Similarities Between Spaceborne Active and Airborne Passive Microwave Observations at 1 km Resolution

For the first time, airborne passive microwave data were collected at 1 km resolution over parts of Central Australia coinciding with spaceborne active data, allowing a comparison of such data sets acquired at medium (1 km) spatial resolution. L-band airborne passive microwave scenes were compared with C-band scenes and temporal parameters from the Advanced Synthetic Aperture Radar. It was found that the radar-returned signal, as well as the “sensitivity” and “correlation” parameters derived from the long time-series of the ASAR GM data, is similar to spatial patterns in the passive microwave data, suggesting that similar physical interactions are underlying both data sets, especially across heterogeneous landscapes. Comparable patterns found over the dry Lake Eyre salt bed (r² = 0.37) suggest that very high-resolution C-band radar data may be used to describe subpixel heterogeneity within coarse resolution radiometer data, such as the future Soil Moisture Active Passive mission.