1. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 Image: MODIS Land Group, NASA GSFC March 2000 Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 Image: MODIS Land Group, NASA GSFC March 2000 Presented by Dave McAdoo Presented by Dave McAdoo Arctic Sea Ice Freeboard Measurements from Satellite Altimetry

2. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 2 Objective, Science, and Benefit Requirements/Objective Research area: Document and understand changes in climate forcings and feedbacks, thereby reducing uncertainty in climate projections Priority research activity: Monitor changes in the Arctic and impacts on ecosystems Science At what volumetric rate is loss of Arctic sea ice occurring and how accurately can we track sea ice thickness changes using altimetry? What is the role of observed sea ice flux in climate system ? Benefits New, refined sea ice volume constraints on climate models. Near-real-time tracking of thick, multi-year sea ice in support of NSPD-66 and Commerce Transportation and Goal #8. Improved oceanographic and geodetic constraints for Arctic Ocean circulation modelling.

3. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 CryoSat-2 Science Challenges -Deriving precise (to ~3-5 cm), detailed (to ~ 10 km) sea ice freeboard and thickness estimates from complex satellite altimeter data sets Next Steps -Publish analyses of CBSIT (2009) data sets -Prepare for and conduct BESIE 2011 - Beaufort Sea Ice Camp as advisors to NASA’s OIB Airborne Campaigns in Antarctic and Arctic -Validate, analyze and exploit sea ice data from ESA’s CryoSat-2 (as ESA Data AO and Cal-val investigators). Process the complex returns from its advanced altimeter for ice freeboard -Prepare for ICESat-2 as members of the Science Definition Team Transition Path -Multi-year ice tracking and thickness products for the NIC, as well as climate models. 3 Challenges and Path Forward

4. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 4 From passive microwave satellite data Sep 2007: Minimum Sea Ice Extent for 30 yrs NSIDC Total: 4.3 million sq. km Motivation: Diminishing Arctic Sea Ice Extent Sep Anomalies 1979-2009 Projected Sep Ice Extent (5-model Average) 2010-2030 2040-2060 2070-2090 ACIA

5. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010.... 5 SNOW SEA ICE WATER RADAR LASER Ice Freeboard Satellite Altimetry (laser and radar) over Sea Ice Sea Ice Thickness Altimeters provide basin-scale freeboard and sea surface height data over the Arctic Ocean Snow Thickness RADAR LASER Satellite Altimetry

6. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010.... 6 Ice - Open Water Discrimination: Detecting Leads Specular Echo (Leads) Diffuse Echo (Ice Floes) Satellite Radar Altimetry (Envisat & ERS) Provides unambiguous detections of leads for sea surface height measurements Large footprint means returns from “mixed” surfaces (distorted echoes) have to be discarded (e.g. Peacock & Laxon, 2004) Satellite Laser Altimetry (ICESat) Leads Ice Floes Highly specular reflections from leads Difficult to distinguish leads from ice floes Several methods for determining SSH (e.g. Kwok et al. 2007; Zwally et al., 2008 ; Farrell et al., 2009)

7. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 7 Seasonal mean removed to create anomaly Change in Arctic Sea Ice Freeboard from ICESat 2003 – 2008 200320082003 2008 Fall (Oct-Nov) Winter (Feb-Mar)

8. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 8 Validating Satellite Altimeter Data over Sea Ice In-situ measurements on ice Airborne surveys above ice NOAA Validation Experiments (all joint with NASA; airborne & in situ)  LaRA–FASIT (2002) Fram Strait  AAA (2006) - Beaufort Sea  Canada Basin Sea Ice Thickness (CBSIT, April 2009)  BESIE (2011)

9. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010.... 9 Envisat Under-flight April 21 2009 Canada Basin Near 2006 survey line Thick MY ice to FY ice Ice Camp Over-flight April 25 2009 GreenArc Ice Camp Thick, Old MY ice Nares Strait Component of NASA’s Operation Ice Bridge (OIB) CBSIT Experiment: April 2009 For details see: Connor et al. poster, “Airborne & in situ validation of aatellite altimetry measurements over sea ice”

10. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010.... 10 In Situ Measurements: EM-31 Ice thickness profiling Snow depth Snow pits Drill holes for calibrations Courtesy J. Yungel, NASA GreenArc Ice Camp Over-flight (CBSIT 2009)

11. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 CryoSat-2 Science Challenges -Deriving precise (to ~3-5 cm), detailed (to ~ 10 km) sea ice freeboard and thickness estimates from complex satellite altimeter data sets Next Steps -Publish analyses of CBSIT (2009) data sets -Prepare for and conduct BESIE 2011 - Beaufort Sea Ice Camp as advisors to NASA’s OIB Airborne Campaigns in Antarctic and Arctic -Validate, analyze and exploit sea ice data from ESA’s CryoSat-2 (as ESA Data AO and Cal-val investigators). Process the complex returns from its advanced altimeter for ice freeboard -Prepare for ICESat-2 as members of the Science Definition Team Transition Path -Multi-year ice tracking and thickness products for the NIC, as well as climate models. 11 Challenges and Path Forward

12. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 Image: MODIS Land Group, NASA GSFC March 2000 Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 Image: MODIS Land Group, NASA GSFC March 2000 Extra Slides

13. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 13 Envisat and ICESat Validation over Sea Ice AAA Experiment flight path in the Canada Basin From Connor et al., RSE, 2009 Arctic Airborne Altimetry AAA: 2006 Along Envisat/RA-2 track - AB Std dev = 0.08m  Envisat vs ATM Lead elevs (using lead detection algorithm)

14. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 14 Principle of Satellite Altimetry Measuring the third / vertical dimension Measuring Surface Elevation (h): R = ct / 2 R = range measured by satellite altimeter c = speed of light t = round-trip travel time h = H – R h = sea surface height relative to reference ellipsoid H = satellite altitude above reference ellipsoid