biomass

TO OBSERVE FOREST BIOMASS FOR A BETTER UNDERSTANDING OF THE CARBON CYCLE

BIOMASS Mission Assessment Group Heiko Balzter Thuy Le Toan (Chair)

University of Leicester, UK Centre d’Etudes Spatiale de la Biosphère, Toulouse, F Philippe Paillou University of Bordeaux, Floirac, F Kostas Papathanassiou German Aerospace Center, Wessling, D Stephen Plummer IGBP, Frascati, I Shaun Quegan University of Sheffield, UK Fabio Rocca Politecnico di Milano, I Lars Ulander FOI, Linköping, S Hank Shugart University of Virginia, Charlottesville, USA Sassan Saatchi Jet Propulsion Laboratory, Pasadena, USA Science Coordinator: Malcolm Davidson Technical Coordinators: Alan Thompson, Chung-Chi Lin

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Global atmospheric CO2 fluxes 9

Carbon flux (Gt C / Yr)

8

Fossil fuel emissions Change in atmospheric CO2

7 6 5 4 3 2 1 0 1950

1960

1970

1980

1990

2000

Year

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Global atmospheric CO2 fluxes 9

Carbon flux (Gt C / Yr)

8

Fossil fuel emissions Change in atmospheric CO2

7 6 5 4 3 2 1 0 1950

1960

1970

1980

1990

2000

Year

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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BIOMASS Primary science objectives Objective

Product

Greatly improve current estimates of forest carbon stocks

Consistent global maps of forest biomass and height at scale of 100 m

Reduce uncertainty in deforestation emissions to a level comparable to uncertainty in net ocean flux

Map annual reductions in biomass globally

Improve estimates of terrestrial carbon sinks from regrowth and reforestation

Map increases in biomass globally across mission lifetime

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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The global carbon cycle for the 1990s Estimates of total biomass vary from 39 to 93 GtC

Addressed by BIOMASS Values from IPCC 2007. Units: Gigatons of carbon/ yr User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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The mean global carbon cycle for the 1990s 9 8 7

High

High

Land use change flux

Residual land sink

Low Low

GtC/year

6 5 4 3

Fossil fuel emissions

2

Net ocean sink

Atmospheric increase

1

Anthropogenic Sources

Changes in C pools

User Consultation Consultation Meeting, Meeting, Lisbon, Lisbon, Portugal, Portugal, 20-21 20-21 January January 2009 2009 User

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The importance of forest biomass in the carbon cycle • Biomass is a proxy for carbon (Carbon ~ 0.5 x Biomass) • Forests account for most of the Earth’s vegetation biomass • Changes in forest biomass with time correspond to carbon fluxes – Loss = Emissions – Growth = Uptake

• Forest biomass is very poorly known and is a major source of uncertainty in carbon flux estimation Biomass = dry weight of woody matter + leaves (tons/ha) User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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International context and users • GCOS/IPCC – Biomass is an Essential Climate Variable within the Global Climate Observing System

• UNFCCC – Post-2012 Kyoto Protocol: sources and sinks due to Land Use, Land Use Change and Forestry – Reduction of Emissions from Deforestation and Forest Degradation (REDD)

• UN Food and Agriculture Organisation – Global Forest Resources Assessments

• UN Convention on Biological Diversity • ESA Living Planet Strategy – BIOMASS addresses all four land challenges

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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What is known about forest biomass at global scale? • UN Global Forest Resources Assessment – Main source of information on global forest carbon stocks – Issued every 5 years – Based on national statistics – 1 value of biomass per country

• FRA limitations – – – – –

No spatial distribution of biomass Inconsistent Incomplete (missing countries) Biased No error reporting

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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What is known about biomass at regional scales? Model + Satellite Interpolation Model

Land cover map

Interpolation44

Brown

Defries

Brown and Lugo

Olson

Potter

Fearnside

Carbon (tC/ha)

Estimates of total biomass vary from 39 to 93 GtC

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

150 tons/ha)

•

RMSE = 1.37 dB r2 = 0.82

Boreal Forest Temperate Forest Tropical Forest 0

100

200

300

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Sensitivity of P-band SAR to disturbance and regrowth Polarimetric P-band SAR image of Yellowstone Park (2003)

A week after burn P-HV = - 27 dB

60-80 years after burn P-HV = - 12 dB

15 years after burn P-HV = - 19 dB

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Estimated biomass (t/ha) Retrievedbiomass (ton/ha)

Forest biomass retrieval at P-band 150

Les Landes

250

RMSE = 9.46 t/ha

200

In situ biomass (t/ha)

Estimated biomass (t/ha) Estimated biomass (ton/ha)

150

`300

100

Biomass (t/ha)

0In-situ stand biomass (ton/ha) 150

50

RMSE = 47.2 t/ha

0

`300

In situ biomass (ton/ha) (t/ha) In situ biomass

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

Remningstorp

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Improving retrieval using polarisation & height Biomass (t/ha)

Polarised intensities only

250

200

Intensity retrieval

150 100

RMSE= 35.6 t/ha

50

Intensity + height

Height (m) 40

30

Height retrieval

20

10

RMSE= 16.3 t/ha

0m

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Height from Polarimetric SAR Interferometry S1

S2 50

25

0m

Amplitude Image L- HH

Volume Coherence

Forest Height Map

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Why P-band for forest height? Scatterer motion causes biases in height estimates from Pol-InSAR

30-day repeat

1cm Height Error 50m

3cm

5cm

C

L

25m P P

0m

26-day coherence User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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P-band forest height retrieval – tropical forest • Height measurement has been demonstrated at P-band during the ESA INDREX-II airborne campaign in Indonesia • Height retrieval was validated with independent lidar height measurements Mawas, Indonesia

50 40 30 20 10 0m

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Product Specification BIOMASS is designed with the following goals: Level-2 Product

Properties

Forest biomass

< 20% error; 100m - 200m resolution; 2 maps/year; global forest coverage

Forest biomass change

< 20% error;100 - 200m resolution; annual; global forest coverage

Forest disturbance

Disturbance maps: 90% accuracy; 50m resolution (major disturbances); 200m resolution (partial disturbances);1 per 2 months or seasonal; global forest coverage

Forest height

< 20-30% error; 100x100m resolution; 1 map/year; global forest coverage

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Mission performance: Speckle • Study of biomass retrieval performance based on: – Global functional relationship between radar backscatter and forest biomass – Pol-InSAR height inversion – Uncertainties (radar backscatter, height estimate) – Bayesian inversion

• Results indicate that accuracy goal of 20% can be achieved

HV polarisation

HV, HH & Height

128 256

20% accuracy goal

512

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Mission performance: Ionospheric effects Scintillation

Faraday Rotation

Rotation of the polarisation plane: FR can be corrected to better than 1º by well-known methods using polarimetric data. In the process, Total Electron Content is measured.

Scintillations can cause defocusing. Autofocus correction has already been demonstrated in the equatorial case. Full processing methodologies will be developed in Phase A.

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Data utilisation concept

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Data utilisation – carbon emission calculation Current basic concept for exploiting biomass in carbon emission calculations: Cem = Deforested area x “average” biomass (UNFCCC Good Practice Guide 2003) BIOMASS concept: Cem = Σi ∆Bi Key additional point: Biomass changes slowly in undisturbed forest. Hence the biomass values derived by BIOMASS can be applied long after the end of the mission. BIOMASS measurements will have a long legacy.

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Data utilisation – carbon cycle data assimilation Geo-referenced Geo-referenced emissions emissionsinventories inventories

Climate and weather fields

Ocean time series Biogeochemical pCO2 Surface observation pCO2 nutrients Water column inventories

Atmospheric Atmospheric measurements measurements

Remote Remote sensing sensing of of atmospheric atmospheric CO CO22

Atmospheric Atmospheric Transport Transport Model Model

Ocean Ocean Carbon Carbon Model Model Coastal Coastal studies studies

Optimised Optimised fluxes fluxes

Terrestrial Terrestrial Carbon Carbon Model Model rivers Lateral fluxes

Integrated Data Global Carbon assimilation Observation System link (Ciais et al 2003) Optimised Optimised model model parameters parameters

Eddy-covariance flux towers Biomass soil carbon inventories Ecological studies

Ocean remote sensing Ocean colour Altimetry Winds SST SSS

Remote sensing of vegetation properties Growth cycle Fires Biomass Radiation Land cover/use

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Links to other missions

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Mission architecture overview GROUND SEGMENT

CO2

C

SUBJECT Terrestrial carbon stock/carbon fluxes by measurement of forest biomass

Flight Operations Segment 1 TT&C Station (Kiruna), S-Band Flight Operation Control Center (ESOC)

Payload Data Ground Segment 1 Science Data Acquisition Station (Svalbard) Processing and Archiving Element (ESRIN)

Auxiliary Data Land cover maps Digital Elevation Models USER SEGMENT Carbon cycle modellers/Research Centres

BIOMASS Mission Elements

LAUNCHER Soyuz/Vega

SPACE SEGMENT Single Spacecraft, 1200 - 2600 kg, 800 - 1200W Payload: P-band SAR 5 year lifetime

ORBIT Sun-synchronous, local time 05:00, 640 km, 27 to 39-day repeat cycle

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Orbit Determining factors • 25 to 45 day revisit • Global forest coverage • SAR swath width & radiometric performance • Minimise ionospheric disturbance • Avoid excessive air drag • Interferometric baseline

Example coverage after 13 days

• Sun-synchronous dawn-dusk orbit • local time ~ 05:00 • altitude ~ 640 km Example coverage after 27 days User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Orbit – interferometric baseline Selection of “controlled drift” orbit (non-exact repeat)

Orbit i Cycle n

Orbit height h

Orbit drift

Ground track i Cycle n Ground track i Cycle n+1

ϑ

Orbit i Cycle n+1

Baseline B (exaggerated)

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Observation geometry Reflector SAR antenna

Orbit

Elongated SAR antenna Sub-satellite track

≥ 25° Nadir point

Nadir point

Antenna footprints

Sub-swath 1 Sub-swath 2 Antenna footprint

Stripmap swath

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Instrument – Concept 1 • Planar array on Snapdragon platform • Four passive antenna panels folded around three hinges (77.6 m2 aperture) • 10 sub-arrays per panel • 18 Solid State Power Amplifiers distributed behind the inner panels • 320 W total peak RF-power • 102 km polarimetric swath

2.82m 27.5m User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Instrument – Concept 2 • Planar array on conventional platform • Central panel attached to the platform with two wings of four deployable, selfsupporting panels (65.9 m2 aperture) • Six solid state power amplifiers feeding six elevation rows of radiators Upper metallisation (CFRP)

Annular slot Feed-lines

• 300 W total peak RF-power • 70 km polarimetric swath

Dielectric honeycomb

Adhesive layers

Dielectric honeycomb

Ground plane (CFRP)

20.16 m 3.36 m

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Instrument – Concept 3 • Deployable reflector on conventional platform (14.7 m x 9.6 m aperture) • 4 x 2 elements array-feed with beam-switching • Four Solid State Power Amplifiers feeding four elevation pairs of radiators • 300 W total peak RF-power • 2 x 60 km polarimetric swaths (dual-beam)

Array-feed with 4 pairs of patch radiators in elevation

Engineering Qualification Model of 12 m diameter reflector User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Instrument block diagram Central electronics

SSPA

Signal Generation & Upconversion

USO

Power divider

Down & A/D conversion H

Bus power

Instrument power unit

V H

Switching network

LO V

Data

V H

V

V

H

H

Power combiner

Circulator & signal routing unit

Passive V Antenna

H

Power combiner Instrument control unit

Low noise amplifiers

Telemetry and Telecommand User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Satellite configurations 9.6 m

Concept 1 14.7 m

Concept 3 27.5 m 20.2 m

Concept 2 2.8 m

3.4 m Mass Data storage

1200-2600 kg 400-700 Gb

Power Data Downlink

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

800-1200 W 260-290 Mb/s

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Stowed configurations in launcher fairings

Concept 1 in Soyuz

Concept 2 in Soyuz Concept 3 in Vega

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Ground Segment

• Re-use of existing ESA Multi-Mission infrastructure • Single station (Svalbard or Kiruna) for reception of scientific data • Provision for auxiliary data

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Performance summary 1/2

Compliant with science requirements User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Performance summary 2/2

Threshold

Goal

MEETS REQUIREMENT

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Programmatics 1/2 • Satellite development – Concept 1 benefits from TerraSAR-L heritage – Concept 2 is based on a conventional platform and benefits from Radarsat-2, Cosmo/Skymed and Sentinel-1 heritage – Concept 3 is based on a conventional platform; further work in Phase A to confirm accommodation in Vega

• Antenna and accommodation – All concepts have a simple passive structure – Feasibility of large deployable planar array antennas is addressed through ESA technology programmes – An Engineering Model, relevant to Concept 3, has been developed for a telecommunications programme – Breadboarding of a P-band feed-array is in progress

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Programmatics 2/2 • Radar electronics – All elements of the radar electronics are based on mature technology – A P-band Solid State Power Amplifier assessment study was initiated in spring 2008

• End-to-end calibration – Instrument calibration benefits from heritage in several SAR missions – Ionospheric correction algorithms exist and their detailed performance will be assessed in Phase A

• Development schedule – Final choice of the antenna concept will determine the payload development approach

Provided a suitable pre-development programme is started in Phase A, payload and satellite development is considered feasible for launch during 2016. User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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Conclusions • BIOMASS addresses major uncertainties in the global carbon cycle. It will: – Greatly improve current estimates of forest carbon stocks – Reduce uncertainty in deforestation emissions to a level comparable to the uncertainty in net ocean flux – Improve estimates of terrestrial carbon sinks from regrowth and reforestation uptake

• The global multi-temporal datasets it provides have long-term scientific, environmental and societal importance • The BIOMASS measurement concept has been extensively demonstrated by airborne campaigns. • First opportunity to explore the Earth’s surface at P-Band • Selection to one mission in 2011- Earliest possible launch in 2016

User Consultation Meeting, Lisbon, Portugal, 20-21 January 2009

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