U.S. and European weather satellite organizations have signed an agreement that sets the conditions that would allow the U.S. government to restrict the flow of data from U.S. instruments flying on European weather spacecraft during a war or some other emergency.

The agreement, the Data Denial Implementation Plan, signed Feb. 22 by Europe’s Eumetsat organization and the U.S. National Oceanographic and Atmospheric Administration (NOAA), ensures that data will flow only to approved users in the United States and Europe when such a crisis occurs. However, it does not apply to data more than three hours old, according to a Feb. 22 NOAA news release.

The agreement also protects European national weather services from any cutoff of short-term weather forecasts, often referred to as nowcasts, from Europe’s future Metop satellites. The first Metop is scheduled for launch in June.

Noting the three-hour clause, Greg Withee, NOAA’s assistant director for satellite and information services, stressed during a Feb. 23 telephone interview that the agreement is not an attempt to permanently cut off access to weather satellite data, and that he hoped it would never be exercised.

Data from weather satellites is accessed by government and civilian users around the world. If denial is employed, data would only be restricted over limited, particular geographic regions, not on a global basis, Withee said.

Metop includes NOAA-provided instruments, and NOAA’s next-generation polar-orbiting meteorological satellites, the National Polar-orbiting Operational Environmental Satellites (NPOESS), will fly a Eumetsat-provided instrument as part of what the two sides call an Initial Joint Polar System.

While Eumetsat and NOAA have shared weather-satellite data and come to each other’s aid following satellite failures for decades, their relationship is changing as Eumetsat takes over responsibility for part of the polar-orbiting satellite system and commits itself to maintain the Metop satellites for at least 15 years.

On a parallel track, NOAA and the U.S. Defense Department are merging their separate weather-satellite systems to save money. This development has added a new military sensitivity to U.S.-European cooperation, and the data-denial policy is one result.

The Metop satellites feature an encryption device that can be activated upon a request from NOAA to the director-general of Europe’s Eumetsat organization. While NOAA’s current fleet of satellites do not include this feature, it may be added to the NPOESS satellites, Withee said.

Eumetsat Director-General Lars Prahm said Feb. 24 that under the new policy, no nowcasting or other data from U.S. instruments may be denied to “public duty users” in Eumetsat’s 19 member states and 11 cooperating states.

Eumetsat’s membership includes all of Western Europe, and extends east and north to Finland, to Latvia, Lithuania and Romania in Central Europe, and in the south as far east as Turkey.

The national weather service agencies in these nations will never need to worry about data denial, but it is possible that another regular Eumetsat user in one of these nations may face cutoff during wartime, Prahm said.

Prahm said that outside the national weather services in these 30 nations, NOAA has the unilateral right to order Eumetsat to use the Metop encryption system to block nowcasting data to any users. “The definition of ‘public duty user’ is quite vague, and we needed to agree” on who would be beyond the reach of data denial in Eumetsat member states, Prahm said in an interview. “What we mean is national weather services and public institutions.”

Withee declined to comment on specific countries or users that the agreement is intended to address. However, he said that the agreement is intended to stop certain users from creating real-time forecasts regarding clouds, temperatures and ocean conditions.

The Metop satellite system has long been planned to feature an encryption system, in keeping with Eumetsat’s data access policy, which distributes data free to some classes of users, and on a fee-paying basis to other users.

Prahm said Eumetsat is able to deny access to Metop data almost instantaneously, user by individual user, on receipt of a formal request from NOAA.

Once data is three hours old, the denial is automatically removed, and there should never be a case where a user is unable to access data older than that. “Real-time data that is older than three hours is not all that useful,” Prahm said. “We’re talking about cloud cover, wind conditions and the like that change quickly.”

Eumetsat has no plans to introduce its own data-denial policy for Metop instruments it built, nor does it plan to enact any such policy for the organization’s geostationary-orbiting Meteosat satellites, Prahm said.

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