Graphic courtesy of USDA.
About the SMEX05 Polarimetry Land Experiment (POLEX)
Soil moisture experiments conducted in 2005 (SMEX05) 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
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.
To view data and documentation, see SMEX05 Data.