Soil moisture retrieval using GNSS-R
/ Dhrishti Caleechurn ; [dirigit per: Adriano José Camps Carmona]Caleechurn, Dhrishti
Dirigida per: Camps Carmona, Adriano José. Universitat Politècnica de Catalunya, 2009
1 recurs electrònic
Treball final de carrera.
The UPC Passive Remote Sensing Lab (RSLab) has developed theoretical models exploiting this technique for soil moisture retrieval. These models are based on the interference pattern produced by interaction between the direct GPS signal and the reflected GPS signal coming from the soil surface. The properties of the received interference pattern are modified by changes in geophysical parameters, such as the soil texture, moisture, roughness and thickness of soil layers. Changes in each of the parameters will induce a characteristic change in the interference pattern. Therefore, by identifying the correct observable change in the pattern, the soil moisture can be inferred. So as to get enough experimental results to validate the theoretical models mentioned above, a ground-based instrument, called the Soil Moisture Interference-pattern GNSS Observations at L-band (SMIGOL) Reflectometer, was placed in a wheat field at Palau d'Anglesola in Lleida province, from January to October 2008. Measurements have been carried out at the different stages in the growth of wheat. Those were then compared to the results produced by the theoretical model by means of a simulator, implemented using Matlab. By fixing geophysical variables in the simulator so as to represent as closely as possible the characteristics of the monitored soil, it is able to produce a theoretical interference pattern. It is then possible to compare this pattern with the experimental results to test the validity of the models. The simulator was in an initial stage so that most of the parameterisation had to be done manually, which takes a lot of time and introduces errors in accuracy. The presented PFC arises in this framework, so that the objective is to automate the simulator taking as input raw data produced by the SMIGOL Reflectometer and producing as output the soil moisture and topography of the monitored site, with minimum human input and delivering a fast response. Having a more accurate and faster simulator gives more results to analyse and better theoretical models for soil moisture retrieval.