This document discusses using GNSS reflection techniques to monitor snow thickness. It details using an interferometric pattern technique with the SMIGOL reflectometer to measure the interference between direct and reflected GPS signals. A field experiment over 6 months showed the technique could retrieve snow thickness maps that correlated with ground measurements. The number and position of signal notches related to snow layer thickness, allowing the algorithm to track thickness changes over time.

1. SNOW MONITORING USING GNSS-R TECHNIQUES § Remote Sensing Lab, Dept. TSC, Building D3, Universitat Politècnica de Catalunya, Barcelona, Spain and IEEC CRAE/UPC ∞ SMOS-Barcelona Expert Centre, Barcelona, Spain Tel. +34934054664, E-08034 Barcelona, Spain. E-mail: [email_address] N. Rodriguez-Alvarez § , A. Aguasca § , E. Valencia § , X. Bosch-Lluis § , I. Ramos-Perez § , H. Park § , A. Camps § ∞ , M. Vall-llossera § ∞ IGARSS’11 – Vancouver, Canada, 24 th -29 th July 2011 FR4.T05: GNSS Remote Sensing in Atmosphere, Ocean and Hydrology II

4. Based on he interference pattern of the GPS direct and reflected signals, after reflecting from the surface. Objective: GNSS-R Technique studied: The Interference Pattern Technique (IPT) Snow thickness monitoring. (3/14) © R.S. Lab, UPC 2011. IGARSS 2011, Vancouver, Canada, 24 th -29 th July 2011 INTRODUCTION SNOW MONITORING USING GNSS-R TECHNIQUES

6. THE USE OF THE IPT FOR WATER LEVEL MONITORING Received interferometric power Where : Figure 4. The SMIGOL Reflectometer basic configuration FUNDAMENTALS OF THE INTERFERENCE PATTERN TECHNIQUE (5/14) © R.S. Lab, UPC 2011. IGARSS 2011, Vancouver, Canada, 24 th -29 th July 2011 SNOW MONITORING USING GNSS-R TECHNIQUES

12. RESULTS (11/14) © R.S. Lab, UPC 2011. IGARSS 2011, Vancouver, Canada, 24 th -29 th July 2011 SNOW THICKNESS MAPS RETRIEVED SNOW MONITORING USING GNSS-R TECHNIQUES

13. RESULTS © R.S. Lab, UPC 2011. IGARSS 2011, Vancouver, Canada, 24 th -29 th July 2011 (12/13) SNOW MONITORING USING GNSS-R TECHNIQUES RETRIEVAL RESULTS. Correlation of the retrievals with the ground-truth snow thickness

15. This work has been sponsored with funds from the Plan Nacional del Espacio of the Spanish Ministry in the frame of the project with reference ESP2007-65567-C04-02 and also by funds from the project with reference AYA2008-05906-C02-01/ESP and the project AYA2010-22062-C05-05/ESP. ACKNOWLEDGEMENTS (14/14) © R.S. Lab, UPC 2011. IGARSS 2011, Vancouver, Canada, 24 th -29 th July 2011 SNOW MONITORING USING GNSS-R TECHNIQUES

16. THANK YOU