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Assessing the geometric accuracy of AVHRR data processed with a state vector based navigation system

We evaluate the geometric accuracy of Advanced Very High Resolution Radiometer (AVHRR) data processed using the Common AVHRR Processing System (CAPS) software. Accurate geometric correction, to known standards, of satellite images is crucial for many remote sensing applications, especially those using a time series of images and integrating other spatially referenced datasets. It is critical that data acquired by satellites with short repeat intervals (e.g., daily) are geolocated using methods that are both automatic and reliable. Landsat Enhanced Thematic Mapper Plus (ETM+) high-resolution imagery was used to establish ground control point (GCP) networks for two coastal regions of Australia, one tropical with 40 GCPs and one temperate with 60 GCPs. The geolocation accuracy was assessed for a total of 12 and 13 AVHRR images, respectively, against the GCPs for each region, respectively, totalling 1039 cloud-free GCP comparisons. Results showed that when the view zenith angle was less than 40°, the average (±1 standard deviation) accuracies are 0.36 ± 0.31 and 0.44 ± 0.35 of an at-nadir AVHRR pixel (1.1 km × 1.1 km) in the cross-track direction for the tropical and temperate regions, respectively, and 0.30 ± 0.26 and 0.36 ± 0.29 at-nadir AVHRR pixel in the along-track direction for the tropical and temperate regions, respectively. For higher satellite view zenith angles, the geometric accuracy decreases systematically with an increase in the pixel size towards the edges of the AVHRR swath.