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On the use of observations from the Aquarius/SAC-D mission to study the cryosphere Emmanuel Dinnat 1,2 and Ludovic Brucker 1,3 1. Cryospheric Sciences.

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Presentation on theme: "On the use of observations from the Aquarius/SAC-D mission to study the cryosphere Emmanuel Dinnat 1,2 and Ludovic Brucker 1,3 1. Cryospheric Sciences."— Presentation transcript:

1 On the use of observations from the Aquarius/SAC-D mission to study the cryosphere Emmanuel Dinnat 1,2 and Ludovic Brucker 1,3 1. Cryospheric Sciences Laboratory, NASA GSFC, Greenbelt, MD, USA 2. Chapman University, Center of Excellence in Earth Systems Modeling & Observations, Orange, CA, USA 3. Universities Space Research Association, GESTAR, Columbia, MD, USA

2 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Acknowledgement: Ludovic Brucker in a storm somewhere in Antarctica …

3 Analyze data spatial distribution Assess the observations' stability Contribute to define cal/val and intercalibration experiments 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A.  Create product adapted to high latitudes Use L-band observations to study the cryosphere. Motivations Aquarius Tb/NRCS available along track only

4 Presentation of the high latitude product Brightness temperatures over Greenland and Antarctica Radar measurements over Antarctica Ocean freshening and ice melt 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Outline

5 Input data sets:Aquarius Level 2 swath data (PO.DAAC, version 3.0) Spatial coverage:latitudes > 50° Temporal resolution:7 days Grid cell size:36 km × 36 km Grid:Equal-Area Scalable Earth (EASE2.0) (Brodzik et al., 2012)  constant resolution in polar regions  consistent with SMAP 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. New Aquarius weekly polar-gridded products

6 Input data sets:Aquarius Level 2 swath data (PO.DAAC, version 3.0) Spatial coverage:latitudes > 50° Temporal resolution:7 days Grid cell size:36 km × 36 km Grid:Equal-Area Scalable Earth (EASE2.0) (Brodzik et al., 2012)  constant resolution in polar regions  consistent with SMAP 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. New Aquarius weekly polar-gridded products #RFI ASCDSC

7 Input data sets:Aquarius Level 2 swath data (PO.DAAC, version 3.0) Spatial coverage:latitudes > 50° Temporal resolution:7 days Grid cell size:36 km × 36 km Grid:Equal-Area Scalable Earth (EASE2.0) (Brodzik et al., 2012)  constant resolution in polar regions  consistent with SMAP 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. New Aquarius weekly polar-gridded products #RFI ASCDSCLarge RFI reduction in 2014

8 Brightness temperature (TB) at V & H polarizations for radiometers 1, 2, and 3 (separately) for ascending orbits, descending orbits, and combined Normalized radar cross section (NRCS) at VV, VH, & HH polarizations for beams 1, 2, and 3 (separately) for ascending orbits and descending orbits separately Sea surface salinity (SSS) for radiometers 1, 2, 3, and all combined for ascending orbits, descending orbits, and combined  Weekly mean and stdev, number of observations, and ice fraction 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. New Aquarius weekly polar-gridded products

9 Brightness temperature (TB) at V & H polarizations for radiometers 1, 2, and 3 (separately) for ascending orbits, descending orbits, and combined Normalized radar cross section (NRCS) at VV, VH, & HH polarizations for beams 1, 2, and 3 (separately) for ascending orbits and descending orbits separately Sea surface salinity (SSS) for radiometers 1, 2, 3, and all combined for ascending orbits, descending orbits, and combined  Weekly mean and stdev, number of observations, and ice fraction 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. New Aquarius weekly polar-gridded products

10 Brightness temperature (TB) at V & H polarizations for radiometers 1, 2, and 3 (separately) for ascending orbits, descending orbits, and combined Normalized radar cross section (NRCS) at VV, VH, & HH polarizations for beams 1, 2, and 3 (separately) for ascending orbits and descending orbits separately Sea surface salinity (SSS) for radiometers 1, 2, 3, and all combined for ascending orbits, descending orbits, and combined  Weekly mean and stdev, number of observations, and ice fraction 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. New Aquarius weekly polar-gridded products

11 Brightness temperature (TB) at V & H polarizations for radiometers 1, 2, and 3 (separately) for ascending orbits, descending orbits, and combined Normalized radar cross section (NRCS) at VV, VH, & HH polarizations for beams 1, 2, and 3 (separately) for ascending orbits and descending orbits separately Sea surface salinity (SSS) for radiometers 1, 2, 3, and all combined for ascending orbits, descending orbits, and combined  Weekly mean and stdev, number of observations, and ice fraction 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. New Aquarius weekly polar-gridded products

12 Brightness temperature (TB) at V & H polarizations for radiometers 1, 2, and 3 (separately) for ascending orbits, descending orbits, and combined Normalized radar cross section (NRCS) at VV, VH, & HH polarizations for beams 1, 2, and 3 (separately) for ascending orbits and descending orbits separately Sea surface salinity (SSS) for radiometers 1, 2, 3, and all combined for ascending orbits, descending orbits, and combined  Weekly mean and stdev, number of observations, and ice fraction 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. New Aquarius weekly polar-gridded products

13 Brightness temperature (TB) at V & H polarizations for radiometers 1, 2, and 3 (separately) for ascending orbits, descending orbits, and combined Normalized radar cross section (NRCS) at VV, VH, & HH polarizations for beams 1, 2, and 3 (separately) for ascending orbits and descending orbits separately Sea surface salinity (SSS) for radiometers 1, 2, 3, and all combined for ascending orbits, descending orbits, and combined  Weekly mean and stdev, number of observations, and ice fraction 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. New Aquarius weekly polar-gridded products

14 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Radiometer #3 ~ 46°, V-pol Brightness Temperature, Greenland, 2013 JanMarch May JulySeptNov

15 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Radiometer #3 ~ 46°, V-pol Brightness Temperature, Greenland, 2013 JanMarch May JulySeptNov

16 L-band TB shows no seasonal/temperature variations, but summer variations due melt and refreeze. South Dome, Greenland, Tb time series 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A.

17 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Summit, Greenland, Tb time series

18 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Surface reflection is an important radiative transfer process even when the radiation has a large penetration depth In 2012, surface layer of refrozen snow => - 5 K Summit, Greenland, Tb time series

19 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Lower Tb inland (dry snow zone), higher Tb near coast, with maximum extent in January because of melt Brightness Temperature in Antarctica SeptNovJan July MayMarch

20 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Areas where melt events occurred since August 1, 2000 were masked. Standard deviation < 1 K. East Antarctica Annual mean and standard deviation TB (Beam 1)

21 Temperature below 15 m: ± 0.07 K (Brucker et al., 2011) Snow accumulation: 8-10 cm of snow (Urbini et al., 2008) 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Ideal site to study the relationship between microwave observations & ice properties Dome C, Antarctic Plateau (3240 m)

22 Fast variations = surface changes Dome C GHz TB time series Beam TB V (K) ± ± ± 0.28 Beam TB H (K) ± ± ± 0.72 Sensitivity ~ 0.2K 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A.

23 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. AMSU-B grain index derived from AMSU-B (Picard et al., 2012), GI = 1 - TB150/TB89 with shallow penetration (few cm) channels Satellite monitoring of the snow surface at Dome C

24 Aquarius radiometers have an excellent sensitivity (0.2 K) are thus appealing to study the ice sheets TB variability at H polarization is larger than at V polarization increases as incidence angle increases is larger than the sensors' sensitivity L-band radiation has a deep penetration but is sensitive to surface snow properties 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Brucker et al., 2014: Effect of Snow Surface Metamorphism on Aquarius L-Band Radiometer Observations at Dome C, Antarctica. IEEE TGRS 52(11): , doi: /TGRS Main conclusions for L-band radiometry of the cryosphere

25 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Antarctica Normalized radar cross section (NRCS, beam 3) Asc. Dsc. VVHHVH

26 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. NRCS over Antarctica Radarsat (RAMP) DEMDrainage system boundaries

27 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. NRCS over Antarctica Radarsat (RAMP) DEMDrainage system boundaries

28 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. No measurements currently characterize melt water flux Can Aquarius SSS retrievals be helpful? Aquarius observations to monitor Greenland ice sheet melt Greenland mass loss rate has increased significantly in last two decades (Sheppard et al., 2012)

29 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Impact of sea ice on SSS retrievals

30 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Impact of sea ice on SSS retrievals

31 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Studying freshening from ice sheet melt requires correction for sea ice  Sea ice emission model needed Impact of sea ice on SSS retrievals

32 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Tb is very sensitive to sea ice … Impact of sea ice on SSS retrievals

33 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. … and sea ice concentration is uncertain. Impact of sea ice on SSS retrievals Over-estimated sea ice concentration

34 3 weekly polar-gridded products are available with Aquarius: * Brightness temperature * Normalized radar cross section * Sea surface salinity 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Brucker, Dinnat and Koenig (2014), “Weekly gridded Aquarius L-band radiometer/scatterometer observations and salinity retrievals over the polar regions -- Part 1 & 2”, The Cryosphere. Relevant for studying: - ice sheets - sea ice - frozen soil - freshening Conclusion

35 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Sheppard et al. 2012

36 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. RFI over Greenland / North polar regions Ascending passesDescending passes

37 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. RFI over Greenland / North polar regions Ascending passesDescending passes

38 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Penetration Depth

39 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A.

40 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A.

41 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A. Hoar crystal on the surface

42 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A.

43 11/14/2014Dinnat and Brucker, Aquarius Science Team Meeting, Seattle, WA, U.S.A.


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