The gPhone-solar-cube: an energy self-sufficient mobile container for
monitoring gravity and climate parameters at remote field sites
Abstract
Throughout the last years, there is an increasing interest of the
geoscientific community in using terrestrial gravimetry as an
integrative and non-invasive method for observing mass change and mass
redistribution in the environment due geophysical processes. The nature
of the observed processes and the need for nearby data collection often
require the gravimeters to be installed at remote field sites. In
contrast to classical deployment at permanent observatory sites, this
often is a challenge because there are three main requirements to be
fulfilled for continuous high-quality operation of the gravimeter:
electrical power, stable site conditions, and data connection. Whereas
the latter can usually be accomplished by wireless solutions, the second
requirement is more demanding as it requires an adequate design of a
gravimeter enclosure and a stable pillar, while the first requirement so
far has been practically insolvable in the absence of a power line.
Here, we present the prototype of a mobile field container for gravity
monitoring that fulfils all above requirements: the gPhone-solar-cube.
The container consists of a cubic steel container as used by ships and
trucks with edge length of about 2 meters. We optimized all components
to host a continuously operating gPhoneX. Components include temperature
shielding, ventilation, solar panels, power management and monitoring,
storage batteries and an integrated backup generator to guarantee
self-sufficient power supply, data loggers and wireless data transfer
components. Furthermore we developed a new type of gravimeter pillar
which is simple to install and to remove, without connection to the
container floor to avoid vibration transfer. The pillar is large enough
to accommodate two CG-6 field gravimeters, next to the gPhoneX. Other
instruments integrated are a complete weather station and a cosmic ray
neutron probe. The gPhone-solar-cube has been installed in the Ore
mountains, Germany, as a continuously operating gravity reference
station for time-lapse field surveys with CG-6 gravimeters to assess
water storage changes in the course of heavy precipitation events. After
6 months of field operation, all requirements concerning data
transmission, remote access, energy consumption, pillar stability and
reliable gravity data were continuously met.