HIGH FREQUENCY (HF) BROADCASTS

Unclassified information from the AWN is forwarded to selected naval communication stations for broadcast via satellite. Each Naval Meteorology and Oceanography regional center monitors the environmental broadcast for their AOR (see table 1-5). The contents of each broadcast are also determined by each regional center. Normally, any data available in the AWN may be included on the environmental broadcast. However, because of the limitations of the system, only selected data are actually included. The regional centers may send a command via an AFMEDS terminal to halt the stream of data sent by the AWN. During these halts, classified traffic is transmitted by the regional center to the communications station for retransmission directly on the environmental broadcast. This classified data typically consists of naval ship observations and forecaster meteorological assistance support (MET Assists). Specific requests for observations or forecasts not included in the broadcast are sent via message to the Fleet CINC and the responsible regional center with an information copy to COMNAVMETOCCOM, as specified in NAVMETOCCOMINST 3140.1. Your LCPO or MET Officer will normally initiate these requests. The content of the environmental broadcast, as well as the channel assignments and the actual communications satellite itself, shifts when naval ships transit from one operational command area to another. Ships usually encounter these shifts when transiting from the Atlantic into the Mediterranean, from the Red Sea into the Arabian Sea, and through the Panama Canal. The FMCB is normally transmitted in encrypted form. Aboard ship, the Radiomen operate and monitor the FMCB receiving equipment and crypto equipment. The decrypted data stream from the Fleet Environmental Broadcast is transferred to the shipboard weather office on a protected circuit. In the weather office, the data may be directed to a TESS or IMOSS terminal, or directly to a printer. Other channels of the FMCB support AUTODIN message service and tactical data that supports systems, such as the Joint Operations Tactical System (JOTS), the Officer-in-Tactical Command Information Exchange System (OTCIXS), or the Tactical Data Information Exchange System (TADIXS). Many environmental products are composed specifically for these systems. The JOTS system in particular is extensively used by USN MET and USMC METMF members when embarked aboard ships without a weather office. The shipboard Aerographer’s Mate normally has no responsibility to operate the shipboard receiving equipment for the JOTS, OTCIXS, or TADIXS broadcasts. HIGH FREQUENCY (HF) BROADCASTS Many meteorological and oceanographic data broadcasts containing either alphanumeric or graphic (facsimile) information are available for ships at sea from HF radio transmissions in different parts of the world. In the past, the National Weather Service, the U.S. Air Force, and NAVMETOC regional centers transmitted a continuous HF broadcast of meteorological data. Due to the high maintenance cost and advancements in communication technology, most of these broadcasts have been reduced or have been eliminated altogether. Table 1-5.—Fleet Environmental Broadcasts Monitored by NAVMETOCCOM Regional Centers NAVMETOCCOM CENTER BROADCASTS MONITORED NLMOC Norfolk (2nd Fleet) East Atlantic: LMHA West Atlantic: LMHB NATO: H52N NEMOC Rota (6th Fleet) NPMOC Pearl Harbor (3rd Fleet) Mediterranean: MMHH East Pacific: PMOO NPMOC WEST Guam (5th/7th Fleet) West Pacific: PMHH Indian Ocean: MMWW 1-34