Global land cover validation activities

Martin Herold (FSU Jena) & Mark Friedl (UBoston)

www.fao.org/gtos/gofc-goldwww.gofc-gold.uni-jena.de Global Observations of Forest Cover and Land Dynamics

With contributions from Curtis Woodcock (UBoston), Olivier Arino (ESA), Steve Stehman (SUNY)

CEOS WGCV LPV Focus Group Lead Meeting, Missoula, Montana, June 15, 2009

Overview1. Political initiatives driving observation

progress and needs for validation– Observing land cover as ECV

2. Global land cover observations and accuracy assessments– MODIS and GLOBCOVER

– Best use of existing reference datasets

3. Coordinated effort to develop LC validation database

4. Accuracy assessment for fine-scale land cover change and area estimates– Post-Kyoto agreement and best practices

International drivers

1. United Framework Convention on Climate Change:– Reduce uncertainties in monitoring the global climate

system through observing essential climate variables– Capacity building needs to address stronger role of

developing countries in post-2012 agreement• Major REDD readiness funds are currently being allocated

2. Group on Earth Observation (GEO) task DA-07-02:– Provide a suite of global land cover datasets, initially based

on improved and validated moderate resolution land cover maps and eventually including land-cover change at high resolution (task co-lead by USGS and GOFC-GOLD)

3. Global land cover monitoring and assessments:– GLOBCOVER, FAO-Forest Resources Assessm. 2010– Operational validation / Efforts for deriving “Best map”

Observing land cover as ECV

www.fao.org/gtos/

International consensus on technical issues

“Best Practices Document”

Strahler et al., 2006

GLOBCOVER (2005/6)

Dataset release: September 2008

GLOBCOVER validation

10

More than 4300 validation points interpreted by int. expertsBlue points: Globcover project (3835 points) + Gond’s set (n~80)

(including 225 double interpretation by 2 experts)Brown points: IMWI data (403 points)Global area weighted accuracy: ~73 % based on 3167 reference pointsValidation report available ~ 15. October 2008

MODIS Collection 5 Land Cover (2001-present)

MODIS Land Cover Validation1860 Training Sites – Cross Validation

Thematic standards Reference database (GLC2000)

Comparative validation & assessment

Thematic standards Reference database (GLC2000)

Comparative validation & assessment

Probability

Overview

1. Political initiatives driving observation progress and needs for validation

2. Global land cover observations and accuracy assessments

3. Coordinated effort to develop LC validation database (Curtis Woodcock)

4. Accuracy assessment for fine-scale land cover change and area estimates

Overview

1. As the land cover community matures, an increasing emphasis on validation and accuracy assessment - a difficult, somewhat unpleasant and somewhat surprisingly expensive activity

2. The GOFC-GOLD LC IT has decided to try to support the broader community through validation

3. Idea is to collect ground reference data independent of any single land cover product to support validation of many land cover datasets

4. Intent is to supplement and complement ongoing validation activities associated with individual land cover datasets

Operational lc validation framework

Degre

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Updated valid./change

Validation of new products

Design based sample of reference

sites

In-s

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Primary validation

LCCS-based Interpretation(Regional Networks)

Reference database:statistically robust, consistent, harmonized, updated, and accessible

Updated interpretations

Time

Comparative validation

Existing global

LC products

Legend

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Productsynergy

Data reprocessing

Link to regional datasets

Operational lc validation framework

• Effort serves purpose for estimating:– Individual map accuracy / best available map– Area of land-cover classes or land-cover change

• Sampling design: – 10 km by 10 km block (Landsat – MODIS)– Flexible to increase sample size to provide precise country

or region specific estimates– Stratification by geographic reporting regions, areas where

maps differ, important rare land-cover classes• Response design:

– Reference data (i.e. SPOT) interpreted by regional experts (i.e. GOFC-GOLD networks) using LCCS classifiers

• Analysis design:– Error matrix for each map and region– Estimates of class area – Supplementary accuracy information on land-cover

composition and landscape pattern

Project Overview (Woodcock Lead)

• Randomized stratified sampling• Primary sampling units by blocks of 10 × 10 km• World divided into seven continents• Strata based on Köppen’s climate zones together with

population density• Strata independant of the land cover products• Currently about 70 samples per continent planned• Validation workshops planned – VHR satellite data (source

not determined) interpreted by local experts• Landsat data will be used to monitor change at sample sites• First workshop will be held in Almaty, Kazakhstan in

September 2009

Stratification and Sample DesignSeven Continents:

North Am./South Am./Europe/Africa/Former USSR/South Asia/Oceania

Current Status –

Early Stages of Stratification and Sample DesignWorkshop tentatively planned for late July in Boston

Observing land cover as ECV

Towards standardization of satellite derived products:1.Coordinated observations2.Integrated and standardized mapping and monitoring3.Independent quality assessment

Overview

1. Political initiatives driving observation progress and needs for validation

2. Global land cover observations and accuracy assessments

3. Coordinated effort to develop LC validation database

4. Accuracy assessment for fine-scale land cover change and area estimates

Fine-scale land cover change

• Suite of national / regional experiences:– National/regional monitoring programs– UNFCCC Kyoto reporting on LULUCF/AFOLU

• UNFCCC process on reducing emissions from deforestation in developing countries:– case studies, readiness activities, post 2012

• Projects with global/large scale focus:– EU/JRC: TREES 3 (sampling approach)– UMD/SDSU: combined MODIS/Landsat approach

• FAO-Forest Resources Assessment 2010• Accuracy assessment of area changes?

FAO FRA 2010 –remote sensing survey

~ 13,500 monitoring

sites

Accuracy assessment of area change estimates

Uncertainties should be quantified and reduced as far as practicable (IPCC reporting guidelines, LULUCF)

Need for standard/best practice methods (CEOS/GOFC-GOLD)

Capacity development in developing countries:• Robust validation may not be achievable or practicable i.e.

monitoring historical land changes in developing countries• Good practice recommendation if no thorough accuracy

assessment is possible or practicable: apply the best suitable mapping method in a transparent

manner consistency assessment allow some estimation of the

quality

Principle of conservativeness: • estimates (i.e. C-emissions) should not be overestimated• assumes reward for more robust and accurate monitoring

system

GOFC-GOLD REDD sourcebook: www.gofc-gold.uni-jena.de/redd/

Final remarks

• Deforestation and land change prominent on the political agenda and driving observation progress:

• Reducing uncertainties in observing the global climate system

• National capacity development (i.e. climate change mitigation)

• Key issues for land cover validation:• Need for continuous and consistent baseline

observations• Move towards operational global system (framework

exists)• Efforts for “best available” land cover map• Best practices and good practices for accuracy

assessment of land cover change and area estimates• Communication with political/policy level (GEO,

UNFCCC)• Key role for CEOS WGCV for evolving ECV monitoring• Sustained support for validation activities