The National Geodetic Survey (NGS) develops and maintains a national coordinate system, which provides the foundation for transportation, navigation, land record systems, mapping and charting efforts, defense operations, and a multitude of scientific and engineering applications. NGS products, services, and data support maritime navigation, aviation safety, hurricane evacuation routes, climate change activities, ocean observing, and more.
NGS highlights from fiscal year 2010 include:
- NOS Supports Relief Efforts in Haiti
On January 16, the Federal Emergency Management Agency’s (FEMA) National Response Coordination Center requested NOAA’s assistance in acquiring high-resolution aerial imagery of portions of Haiti impacted by the earthquake that took place on January 13. NGS’s Remote Sensing Division and NOAA’s Office of Marine and Aviation Operations Aircraft Operations Center began data collection operations on January 17, and operations continued over the area until sufficient data was collected to support the recovery efforts. The imagery and associated products were used to support detailed damage assessment, locating and digitizing footprints of major demolition projects necessary for long-term recovery and rebuilding, and to preserve a high-resolution record of the initial post-disaster state to assess recovery efforts.
- Operational Phase of Gravity for the Redefinition of the American Vertical Datum Began
In May, NGS staff from the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) team traveled to Minneapolis, MN, to install equipment for the summer 2010 GRAV-D airborne gravity survey mission in Alaska. The summer survey was conducted from Anchorage and Kodiak aboard the NOAA Turbo Commander, an aircraft used most of the year to conduct aerial snow survey operations. This phase of the GRAV-D survey in Alaska began the last week of May and continued through the end of August, with 300 flight hours planned. The survey began filling in the central region not covered by the 2008 and 2009 surveys. NGS will continue to survey Alaska and then the rest of the nation in fiscal year 2011 and beyond.
- Infrastructure Enhanced for Precise Positioning in Alaska
To improve the infrastructure for precise positioning in Alaska, NGS added over 20 Continuously Operating Reference Stations (CORS) to the National CORS Network in 2010 in Alaska. These remote outposts of GPS equipment, owned and operated predominantly by the Plate Boundary Observatory as funded by the National Science Foundation, are a subset selected by NGS for their grid-like distribution and for their expected stability and reliability of operation in the harsh Alaskan landscape. Another 50 potential CORS were identified that could be added to the network in fiscal year 2011.The region currently has limited geodetic infrastructure for accurate positioning compared with the rest of the nation, and these stations helped fill some of the critical gaps in CORS coverage in Alaska.
- NOS Releases Real-Time Guidelines
NGS announced the approval and release of a document titled “National Geodetic Survey User Guidelines for Single Base Real-Time GNSS Positioning.” The guidelines provide definitive criteria to achieve various specific tiers of precision, with high confidence, using global navigation satellite systems (GNSS). Due to the plethora of variables associated with real time GNSS positioning, a consistent documented approach for using this technology to the best advantage was lacking. Extensive research was completed to evaluate, refine, and compile comprehensive information into an integrated form, thereby ensuring the most practical and reliable methodologies were developed.
- New Software Released for Improved Height Accuracy in Coastal Areas
In June, a newly updated version of the NGS PAGE-NT GPS software was released to allow NGS state geodetic advisors, contractors, state geodetic agencies, and other interested parties to achieve better height accuracy (and horizontal accuracy) when positioning sites near the coast. In some areas, such as southern Alaska, the weight of the ocean’s tides pressing down on the Earth’s crust can cause site motions of up to six centimeters (2.4 inches) in height and five millimeters (0.2 inches) horizontally. With relative positioning (using two or more GPS receivers simultaneously), these effects are small when the distances between sites are small, because the sites tend to move up and down by the same amount. But when distances between sites are greater, and particularly when sessions are significantly different than 12 or 24 hours (the usual tidal cycle), these effects can cause height errors of several centimeters.
- NOS Participates in Collaborative Survey at Poplar Island
In July, NGS, in collaboration with the U.S. Army Corps of Engineers (USACE), NOAA’s Office of Coast Survey, and NOAA’s Center for Operational Oceanographic Products and Services, led a Height Modernization project connecting the USACE Poplar Island datum to the National Spatial Reference Station. The survey involved the simultaneous deployment of geodetic Global Navigation Satellite System (GNSS) receivers and antennas at fixed marks on the mainland as well as at numerous marks established on the island. The data was corrected using long-term data from the nearest Continuously Operating Reference Stations.
Although much of the island had eroded and subsided away by the end of the last century, material recovered as part of normal dredging operations along the approach channels to the Baltimore harbor has been used to restore Poplar Island to its original size. The success of the construction hinges largely on the ability to grade the sediments to the appropriate elevation with respect to local water levels. NOAA is providing valuable assistance in connecting different observations systems (both land-based and water-based) to the same, consistent, positional reference frame—the National Spatial Reference System.
- NOS Participates in Airport Survey Pilot Project for Department of Defense
Representatives from the NGS Field Operations Branch participated in two airfield surveys for the National Geospatial-Intelligence Agency (NGA), Department of Defense (DOD). By establishing this joint partnership between NGS and NGA, the need for DOD airport surveys can be served, while providing for mutual technology transfers. NGS and NGA have previously worked together in the GRAV-D initiative’s absolute gravity survey work, and this DOD airport survey pilot project provided NGS with the opportunity to investigate other collaborative efforts. NGS has a long history of working with the Federal Aviation Administration and its predecessor agencies on airport obstruction surveys. This collaboration formally expands NGS's expertise in obstruction surveys to military airfields.
- NOS Assists Navy Bathymetric Lidar Team in Nicaragua
In February and March, a NOAA Corps Officer assigned to the NGS Remote Sensing Division was in Nicaragua with other members of the Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX), working alongside Navy personnel during Lidar data acquisition and processing operations. This work was conducted to meet the navigation requirements of Nicaragua and the U.S. Navy and under mutual agreement to share the data.
The goal was to develop a better understanding of the Lidar data processing pipeline; the capabilities, limitations, and deliverables of a bathymetric Lidar system; and their possible application to NOAA requirements. JALBTCX research and development supports and leverages work in government, industry, and academics to advance airborne lidar and coastal mapping and charting technology and applications.
- NGS and Thunder Bay National Marine Sanctuary Collaborate on Vessel Survey
NGS assisted NOAA’s Thunder Bay National Marine Sanctuary in Lake Huron, Alpena County, MI, by conducting a vessel survey of the newly acquired 50-foot research vessel RV Storm. The vessel conducted side scan sonar and multi-beam operations in the Thunder Bay National Marine Sanctuary. The survey positioned GPS antennas, Inertial Measurement Unit (IMU), sonar, and their relationship to the vessel as required to georeference the sonar data used in mapping and charting. Surveys of this type are required to precisely measure the spatial relationship—relative to the centerline of the vessel upon which they are located—of the various sensors used to collect and geo-reference hydrographic information. Defining the spatial relationship of the sensors in this manner improves the overall accuracy of the hydrographic data collected.