f Effective Atmospheric Modelling of Soufriere Hills Volcano, Montserrat for Space Geodesy

Turbulent mixing processes around terrain cause local variations in water vapour from its vertically stratified profile. Temporal variations in water vapour distribution cause delays in phase used in the space geodetic InSAR techn ique. 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 Soufriere Hills Volcano is an active source of water vapour. High resolution terrain and landuse data sets are used to build a static model 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 250m. This simulation is nested through five steps from a Global Forecast System weather model (GFS) providing the initial conditions. This can be used to find the InSAR delay and hence correct for the true deformation of the volcano. It is anticipated that InSAR data provided by Sentinel 1 in 2013 will be used to test the method. The WRF model has been used so far to validate results against large precipitation events over Soufriere Hills such as that connected with the 2001 dome collapse and the 2011 tropical cyclone season.