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What is HADS?

The Hydrometeorological Automated Data Systems (HADS) is a real-time data acquisition, processing, and dissemination system running as part of the Meteorological Assimilation Data Ingest System (MADIS) operated by NCEP Central Operations (NCO). The system exists in support of National Weather Service (NWS) activities of national scope, specifically the Flood and Flash Flood Warning programs administered by the Weather Service Forecast Offices and the operations performed at River Forecast Centers throughout the United States. Additionally HADS created data products bolster several other NWS program areas including fire weather support services, local and national analysis of precipitation events, hydrological and meteorological modeling, and the verification of NEXRAD precipitation estimates and hydrological models.

HADS 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 200 cooperators and a small network of NWS 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), an 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. The facility is responsible for downlinking the data from the GOES satellites and relaying the data to HADS as well as to the larger DCS community. The data is available to HADS via Local Readout Ground Station (LRGS) software as well as a file transfer through a dedicated circuit to the National Weather Service Telecommunication Gateway (NWSTG).

HADS uses LRGS as its primary data feed. The data are received in a nearly continuous flow from Wallops Island and the USGS EDDN through LRGS communications. HADS pulls the data every 5-8 seconds and buffers this data and processes this data on 2 minute 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 17,500 data sites in this processing environment.

Within the HADS database is metadata about each of the data sites, some of which is used to translate the data to SHEF. This includes the following:

Owner of the DCP
NESDIS Identifier
NWS Location Identifier associated with the NESDIS Identifier
Decoding scheme
Type of data observed (river stage, precipitation, air temperature, etc)
Unit of measure for each value
Numerical precision of these values
Time interval for each type of data observed
Time and interval at which the DCP uplinks to a GOES satellite
Geographical location (location name, latitude, longitude)

During the processing and translation of the data from raw to SHEF form, the data is put into individual user reports, which are tailored for the needs of each of the NWS Weather Forecast Offices and River Forecast Centers. The data products are disseminated through the NWSTG which then routes the data products to the AWIPS Network Control Facility (NCF) which in turn broadcasts the data products on the Satellite Broadcast Network. The end users can downlink the reports via NOAAPORT. Additionally HADS will place all users data products on ftp server (ftp://madis-data.ncep.noaa.gov/hads/shef_products) where they remain a number of hours. Finally HADS makes DCP metadata and decoded data available to the field and public via the HADS web site.

HADS has many built in redundancies for data acquistion, processing, and dissemination to prevent outages.

DCP Characteristics

The GOES Data Collection Platforms operated and maintained by the cooperators have 4 basic components.

Datalogger for recording the sensor's information
UHF radio transmitter
Yagi or omni-directional antenna
One to many Environmental sensors

DCPs are capable of operating into two distinct modes, self-timed and random.

In self-timed mode, a DCP uplinks its data on an assigned channel and time. It also has an assigned transmission interval. The vast majority of DCPs transmit on a one hour cycle, but some transmit at 12, 15, 30 minute, 2 hour, 3 hour, and 4 hour cycles. Within each DCP's message, the actual interval of the data may be 1, 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.

Page Updated: January 15, 2021