Ground-based active and passive microwave remote sensing
Knowledge of spatiotemporal distribution of soil moisture is essential as it represents a key variable in many hydrological, climatological, and environmental processes. Microwave remote sensing offers the potential to accurately monitor surface soil moisture over large areas. In this context, our main research focus is to develop and evaluate new forward and inverse modeling approaches for soil moisture retrieval using active and passive microwave systems. Ground-based microwave systems are of particular interest to characterize the within variability of field-scale soil moisture and also to improve and validate soil moisture products obtained from spaceborne remote sensing. Both active and passive ground-based systems are either placed on mobile platforms (truck, quad) or fixed platforms (arc, tower, and crane). For passive microwave measurements, three L-band radiometers are available at the Agrosphere Institute, namely, ELBARA I, ELBARA II, and JÜLBARA. For active measurements, the radar system used consists of a vector network analyzer (VNA) connected to an ultrawideband monostatic horn antenna.
Surface soil moisture retrieval using L-band radiometer and ground-penetrating radar (GPR).
Development of algorithms accounting for vegetation and soil surface roughness in the inversion of radiometer and radar data for accurate soil moisture retrieval.
Soil hydraulic properties retrieval using microwave remote sensing based on a well-controlled outdoor setup.
Characterization of crop canopies and water stress related phenomena using microwave remote sensing methods.
Calibration and validation activities associated with ESA’s Soil Moisture and Ocean Salinity (SMOS) mission launched in 2009 and the NASA’s upcoming Soil Moisture Active Passive (SMAP) mission scheduled for launch in 2014.
Jonard F., Weihermüller L., Jadoon K.Z., Schwank M., Vereecken H., and Lambot S. 2011. Mapping field-scale soil moisture with L-band radiometer and ground-penetrating radar over bare soil, IEEE Transactions on Geoscience and Remote Sensing, 49(8), 2863-2875.
Jonard F., Weihermüller L., Vereecken H., and Lambot S. 2012. Accounting for soil surface roughness in the inversion of ultrawideband off-ground GPR signal for soil moisture retrieval, Geophysics, 77(1), H1-H7.
Vereecken H., Weihermüller L., Jonard F., and Montzka C. 2012. Characterization of crop canopies and water stress related phenomena using microwave remote sensing methods: A review, Vadose Zone Journal, 11(2).
Montzka C., Bogena H., Weihermüller L., Jonard F., Bouzinac C., Kainulainen J., Balling J. E., Löw A., Dall’Amico J., Rouhe E., Vanderborght J., and Vereecken H. 2013. Brightness temperature and soil moisture validation at different scales during the SMOS Validation Campaign in the Rur and Erft catchments, Germany, IEEE Transactions on Geoscience and Remote Sensing, 51(3): 1728-1743.
Jonard, F., Mahmoudzadeh, M., Roisin, C., Weihermüller, L., André, F., Minet, J., Vereecken, H., and Lambot, S. 2013. Characterization of tillage effects on the spatial variation of soil properties using ground-penetrating radar and electromagnetic induction, Geoderma, 207.208: 310-322.
Forschungszentrum Jülich GmbH
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