Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Hydrol. Earth Syst. Sci., 21, 6049-6067, 2017
https://doi.org/10.5194/hess-21-6049-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
01 Dec 2017
Multiscale soil moisture estimates using static and roving cosmic-ray soil moisture sensors
David McJannet1, Aaron Hawdon2, Brett Baker2, Luigi Renzullo3, and Ross Searle1 1CSIRO Land and Water, EcoSciences Precinct, Dutton Park, Brisbane, QLD, Australia
2CSIRO Land and Water, ATSIP, James Cook University, Townsville, QLD, Australia
3CSIRO Land and Water, Canberra, ACT, Australia
Abstract. Soil moisture plays a critical role in land surface processes and as such there has been a recent increase in the number and resolution of satellite soil moisture observations and the development of land surface process models with ever increasing resolution. Despite these developments, validation and calibration of these products has been limited because of a lack of observations on corresponding scales. A recently developed mobile soil moisture monitoring platform, known as the rover, offers opportunities to overcome this scale issue. This paper describes methods, results and testing of soil moisture estimates produced using rover surveys on a range of scales that are commensurate with model and satellite retrievals. Our investigation involved static cosmic-ray neutron sensors and rover surveys across both broad (36 × 36 km at 9 km resolution) and intensive (10 × 10 km at 1 km resolution) scales in a cropping district in the Mallee region of Victoria, Australia. We describe approaches for converting rover survey neutron counts to soil moisture and discuss the factors controlling soil moisture variability. We use independent gravimetric and modelled soil moisture estimates collected across both space and time to validate rover soil moisture products. Measurements revealed that temporal patterns in soil moisture were preserved through time and regression modelling approaches were utilised to produce time series of property-scale soil moisture which may also have applications in calibration and validation studies or local farm management. Intensive-scale rover surveys produced reliable soil moisture estimates at 1 km resolution while broad-scale surveys produced soil moisture estimates at 9 km resolution. We conclude that the multiscale soil moisture products produced in this study are well suited to future analysis of satellite soil moisture retrievals and finer-scale soil moisture models.

Citation: McJannet, D., Hawdon, A., Baker, B., Renzullo, L., and Searle, R.: Multiscale soil moisture estimates using static and roving cosmic-ray soil moisture sensors, Hydrol. Earth Syst. Sci., 21, 6049-6067, https://doi.org/10.5194/hess-21-6049-2017, 2017.
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Short summary
Satellite and broad-scale model estimates of soil moisture have improved in resolution. However, validation and calibration of these products has been limited because of a lack of observations on corresponding scales. We use a mobile soil moisture monitoring platform, known as the rover, to derive soil moisture at 9 km and 1 km resolution. We describe methods to calculate soil moisture and present results from multiple surveys. The products produced are well suited to validation studies.
Satellite and broad-scale model estimates of soil moisture have improved in resolution. However,...
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