1a.Objectives (from AD-416):
The goal of this project is to develop a set of soil moisture retrieval algorithms that can be used with the NASA Aquarius satellite due for launch in 2010. Aquarius was designed for ocean studies but the microwave sensors employed is also ideally suited for soil moisture monitoring. This will be the first satellite to provide both passive and active microwave observations, which will require additional research in order to fully exploit the combined information. The algorithms that are developed and validated would contribute to improved monitoring and modeling of land surface hydrology and weather and climate forecasting and would improve the implementation of these techniques on future soil moisture satellites.
1b.Approach (from AD-416):
Aquarius will provide an improved passive microwave sensor operating at a lower frequency than previous satellites. Established passive microwave soil moisture algorithms will be adapted and implemented to produce a global baseline soil moisture product. This product will be validated using existing ground-based observation resources and model products. Algorithms capable of utilizing the active microwave observations and/or the combined data sets have not been developed and will require extensive analysis of the satellite data over an extended post-launch period. Theory and validation data will be used to develop and select these improved retrieval methods.
The Aquarius satellite was launched by the NASA cooperator in June 2011. The satellite uses combined active-passive microwave remote sensing and was developed to support ocean applications. ARS cooperators have evaluated the use of Aquarius in soil moisture remote sensing since it shares some features of a future dedicated soil moisture satellite. Since launch, extensive efforts have been made to verify the calibration of the satellite instruments over land. A method for retrieving soil moisture was evaluated using surrogate data from available satellite systems. Data from the European Space Agency Soil Moisture and Ocean Salinity satellite were re-processed to simulate the passive component of Aquarius. Significant contributions have been made to the calibration of the satellite over land. Data products from Aquarius and the algorithms developed will advance the development of future dedicated soil moisture satellites and provide interim products that will benefit agricultural hydrology.