Effective Atmospheric Modelling of Soufrière Hills Volcano, Montserrat for Space Geodesy
Webb, Thomas; Wadge, Geoff
University of Reading, UNITED KINGDOM

Turbulent mixing processes over terrain cause local variations in water vapour from a vertically stratified profile. Temporal variations in water vapour distribution cause delays in phase used in the space geodetic InSAR technique. To correct for this, accurate simulations of the 3D water vapour field at the times of radar acquisition are needed. On Montserrat this effect is compounded because Soufrière Hills Volcano is itself an active source of water vapour. High-resolution terrain and land-use data sets are used to build a static model of the surface of Montserrat. The Weather Research and Forecasting model (WRF) is used to simulate the dynamics of the atmosphere over the island at a resolution of 200m. This simulation is nested through five steps from a Global Forecast System weather model (GFS) that provides the initial conditions. This can be used to simulate the InSAR delay and hence correct for the true deformation of the volcano. InSAR data provided by the Sentinel-1 satellite in 2013 will be used to test the method. Montserrat-WRF models have been tested and validated in 2012 against water vapour results from the GPS network on Montserrat.