Skip Navigation Linkwww.nws.noaa.gov   
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
Hydrometeorological Automated Data System
 
 


The Office of Hydrologic Development of the National Weather Service operates HADS...

The Hydrometeorological Automated Data System

  Real-time and near real-time data acquisition, data processing and data distribution are the attributes of HADS.  The functional requirement of this system encompass a cooperative effort involving a number of federal, state and local agencies.

  HADS 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, hydrologic modeling and the verification of NEXRAD precipitation estimates.

  The data acquisition aspect of HADS involves the receipt of raw hydrologic and meteorologic observation messages from Geostationary Operational Environmental Satellites (GOES) Data Collection Platforms (DCPs).  The NWS operates a relatively small network of DCPs while the vast majority of these observing systems are owned and operated by federal, state and local agencies who share their data resources with the NWS.  In return the NWS shares other hydrologic and meteorologic products and information with these agencies.

  The primary cooperators involved with HADS are the Water Resources Division of the U.S. Geologic Survey, the U.S. Army Corp of Engineers, the Tennessee Valley Authority, the Bureau of Land Management, the U.S. Forest Service, the Bureau of Reclamation, and departments of natureal resouces from numerous state and local agencies through the county.

  Additionally, the National Environmental Satellite, Data Information Service (NESDIS), a component of 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 here that the DCP messages are down-linked from the GOES East and GOES West satellites and relayed to a communication system for subsequent distribution to a large audience, including HADS.

  Raw DCP messages are received in a nearly continuous flow from Wallops Island.  HADS buffers this information into files at 1 minute intervals.  Then every 3 minutes (beginning on the hour) the HADS processor program operates on these files and translates the raw information into Standard Hydrometeorological Exchange Format (SHEF) products.   This translating of raw data to SHEF products, the second attribute of HADS, is a rather complicated process that requires detailed, descriptive information for every one of the more than 12,600 data sites in this processing environment.

  Within HADS, each data site is defined by its reporting characteristics, which include:

  • owner/operator of the DCP
  • GOES address/NESDIS identifier
  • physical elements observed...... (river stage readings, precipitation counters, air temperature sensor, etc)
  • unit of measurement for each value
  • numerical precision of these values
  • time interval at which each element is observed
  • time and interval at which the DCP up-links to a GOES satellite
  • geographical location (latitude & longitude)

  The third attribute of HADS is its ability to disseminate a finished product, SHEF encoded and tailored to the end users needs, to each of the 13 river forecast centers and 123 weather forecast offices in the county as well as to several specialized users within the NWS.  Products are distributed via the internal NWS communication system AWIPS - Satellite Broadcast Network (SBN) and to external users via NOAAPORT.  Certain data products are also distributed to the river forecast centers via the Internet.  Additionally, each reporting site's meta-data along with an extensive amount of tabular and graphic data is made available on the Internet.

  The HADS processing environment represents a complete information system, but not in a typical server/client functional configuration.  Hardware components include five Linux based workstations, two functioning as data processing platforms and others fulfilling the requirements for HADS data site configuration maintenence and HADS software maintenance.   The normal operating activities provides for 1 operational system and 1 'hot' backup.  All processes that execute on the operational unit are likewise performed in real-time on the backup system, providing for a truely redundant matrix.

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

  • Environemntal sensors
  • A datalogger for recording the sensor's information
  • A UHF radio transmitter
  • A yagi antenna

  DCPs are capable of operating into two distinct modes, Selftimed and Random.

  In selftimed mode, a DCP uplinks its' data at a predefined time and on a specifically assigned radio frequency and uplinks occur at defined time intervals.  The majority of DCPs operate on a one hour cycle, the second largest number of platforms operator in a four hour cycle, and others have been programmed report at two and three hour intervals.   Within each DCP's message, the actual data may have been recorded at 3, 5, 15, 30 or 60 minute time intervals.

  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.


Main Link Categories:
HADS Home Page, OHD Home Page, Contact Us
National Weather Service
Office of Hydrologic Development
Page last modified: 22 May, 2007