Validation of Satellite Observations of Soil Moisture to Facilitate Forecasts of Soil Water Storage in Iowa

Principal Investigators: 

Brian Hornbuckle

Year Funded: 

Soil moisture is the reservoir of water that supports agriculture.  Soil moisture also affects the amount and variability of precipitation and hence the occurrence of drought. Remote sensing satellites  that observe near–surface soil moisture have recently  been launched or will be launched in the near future.  Before measurements of near–surface soil  moisture  made from space can be used to  estimate  the  amount  of water  stored in the soil and improve weather and climate predictions, the quantitative value of the measurements must be known.
My long–term goal is to contribute to the construction of a water balance model for Iowa consisting of atmospheric and land surface models along with a data assimilation scheme.  This model would ingest real–time information regarding soil moisture, river levels, precipitation, and atmospheric conditions, in order to give the best estimate of current and future soil water conditions throughout the state.  Ultimately this system could be used to monitor the evolution of soil moisture, and as a tool to test actions that could be taken to ameliorate the impacts of drought and future climate variabil- ity. My objective in this proposal is to contribute to the validation of near–surface soil moisture observations made by current and future satellite remote sensors in order to assess the quantitative value of these space–based observations.  My central hypothe- sis is that satellite observations of near–surface soil moisture are valid as determined by point–based  in–situ  observations  of soil  moisture  scaled  to  match  the  size  of the satellite  footprint.   My rationale  for this  project  is  two–fold:  the  quantitative  value of remotely–sensed  near–surface  soil  moisture  must  be known before it can be used effectively;  and the state of Iowa should seize this opportunity to benefit from these new satellite  measurements.   I have a unique  competitive  advantage  to  test  my hy- potheses because I am currently a team–member of the European Space Agency’s Soil Moisture and Ocean Salinity (SMOS) mission, a satellite launched in late 2009 that is currently making near–surface soil moisture observations, and NASA’s Soil Moisture Active Passive (SMAP) mission, which will be launched in late 2014.
My specific research objectives for this project are as follows.
• Improve and then validate SMOS near–surface soil moisture observations in Iowa.
• Initiate the validation of SMAP near–surface soil moisture observations in Iowa.
The expected outcome of this project will be validated near–surface soil moisture observations that could be used by hydrologists and atmospheric scientists to estimate soil water storage and improve the prediction of weather and climate in Iowa.  I will use professional relationships developed during this project to submit proposals to NASA that will support future research on SMAP mission observations and water cycle studies in Iowa.  If we are successful at validating these new satellite soil moisture observations, Iowa scientists will have a unique opportunity to estimate current soil moisture reserves and better understand the conditions leading to drought and hence mitigate the impact of this type of natural disaster on the citizens of Iowa.

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