Global Vegetation Monitoring Unit

GLC 2000 Project

Results from Southeast Asia

Stibig H-J., Upik R.W., Beuchle R., Mubareka, S., Hildanus, Giri C.

Global Vegetation Monitoring Unit

Southeast Asia

Continental Southeast Asia: Monsoon ClimateWet Season: May – NovemberDry Season: December – AprilVariable conidtions over Vietnam

Mix of evergreen and seasonal / dry vegetationReasonably cloud-free images : end Dec – middle of March

Insular Southeast Asia: Moist tropical climate all year: short ‘less humid’ periods (hemisphere, spec. island, spec. loc.)

Evergreen vegetationNo cloud & haze free images all year

Global Vegetation Monitoring Unit

Example for good quality 10 - day mosaic: February 1999

Global Vegetation Monitoring Unit

Example: Typical 10 - day mosaic from May 2000

Global Vegetation Monitoring Unit

Main challenges for mosaic generation and mapping

Continental Southeast Asia– obtain good differentiation between seasonal and

evergreen vegetation formations– to cope with the mixed pattern of cropland, shrub, re-

growth, & forest (active and abandoned shifting cultivation)

– get sufficient haze and cloud free data over Vietnam

Insular Southeast Asia– cope with persistent haze and cloud cover

Global Vegetation Monitoring Unit

Test with S1 Data from the year 2000 (S. Mubareka)

Continental SE-Asia: S1-images for Jan-Feb 2000 Insular SE-Asia: S1-Images full year 2000

• SWIR line error mask• Cloud mask threshold: blue < 720; SWIR < 320• Filter for angle Φ<45º and hot spots (Φ,φ)• Water mask

Mosaic GenerationSelecting from the top15 percent of NDVI values

Minimum value in the red channel

Global Vegetation Monitoring Unit

Test with S1 data from 2000 (S. Mubareka)

acceptable result – more images to be included - remaining holes and mosaic effects - separation evergreen / deciduous limited - low quality over parts of Vietnam

insufficient for removal of cloud & haze

Contin. Se-Asia: Jan-Feb 2000 Insular SE-Asia: Year 2000

Global Vegetation Monitoring Unit

Mosaic generation from S10 data: year 1998 to early 2000

Cont. SE-Asia: S10 composites of dry seasons 1999 & 2000 (Jan-Mar) Ins. SE-Asia: S10 composites Mar-Nov 1998-1999, Jan-Mar 2000

•Threshold for SWIR line errors (>5% in the SWIR band)

•Cloud-haze threshold ( <10% in the blue band)

•Cloud-shadow masks by unsupervised classification

Mosaic Generation in 2 Steps: Monthly Mosaics: Pixel selection by minimum in SWIR

(good contrast for forest, reduction of atmospheric & angular effects, line errors)

Annual Mosaics: Pixel selection by minimum in NIR (further enhancement of contrast between evergreen and deciduous vegetation)

Global Vegetation Monitoring Unit

Mosaic detail: Continental SE-Asia

Global Vegetation Monitoring Unit

Mosaic detail: Insular SE-Asia

Global Vegetation Monitoring Unit

Mapping Approach for SE-Asia

Unsupervised clustering and maximum likelihood classification70 clusters cont. SEA, 60 clusters ins SEA

Cluster labeling and grouping to land cover classessupported by interpretation from available TM scenes, maps, field records

– Specific for continental SE-Asia:• Splitting up of clusters for different bioclimatic zones • Correction of errors for selected AOIs

– Specific for Ins. SE-Asia:• mapping of formerly burnt areas and of irrigated cropland

supported by a rough stratification of vegetation and non-vegetation from the S1 Mosaic

Global Vegetation Monitoring Unit

GLC2000 Map Continental SE-Asia

Evergreen forest

Shifting cultivation mosaics

Deciduous forest & woodland

Cropland inundated

Cropland

Evergreen forest

Deciduous forest & woodland

Global Vegetation Monitoring Unit

GLC2000 Map Insular SE-Asia

Evergreen forest

Shrub & re-growth, burnt 1997/98

Mix of thickets, shrubs, perennial cropland (oil palm, rubber plantations)

Cropland annual

Global Vegetation Monitoring Unit

Legend SE-Asia • transitions to shrubs• differentiation closed –

open not possible

• includes cropland mosaics • other land cover components partly

unknown

Natural Vegetation / Cropland

& shifting cultivation ]

• incl. degraded forests, shrub cover

Global Vegetation Monitoring Unit

Map comparison for the Lower Mekong Basin

MRC Map from interpretation of 1997 TM Scenes GLC2000

Global Vegetation Monitoring Unit

Forest Cover Map of Peninsular Malaysia

National Forest Inventory Map 92 GLC2000 Map

Global Vegetation Monitoring Unit

The End…