SMEX05-related images (Graphic courtesy of USDA)

Soil moisture experiments conducted in 2005 were part of a campaign called POLEX, or the Polarimetry Land Experiment. Based in Ames, Iowa USA, POLEX measurements were collected from 15 June to 3 July 2005. The experiment was intended to address algorithm development and validation related to all current and scheduled soil moisture satellite systems. Specific objectives included the following:

• Exploration of unique polarimetric information from satellites such as Windsat and CMIS for soil moisture with supporting aircraft instrumentation
• Diurnal effects associated with soil, vegetation and atmosphere at the 6 a.m. to 6 p.m. observing times of Hydros, SMOS, CMIS, and Windsat
• Enhancement of Aqua AMSR-E soil moisture validation
• Statistics and mitigation of radio frequency interference (RFI) for CMIS risk reduction

Of these objectives, polarimetric microwave studies was the primary driver for experiment design. POLEX is the first campaign designed to study the unique and unexplored information that can be extracted for land applications using fully polarimetric observations. The Airborne Polarimetric Microwave Imaging Radiometer (APMIR), an aircraft simulator of WindSat and CMIS, facilitated replicate observations of a range of landscape features. In addition, with APMIR sub-band and emitter database, collected regional RFI statistics further evaluated the sensor capability in terms of RFI mitigation and its benefit in improving soil moisture retrieval performance. Many satellites, including WindSat, CMIS, SMOS, and Hydros, share the same diurnal observation characteristics (such as 6 a.m. to 6 p.m. coverage). Efforts during SMEX05 to focus on this timeframe offered the opportunity to understand phenomena that may be specific to these observing times. Of particular interest is the effect of dew on microwave brightness temperatures (Jackson and Moy 1999).

All ground and aircraft observations also support the soil moisture algorithm validation of Aqua AMSR-E. WindSat will transition to CMIS on the NPOESS operational platforms and AMSR to the Japanese GCOM satellites. All efforts in SMEX05 POLEX will contribute to these programs.

SMEX05 POLEX Data

Data are in the process of being organized and will be distributed via this site. If you have questions, please contact NSIDC User Services.