NOAA observes, monitors, and models different Earth systems on land, in the ocean and above the Earth’s surface. These Earth-based systems are constantly in motion. As such, it is also important to account for the dynamic Earth system processes in the geospatial infrastructure. NOAA’s National Geodetic Survey has been investigating the spatial change of the Earth’s surface and its seafloor. In the past, location with respect to water surface (tidal or geopotential) was fixed until the next version of a reference system was developed. Today, it is possible to provide a time correction to the reference system accounting for geologic and oceanographic changes over climate-scale periods on the order of years to decades. In addition to updates to the geodetic network, the geodetic climate-scale products can be used for non-geodetic applications within NOAA and other federal agencies, such as the inter-agency geohazard monitoring programs (such as, Earthquakes and Tsunamis), ground water activities, and sea level rise monitoring.
NGS was originally part of the Coast and Geodetic Survey that was established in 1807. The survey observations and records collected over more than two centuries can be leveraged to detect changes over climate scales, provide observations, and relate changes in bench mark locations to natural or man-made processes. It all depends on how well the observations were documented. Uncertainty values are being attributed to geodetic surveying allowing us to develop reliable time series of land deformation. Metadata associated with the NOAA’s National Geodetic Survey’s include proper documentation on the survey itself and the conditions that the survey was conducted, such as benchmarks being used, number of repeated observations, and weather conditions.
Read moreNOAA’s National Geodetic Survey does not investigate the geological and geophysical processes for land deformation. With that said, its high accuracy control is used for linking observations into the National Spatial Reference System to monitor mm/yr rates of change of the Earth’s surface and enhance ocean climate scale observations, such as sea level rise. Satellite geodesy techniques are used to provide spatial monitoring of these deformations, especially with respect to the geopotential surface that can be used to indicate elevated risks for flooding and inundation.Continuous observations from GNSS-based stations with Interferometric Synthetic Aperture Radar (InSAR) imagery generate deformation models over land for public use.
Read moreThe Earth’s tectonic plates are separated by faults that are constantly grinding and scraping against one another at slow moving rates that are measured at a mm/yr scale. We only feel this motion when the energy locked between two plates is released as moderate earth tremors, or sometimes as earthquakes. The deformation process prior to the release of energy is defined by geologists as “strain.” For plate boundaries over land, like the San Andreas Fault system, it is possible to use traditional surveying technologies. However, many of the tectonic plate boundaries are underwater. NOAA’s National Geodetic Survey is investigating emerging technologies that incorporate acoustic observations with traditional land surveying monitoring approaches, such as geodetic grade Global Navigation Satellite System (GNSS) receivers. Potentially, these studies can provide advance warning systems for earthquake and tsunami monitoring programs.
Read moreIn addition to positioning, climate-scale changes to our national geospatial infrastructure impact navigation operations. Marine and aerial transportation depend on the gravity (geopotential) and magnetic (geomagnetic) field of the Earth for leveling and orientation. The National Geodetic Survey established the Geoid Monitoring Service (GeMS) in 2019 to account for geoid changes in time. This product is one the outcomes from NOAA’s ongoing research into gravity observations, and into the potential physical processes that could modify the geoid over time. The compass is still one of the key components in marine navigation. NOAA’s marine charts provide a layer of the Earth's magnetic field. This layer is updated annually as the location of the magnetic north pole has been drifting at a rate of 16 km/yr to about 55 km/yr.
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