SCANNING L-BAND ACTIVE PASSIVE (SLAP)—FLIGHT RESULTS FROM A NEW AIRBORNE SIMULATOR FOR SMAP

Abstract:

1. Introduction and Background

This paper introduces a new NASA airborne instrument, the Scanning L-band Active Passive (SLAP), which is specially tailored to simulate SMAP.

2. Description of SLAP

SLAP has both passive (radiometer) and active (radar) microwave L-band imaging capabilities. The radiometer observes at 1.4 GHz using duplicate front end hardware from the SMAP satellite radiometer. It also includes a duplicate of the digital backend development unit for SMAP, thus the novel Radio Frequency Interference (RFI) detection and mitigation features and algorithms for SMAP are duplicated with very high fidelity in SLAP. The digital backend provides 4-Stokes polarization capability. The real-aperture radar operates in the 1215-1300 MHz band with quad-pol capability. Radar and radiometer share one antenna via diplexers that are spare units from the Aquarius satellite instrument.

 3. Flight Results

SLAP’s initial flights were conducted in Dec 2013 over the eastern shore of Maryland and successfully demonstrated radiometer imaging over 2 full SMAP 36x36 km grid cells at 1km resolution within 3 hrs, easily meeting the SMAP post-launch cal/val airborne mapping requirements. A second flight on the same day also demonstrated SLAP’s quick-turn abilities and high-resolution/wide-swath capabilities with 200m resolution across a 1500m swath from 2000 ft AGL. Additional flights were conducted as part of the GPM iPHEX campaign in May, 2014.

 4. Conclusion

This paper presents flight data and imagery, as well as details of the radiometer and radar performance and calibration. The paper will also describe the mission performance achievable on the King Air and other platforms.