Assessing the Angular Density of Passive Microwave L-band Data

With the launch of the European Space Agency’s (ESA) Soil Moisture and Ocean Salinity (SMOS) mission on 2 November 2009, there is a new opportunity for global near-surface soil moisture mapping from space [1-2]. Along with its innovative sensor design, a 2-dimensional array of L-band passive microwave radiometers distributed on a Y-shaped synthetic aperture antenna, a new generation of retrieval models were developed [3]. One aspect of the novel technology is the capability of multi-incidence angle brightness temperature measurements by SMOS. This is understood to facilitate the retrieval process by i) enabling the simultaneous retrieval of ancillary parameters and thus reducing the dependency on external sources, and ii) enhancing the retrieval accuracy [4]. This paper investigates the impact of the total number of available multi-incidence angle L-band data, following described as angular density, on the performance of the soil moisture retrieval model.