Laboratory-based bidirectional reflectance distribution functions of radiometric tarps

Area of Science:

• Earth Remote Sensing
• Optical Physics
• Metrology

Background:

• Radiometric tarps are crucial for vicarious calibration of Earth observation satellites.
• Understanding tarp reflectance properties is vital for accurate satellite data.
• Existing BRDF data for tarps may not fully capture directional effects.

Purpose of the Study:

• To present laboratory-based bidirectional reflectance distribution functions (BRDFs) for radiometric tarp samples.
• To investigate the dependence of BRDF on tarp thread orientation (weft and warp).
• To provide new data on forward and backscatter properties of radiometric tarps.

Main Methods:

• Measurements performed using the GSFC scatterometer.
• Incident zenith angles: 0°, 10°, 30°.
• Scatter angles: zenith 0°-60°, azimuth 0°-180°.
• Wavelengths: 485 nm, 550 nm, 633 nm, 800 nm.

Main Results:

• BRDF shows significant dependence on weft and warp thread orientation across all geometries and wavelengths.
• BRDF differences reached up to 8% (0° incident) and 12% (30° incident).
• White tarps exhibit pronounced backscatter; black tarps show pronounced forward scatter.

Conclusions:

• The weft and warp orientation significantly impacts tarp BRDF, crucial for calibration accuracy.
• The study provides a valuable reference for radiometric tarp characterization in satellite calibration.
• NIST-traceable BRDF data enhance the reliability and usability of radiometric tarps.