Snow depth estimation based on combination of pseudorange measurements of GNSS geodetic receivers

Abstract

Snow depth is an essential climate variable (ECV) in hydrologic cycle and is widely used for policy-making in agriculture and water resource management. Regional and global snow depth data also provide useful information for the study of climate change. In this paper, two new methods for snow depth estimation are proposed, which are based on combination of pseudorange measurements recorded by GNSS (Global Navigation Satellite System) geodetic receivers. The first one is the linear combination of pseudorange measurements of GNSS dual-frequency signals, which is geometry-free i.e. free of the effect of geometry between satellite and receiver. The second one is the linear combination of pseudorange measurements of GNSS triple-frequency signals, which is free of effects of both geometry and ionospheric delays. Both pseudorange combination methods do not rely on cycle slip detection and repair, which are required by carrier phase combination methods. Theoretical models are developed to describe the relationship between the spectral peak frequency of the combined multipath series and the antenna height. Two experimental datasets collected by UNAVCO community are employed to validate the proposed methods. The results demonstrate that there exists good agreement between the proposed methods and field observations of snow depth and the RMSE of the proposed methods are less than 3.2 cm at first experimental station. In addition, there is good consistency and similarity in snow depth estimation among the proposed method, SNR method and dual-frequency carrier phase and pseudorange combination method.