Polar Space Task Group 2017 Meeting CNES … · PF ~ Proteus SAR/SARin configuration compared for...

24
Polar Space Task Group 2017 Meeting CNES contribution to polar activities Anne Lifermann CNES/DIA/TEC

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

2

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

[email protected]

• 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.

PGO –

Summer 2016

northern

Hemisphere

Central Asia

North America

Europe

Central Asia

Andes and

Antarctic

Peninsula

PGO –

Summer 2017

Southern

Hemisphere

New Zealand

PGO –

Summer 2017

northern

Hemisphere

ALPS

Arctic

CAUCASUS & High

Mountain Asia

DEM of Elbrus, september 2017

Example of first results: ©D. Burgess

Natural Resources Canada

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)

9

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

CNES support to science studies

11

CNES support to insitu measurements by LOPS

12

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

16

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/

SKIM

Future missions – PSTG 2017

17

Algorithm development @ LOPS – PSTG 2017

18

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

19

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

23

• 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

24

Greenland, Olsen Ice CapPléiades stereo acquisition – 22 July 2017

Thank you for your attention!