AMSR-E and Enhanced Resolution SSM/I Sea Ice Drift

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AMSR-E and Enhanced Resolution SSM/I Sea Ice Drift

• Walt Meier
• AMSR Science Team Meeting, 15 July 2008

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Enhanced Resolution SSM/I Brightness Temperatures

• Uses BYU SIRF algorithm (D. Long
  et al.)
• Image reconstruction not simply spatial
  interpolation
• Daily fields of 36-hour composites, 1995 2006
• Limited to poleward of 60º N in Arctic misses
  significant winter sea ice
• 19, 22, 37 GHz at 8.9 km grid spacing
• 85 GHz at 4.45 km grid spacing
• Research-level product, needs to be validated
• Not publicly available, but researchers
  interested in testing are encouraged
• contact walt_at_nsidc.org or stroeve_at_nsidc.org

85V GHz 15 Mar 2004
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Sea Ice Drift Algorithm

• Maximum cross-correlation method feature
  matching in coincident, geo-located imagery (C.
  Fowler et al., Univ. of Colorado)
• Potentially affected by weather, especially 89
  GHz filtering done to remove most of these
  effects
• Optimal interpolation of 36/37 GHz and 89/85 GHz
  drift in final products
• Limited performance during summer, especially
  during peak of melt season (July -August)
• 18 GHz performs better for AMSR (Kwok, 2008)
  resolution too low for SSM/I

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AMSR and SSM/I Hi-Res Tb Spatial Resolution
Spatial Resolution (km) 36/37 GHz 36/37 GHz 89/85 GHz 89/85 GHz
Spatial Resolution (km) AMSR-E SSM/I AMSR SSM/I
Footprint/IFOV 14 x 8 38 x 30 6 x 4 16 x 14
Initial Gridded 12.5 25 6.25 12.5
Enhanced Gridded NA 8.9 NA 4.45
Final Gridded 12.5 12.5 6.25 6.25
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Daily Motion, 1 Mar 2004
U
10 km day-1
V
AMSR
SSM/I
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Weekly Sea Ice Drift, Jan May 2004
AMSR
SSM/I
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Comparison with IABP Buoys Daily Drift
Bias (PM-Buoy) km day-1 Number of Samples U U V V
Bias (PM-Buoy) km day-1 Number of Samples AMSR SSM/I AMSR SSM/I
All 2048 0.06 0.25 0.08 -0.03
Jan 474 -0.31 -0.14 0.36 0.36
Feb 423 0.20 0.54 -0.04 -0.12
Mar 459 0.01 0.23 0.05 -0.17
Apr 416 0.19 0.21 -0.02 -0.13
May 276 0.37 0.54 -0.02 -0.19
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Comparison with IABP Buoys Daily Drift
RMSe (PM-Buoy) km day-1 Number of Samples U U V V
RMSe (PM-Buoy) km day-1 Number of Samples AMSR SSM/I AMSR SSM/I
All 2048 3.24 2.91 2.93 2.55
Jan 474 4.39 3.56 3.94 3.10
Feb 423 2.20 2.27 2.20 2.04
Mar 459 2.88 2.59 3.18 2.76
Apr 416 2.48 2.49 2.25 2.17
May 276 3.78 3.51 2.38 2.40
Non-enhanced SSM/I RMS 4-5 km day-1
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Application of Sea Ice Motions

• SSM/I, AVHRR, and buoy motion
• Lagrangian tracking of ice parcels by age
• Average thickness for each age class
• Developed by Maslanik and Fowler, Univ. of
  Colorado

March Thickness
Image from Stroeve et al., 2008
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Application of Sea Ice Motions
Image courtesy S. Drobot and J. Maslanik, Univ.
of Colorado
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AMSR 2007 Melt Season Sea Ice Drift, Apr - Sep

• Strong poleward drift at end of summer
  contributed to extreme minimum
• AMSR motions limited during peak of melt season
  (late July, August)
• Still capture most of weekly variability
• 18 GHz channel performs better (Kwok, 2008)

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AMSR 2008 Sea Ice Drift, January - June

• Poleward drift in Feb/Mar pushed perennial ice
  northward from Siberian sector
• Perennial ice fraction in central Arctic
  decreased through winter

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2008 Sea Ice Conditions

• NSIDC Arctic News and Analysis
• Partially funded by NASA
• Primarily SMMR-SSM/I for long-term trend and
  variability
• AMSR provides much better spatial detail on
  conditions
• AMSR has smaller pole hole will North Pole be
  ice-free this summer?

http//nsidc.org/arcticseaicenews/
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2008 Arctic Sea Ice Conditions, 14 July
Daily Sea Ice Extent From SSM/I F15
SSM/I F15 25 km Sea Ice Concentration
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2008 Arctic Sea Ice Conditions, 14 July
Daily Sea Ice Extent From SSM/I F15
AMSR 6.25 km Sea Ice Concentration
AMSR image from Univ. Bremen, http//www.iup.uni-b
remen.de8084/amsr/amsre.html
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2008 vs. 2007 Summer Set-Up from AMSR
14 July 2007
14 July 2008
AMSR image from Univ. Bremen, http//www.iup.uni-b
remen.de8084/amsr/amsre.html
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Conclusion

• Enhanced resolution SSM/I provides sea ice drift
  of comparable quality to AMSR
• Extended timeseries of high-resolution passive
  microwave drift
• Potential for combined product?
• D. Long et al. at BYU has developed enhanced
  fields from AMSR-E Tbs

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Thanks!

• Research funded by NASA Grant NNG04GG72A
• Enhanced resolution SSM/I data provided by David
  Long and NASA-funded BYU Scatterometer Climate
  Record Pathfinder
• Thanks to Julienne Stroeve, Jeff Smith, Terry
  Haran, NSIDC

walt_at_nsidc.org
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Standardized sea ice trends
Extent Anomaly ( st. dev. From 1979-2000 mean)
Arctic 12-month running mean
Antarctic 12-month running mean
Year
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Antarctic trend magnitude and significance
Total Weddell Indian Pacific Ross Bell.-Am.
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Significance based on f-test with null hypothesis
of no trend
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Arctic trend magnitude and significance
Total Okhotsk Bering Hudson St. Lawr Baffin Grnland Barents Kara Laptev E. Sib Chukchi Beaufort Can. Arch Cen. Arc.
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Significance based on f-test with null hypothesis
of no trend No variability always 0 or 100
ice throughout region during the month
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Regional analysis of sea ice extent trends
15 Arctic Regions
5 Antarctic Regions
Okhotsk
Weddell
Indian
Bering
Laptev
E. Sib
Chukchi
Kara
Central Arctic
Beaufort
Bellingshausen- Amundsen
Barents
Canadian Archipelago
Baffin
Hudson
Greenland
Ross
Pacific
St. Lawrence
Regions adapted from Parkinson et al. (1999) and
Zwally et al. (2002), JGR
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Arctic Sea Ice and Forcing Trends
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References

• Haarpaintner, J., and G. Spreen, 2007. Use of
  enhanced-resolution QuikScat/SeaWinds data for
  operational ice services and climate research
  Sea ice edge, type, concentration, and drift,
  IEEE Trans. Geosci. Rem. Sens., 45(10),
  3131-3137.
• 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,
  doi10.1029/2007GL032692
• Long, D.G., P.J. Hardin, and P.T. Whiting, 1993.
  Resolution enhancement of spaceborne
  scatterometer data, IEEE Trans. Geosci. Rem.
  Sens., 31(3), 700-715.
• Long, D.G., and D.L. Dunn, 1998. Spatial
  resolution enhancement of SSM/I data, IEEE Trans.
  Geosci. Rem. Sens., 36(2), 407-417.
• Meier, W.N., and T. Vermeychuk, 2003. Sea ice
  motions from microwave imagery, Amer. Meteorol.
  Soc. 7th Conf. on Polar Meteorol. and Oceanogr.,
  Hyannis, MA, 12-16 May.
• Meier, W.N., 2005. Comparison of passive
  microwave concentration algorithm retrievals with
  AVHRR imagery in Arctic peripheral seas, IEEE
  Trans. Geosci. Rem. Sens., 43(6), 1324-1337.
• Remund, Q.P., and D.G. Long, 1999. Sea ice
  extent mapping using Ku band scatterometer data,
  J. Geophys. Res., 104(C5), 11,515-11,527.
• Stroeve, J., S. Drobot, S. Gearheard, T. Scambos,
  M. Serreze, J. Maslanik, W. Meier, M. Holland,
  2008. Arctic sea ice plummets in 2007, Eos
  Trans. AGU, 89(2), 13, doi 10.1029/2008EO020001.