A. Nguyen, R. Lindsay, C. Haas, J. Zhang, N. Diansky, R. Kwok, W. Maslowski, S. Häkkinen, I. Ashik, B. de Cuevas, (2012), J. Geophys. Res., Vol. 117, DOI:10.1029/2011JC007257.

Summer Antarctic sea ice as seen by ASAR and AMSR-E and observed during two IPY field cruises: A case study – AHMET E. TEKELI, STEFAN KERN, STEPHEN F. ACKLEY, BURCU OZSOY-CICEK, HONGJIE XIE, Annals of Glaciology 52(57) (2011)

Comiso, J. C., R. Kwok, S. Martin, and A. L. Gordon (2011), Variability and trends in sea ice extent and ice production in the Ross Sea, J. Geophys. Res., 116, C04021, DOI:10.1029/2010JC006391.

Drucker, R., S. Martin, and R. Kwok (2011), Sea ice production and export from coastal polynyas in the Weddell and Ross Seas, Geophys. Res. Lett., 38, L17502, DOI:10.1029/2011GL048668.

Kwok, R. (2011), Observational assessments of Arctic Ocean sea ice motion, export, and thickness in CMIP3 climate simulations, J. Geophys. Res., DOI:10.1029/2011JC007004.

Kwok, R. and J. Morison (2011), Dynamic topography of the ice-covered Arctic Ocean from ICESat, Geophys. Res. Lett., 38, L02501, DOI:10.1029/2010GL046063.

Kwok, R. and N. Untersteiner (2011), The thinning of Arctic sea ice, Phys. Today, 64(4), 36-41.

Kwok, R., and N. Untersteiner (2011) New High-Resolution Images of Summer Sea Ice, EOS Trans. AGU, 92(7), 53-54.

Kwok, R. and G. F. Cunningham (2011), Deformation of the Arctic Ocean ice cover after the 2007 record minimum in summer ice extent, CRST, DOI: 10.1016/j.coldregions.2011.04.003.

Kwok, R., B. Panzer, C. Leuschen, S. Pang, T. Markus, B. Holt, and S. Gogineni (2011), Airborne surveys of snow depth over Arctic sea ice, J. Geophys. Res., 116, C11018, DOI:10.1029/2011JC00737.

Nguyen, A., D. Menemenlis, R. Kwok, (2011), Arctic ice-ocean simulation with optimized model parameters: Approach and assessment, J. Geophys. Res., 116, C04025, DOI:10.1029/2010JC006573.

Farrell, S., T. Markus, R. Kwok, L. Connor (2011), Laser altimetry sampling strategies over sea ice, Ann. Glacio., 52(57), 69-76.

Schweiger A., R. Lindsay, J. Zhang, M. Steele, H. Stern, and R. Kwok (2011), Uncertainty in sea ice volume, J. Geophys. Res., 116, C00D06, DOI:10.1029/2011JC007084.

Spreen, G., R. Kwok, and D. Menemenlis (2011), Trends in Arctic sea ice drift and role of wind forcing: 1992-2009, Geophys. Res. Lett., 38, L19501, DOI:10.1029/2011GL048970.

Toyota, K., J. C. McConnell, A. Lupu, L. Neary, C. A. McLinden, A. Richter, R. Kwok, K. Semeniuk, J. W. Kaminski, S.-L. Gong, J. Jarosz, M. P. Chipperfield, and C. E. Sioris (2011), Synoptic-scale meteorological control on reactive bromine production and ozone depletion in the Arctic boundary layer: 3-D simulation with the GEM-AQ model, Atmos. Chem. Phys., 11, DOI:10.5194/acp-11-3949-2011.

van Angelen, J. H., M. R. van den Broeke, R. Kwok (2011), The Greenland Sea Jet: A mechanism for wind-driven sea ice export through Fram Strait, Geophys. Res. Lett., 38, L12805, DOI:10.1029/2011GL047837.

Jay, C. V., M. S. Udevitz, R. Kwok, A. S. Fischbach, and D. C. Douglas. (2010). Divergent movements of walrus and sea ice in the northern Bering Sea, Marine Ecology Progress Series, 407:293-302. DOI: 10.3354/meps08575.

Kwok, R. (2010), Satellite remote sensing of sea ice thickness and kinematics: A review, J. Glacio., 56, 200.

Kwok, R. and G. F. Cunningham (2010), Contribution of melt in the Beaufort Sea to the decline in Arctic multiyear sea ice coverage: 1993-2009, Geophys. Res. Lett., 37, L20501, DOI:10.1029/2010GL044678.

Kwok, R. and D. Sulsky (2010), Arctic Ocean sea ice thickness and kinematics: Satellite retrievals and modeling, Oceanography, 23(4): 134-143.

Kwok, R., L. Toudal Pedersen, P. Gudmandsen, and S. S. Pang (2010), Large sea ice outflow into the Nares Strait in 2007, Geophys. Res. Lett., 37, L03502, DOI:10.1029/2009GL041872.

Perovich, D., R. Kwok, W. Meier, S. Nghiem, J. Richter-Menge., (2010): The Arctic: Sea ice cover [in State of the Climate in 2009], Bull. Amer. Meteor. Soc., 91 (6), S88-S90.

Kwok, R., and D. A. Rothrock (2009), Decline in Arctic sea ice thickness from submarine and ICESat records: 1958 2008, Geophys. Res. Lett., 36, L15501, DOI:10.1029/2009GL039035.

Kwok, R., G. F. Cunningham, M. Wensnahan, I. Rigor, H. J. Zwally, and D. Yi (2009), Thinning and volume loss of Arctic sea ice: 2003-2008, J. Geophys. Res., DOI:10.1029/2009JC005312.

Nguyen, A. T., D. Menemenlis, and R. Kwok (2009), Improved modeling of the Arctic halocline with a subgrid-scale brine rejection parameterization, J. Geophys. Res., 114, C11014, DOI:10.1029/2008JC005121.

Kwok, R. (2008), Outflow of Arctic sea ice into the Greenland and Barents Seas: 1979-2007. J. Clim., 22(9), 2438 2457, DOI: 10.1175/2008JCLI2819.1.

Lindsay, R. W., R. Kwok, L. de Steur, and W. Meier (2008): Halo of ice deformation observed over the Maud Rise seamount, Geophys. Res. Lett., 35, L15501, DOI:10.1029/2008GL034629.

Kwok, R., E. C. Hunke, W. Maslowski, D. Menemenlis, and J. Zhang (2008): Variability of sea ice simulations assessed with RGPS kinematics, J. Geophys. Res., 113, C11012, DOI:10.1029/2008JC004783.

Kwok, R., and G. F. Cunningham (2008): ICESat over Arctic sea ice: Estimation of snow depth and ice thickness, J. Geophys. Res., 113, C08010, DOI:10.1029/2008JC004753.

Kwok, R. (2008): Summer sea ice motion from the 18 GHz channel of AMSR-E and the exchange of sea ice between the Pacific and Atlantic Sectors, Geophys. Res. Lett., 35, L03504, DOI:10.1029/2007GL032692.

Zwally, H. J., D. Yi, R. Kwok, and Y. Zhao (2008): ICESat measurements of sea ice freeboard and estimates of sea ice thickness in the Weddell Sea, J. Geophys. Res., 113, C02S15, DOI:10.1029/2007JC004284.

Kwok, R., G. F. Cunningham, H. J. Zwally, and D. Yi (2007): Ice, Cloud, and land Elevation Satellite (ICESat) over Arctic sea ice: Retrieval of freeboard, J. Geophys. Res., 112, C12013, DOI:10.1029/2006JC003978.

Kwok, R., J. C. Comiso, S. Martin, and R. Drucker (2007): Ross Sea polynyas: Response of ice concentration retrievals to large areas of thin ice, J. Geophys. Res., 112, C12012, DOI:10.1029/2006JC003967.

Kwok, R. (2007), Baffin Bay ice drift and export, 2002-2007: Geophys. Res. Lett., 34, L19501,DOI:10.1029/2007GL031204.

Kwok, R. (2007): Near zero replenishment of the Arctic multiyear sea ice cover at the end of 2005 summer, Geophys. Res Lett., 34, L05501, DOI:10.1029/2006GL028737.

Martin, S., R. Drucker, and R. Kwok (2007): The areas and ice production of the western and central Ross Sea polynyas, 1991-2002 and their relation to the B-15 and C-19 iceberg events of 2000 and 2002, J. Mar. Sys., 68, DOI:10.1016/j.jmarsys.2006.11.008.

Coon, M., R. Kwok, G. Levy, M. Pruis, H. Schreyer, and D. Sulsky (2007): Arctic Ice Dynamics Joint Experiment (AIDJEX) assumptions revisited and found inadequate, J. Geophys. Res., 112, C11S90, DOI:10.1029/2005JC003393.

Sulsky, D., H. Schreyer, K. Peterson, R. Kwok, and M. Coon (2007): Using the material-point method to model sea ice dynamics, J. Geophys. Res., 112, C02S90, DOI:10.1029/2005JC003329.

Kwok, R., and M. D. Coon (2006): Introduction to special section:  Small-Scale Sea Ice Kinematics and Dynamics, J. Geophys. Res., 111, C11S21, DOI:10.1029/2006JC003877.

Kwok, R. (2006): Exchange of sea ice between the Arctic Ocean and the Canadian Arctic Archipelago, Geophys. Res. Lett., 33, L16501, DOI:10.1029/2006GL027094.

Schreyer, H. L., D. L. Sulsky, L. B. Munday, M. D. Coon, and R. Kwok (2006): Elastic-decohesive constitutive model for sea ice, J. Geophys. Res., 111, C11S26, DOI:10.1029/2005JC003334.

Kwok, R, (2006): Contrasts in Arctic Ocean sea ice deformation and production in the seasonal and perennial ice zones, J. Geophys. Res., 111, C11S22, DOI:10.1029/2005JC003246, 2006.

Kwok, R., G. F. Cunningham, H. J. Zwally, and D. Yi (2006): ICESat over Arctic sea ice: Interpretation of altimetric and reflectivity profiles, J. Geophys. Res., 111, C06006, DOI:10.1029/2005JC003175.

Kwok, R.: Variability of Nares Strait ice flux, Geophys. Res. Lett., 32, L24502, doi:10.1029/2005GL024768, 2005.

Kwok, R.: Ross Sea ice motion, flux, and deformation, J. Clim., 18(18), 3759-3776, 2005.

Kwok, R., W. Maslowski, and S. W. Laxon (2005): On large outflows of Arctic sea ice into the Barents Sea, Geophys. Res Lett., 32, L22503, doi:10.1029/2005GL024485.

Cuny, J., P. Rhines, and R. Kwok: Davis Strait fluxes, Deep Sea Research I: Oceanographic Research Papers, 52(3), 519-542, 2005.

Martin, S., R. Drucker, R. Kwok and B. Holt: Improvements in the estimates of ice thickness and production in the Chukchi Sea polynyas derived from AMSR-E, Geophys. Res. Lett., 32, L05505, doi:10.1029/2004GL022013, 2005.

McPhee, M., R. Kwok, R. Robbins, and M. Coon: Upwelling of Arctic pycnocline associated with shear motion of sea ice, Geophys. Res. Lett. 32, L10616, doi:10.1029/2004GL021819, 2005.

Kwok, R., H. J. Zwally, and D. Yi: ICESat observations of Arctic sea ice: A first look, Geophys. Res. Lett., 31, L16401, doi:10.1029/2004GL020309, 2004.

Kwok, R.: Annual Cycles of Multiyear Sea Ice Coverage of the Arctic Ocean: 1999-2003. J. Geophys. Res., 109, C11004, doi:10.1029/2003JC002238, 2004.

Kwok, R., G. F. Cunningham, and S. S. Pang: Fram Strait sea ice outflow, J. Geophys. Res., 109, C01009, doi:10.1029/2003JC001785, 2004.

Martin, S., R. Drucker, R. Kwok and B. Holt: Estimation of the thin ice thickness and heat flux from SSM/I data for the Chukchi Sea Alaskan coast polynya for 1990 – 2001, J. Geophys. Res., 109, C10012, doi:10.1029/2004JC002428, 2004.

Zhang, J., D. Thomas, D. Rothrock, R. Lindsay, Y. Yu, and R. Kwok: Assimilation of ice motion observations and comparisons with submarine ice thickness data. J. Geophys. Res., 108(C6):3170, DO1: 10.1029/2001JC001041, 2003.

Wang, J., R. Kwok, F. J. Saucier, J. Hutchings, M. Ikeda, W. D. Hilbler III, J. Haapala, M . D. Coon, H. E. Markus Meier, H. Eicken, N. Tanaka, D. Prentki, W. Johnson: Working Toward Improved Small-scale Sea Ice Ocean Modeling in the Arctic Seas, EOS Trans. AGU, 84(34) 325-336, 2003.

Kwok, R., G. F. Cunningham, and W. D. Hibler III: Sub-daily ice motion and deformation from RADARSAT observations, Geophy. Res. Lett,, 30(23), 2218, doi:10.1029/2003GL018723, 2003.

Kwok, R., G. F. Cunningham, and S. V. Nghiem: A study of melt onset in RADARSAT SAR imagery, J. Geophys. Res., 108(C11), 3363, doi:10.1029/2002JC001363, 2003.

Zhang, J., D. Thomas, D. Rothrock, R. Lindsay, Y. Yu, and R. Kwok: Assimilation of ice motion observations and comparisons with submarine ice thickness data. J. Geophys. Res., 108(C6):3170, DO1: 10.1029/2001JC001041, 2003.

Wang, J., R. Kwok, F. J. Saucier, J. Hutchings, M. Ikeda, W. D. Hilbler III, J. Haapala, M . D. Coon, H. E. Markus Meier, H. Eicken, N. Tanaka, D. Prentki, W. Johnson: Working Toward Improved Small-scale Sea Ice Ocean Modeling in the Arctic Seas, EOS Trans. AGU, 84(34) 325-336, 2003.

Kwok, R., and J. C. Comiso: Spatial patterns of Antarctic surface temperature: Connections to the Southern Hemisphere Annular Mode and the Southern Oscillation, Geophys. Res. Lett, 29(12), 10.1029/2002GL015415,2002.

Kwok, R.: Sea ice concentration from passive microwave radiometry and openings from SAR ice motion, Geophys. Res. Lett, 29(10), 10.1029/2002GL014787, 2002.

Kwok, R.: Arctic Ocean sea ice area and volume production: A contrast of two years – 1996/97 and 1997/98. Ann. Glacio. 34, 447-453, 2002.

Kwok, R. and J. C. Comiso: Southern Ocean Climate and Sea Ice Anomalies Associated with the Southern Oscillation, J. Clim., 15(5), 487-501, 2002.

Kwok, R. and G. F. Cunningham: Seasonal ice area and volume production of the Arctic Ocean: November 1996 through April 1997, J. Geophys. Res., 107(C10), 8038, 10.1029/2000JC000469, 2002.

Richter-Menge, J. A., S. L. McNutt, J. E. Overland, and R. Kwok: Relating arctic pack ice stress and deformation under winter conditions, J. Geophys. Res., 107(C10), 8040, doi:10.1029/2000JC000477, 2002.

Bardel, P., A. G. Fountain, D. Hall, and R. Kwok: Synthetic Aperture Radar Detection of the Snowline on Polar Glaciers, Taylor Valley, Antarctica, Ann. Glacio. 34, 177-183.

Nghiem, S. V., D. K.. Perovich, A. J. Gow, R. Kwok, D. G. Barber, and J. C. Comiso: Observation of sea ice surface thermal states under cloud cover, JGR-Oceans.

Nghiem, S. V., K. Steffan, R. Kwok, and W-Y. Tsai: Detection of snowmelt regions on the Greenland ice sheet using diurnal backscatter change, J. Glaciol., 47(159), 539-547, 2002.

Wu, Xiaoping, M.M. Watkins, E.R. Ivins, R. Kwok, P. Wang, J.M. Wahr: Toward global inverse solutions for the determination of currrent and past mass variations: Contribution of secular satellite gravity and topography change measurements J. Geophys. Res., 107 (B11), 2291, doi:10.1029/2001JB000543, 2002.

Kwok, R., M. Seigert, and F. D. Carsey: Ice motion over Lake Vostok, J. Glacio., 46(155), 689-694, 2001.

Fahnestock, M.A., I. Joughin, T.A. Scambos, R. Kwok, W.B. Krabill, and S. Gogineni: Ice stream related patterns of ice flow in the interior of northeast Greenland, J. Geophys. Res., 106(D24), 34035-34045, 2001.

Fahnestock, M. A., T. A. Scambos, C. A. Shuman, R. J. Arthern, D. P. Winebrenner, and R. Kwok: Snow megadune fields on the East Antarctic Plateau: extreme atmosphere-ice interaction Geophys. Res. Ltrs. 27(22), 3719-3722, 2000.

Kwok, R.: Recent changes of the Arctic Ocean sea ice motion associated with the North Atlantic Oscillation, Geophys. Res. Lett, 27(6), 775-778, 2000.

Siegert, M. J., R. Kwok, C. Mayer, and B. Hubbard: Water exchange between the subglacial Lake Vostok and the overlying ice sheet, Nature, 403(6770), 643-646, 2000.

Siegert, M.J. and Kwok, R.: Ice-sheet radar layering and the development of preferred crystal orientation fabrics between Lake Vostok and Ridge B, central East Antarctica. Earth and Planetary Science Letters. 179 (2), 227-235, 2000.

Joughin, I.R., M. Fahnestock, R. Kwok, R. Gogineni, and C. Allen: Ice flow of Humboldt, Petermann and Ryder Fletscher, northern Greenland, J. Glacio., 45(150), 231-241, 1999.

Yueh, S. and R. Kwok: Arctic sea ice extent and melt onset from NSCAT observations, Geophys. Res. Lett., 25(23), 4369-4372, 1999.

Kwok, R., G. F. Cunningham, and S. Yueh: Area Balance of the Arctic Ocean Perennial Ice Zone: Oct 1996- April 1997, J. Geophys. Res., 104(C11), 25747-25749, 1999.

Kwok, R., G. F. Cunningham, N. LaBelle-Hamer, B. Holt, and D. A. Rothrock, Ice thickness Derived from high-resolution SAR imagery, Eos, Trans. AGU, 80(42), 495-497,1999.

Kwok, R. and D. A. Rothrock, Variability of Fram Strait Flux and North Atlantic Oscillation, J. Geophys. Res., 104(C3), 5177-5189, 1999.

Kwok, R., A. Schweiger, D. A. Rothrock, S. Pang and C. Kottmeier: Sea ice motion from satellite passive microwave data assessed with ERS SAR and buoy data, J. Geophys. Res.,103(C4), 8191-8214, 1998.

Kwok, R., S. V. Nghiem, S. Martin, D. P. Winebrenner, A. J. Gow, D. K. Perovich, C. T. Swift, D. G. Barber, K. M. Golden and E. Knapp: Laboratory measurements of sea ice: Connections to microwave remote sensing, IEEE Trans. Geosci. and Rem. Sens. , 36(5), 1716-70, 1998.

Kwok, R. and J. C. Comiso: The perennial ice cover of the Beaufort Sea from active and passive observations, Annals of Glaciol., 25, 376-381, 1998.

Nghiem, S.V., R. Kwok, S. H. Yueh: Diurnal Cycling effects on the microwave signatures of thin sea ice, IEEE Trans. Geosci. Remote Sens., Vol. 36, No. 1, 111-124, 1998

Golden, K. M., D. Borup, M. Cheny, E. Cherkaeva, M. S. Dawson, K.-H. ding, A. K. Fung, D. Issacson, S. A. Johnson, A. K. Jordan, J. A. Kong, R. Kwok, S.V. Nghiem, R. G. Onstott, J. Sylvester, D. P. Winebrenner, I. H. H. Zabel: Inverse electromagnetic scattering models for sea ice, IEEE Trans. Geosci. and Rem. Sens. , 36(5), 1675-1704, 1998.

Joughin, I. R., R. Kwok and M. A. Fahnestock: Interferometric estimation of three-dimensional ice-flow using ascending and descending passes, IEEE Trans. Geosci. Remote Sens., Vol. 36, No. 1, 1998.

Yueh, S. R. Kwok, S. H. Lou and W. Y. Tsai: Sea ice identification using dual-polarized Ku-band scatterometer data. IEEE Trans. Geosci. Remote Sens. 35(3), 560-569, 1997.

Joughin, I. R., M. Fahnestock, S. Ekholm and R. Kwok: Balance velocities of the Greenland ice sheet, Geophys. Rev. Lett., 24(23), pp. 3045-3048, 1997.

Liu, A. K., S. Martin and R. Kwok: Tracking of ice edges and ice floes by Wavelet analysis of SAR Images, J. Atmos. Oceanic Tech., 14, 1187-1198, 1997.

Nghiem, S., R. Kwok, S. Yueh, A. J. Gow, D. K. Perovich, J. A. Kong and C. C. Hsu: Evolution in polarimetric signature of thin saline ice under constant growth, Radio Science, Vol. 32, No. 1, pp. 127-151, 1997.

Nghiem, S., S. Martin, D. K. Perovich, R. Kwok, R. Drucker, A. J. Gow, K. H. Ding, and J. A. Kong: A laboratory study of the effect of frost flowers on C-band radar backscatter from sea ice, J. Geophys. Res., 102(C2), 3357-3370, 1997.

Kwok, R., J. C. Comiso and G. F. Cunningham: Seasonal Characteristics of the Perennial sea ice cover of the Beaufort sea. J. Geophys. Res., 101 (C12), 28417-28439, 1996.

Kwok, R. and M. Fahnestock: Ice Sheet Motion and Topography from Radar Interferometry, IEEE Trans. Geosci. Remote Sens. Vol. 34, No. 1, 189-200, 1996.

Comiso, J. C. and R. Kwok: Surface and radiative characteristics of the summer Arctic sea cover from multisensor satellite observations. J. Geophys. Res., 101 (C12), 28397-28416, 1996.

Joughin, I., S. Tulaczyk, M. Fahnestock, R. Kwok: A Mini-Surgeon the Ryder Glacier, Greenland Observed via Satellite Radar Interferometry, Science, vol 274, pp. 228-230, 1996.

Joughin. I, R. Kwok, M. Fahnestock: Estimation of Ice Sheet Motion Using Satellite Radar Interferometry: Method and Error Analysis with Application to the Humboldt Glacier, Greenland, J. of Glaciol., 42(142), 564-575, 1996.

Joughin, I., D. Winebrenner, M. Fahnestock, R. Kwok, and, W. Krabill: 1996, Measurement of ice-sheet topography using satellite radar interferometry, J Glacio., vol. 42, no. 140, 1996.

Nghiem, S. V, R. Kwok, J. A. Kong, R. T. Shin, S. A. Arcone and A. J. Gow: An electrodynamic model with distributed properties for effective permittivities of sea ice, Radio Sci., 31(2), 297-311, 1996.

Kwok, R., D. A. Rothrock, H. L. Stern and G. F. Cunningham: Determination of Age Distribution of Sea Ice from Lagrangian Observations of Ice Motion, IEEE Trans. Geosci. Remote Sens., Vol. 33, No. 2, pp. 392-400, 1995.

Kwok, R., S. V. Nghiem, S. H. Yueh: Retrieval of Thin Ice Thickness from Multi-frequency Polarimetric SAR Data, Remote Sensing of Environment, Vol. 51, No. 3, 361-374, 1995.

Stern, H. L., D. A. Rothrock and R. Kwok: Open Water Production in Arctic Sea Ice: Satellite measurements and model parameterizations, J. Geophys. Res., 100 (C10), 20601-20612, 1995.

Kwok, R. and T. Baltzer: The Geophysical Processor System at the Alaska SAR Facility. Photogramm. Engrg. and Remote Sens., Vol. 61, No. 12, 1445-1453, 1995.

Nghiem, S. V., R. Kwok, S. H. Yueh and M. R. Drinkwater: Polarimetric Signatures of Sea Ice – Part I: Theoretical Model, J. Geophys. Res., 100(C7), 13665-13679, 1995.

Nghiem, S. V., R. Kwok, S. H. Yueh and M. R. Drinkwater: Polarimetric Signatures of Sea Ice – Part II: Experimental Observations, J. Geophys. Res., 100(C7), 13681-13698, 1995.

Hara, Y., R. G. Atkins, R. T. Shin, J. A. Kong, S. Yueh and R. Kwok: Application of Neural Networks for Sea Ice Classification in Polarimetric SAR Images, IEEE Trans. Geosci. Remote Sens., Vol. 33, No. 3, pp. 740-748, 1995..

Kwok, R and G. F. Cunningham: Backscatter Characteristics of the Winter Sea Ice Cover in the Beaufort Sea, J. Geophys. Res., 99 (C4), 7787-7803, 1994.

Fetterer, F., D. Gineris and R. Kwok: Sea ice type maps from Alaska synthetic aperture radar facility imagery: An assessment, J. Geophys. Res., 99 (C11), 22443-22458, 1994.

Lee, J. S., R. Grunes and R. Kwok: Classification of multi-look polarimetric SAR imagery based on complex Wishart distribution, Int. J. Remote Sensing, Vol. 15, No. 11, 2299-2311.

Yueh, S., S. Nghiem and R. Kwok: Polarimetric scattering and emission properties of targets with reflection symmetry, Radio Science, Vol. 29, No. 6, pp. 1409-1420, 1994.

Johnson, J. T., J. A. Kong, R. T. Shin, S. H. Yueh, S. V. Nghiem and R. Kwok: Polarimetric thermal emission from Rough Ocean Surfaces. JEMA, Vol 8, No. 1, 43-59, 1994.

Yueh, S. H., S. V. Nghiem, R. Kwok, W. J. Wilson, F. K. Li, J. T. Wilson and J. A. Kong: Polarimetric thermal emission from periodic water surfaces, Radio Science, Vol 29, No. 1, 87-96, 1994.

Kwok, R., E. Rignot, J. Way, A. Freeman and J. Holt.: Polarization Signatures of Frozen and Thawed Forests of Varying Environment State, IEEE Trans. Geosci. Remote Sens., Vol. 32, No. 2, pp. 371-381, 1994.

Way, J., E. Rignot, K. C. McDonald, R. Oren, R. Kwok, G. Bonan, M. C. Dobson, L. A. Vierick, J. E. Roth: Evaluating the type and state of Alaska Taiga forests with imaging radar for use in Ecosystem models, IEEE Trans. Geosci. Remote Sens., Vol. 32, No. 2, pp. 353-370, 1994.

Fahnestock, M., R. Bindschadler, R. Kwok, and K. Jezek: Greenland Ice Sheet Surface Properties and Ice Dynamics from ERS-1 Synthetic Aperture Radar Imagery, Science, Vol. 262, 1530-1534, 1993.
Nghiem, S. V., S. Yueh, R. Kwok, and D. T. Nguyen: Polarimetric Remote Sensing of Geophysical Medium Structures, Radio Science, Vol 28, No. 6, 1111-1130, 1993.
Nghiem, S. V., R. Kwok, J. A. Kong, and R. T. Shin: A Model with Ellipsoidal Scatterers for Polarimetric Remote Sensing of Anisotropic Layered Media. Radio Science, Vol 28, No. 5, 687-703, 1993.
Nghiem, S., S. H. Yueh, R. Kwok, and F. K. Li.: Symmetry Properties in Polarimetric Remote Sensing. Radio Science, Vol 27, No. 5, 693-711, 1992.
Jezek, K., J. P. Crawford, R. Bindschadler, M. Drinkwater, and R. Kwok: Analysis of Synthetic Aperture Radar Data Collected Over the Southwestern Greenland Ice Sheet. J. of Glaciology, Vol. 39, No. 131, pp 119-132.
Kwok, R., E. Rignot, B. Holt, and R. G. Onstott: Identification of Sea Ice Type in Spaceborne SAR Data. J. Geophys. Res., 97 (C2), 2391-2402, 1992.
Rignot, E. and R. Kwok: Spatial Statistics of Distributed Targets in SAR Image Data., Int. J. of Remote Sens., Vol. 14, No. 2, 345-363, 1993.
Drinkwater, M., R. Kwok,, D. Winebrenner and E. Rignot: Multifrequency Polarimetry Synthetic Aperture Radar Observations of Sea-Ice. J. Geophys. Res., 96 (C11), 20,679-20,698, 1991.
Rignot, E., R. Kwok, J. Curlander and S. Pang: Automated Multisensor Registration: Requirements and Techniques. Photogram. Engrg and Rem. Sens., Vol. 57, No. 8, August 1991, 1029-1038.
McConnell, R., R. Kwok, J. Curlander, S. Pang and W. Kobe:, Ψ-S Correlation and Dynamic Time Warping: Two Methods for Tracking Ice Floes in SAR Images. IEEE Trans. Geosci. Remote Sens., Vol. 29, No. 6, pp. 1004-1012, 1991.
Kwok, R., J.C. Curlander and S.S. Pang: An Automated System for Mosaicking Spaceborne SAR Imagery, Int. J. of Remote Sens., Vol. 11, No. 2, 1990, 209-223.
Kwok, R., J.C. Curlander, R. McConnell and S. Pang: An Ice Motion Tracking System at the Alaska SAR Facility, IEEE J. of Oceanic Engineering, Vol. 15, No. 1, Jan 1990, 44-54.
Kwok, R. and W.T.K. Johnson: Block Adaptive Quantization of Magellan SAR Data, IEEE Trans. Geosci. and Remote Sens., Vol. 27, No. 4, July 1989.
Chang, C.Y., R. Kwok and J.C. Curlander: Spatial Compression of SEASAT SAR Imagery, IEEE Trans. on Geoscience and Remote Sensing, Vol. 26, No. 5, September 1988.
Arvidson, R., M. Schulte, R. Kwok, J.C. Curlander, C. Elachi, J. Ford and R.S. Saunders: Construction and Analysis of Simulated Venera and Magellan Images of Venus, ICARUS, 75, 1988, 161-181.
Kwok, R., J.C. Curlander and S. Pang: Rectification of Terrain Induced Distortion in Radar Imagery, Photogrammetric Engineering and Remote Sensing, Vol. 53, No. 5, May 1987, pp 507-513.
Curlander, J. C., R. Kwok and S. Pang: A Post-Processing System for Automated Rectification and Registration of SAR Imagery, Int.l J. of Remote Sensing, 1987, Vol. 8, No. 4, pp 621-638.
Friedmann, D.E., J.P. Friedel, K.L. Magnussen, R. Kwok, and S. Richardson: Multiple Scene Precision Rectification of Spaceborne Imagery with very Few Ground Control Points, Photogrammetric Engr. and Remote Sens. Vol. 49, No. 12, p. 1657, 1983.
Evans, E. and R. Kwok: Mechanical Calorimetry of Large DMPC Vesicles in the Phase Transition Region, Biochem. 20:4874, 1982.
Evans, E. and R. Kwok: Controlled Aggregation of PS-PC vesicles in Calcium, Biophy. J. 37:A165-A165, 1982
Kwok, R. and E. Evans: Thermoelasticity of Large Lecithin Bilayer Vesicles, Biophy. J. 35:637-652, 1982.
Evans, E., R. Kwok and J.T. McKown: Calibration of Beam Deflection produced by Cellular forces in the 10-9 to 10-6 gram range, Cell Biophys. 2:99, 1980.

3 Case Studies

RGPS Melt Onset

The melt onset product consists of a gridded field containing the date of surface melt at each grid location. This date is derived from changes in the radar backscatter signature within the Lagrangian cells between April and June. The grid is at 10-kilometer resolution within the interior of the Arctic basin and 25-kilometer resolution near the coasts.

Summer 1998 Summer 1999
Download Download

A study of the onset of melt over the Arctic Ocean in RADARSAT synthetic aperture radar data — R. Kwok, G. F. Cunningham, S. V. Nghiem. Journal of Geophysical Research, 108 (C11), 3363, DOI: 10.1029/2002JC001363.

RGPS SHEBA Ice Motion 1997-1998

These Eulerian Ice Motion products were produced by tracking ice-cover features on a 200-kilometer-by-200-kilometer area centered on the SHEBA ice camp. This observation site was established in November 1997 in the Beaufort Sea some 500 km off the north coast of Alaska and drifted with the ice pack for almost one year. This product is made with a cell spacing of 5 km resulting in a 41-by-41 element grid. The ice motion measurements were made on a near daily schedule covering two time periods from November 1, 1997 through December 25, 1997 and January 10, 1998 through October 6, 1998.

Download Data: November 1997-October 1998

CASES 2003-2004

These Eulerian Ice Motion products were produced for the Canadian Arctic Shelf Exchange Study (CASES) Project during the winter of 2003-2004. Displacements are derived from successive SAR images by tracking common features over a region off the Canadian coast, stretching out some 200 km from the middle of the Amundsen Gulf to the Mackenzie River delta. Grid spacing is approximately 22 km. The product dataset covers the dates of ice-covered conditions between November 3, 2003 and June 6, 2004.

Download Data: November 2003-June 2004

Data Formats in Depth

1. CEOS (Committee on Earth Observation Satellites)

A standard format published in 1988, used for radar data and originally expected to be used with tape media. The format does not specify a naming convention.

How to Open

CEOS data may be viewed using ASF’s MapReady. ESA’s Sentinel-1 Toolbox (S1TBX) is also available.

For users who do not wish to use MapReady or S1TBX, some useful information:

  • CEOS is a wrapper — image data are wrapped in an image file descriptor and record headers which must be discarded in order to work with the data.
  • Each file starts with a file descriptor record, which provides details on the format used to store the data. In addition, there is one record header for each line of data. Each line has a 12-byte record header (which contains the record count in the file, record type identification, and record length in bytes); data values, and possibly fill values
  • Note that the units for state vectors may be either meters or kilometers (not a worry if using MapReady).

CEOS File Format and Content Information

Data format information for ASF’s CEOS L1 and L1.5 (image) products:

File Type Description ERS-1, ERS-2, JERS-1 and RSAT-1 File Extension (L1) ALOS PALSAR File Prefix (L1.5)
SAR VOLUME file Stores the volume-management and file-management information. N/A VOL-
SAR LEADER file Contains detailed metadata. Useful records include the Dataset Summary, Platform Position, and the Facility-Related records. Contents can be read in plain text if the .L.txt file is available. .L LED-
SAR DATA file Contains image data .D IMG-
SAR TRAILER file .P contains basic metadata including orbit, beam mode, start/stop times and lat/long corners and center. Can be read with a text editor.
TRL contains a file descriptor, and for L1.1 and L1.5 data, low resolution image data.

Product CEOS Naming Conventions

The CEOS format does not specify a naming convention, so naming is facility or agency-specific.

2. GeoTIFF (Tagged Information File Format)

Format for handling images and data within a single raster file, by including header tags such as size, definition, image-data arrangement, and applied image compression.

The GIS-friendly GeoTIFF format is an extension of TIFF that includes georeferencing or geocoding information embedded within a TIFF file (such as latitude, longitude, map projection, coordinate systems, ellipsoids, and datums) so an image can be positioned correctly on maps of Earth. It is a public domain metadata standard.

A georeferenced image is oriented in parallel with orbit direction:
Descending: The scene start is at the top of the image, and scene end is at the bottom.
Ascending: The scene end is at the top of the image, and the scene beginning is at the bottom
A geocoded image is projected on a map oriented in a north-south direction:

Product GeoTIFF Naming Conventions

ALOS PALSAR RTC GeoTIFF File Extension and Description

File Extension Description Example
_HH.tif _HV.tif _VH.tif _VV.tif Terrain-corrected product stored in separate files for each available polarization in GeoTIFF format. AP_26939_PLR_F3170_RT1_HH.tif AP_26939_PLR_F3170_RT1_HV.tif AP_26939_PLR_F3170_RT1_VH.tif AP_26939_PLR_F3170_RT1_VV.tif
.iso.xml ISO-compliant metadata in XML format AP_26939_PLR_F3170_RT1.iso.xml
.inc_map.tif Incidence angle map in GeoTIFF format AP_26939_PLR_F3170_RT1.inc_map.tif
.ls_map.tif Layover/shadow mask in GeoTIFF format AP_26939_PLR_F3170_RT1.ls_map.tif
.dem.tif Digital elevation model used for terrain correction in GeoTIFF format AP_26939_PLR_F3170_RT1.dem.tif
.geo.jpg Browse image of the amplitude (including world and auxiliary file) in JPEG format AP_26939_PLR_F3170_RT1.geo.jpg
.kmz Browse image in Google Earth format AP_26939_PLR_F3170_RT1.kmz

3. SAFE (Standard Archive Format for Europe)

SAFE Product Folder Structure​

Sentinel data products use a Sentinel-specific variation of the SAFE format, an ESA folder structure containing data and information as follows:

The file is an XML file containing the mandatory product metadata common to all Sentinel-1 products.

Annotation datasets contain metadata describing the properties and characteristics of the measurement data or how they were generated. For each band of data there is a product annotation data set that contains metadata describing the main characteristics corresponding to that band such as the state of the platform during acquisition, image properties, polarization, Doppler information, swath merging and geographic location. Calibration annotations contain calibration information and the beta naught, sigma naught, gamma and digital number look-up tables that can be used for absolute product calibration. Noise data annotations contain the estimated thermal noise look-up tables. Annotated data sets are provided in XML format.

Measurement datasets contain the binary information of the actual acquired or processed data. For Level-0 this is the instrument data, for Level-1 it is processed data. Measurement datasets are provided in GeoTIFF format (georeferenced) for Level-1 products. There is one measurement data set per polarization and per swath. TOPSAR SLC products contain one complex measurement data set in GeoTIFF format (georeferenced) per swath per polarization. Level-1 GRD products contain one detected measurement data set in GeoTIFF format (georeferenced) per polarization.

In the Preview folder, quick-look datasets are power detected, averaged and decimated to produce a lower resolution version of the image. Single polarization products are represented with a grey scale image. Dual polarization products are represented by a single composite color image in RGB with the red channel (R) representing the first polarization, the green channel (G) represents the second polarization and the blue channel (B) represents an average of the absolute values of the two polarizations.

Representation datasets found in the Support folder contain information about the format or syntax of the measurement and annotated data sets and can be used to validate and exploit these data. Representation data sets are provided as XML schemas.

Sentinel-1 SAFE Naming Convention

The top-level Sentinel-1 product folder name is composed of upper-case alphanumeric characters separated by an underscore (_).

Product Name

Naming Notes:

  • In Resolution (R), underscore (_) is a valid input to mean “not applicable.”
  • Product Class — A (Annotation) is internal only and not distributed.
  • In Start/Stop Date-Time, date and time are separated by the character ‘T’
  • Absolute orbit (OOOOO) ranges from 000001 to 999999.
  • Mission data-take ID (DDDDDD) ranges from 000001 to FFFFFF.
  • The folder extension is always “SAFE”

4. HDF5

Hierarchical Data Format (HDF) is a set of file formats designed to store and organize large amounts of data.

HDF5 simplifies the file structure to include only two major types of object:

  • Datasets, which are multidimensional arrays of a homogeneous type
  • Groups, which are container structures which can hold datasets and other groups

HDF5 is a general purpose file format and programming library for storing scientific data. Use of the HDF library enables users to read HDF files on multiple platforms regardless of the architecture the platforms use to represent integer and floating point numbers.

ASF DAAC SAR datasets available in HDF5 format and tools

  • Seasat products are offered in either HDF5 or GeoTIFF formats. HDF5 products may be viewed with MapReady.
  • All SMAP standard products are in the Hierarchical Data Format version 5 (HDF5). SMAP products can be viewed with Panoply.

HDF5 Data Recipe

How to View Seasat HDF5 Files in ASF MapReady

Product HDF5 Naming Conventions


From JPL’s Polarimetric (PolSAR) Data Format and Interferometric (InSAR) Pair Data Format.

Polarimetric and RPI Product File Formats

SLC files (.slc): calibrated single look complex files; floating point format, little endian, 8 bytes per pixel, corresponding to the scattering matrix.

  • Polarimetric product: one SLC file for each polarization (HH, HV, VH, and VV)
  • Repeat-pass interferometric product: one SLC file for each flight track (track 1, T1; and track 2, T2). Files are available by request, but are not normally included in the data distribution.

Ground projected files (.grd): calibrated complex cross products (Polarimetric product) or interferometric products (RPI product) projected to the ground in simple geographic coordinates (latitude, longitude). There is a fixed number of looks for each pixel. Floating point or complex floating point, little endian, 8 or 4 bytes per pixel.

HGT file: the DEM that the imagery was projected to, in the same geographic coordinates as the ground projected files. Floating point (4 bytes per pixel), little endian, ground elevation in meters.

Annotation file (.ann): a text file with metadata.

Additional Polarimetric Product File Formats

MLC files (.mlc): calibrated multi-looked cross products, floating point format, three files 8 bytes per pixel, three files 4 bytes per pixel, little endian.

Compressed Stokes Matrix product (.dat): AIRSAR compressed stokes matrix format for software compatibility (AIRSAR Integrated Processor Documentation). 10 bytes per pixel.

Terrain slope file (.slope): The terrain slope file (.slope) contains the derivatives of the digital elevation model (DEM) in the East and North direction. The file is an array of two interleaved floating point numbers (2 x 4 bytes per pixel) with geometry identical to the other ground-projected data layers (.grd, .hgt, .inc). For each interleaved pixel, the first 4 byte value is the terrain slope in the east direction, and the second 4 byte value is the slope in the north direction. Floating point, little endian.

Incidence angle file (.inc): the local incidence angle, the angle between the surface normal and the radar line of site. The file consists of 4-byte floating point values, co-registered with the slope file. The floating point, little endian file contains values reported in radians, as shown in the image.

Terrain slope file (.slope): The terrain slope file (.slope) contains the derivatives of the digital elevation model (DEM) in the East and North direction. The file is an array of two interleaved floating point numbers (2 x 4 bytes per pixel) with geometry identical to the other ground-projected data layers (.grd, .hgt, .inc). For each interleaved pixel, the first 4 byte value is the terrain slope in the east direction, and the second 4 byte value is the slope in the north direction. Floating point, little endian.

Incidence angle file (.inc): the local incidence angle, the angle between the surface normal and the radar line of site. The file consists of 4-byte floating point values, co-registered with the slope file. The floating point, little endian file contains values reported in radians, as shown in the image.

Additional RPI Product File Formats

AMP files (.amp1 and .amp2): calibrated multi-looked amplitude products, one file per repeat track, floating point format 4 bytes per pixel, little endian.

INT files (.int): interferogram product, one file per pair of repeat tracks, complex floating point format 8 bytes per pixel, little endian.

UNW files (.unw): unwrapped interferometric phase product, one file per pair of repeat tracks, floating point format 4 bytes per pixel, little endian.

COR files (.cor): interferometric correlation product, one file per pair of repeat tracks, floating point format 4 bytes per pixel, little endian.

KML and KMZ files (.kml or .kmz): these files allow you to view a representation of their corresponding file type in Google Earth or similar software.

PNG files (.png): these are representations of the corresponding products in standard PNG Format.

Formation of Interferometric Products:

Prior to creating interferometric products, the SLC images from both tracks are co-registered to each other using GPS data and the data itself to estimate and compensate for the variable motion between the tracks.

The single look complex (SLC) data for each track is summed in range and azimuth by the number of looks specified in the annotation file (“Number of Looks in Range” and “Number of Looks in Azimuthz”) (typically 3 looks in range and 12 looks in azimuth), divided by the product of the number of looks in range and azimuth, and output as the amp1 and amp2 files.

The interferogram in the .int file is formed by multiplying the single look complex image from track 1 times the complex conjugate of the single look complex image from track 2. The resulting complex values are then summed in range and azimuth according to the desired number of looks in the range and azimuth direction, with each pixel then divided by the product of the the number of azimuth looks and the number of range looks.

The correlation file .cor is formed by dividing the interferogram values (the .int file) by the product of the multilooked amplitude values for track 1 and track 2 (the .amp1 and .amp2 files).

The unwrapped interferometric phase file UNW (the .unw file) is obtained by applying the Goldstein/Werner method on the interferogram: Goldstein, R. M. and Werner, C. L., 1998. Radar interferogram filtering for geophysical applications. Geophysical Research Letters, 25(21):4035-4038.

Calibration of the data:

Please see JPL’s calibration page for documentation on calibration of the data.

UAVSAR Product Naming Conventions

6. AIRSAR (data format)

From JPL’s AirSAR website.

File Headers

All AIRSAR data files start with 3-4 header records.

  • First header: general information about data file including # of lines and samples and offset to the first data record
  • Parameter header: information specific to the scene
  • Calibration header: information on data calibration
  • DEM header: only present for TOPSAR data; contains the elevation offset and elevation increment needed to translate the integer*2 values to elevations in meters

Data Modes

POLSAR Data Mode

The POLSAR operating mode collects twelve channels of data, four in each of the three frequencies of AIRSAR: P-, L-, and C-band.  The four data channels are:

HH horizontally polarized transmit wave, horizontally polarized receive wave
HV horizontally polarized transmit wave, vertically polarized receive wave
VH vertically polarized receive wave, horizontally polarized receive wave
VV vertically polarized receive wave, vertically polarized receive wave

TOPSAR Data Modes

XTI1 – Generates a C-band DEM along with L- and P-band polarimetry
XTI2 – Generates a C-band and an L-band DEM, along with P-band polarimetry
(see exception below for when P-band data will not be present)

TOPSAR data are processed on the AIRSAR Integrated Processor (ver. 5.1 or ver. 6.1).

Data Files

POLSAR Data Files

Data Format — Compressed Stokes matrix data in slant range. File Size (10 km) is 15 Mbytes. CM data are oriented so that each pixel sample is decreasing azimuth (along track) and each pixel line is of increasing range (cross-track).

Each POLSAR set typically contains:


TOPSAR Data Files

Each TOPSAR scene typically contains:

  • 4 or 8 DEM (C-band or C-band and L-band) and related data files
  • 1 or 2 Polarimetric data files (see note below for exception)

They have the following files:

DEM Data (C-band, maybe L-band)

  • c.vvi2 – C-band VV polarization only
  • integer2 (signed 16 bit)
  • .demi2 – C-band DEM
  • byte file
  • .corgr – Correlation coefficient map
  • .incgr – Local incidence angle map

Polarimetric Data

  • l.datgr  – L-band polarimetry compressed Stokes matrix
  • p.datgr – P-band polarimetry compressed Stokes matrix

Note: Due to FCC restrictions, since 1994, P-band data are not included for TOPSAR datasets collected at 40 MHz bandwidth over sites in the United States.

AIRSAR Naming Conventions

TOPSAR Data Conversions

Data collected since 1993 are processed using Version 5.1 and Version 6.1.

Note that the integer*2 data will need to be converted using the following equations:

Convert demi*2 data to elevations in meters:
hs = (elevation increment) * DN + (elevation offset)

  • Elevation increment and offset are found in the DEM header record
  • DN is the integer*2 (signed) number from the .demi2 data file

Convert vvi*2 data to radar cross sections
sigma naught =(DN**2)/(General Scale Factor GFS)

  • DN is the integer*2 (signed) number as the amplitude (linear value) from the .vvi2 data file
  • GSF is in the second field of the Calibration Header.
  • Note that the GSF = 10**6

Polarimetric data collected in the TOPSAR mode are read the same way as POLSAR data.