What is HADS?
The Hydrometeorological Automated Data Systems (HADS) is a real-time system for acquiring, processing, and distributing hydrometeorological data. It operates within the Meteorological Assimilation Data Ingest System (MADIS), managed by NCEP Central Operations (NCO). HADS primarily supports National Weather Service (NWS) programs, including Flood and Flash Flood Warning efforts conducted by Weather Service Forecast Offices and River Forecast Centers across the U.S. Additionally, HADS data enhances fire weather support, precipitation analysis, hydrological and meteorological modeling, and the verification of NEXRAD precipitation estimates.
HADS collects raw hydrological and meteorological observations from Geostationary Operational Environmental Satellites (GOES) Data Collection Platforms (DCPs). These platforms are managed by over 200 cooperators, including agencies like the U.S. Geological Survey (USGS), U.S. Army Corps of Engineers, Tennessee Valley Authority, Bureau of Land Management, U.S. Forest Service, Bureau of Reclamation, and various state and local natural resource departments. In return, the NWS shares hydrological and meteorological products with these agencies.
The National Environmental Satellite, Data Information Service (NESDIS), a NOAA agency, operates and maintains the GOES Data Collection System (DCS) at Wallops Island, Virginia. This facility downlinks satellite data, relaying it to HADS and the broader DCS community. HADS receives this data through the Local Readout Ground Station (LRGS) software and a dedicated file transfer circuit connecting to the National Weather Service Telecommunication Gateway (NWSTG).
Using LRGS as its primary feed, HADS continuously receives data from Wallops Island and the USGS EDDN every 5-8 seconds, buffering and processing it in two-minute cycles. This process includes translating raw data into Standard Hydrometeorological Exchange Format (SHEF) products. Given the complexity of this translation, HADS requires extensive site-specific information for over 18,500 locations.
HADS Database MetadataWithin the HADS database are metadata about each of the data sites, some of which are used to translate the data to SHEF. This includes the following:
- Owner of the DCP
- NESDIS Identifier
- NWS Location Identifier (NWSLI) associated with the NESDIS Identifier
- Decoding scheme
- Type of data observed (river stage, precipitation, air temperature, etc)
- Units of measurement for each value
- Numerical precision of these values
- Data 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 are 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 website.
HADS has many built in redundancies for data acquistion, processing, and dissemination to prevent outages.
DCP Characteristics
The GOES Data Collection Platforms have four 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.
Self-Timed Mode: Most DCPs transmit on a one-hour cycle, but some transmit at intervals as frequent as 6 minutes. Actual data intervals within self-timed messages range from 1 to 60 minutes.
Random Mode: Also known as critical mode, these generate short messages when a water level or precipitation rate exceeds a predefined threshold.
