Long-term Soil Moisture Time Series Analyses based on Active Microwave Backscatter Measurements
Other literature type
(issn: 2194-9034, eissn: 2194-9034)
Active microwave sensors operating at lower microwave frequencies in the range from 1 to 10 GHz provide backscatter
measurements that are sensitive to the moisture content of the soil. Thanks to a series of European C-band (5.3 GHz) scatterometers,
which were first flown on board of the European Remote Sensing satellites ERS-1 and ERS-2, and later on board of MetOp-A and
MetOp -B, we are now in the possession of a long-term soil moisture time series starting in 1991. The creation of globally consistent
long-term soil moisture time series is a challenging task. The TU-Wien soil moisture algorithm is adopted to tackle these challenges.
In this paper we present two methodologies that were developed to ensure radiometric stability of the European C-band
scatterometers. The objective of sensor intra-calibration is to monitor and correct for radiometric instabilities within one
scatterometer mission, while sensor inter-calibration aims to remove radiometric differences across several missions. In addition, a
novel vegetation modelling approach is presented that enables the estimation of vegetation parameters for each day across several
years to account for yearly to longer-term changes in vegetation phenology and land cover.