Forest Canopy FPAR Measurements for MODIS Validation in Zambia

Three parallel 750-meter transects in a Zambian forest were sampled monthly from 1999 to 2002 to measure the fraction of intercepted photosynthetically active radiation (FPAR). The high-frequency (32 Hz) sensor data was aggregated into 25-meter segment averages, designed to validate 1 km MODIS satellite pixels. This dataset was created by the ORNL_CLOUD organization using the TRAC instrument.

Use Cases

• Validating MODIS FPAR and LAI products using ground-truth measurements from a 1 km representative area.
• Modeling spatial and temporal variability of light interception in a semi-arid savanna forest ecosystem.
• Analyzing the relationship between canopy gap fraction and photosynthetically active radiation transmittance.
• Studying seasonal and inter-annual changes in forest biophysical properties over a multi-year period.

Strengths

• Data collection spans over three years (1999-2002), providing temporal depth for seasonal analysis.
• High-resolution sampling at 32 Hz results in a fine horizontal sampling interval of approximately 1.7 cm.
• Measurement design uses three long transects (750 m each) specifically to represent a 1 km MODIS pixel for validation.

Limitations

• Key metadata such as row count, column names, and exact file size are unknown across all sources.
• There is a conflict in the reported 'last updated' date: one source states 2002-02-23, while others state 2026 03-12.
• The license is ambiguously described as 'other-license-specified', requiring further investigation for reuse.

Provenance

Source

ORNL_CLOUD organization, using the TRAC (Tracing Architecture and Radiation of Canopies) instrument.

Collection Method

Instrument carried along three parallel 750m transects, 0.7m above ground, on clear days near midday. PAR measured at 32 Hz, processed into segment-average and transect-average FPAR values.

Time Range

1999 to 2002

Freshness

2026-03-12 22:17:19.168250

Geography

EOS Validation Core Site in Kataba Local Forest, approximately 20 km south of Mongu, Zambia.