Data from the Continuously Operating Reference Station (CORS) network supported numerous surveying and mapping projects designed to assess damage and speed recovery efforts, following several recent hurricanes along the Gulf Coast of the United States. Each CORS collects GPS signals around the clock. The CORS network spans the United States, its territories, and several foreign countries with over 800 sites, managed by NOAA’s National Geodetic Survey in collaboration with more than 155 partnering organizations.
Many of the post-hurricane projects relied on using the NOAA web utility, the Online Positioning User Service (OPUS); as indicated by the red dots in the attached figure. The dots identify locations whose positional coordinates were computed by OPUS during a 3-week period shortly following the landfall of Hurricanes Katrina and Rita. OPUS allows its users to submit at least 2 hours of GPS data, collected from a single location, to www.ngs.noaa.gov/OPUS. The OPUS utility automatically computes positional coordinates for the location, and then e-mails the coordinates to a user-specified address, within minutes. OPUS achieves an accuracy of approximately one inch, in all three dimensions, by using corresponding GPS data from three nearby CORS sites.
Shortly after each hurricane struck the U.S. coast, NOAA’s Remote Sensing Division and others obtained aerial imagery used to assess hurricane damage. Generally speaking, these missions are best served by CORS data, collected at a 1-second sampling rate, to accurately track the aircraft capturing the aerial images. As most CORS sites normally collect data at rates of 5-seconds, or slower, NOAA personnel work closely with their CORS partners to upgrade data collection rates, temporarily, after each hurricane. Aerial imagery – obtained by NOAA – of areas affected by several recent hurricanes is available at www.ngs.noaa.gov.
NOAA’s Earth System Research Laboratory applies CORS data, in a rather unique way, to describe and predict the distribution of moisture in the atmosphere, for several hours into the future. This capability enhances NOAA’s ability to forecast severe weather and heavy precipitation associated with impending hurricanes and other storms. NOAA would be more effective at assessing and predicting the intensity of future hurricanes, if CORS were installed on platforms in the Gulf of Mexico, the Caribbean Sea, and in the western portion of the Atlantic Ocean.
In the days immediately following Hurricane Katrina, unfortunately, data were inaccessible from several CORS sites, due to the disruption of local land-based telecommunications. As a result, CORS partners are currently exploring alternative methods for communicating data during such disasters. For example, two partners — Louisiana State University and UNAVCO, Inc. — installed satellite-based telecommunications when they created a new CORS site at the U.S. Coast Guard facility located on Grand Isle, Louisiana, within a few days after Hurricane Katrina made landfall.
For further information, contact:
Richard Snay
Manager, National & Cooperative CORS Network
NOAA’s National Geodetic Survey
1315 East-West Highway/Room 8813
Silver Spring, MD 20910
Tel: 301-713-3191 x103
Fax: 301-713-4324
E-mail: Richard.Snay@noaa.gov
This article benefited from contributions by Seth Gutman, Neil Weston, Cindy Craig, Joe Evjen, Don Mulcare, and Ruth Osborne; all NOAA employees.
Figure Caption: OPUS usage following landfall of Hurricanes Katrina and Rita.