In late September, a key NOAA weather satellite for monitoring storms over the Eastern U.S. and Atlantic ocean failed. But yesterday, NOAA announced its engineers had restored the satellite - known as GOES-13 - to full operation.
On September 23, GOES-13’s future was very much in question when “instrument anomalies” prompted engineers to shut it down. Data from the sounder instrument - which receives atmospheric data - looked bad, and the imager data - the pictures you see on television - were also getting jittery and blurry.
“The engineers have worked hard to understand and correct the problem, and now data from both the imager and the sounder will flow shortly to our key user, NOAA’s National Weather Service,” said Mary Kicza, assistant administrator of NOAA’s Satellite and Information Service.
NOAA historically keeps a “spare” GOES satellite in orbit between the two operational ones just in case one of them should fail.
When GOES-13 failed, that spare was GOES-14.
For the past few weeks, as an interim solution, GOES-14 was maneuvering eastward at a rate of 0.9 degrees per day to fill in for GOES-13 and perhaps eventually replace it completely.
“With severe weather always a threat, NOAA had back-up resources and contingency plans already established, so the critical flow of satellite data was uninterrupted,” Kicza said.
The diagram to the right shows the relative locations of NOAA’s three geosynchronous satellites, as well as GOES-14’s temporary eastward migration in the dashed yellow line. The satellites and distances are not to scale, but you get a sense of what areas each satellite “sees”.
Just yesterday, after extensive testing, engineers successfully brought GOES-13 back online. It was determined that “aging lubricant in the sounder instrument” was responsible for the anomalies. At 10:44 a.m. EDT this morning, GOES-13 was reverted back to the operational GOES-East satellite, and GOES-14 will cease its eastward migration tomorrow, then go back into standby mode.
NOAA operates two primary geosynchronous satellites to cover the United States with continuous satellite imagery. GOES-East (13) orbits above the equator at 75W (same longitude as Philadelphia, PA), while GOES-West (15) orbits above the equator at 135W (same longitude as Juneau, AK).
At a required altitude of 22,236 miles above the Earth’s surface, these unique orbits allow the satellite to remain fixed over the same place at all times (“geo-synced”).
Data and imagery from these satellites are important for forecasting and data assimilation into weather models.
* Brian McNoldy is a senior researcher at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science.
Jason Samenow contributed to this post