NG309312 - Revised Chapter G-30, "Facsimile Systems."

August 24, 1993 W/OSO15

TO: All Holders of Operations Manual

SUBJECT: Transmittal Memorandum for Operations Manual Issuance

1. Material Transmitted:

Revised Chapter G-30, "Facsimile Systems."

2. Summary:

This chapter was updated to accurately describe the various facsimile systems operated by the NWS and identify the organizations that are responsible for management of the systems.

3. Effect on Other Instructions:

Supersedes the entire WSOM Chapter G-30, Issuance 82-14, dated August 12, 1982.

Assistant Administrator
for Weather Services

1. Purpose. This chapter provides an overview of the facsimile systems operated by the National Weather Service (NWS) and identifies the organizations responsible for the establishment of policy and management of the systems.

2. Description. The primary mission of the NWS is to provide timely and accurate meteorological, hydrological, and oceanographic warnings, forecasts, and planning information to ensure the safety of the population, mitigate property losses, and improve the economic efficiency of the Nation. Distribution of weather products, e.g., data, graphs, and charts,in support of this mission is provided through a variety of communications networks established for the common goal of disseminating vital weather information. The NWS facsimile systems described herein help support the NWS mission.

2.1 Digital Facsimile (DIFAX). DIFAX is a satellite broadcast system that disseminates graphical versions, i.e., "charts," of selected observational data, analyses, and forecast guidance materials prepared by the National Meteorological Center (NMC) to selected NWS field offices and other Government users. The information transmitted is used, primarily, by NWS offices that provide support to the international aviation and agricultural communities. The DIFAX satellite dissemination system is operated by a private company under contract to the NWS.

The DIFAX charts are transmitted from the National Weather Service Telecommunication Gateway (NWSTG) in Silver Spring, Maryland, to the system contractor's facilities, where they are uplinked to a commercial communications satellite. The DIFAX charts are then broadcast via satellite to over 300 user locations of the NWS, Federal Aviation Administration, Department of Defense, and other Government agencies throughout the conterminous United States, Bermuda, Cuba, and Puerto Rico. DIFAX is also broadcast to foreign government agencies in Mexico.

The DIFAX broadcast is received at user sites via receive-only Very Small Aperture Terminals. In addition to the DIFAX satellite broadcast system, DIFAX charts are also available on the NWS Family of Services (see WSOM Chapter G-22).

2.2 Alaska Facsimile (AKFAX). The AKFAX network distributes graphical meteorological data that include surface analysis, upper air, marine, and aviation charts. The AKFAX products are prepared by the NMC in Washington, D.C., and transmitted from the NWSTG via a commercial satellite data link to the Anchorage Weather Service Forecast Office (WSFO). The AKFAX charts are then distributed to NWS (and other Government) offices throughout Alaska via a variety of communications facilities that are employed in the AKFAX network. Additional weather data (charts) are added to the AKFAX network by the Anchorage WSFO.

The AKFAX data stream from the NWSTG is transmitted to Anchorage, at 4800 bps, as one channel of a composite 19.2-Kbps data link. Additional (non-AKFAX) meteorological and hydrological data are transmitted on the other channels of the NWSTG Anchorage link.

2.3 Honolulu Facsimile (HONOFAX). HONOFAX consists mainly of marine and aviation charts prepared at NMC and transmitted from the NWSTG to the Honolulu WSFO on a 4800-bps data channel that is part of a 9600-bps satellite data link between the NWSTG and the Honolulu WSFO. The HONOFAX data is further distributed by the Honolulu WSFO to other NWS and Government users throughout Hawaii via local telecommunications networks.

2.4 Geostationary Operational Environmental Satellite Facsimile (GOESFAX). The GOESFAX network enables WSFOs, other Government agencies, and non-Government users to receive high quality meteorological satellite imagery on a near-real-time basis. GOES satellite imagery products are prepared by the National Environmental Satellite, Data, and Information Service (NESDIS) at Camp Springs, Maryland, and are distributed via dedicated, terrestrial circuits to Satellite Field Distribution Facilities (SFDF). The SFDFs serve as primary distribution points for GOES data users and are located at: Camp Springs, Maryland; the San Francisco WSFO in Redwood City, California; the National Severe Storms Forecast Center in Kansas City, Missouri; the National Hurricane Center in Coral Gables, Florida; and the Honolulu and Anchorage WSFOs. The SFDFs receive selected satellite sectors and products pertaining to their specific region.

Distribution of products from SFDFs to WSFOs and other users throughout the continental United States is via dedicated point-to-point circuits. The circuits from SFDFs to WSFOs are collectively known as the GOES-TAP network. The GOES products received at the SFDFs are available to GOES-TAP users via a user-activated touch-tone selection system. The NWS allows external users (non-NWS) to access the GOES-TAP data distribution network at local servicing telephone company facilities via "GOESFAX" connections .

Connection to GOESFAX is the responsibility of the user and is typically provided via a dedicated terrestrial circuit. GOESFAX customers do not have the capability to select products, and they receive only the data that has been selected by the servicing WSFO.

2.5 Marine Weather Radiofacsimile Broadcast. The Marine Weather Radiofacsimile Broadcast provides analysis and forecast charts of ocean surface weather for the maritime community. Several NWS offices provide a broadcast signal to other agencies, most often the Coast Guard, which then transmit to marine interests at sea. Examples of these circuits are: Pt. Reyes, California, and Marshfield, Massachusetts, Coast Guard Communication Station broadcasts fed by the NMC's Marine Forecast Branch; and Marine Radio Station WLO, New Orleans, Louisiana, that is provided a signal from WSFO Miami, Florida. These circuits serve particular marine areas determined by the power and broadcast range of the transmitter. The broadcast frequencies vary from site to site but are generally in the single-sideband range. Typically, these systems are active only several hours each day.

3. Data Products. The various facsimile systems of the NWS provide for the timely dissemination of graphical depictions of meteorological, hydrological, and oceanographic observations and forecasts that are generated, primarily, at the NMC and/or NESDIS. These data products include meteorological satellite imagery, meteorological weather charts for international aviation users, selected observational data, analyses, and forecast guidance materials.

4. Organizational Responsibility. The Telecommunications and Dissemination Branch (OS015) is responsible for the overall management of NWS facsimile distribution systems. The Telecommunications and Dissemination Branch is part of the Systems Integration Division of the Office of Systems Operations.

4.1 Ordering Facsimile Service. Orders for circuit connections, relocations, and removals or discontinuance of DIFAX, AKFAX, HONOFAX, GOESFAX, or Marine Weather Radiofacsimile service are processed by OS015. NWS field offices should request communications services through their regional headquarters. Communications requirements should be planned so that adequate lead time (45-60 calendar days) is provided for proper coordination of vendor activities.

4.2 Maintenance of Leased Equipment. At installations where facsimile equipment is leased with maintenance to be provided by the contractor, the Meteorologist In Charge or Official In Charge is responsible for reporting equipment malfunctions to the local service representative of the contractor. If the unsatisfactory maintenance cannot be resolved at the local level, the regional headquarters and OS015 should be advised of the problem.

4.3 Facsimile Transmission Schedule. Transmission schedules listing the various products and transmission times for each product are maintained by OS015 for all NWS facsimile systems except GOESFAX and the marine radiofacsimile circuits. The GOESFAX schedules are maintained by NESDIS. The marine radiofacsimile circuit schedules are maintained by the respective originating offices. Changes to transmission schedules are announced to users by notices sent over the affected facsimile system during the General Notice period of the transmission schedule. Except for the marine circuits, when significant changes are made, the schedule is reprinted and distributed to all users. If time permits, each new schedule is transmitted on the circuit two or three times prior to its effective date.

A DIFAX schedule change or the introduction of new charts requires prior approval of the Meteorological Requirements Review Group (MRRG) and the Data Review Group (DRG). The MRRG is an advisory and review group within the Office of Meteorology, organized to review and evaluate operational requirements for NWS offices. The DRG provides for coordinated review and processing of Requests for Change to data products that are transmitted over NWS communications systems.