Our radar research work started in 2002 with the AVTIS project to develop a portable surveying FMCW radar to measure the 3D surface of the changing shape of volcanic lava domes through poor weather and low visibility. The AVTIS (All-weather Volcano Topography Imaging Sensor) instruments are high-resolution 94 GHz radars built in St Andrews originally designed for round the clock monitoring of the 3D surface topography of the volcanic lava dome on the island of Montserrat. AVTIS instruments are also capable of mapping rainfall with high spatial and temporal resolution which could potentially provide early warning of flood risks and lahars.
You can read about the original AVTIS instrument on our public outreach website here.
There are currently two systems: AVTIS2, a long range (7 km) rover designed for field surveying campaigns and AVTIS3 operating at shorter range (4 km), housed in a semi-permanent installation at a telemetered location in Montserrat to monitor the Soufrière Hills Volcano (SHV).
The AVTIS instruments use a single real beam which is mechanically rastered across the scene of interest to produce radar return spectra as a set of 3D volumetric data (i.e. return powers are encoded as a function of raster angle and range). Each line of sight is low pass filtered to better represent the mean beam footprint on the mountain (rather than potentially being dominated by individual point scattering elements within the beam footprint) and maximum power reflected is then used to give the range to bulk topography in the form of an xyz point cloud. The point cloud is then power thresholded to remove ‘sky’ returns and interpolated onto a regular GPS grid (referenced by locating fixed surveyed CC points in the field). The final DEM surface is produced using a distance to point cloud metric to remove false surfaces due to occlusions.
Initially installed in 2011, we have recently refurbished the AVTIS3 system and continue to collaborate with the Montserrat Volcano Observatory (MVO) to monitor the Soufrière Hills Volcano.
Funding: NERC (2002-2005, 2007-2011), EPSRC Impact Acceleration Account (2013-2015, 2016-2017, 2017-2018, 2019)