The Hydrometeorological Automated Data System
The HADS system acquires raw hydrological and meteorological observation messages from Geostationary Operational Environmental Satellites (GOES) Data Collection Platforms (DCPs). The data originates from DCPs owned and/or operated by more than 100 cooperators. The NWS operates a relatively small network of DCPs. The majority of the data acquired and processed by HADS comes from DCPs owned and/or operated by the Water Resources Division of the U.S. Geologic Survey, the U.S. Army Corps of Engineers, the Tennessee Valley Authority, the Bureau of Land Management, the U.S. Forest Service, the Bureau of Reclamation, and departments of natural resources from numerous state and local agencies throughout the country. In return the NWS shares other hydrological and meteorological products and information with these agencies.
The National Environmental Satellite, Data Information Service (NESDIS), another agency within NOAA, operates and maintains the GOES Data Collection System (DCS) in support of the NWS and the cooperating agencies (HADS Cooperators). The GOES DCS is physically located at the Wallops Island, Virginia Flight Facility. It is at this facility where the DCP data is downlinked from the GOES satellites and relayed to HADS as well as to the larger DCS community. The data is relayed through an uplink to the DOMSAT satellite as well as a file transfer through dedicated circuit to the National Weather Service Telecommunication Gateway (NWSTG).
HADS uses DOMSAT as its primary data feed. The data are received in a nearly continuous flow from Wallops Island though uplinks to DOMSAT. HADS downlinks and buffers this data into two files per minute and processes this data at 3 minutes cycles. The processing involves the translation of the raw data into Standard Hydrometeorological Exchange Format (SHEF) products. This translation of raw data to SHEF products is a rather complicated process that requires detailed and very descriptive information for every one of the more than 14,850 data sites in this processing environment.
Within the HADS database is meta-data about each of the data sites, some of which is used to translate the data to SHEF. This includes the following:
The HADS processing environment has many redundant features. There are two servers capable of processing the data, one considered the primary system, one the hot backup. There are 3 ways HADS acquires the raw DCP data. The first is a downlink of data from DOMSAT, which is considered the primary method. HADS can failover to an internet feed and/or to a feed from the dedicated circuit from Wallops Island to the NWSTG.
The GOES Data Collection Platforms operated and maintained by the cooperators have 4 basic components.
In self-timed mode, a DCP uplinks its data on a specifically assigned radio frequency, at specific time, on a specific GOES channel, and at defined time intervals. The vast majority of DCPs transmit on a one hour cycle, but some transmit at 30 minute, 2 hour, 3 hour, and 4 hour cycles. Within each DCP's message, the actual interval of the data may be 2, 3, 5, 6, 10, 15, 20, 30 or 60 minutes.
In random mode, also known as critical mode, a DCP will uplink a short message containing 1, 2 or 3 values of one or two 'critical' sensors. The threshold for this type of data transmission is dependent upon how the DCP has been programmed. Typically a random message is generated when a water level reaches and exceeds a predefined height or increases at a predefined rate. Random messages of precipitation data are typically generated when the rainfall rate for a defined time interval is met or exceeded.
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Page last modified: November 27, 2012