Aquarius soil moisture 14 AQUARIUS 12 Soil moisture 12 Remote sensing 10 Observing system simulation experiments 8 Soil moisture retrievals 8 Computer simulation 6 Experiments 6 Microwaves 6 Volumetric soil moistures 6 radiative transfer 6 satellite data 6 Algorithms 4 Bayesian inference 4 Error analysis 4 Markov Chain Monte Carlo 4 Meteorological instruments 4 Microwave emission models 4 OSSE 4 Quantitative error analysis 4 Radiative transfer model 4 Radiometers 4 Retrieval algorithms 4 Soil moisture estimation 4 Vegetation 4 accuracy assessment 4 AMSR2 2 Active and passive microwave systems 2 Aquarius/SAC-D 2