Title: Ground Network Design and Dynamic Operation for Validation of Space-Borne Soil Moisture Measurements
Primary Author: Moghaddam, Mahta
Organization: The University of Michigan
Co-Author(s): Dara Entekhabi, Mingyan Liu, Demos Teneketzis, Mariko Burgin, Yuriy Goykhman, Erik Li, Ashutosh Nayyar, David Shuman

In this talk we discuss new technologies under development by our team for dynamic and near-real-time validation of space-borne soil moisture measurements, in particular those from the Soil Moisture Active and Passive (SMAP) mission, one of the four first-tier Earth Science missions identified by the National Research Council Decadal Survey. Soil moisture fields are functions of variables that change over time across the range of spatial scales from a few meters to several kilometers. Satellite measurements, such as those to be provided by SMAP, are taken at spatial resolutions of 3km to 40km and at 3-day time intervals, which include soil moisture variability at several finer scales. Therefore, an optimal spatial and temporal sampling strategy needs to be developed that will not only make the task of satellite product validation feasible, but will also result in substantial improvement in science quality for soil moisture validation over conventional techniques. Through a previous ESTO/AIST task, we have gained significant expertise in the dynamic control of ground sensors based on temporal statistics of soil moisture fields. Here, we leverage our expertise to solve the joint problems of optimum sensor placement and sensor scheduling. We develop the optimal sensor placement policy based on spatial statistics of soil moisture (which could be nonstationary), and for each location, develop dynamic scheduling policies based on physical models of soil moisture temporal dynamics and microwave sensor models for heterogeneous landscapes. Tractable and scalable computational strategies are being developed for this purpose. Furthermore, we are developing relationships between the ground-based estimates of the true mean to its space-based estimates through a comprehensive physics-based modeling and statistical aggregation landscape simulator. An integrated communication and actuation platform is under development to command the sensors and transmit their data to a base station in real time. Full-scale field experiments are planned in coordination with SMAP cal/val experiments to prototype the validation system. We discuss the latest progress in each of these project elements, and show computational and experimental results.