Polar Space Task Group 2017 Meeting CNES … · PF ~ Proteus SAR/SARin configuration compared for...
Transcript of Polar Space Task Group 2017 Meeting CNES … · PF ~ Proteus SAR/SARin configuration compared for...
Polar Space Task Group 2017 Meeting
CNES contribution to polar activities
Anne Lifermann CNES/DIA/TEC
Outline
YOPP, MOSAIC
PSTG glaciers
� Pleiades Glacier Observatory
In-situ observations
Technology advancement
� Alti-Cryo phase 0 study
� Future missions CFOSAT, SKIM
Algorithm development
� Contribution to Radar/Altimetry missions
� Arctic sea ice thickness and snow retrieval
� Snow
CNES Contribution to polar activities
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On behaf of CNES and scientificteams
CNES Contributions to polar science studies
- LEGOS : sea ice, Antarctica
- LOPS : Altiberg, SARice
- LOCEAN : IAOOS, Seals
- TAKUVIK, LOV : Greenedge
- CESBIO, CNRM, IGE : snow
Pléiades Glacier Observatory PGO
Berthier E., Fontannaz D., Hosford S., Lifermann A., Zemp M.
PGO In a few words:
• Facilitate access to Pléiades satellite stereo-imagery and
DEMs for glaciologists
• Acquire imagery at the right time of the year (i.e.,
generally, end of the melt season)
• PGO stereo images are freely available to all science
users, on the condition that they sign an agreement
with CNES.
• Raw stereo-data are provided. Possibility to get a DEM +
ortho-image (generation @LEGOS using Ames Stereo
Pipeline)
• Three acquisition campaigns nearly completed: Aug-Oct
2016 & 2017 (NH) and Feb-April 2017 (SH). Highly
• Sites selected in coordination with WGMS:
initial goals are to use these data to (i)
provide a DEM/image of benchmark glaciers
and (ii) help to assess the regional
representativeness of the glaciers monitored
in the field.
• ∼20 sites/year, > 80 sites, 5 yrs repeat
• One contact scientist for each site to define
the acquisition parameters and validate the
images when acquired.
AltiCryo : a CNES altimetry concept dedicated to cryosphere
Phase 0 study > to propose an altimetry concept opt imized for cryosphere (sea ice and ice sheets) and based on the SARAL/AltiKa herita ge (Ka-band, 1 antenna).
� Users needs ( and the whole European community) collected with
� Instrument design performed by TAS-F
� Ka/Ku altimeter in SAR mode
� K/Ka radiometer
� PF ~ Proteus
� SAR/SARin configuration compared for range estimation over ice performance by CLS
� On-going (will end this December)
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Technology advancement – PSTG 2017
Analysis of Ku / Ka information content
Technology advancement – PSTG 2017
10Rémy et al, CNES/ESA User workhop, Paris 02/2017
In SAR mode, volume appears,mostly inthe trailing edge part
Ku
Ka
Comparison between Ku and Ka band over the Antarctica icesheet
Rémy et al, 2015, Verron et al, 2015, 2018
Ku (Envisat) Penetration depth 4-5 m Temporal variab explained by surface
Ka Band (AltiKa) Penetration depth 0.5 to 1 m Temporal variab explained by both surface and volume
SAR for Ka/
LRM for Ku
> different
information
> possibility to
invert volume
parameters
> extend
previous Ku
series
> modelise the
volume echo to
correct for
China France Oceanography SATelliteA new satellite for the observation of wind and waves
© CNES/Emmanuel GRIMAULT, 2017
Launch October 2018
Future missions – PSTG 2017
Two Ku radar payloads on CFOSAT
SWIM: the first spaceborne wave scatterometer
� 6 incidence angles: 0°, 2°, 4°, 6°, 8°, 10°
� Rotating antenna: 5,6 rpm
� Ku band
� Minimum detectable wavelength of about 70 m, maximum detectable wavelength about 500 m.
� Accuracy in wave propagation direction of about 15°
� Accuracy in wavelength of 10% to 20%.
� Accuracy on wind speed estimates of ±2 m/s or 10%
SCAT: a wind scatterometer
� Fan beam concept
� Large swath
� Rotating antenna: 3 rpm
� Incidences between 26° and ~50°
� Ku band
SWIM
SCAT
CFOSAT assets for ice studies
� Polar orbit
� Daily revisit of polar areas 97,5° inclination/83° obs
� 3 days global coverage
� Available data:
� Large range of incidence angles (0° to 50° with small gaps)
� Full azimuth scanning
� Calibrated radar waveforms
� Applications
� Improvement of σ0 models and physics understanding
� Better characterization of ice/snow properties
� Synergy with altimeters (Sentinel-3, Cryosat-2 and AltiKa)
� Impact of waves on the ice sheet
1 day of CFOSAT orbits over Antarctica
Future mission – PSTG 2017
SKIM
Future missions – PSTG 2017
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SKIM combines
- A nadir looking altimeter (Ka-band, 32 Khz PRF, 200 MHz bandwidth, SAR LRM)→ very low noise for sea level, wave height, ice freeboard
- A novel wave + current spectrometer: 5 to 7 rotating beams @ 6° and 12° incidence → measurement of full wave spectrum L > 20 m, 5° resn + Stokes drift, current & wind vectors
→ heritage of SWIM on CFOSAT, translated to Ka (HPA from SWOT) + Doppler
Instrument : < 130 kg , 414 WData rate: 15 Mbits/s5 to 7 year lifetime duration F. Ardhuin, et al., 2017
doi : 10.5194/os-2017-65/
CNES studies focused on cryosphere
Algorithm development @ CNES – PSTG 2017
Sea ice
� AltiKa and Sentinel3 freeboard (data to be released in 2018)
� SAR imagery/altimetry comparison for lead detection (ESTEC contract)
Land ice
� SAR mode altimeter performances over ice sheet
� New method for DEM estimation over Antarctica
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First continuous Arctic Sea Ice Thickness (SIT)from space record for 2002-2017
• A first continuous record of the Arctic SIT up to 81.5°N for 2002-2017 has been published this year
• Extensions to the past (from 1995 using ERS2) and to the future (S3A, S3B, …) are expected soon
Such product can strongly improve:• sea ice model (such as PIOMAS above)• cold oceans circulation models, • global climatic models, • water mass for sea level studies, …
FB
Sea-Ice
ranges
Water (lead, polynya)
SIT
References: [Kwok-2009, Laxon-2013, Ricker-2014, Tilling-2015, Guerreiro-2017]Projects: SI-CCI, ESA CryoSeaNice, ESA Arctic+, CNES SICKAyS/Sea Change, OIB, CryoVex…
> urgent need for topographic data continuity over the poles
Algorithm development @ LEGOS – PSTG 2017
Envisat SIT 03/2011 CryoSat SIT 03/2011
Snow depth is a critical parameter for the sea ice community:• Snow depth uncertainties can induce 100% error on SIT retrieval• Because of its insulation properties snow depth is a key parameter for ice
growth in sea ice models.• Snow absorbs the solar radiation and limits the photosynthesis below the
ice.
Cor
rect
ed W
arre
n99
clim
atol
ogy
Sno
w D
epth
Alti
Sno
w D
epth
OIB airborne snow radar SD
ΔRanges≈ SD
Range Ku Range Ka
Snow
Sea Ice
Water
Cryosat-2 Saral/AltiKa
Alti Snow Depth April 2014
References: [Guerreiro-2016, Armitage-2016]Projects: airborne Ka/Ku within CryoVex/Karen2017
campaign, SI-CCI, Clic, ESA CryoSeaNice, ESA Arctic+, CNES SICKAyS, OIB, …
CM
IP5
CN
RM
dy
nam
ic m
odel
OIB airborne snow radar SD
OIB airborne snow radar SD
First Arctic Snow Depth (SD) from space over sea ice
> urgent need for dual-frequency polar topographic satellite mission
Algorithm development @ LEGOS – PSTG 2017
ALTIBERG Project
• Detection and analysis of icebergs (0.01 to 9 km²) usingaltimeter waveforms data in the Southern Ocean.
• 9 Altimeters processed from 1992 to 2017• Level 1 product
• Individual icebergs location time and area
• Level 2
� Monthly gridded fields on regular polar or lat/lon grid
� Probability of presence of icebergs
� Mean area of icebergs
� Volume of ice
� Product by satellite and merged
• Distributed by CERSAT http://cersat.ifremer.fr/data/products/catalogue
(ALTIBERG) Ref J.Tournadre et al
Algorithm development @ LOPS – PSTG 2017
SNOW
Algorithm development for SNOW – PSTG 2017
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• Snow products from Sentinel2 @Theia thematic center
> http://theia.cnes.fr
• Kalideos Alps https://alpes.kalideos.fr
� F. Karbou & M. Dumont (CNRM/CEN); C. Proy & A. Sellé (CNES)
� Data base over the French Alps : PLEIADES (50cm), SPOT-6 (1.5m), SPOT-7 (1.5m), SENTINEL-2 (10m, 20m, 60m) SAR SENTINEL-1 (20m), ALOS-2 (3m, 6m, 10m) , TERRASAR-X (25cm, 3m, 19m)
• Grenoble snow communityhttp://www.osug.fr/la-recherche/ateliers-transversaux/neige/
� Ghislain Picard (IGE), Vincent Vionnet (CEN), Florence Naaim (IRSTEA)
• Pyrenees Climate Change Observatory CLIM'PY
CESBIO contributes to the Pyrenees Climate Change Observatory through the analysis of the snow cover evolution using satellite imagery
� Daily cloud-free maps of the snow cover area in the Pyrenees at 500 m resolution since 2000 from; MODIS
� Maps of the snow cover area in the Pyrenees at 20 m and 30 m resolution since 2013 from Sentinel-2 and Landsat-8
� Maps of the annual peak snow depth in the Bassiès-Vicdessos region at 4 m resolution since 2015 (one map per year) from Pléiades stereo imagery
[email protected]@cnes.fr
Pléiades
TANDEM X MNT