NOAA Water Level (Tidal) Data of 205 Stations for the Coastal United States and Other Non-U.S. Sites

Metadata also available as - [Outline] - [Parseable text] - [XML]

Frequently anticipated questions:


What does this data set describe?

Title:
NOAA Water Level (Tidal) Data of 205 Stations for the Coastal United States and Other Non-U.S. Sites
Abstract:
The National Ocean Service (NOS) maintains a long-term database containing water level measurements and derived tidal data for coastal waters of the United States and U.S. territories. These data allow for the determination and maintenance of vertical reference datums used for surveying and mapping, coastal construction, waterborne commerce, water level regulation, marine boundary determination, and tide prediction, and for the determination of long-term water level variations (e.g. trends). The data also supports other U.S. government programs, including the National Weather Service (NWS) Tsunami Warning System, the NWS storm surge monitoring programs, and the NOAA Climate and Global Change Program. The database contains an extended series of water level measurements recorded at different tide observation stations. These data are processed to generate a number of products, including monthly and yearly averages for mean tide level, mean sea level, diurnal tide level, mean high and low water, mean range, diurnal mean range, monthly extremes for high and low waters, and frequency and duration of inundations (the number of times and length of time at which the water level has equaled or exceeded a specific elevation for a period of analysis). Data are compiled for coastal waters of the United States, Puerto Rico, the Virgin Islands, and U.S. territories in the Pacific region. Water levels are monitored from a network of over 200 permanent, continuously operating tide observation stations and from numerous stations operated for short-term and long-term projects. Water level measurements are compiled for a variety of observation periods, depending upon the location. For some tide observation stations, records date back to the late 1800s. Observed water level values are compiled primarily at six minute increments. In addition, some stations provide real-time data for planning and emergency situations. The observed values are processed to generate mean and extreme values for different temporal intervals, as noted above. The data consist simply of elevations of water, in feet, observed at specific geographic locations and temporal periods. All water level measurements are referenced to staff '0' and can be referenced to other datums, such as the North American Vertical Datum of 1988 (NAVD 88). Recent data are recorded to the hundredth of a foot; data collected prior to the mid-1960s are recorded to the tenth of a foot. The foundation of the water level database is the National Water Level Observation Network (NWLON), a system of long-term operating tide stations maintained by NOS. Data also are obtained through short-term and long-term cooperative projects with other federal, state, and local agencies and governments to accomplish mutual goals in water level measurement. For example, tide stations are operated temporarily for marine boundary determination and hydrographic survey projects. NOS also maintains several cooperative stations with foreign governments for the Climate and Global Change Program. Indices of tide stations maintained by NOS are available which include for each station the latitude, longitude, dates of observations, bench mark sheet publication date, and tidal epoch. NOS also issues tidal bench mark sheets upon completion of a data collection series or as needed for long-term NWLON stations. Tidal bench mark sheets provide location descriptions and vertical elevations referenced to tidal datums of the station bench marks. A table of tidal datums and the 1929 NGVD, when available, are referenced to the station reference datum. A number of products are issued monthly and annually, for free or on a cost recovery basis. The products are distributed on either hard copy, floppy disk, CD, or over the web and include the following: o Tide Observation Station Lists o Tides, 6-Minute Heights o Tides, Hourly Heights of Tides, Times and Heights of High and Low Waters o Tides, Monthly Mean Summaries o Tidal Bench Mark Sheets with Tidal Datums o Frequency and Duration Analysis of Tidal Water Levels o Daily Mean Sea Level CO-OPS also provides a number of information services for which it charges a fee, based on a professional service rate of $30.00 per hour. The services include the following: o Computation of bench mark elevations and tidal datums. o Computation of the NAVD88 referenced to other tidal datums. o Computation of historical tidal datums. o Providing tidal zoning for hydrographic projects. o Preparing and reviewing certified documents for court use. o Retrieval of requested historical data sets not provided over the web.
  1. How should this data set be cited?

    Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Center for Operational Oceanographic Products and Services (CO-OPS), 200902, NOAA Water Level (Tidal) Data of 205 Stations for the Coastal United States and Other Non-U.S. Sites: NOAA's Ocean Service, Center for Operational Oceanographic Products and Services (CO-OPS), Silver Spring, MD.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -180.0
    East_Bounding_Coordinate: 180.0
    North_Bounding_Coordinate: 70.4
    South_Bounding_Coordinate: -54.8

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date:
    Ending_Date: Present
    Currentness_Reference: Data collected every 6 minutes

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: map

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • Point (205)

    2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.001. Longitudes are given to the nearest 0.001. Latitude and longitude values are specified in Decimal Degrees.

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    CO-OPS water level stations collect data using six different sensor types (However, note that not every water level station collects data using all six sensor types): - Air Temperature gauges measure the average kinetic energy of the air molecules that surround it. The kinetic energy if an air molecule is directly proportional to the velocity of the molecule. - Water Temperature gauges measure the average kinetic energy of water particles. - Conductivity Sensors measure the ability of water molecules to pass an electrical current - Water level sensor is an air acoustic measurement device. It is both self-calibrating for variations in the speed of sound and can be leveled directly to local benchmarks that provide absolute measurements referenced to local water level datums. - Wind Measurement Sensor- scientific instrumentation to measure wind speed and direction. - Barometric Pressure Sensors- scientific instrumentation to measure barometric pressure.
    Entity_and_Attribute_Detail_Citation: Specific Water Level Gages:
    Entity_and_Attribute_Detail_Citation:
    - Aquatrak Model 4100 (air acoustic sensor) measures liquid level using a ratio metric technique. The sensor is driven by a microprocessor, a series of electrical pulses are transmitted from the sensor controller and to the transducer. The transducer converts the electrical pulses into acoustic pulses and sends them to the water surface via a sounding tube. As the acoustic signal passes through the cal tube an echo is produced which is returned to the sensor receiver. When the pulse strikes the liquid surface another echo is produced which is also returned to the receiver. The patented ratio metric technique is based upon a pulse time of travel comparison within the known (through the cal tube) to an unknown distance to the liquid level (through the sounding tube). The controller initiates the transducer, times and stores the cal echo, and times and stores the liquid level return echo. The on-board microprocessor calculates the ratio, applies any programmed offsets, performs engineering conversions, and stores the data awaiting a data request from the host data logger or PC (www.aquatrak.com).
    Entity_and_Attribute_Detail_Citation:
    - Aquatrak liquid level sensor VX1080 uses a ratio metric technique that compares pressure pulses. The VX 1080 is one of two versions of the Aquatrak rail-mount package for simple integration into the VX1100 system (www.vitelinc.com).
    Entity_and_Attribute_Detail_Citation:
    - Dual Orifice Bubbler Paroscientific Quartz Sensor is a pressure transducer sensing device for water level measurement. A relative transducer is vented to the atmosphere and pressure readings are made relative to atmospheric pressure. An absolute transducer measures the pressure at its location. The readings are then corrected for barometric pressure taken at the surface. The accuracy, relative to the Datum, is 0.02 meters (individual measurement) and 0.005 meters (monthly means). Thirty-six five second water level samples centered on each tenth of an hour are averaged, a three standard deviation outlier rejection test applied, the mean and standard deviation is recalculated and reported along with the number of outliers (www.paroscientific.com).
    Entity_and_Attribute_Detail_Citation:
    - Absolute Shaft Angle Encoder (BEI Sensors) provides an absolute position information over multiple turns of the input shaft. This sensor is attached to a float/wire system and is used to determine the water level at CO-OPS water level station located on the Great Lakes. These systems are typically configured with 6 ft. diameter sumps that are connected to the lake via an intake pipe. These substantial structures are required to provide reliable water level measurements throughout the harsh Great Lakes winters. (www.beiied.com).
    Entity_and_Attribute_Detail_Citation:
    - Single Orifice Bubbler Strain Gauge Sensor (Druck, IMO, KPSI) A pressure transducer sensing device for water level measurement. The sensor measures water depth by measuring the water head on top of the orifice (www.kpsi.com; www.druck.com).
    Entity_and_Attribute_Detail_Citation:
    - Air Temperature gauges (Yellow Springs Instruments YSI) measure the average kinetic energy of the air molecules that surround it. The kinetic energy of an air molecule is directly proportional to the velocity of the molecule. Twenty equally spaced samples collected over a two minute period are averaged for each measurement. Accuracy for this sensor is 0.2 degree C (www.ysi.com).
    Entity_and_Attribute_Detail_Citation:
    - Water Temperature gauges (Yellow Springs Instrument YSI) measure the average kinetic energy of water particles. Twenty equally spaced samples collected over a two minute period are averaged for each measurement. Accuracy for this sensor is 0.2 degree C (www.ysi.com).
    Entity_and_Attribute_Detail_Citation:
    - WS425 Ultrasonic Wind Sensor (Vaisala) uses ultrasound to determine horizontal wind speed and direction. The measurement is based on transit time, the time it takes for the ultrasound to travel from one transducer to another, depending on the wind speed. The transmit time is measured in both directions for a pair of transducer heads. Using two measurements for each of the three ultrasonic paths at 60 degree angles to each other, the WS425 computes the wind speed and direction. Wind speed accuracy: +/- 0.135 m/s or 3% of the reading, whichever is greater. Wind direction accuracy: +/- 2 degrees (www.vaisala.com).
    Entity_and_Attribute_Detail_Citation:
    - RM YOUNG Wind Monitor measures wind speed and direction. The wind sensor is a propeller with a rotation that produces an AC sine wave voltage signal with a frequency directly proportional to wind speed. The wind direction sensor is a vane whose angle is sensed by a precision potentiometer. When a known excitation voltage is applied to the potentiometer, the output is directly proportional to the vane angle. Accuracy: Wind Speed: +/- 0.3 m/s and Wind direction: +/- 3 degrees (www.youngusa.com).
    Entity_and_Attribute_Detail_Citation:
    - Barometric sensors (Vaisala and Setra) are designed to take accurate barometric measurements at room temperature and for general environmental pressure monitoring over a wide temperature range. The barometric surface pressure is taken into account due to the effect of the hydrostatic pressure of air in different areas. Accuracy: Vaisala: +/- 0.3 hPa; Setra: +/- 0.05% full scale (www.vaisala.com; www.setra.com)
    Entity_and_Attribute_Detail_Citation:
    - Conductivity Sensor (Falmouth Science and Greenspan) measure the ability of water molecules to pass an electrical current. Twenty equally spaced samples collected over a 2 minute period are averaged for each measurement. Accuracy for this sensor is 0.1 mS/cm (www.falmouth.com; www.greenspan.com).
    Entity_and_Attribute_Detail_Citation:
    - Visibility Sensor (Belfort Model 6000) is designed to monitor visibility over a range of 0-10 miles (0-16 km). It includes both analog and digital outputs. Visibility is detected using widely accepted principles of forward scattering. A high output infrared LED transmitter projects light onto a sample volume, and light scattered in a forward direction is collected by the receiver. The sensor's analog output is proportional to the visibility (www.belfortinstrument.com).
    Entity_and_Attribute_Detail_Citation:
    - Sutron Xpert Datalogger/Controller (Sutron) is the new primary data collection platform for the National Water Level Observation Network. Low power is 486 CPU-66MHz. It has a 1/4 VGA active touch screen. The system memory specifications are 1 MB flash log, 1 MB flash Applications, 4 MP Ops system, a 8 MB RAM, and a PCMCIA memory card can be added for additional storage up to 1 GB. The system has a high data rate GOES transmitter; a GPS receiver for time synchronization; eight RS232's for data retrieval; an SDI- 12; 1^2C expansion modules with two analog modules that contain 12 single ended, 6 differential and a 16 bit A/D and one digital module with 8 digital I/O lines supporting CMOS level inputs. There is a separate termination board for each module with additional surge suppression. All the RS-232 connections that will be talking to external devices have separate termination boards. A 56K modem is also included which has an additional surge suppression (www.sutron.com).
    Entity_and_Attribute_Detail_Citation:
    - Sutron 9210 (Sutron) is the new backup data collection platform for the National Water Level Observation Network. Low power is 486 CPU-66MHz. The system memory specifications are 1 MB flash log, 1 MB flash Applications, 4 MB Ops system, a 8 MB RAM, and a PCMCIA memory card can be added for additional storage up to 1 GB. The specifications are three RS232 connections that have separate termination boards with additional surge suppression for the ones that will be talking to external devices; a SDI-12; one digital I^2 expansion module with 8 digital inputs. There us a separate termination board for each module with additional surge suppression. A 56K modem is also included which has an additional surge suppression (www.sutron.com).
    Entity_and_Attribute_Detail_Citation:
    - Hydro Water Level Gauge systems (new) are based on the Sutron 9210 and they include a GOES transmitter and a telephone modem. Low power is 486 CPU-66MHz. The system memory specifications are 1 MB flash log, 1 MB flash Applications, 4 MB Ops system, a 8 MB RAM, and a PCMCIA memory card can be added for additional storage up to 1 GB. The specifications are three RS232 connections that have separate termination boards with additional surge suppression for the ones that will be talking to external devices; a SDI-12; one digital I^2 expansion module with 8 digital inputs. There is a separate termination board for each module with additional surge suppression. A 56K modem is also included which has an additional surge suppression (www.sutron.com).


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    NOAA's Ocean Service, Center for Operational Oceanographic Products and Services (CO-OPS)

  3. To whom should users address questions about the data?

    National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Center for Operational Oceanographic Products and Services (CO-OPS)
    1305 East-West Highway N/OPS3
    Silver Spring, MD 20910
    U.S.A.

    301-713-2981 (voice)
    301-713-4392 (FAX)
    co-ops.userservices@noaa.gov Hours: 0900 - 1700, Monday to Friday, EST


Why was the data set created?

The National Water Level Observation Network is a key part of the NOAA Tsunami Warning System and the NOAA Storm Surge Warning System. NWLON stations support Physical Oceanographic Real-Time Systems (PORTS) in major ports and harbors. NWLON stations have standard configurations of water level sensors (including backup sensors), backup and primary data-collection platforms, solar panel power, GOES satellite radios, and telephone modems. Sensors are calibrated and vertically referenced to nearby networks of benchmarks. The data continuity, the vertical stability and careful referencing of NWLON stations have enabled the data to be used to estimate relative sea-level trends for the nation.


How was the data set created?

  1. From what previous works were the data drawn?

    National Water Level Observation Network (NWLON) (source 1 of 1)
    NOAA's Ocean Service, Center for Operational Oceanographic Products and Services (CO-OPS), Unknown, National Water Level Observation Network: NOAA's Ocean Service, Center for Operational Oceanographic Products and Services (CO-OPS), Silver Spring, MD.

    Online Links:

    Other_Citation_Details:
    CO-OPS Data Disclaimer: These raw data have not been subjected to the National Ocean Service's quality control or quality assurance procedures and do not meet the criteria and standards of official National Ocean Service data. They are released for limited public use as preliminary data to be used only with appropriate caution.
    Type_of_Source_Media: online, CD ROM, paper
    Source_Contribution: NWLON and NOS Water Level Stations

  2. How were the data generated, processed, and modified?

    Date: Not complete (process 1 of 1)
    Data is recorded and transmitted then goes through a quality control procedure and is loaded into a database.

    Person who carried out this activity:

    National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Center for Operational Oceanographic Products and Services (CO-OPS)
    1305 East-West Highway N/OPS3
    Silver Spring, MD 20910
    U.S.A.

    301-713-2981 (voice)
    301-713-4392 (FAX)
    co-ops.userservices@noaa.gov Hours: 0900 - 1700, Monday to Friday, EST

  3. What similar or related data should the user be aware of?


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    One hundred and eighty one, one-second water level samples centered on each tenth of an hour are averaged, a three standard deviation outlier rejection test applied, the mean and standard deviation is recalculated and reported along with the number of outliers.

  2. How accurate are the geographic locations?

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    Preliminary Data Preliminary data have not been subjected to the National Ocean Service's quality control or quality assurance procedures and do not meet the criteria and standards of official National Ocean Service data. They are released for limited public use as preliminary data to be used only with appropriate caution. Predicted Tidal Data The accuracy of the tide predictions is different for each location. Periodically we do a comparison of the predicted tides vs. the observed tides for a calendar year. The information generated is compiled in a Tide Prediction Accuracy Table. We work to insure that the predictions are as accurate as possible. However, we can only predict the astronomical tides, we cannot predict the effect that wind, rain, freshwater runoff, and other short-term meteorological events will have on the tides.

  5. How consistent are the relationships among the observations, including topology?

    Preliminary Data Preliminary data have not been subjected to the National Ocean Service's quality control or quality assurance procedures and do not meet the criteria and standards of official National Ocean Service data. They are released for limited public use as preliminary data to be used only with appropriate caution. Predicted Tidal Data The accuracy of the tide predictions is different for each location. Periodically we do a comparison of the predicted tides vs. the observed tides for a calendar year. The information generated is compiled in a Tide Prediction Accuracy Table. We work to insure that the predictions are as accurate as possible. However, we can only predict the astronomical tides, we cannot predict the effect that wind, rain, freshwater runoff, and other short-term meteorological events will have on the tides. In general, predictions for stations along the outer coast are more accurate than those for stations farther inland; along a river, or in a bay or other estuary. Inland stations tend to have a stronger non-tidal influence; that is, they are more susceptible to the effects of wind and other meteorological effects than stations along the outer coast. An example of an inland station which is difficult to predict is Baltimore, Maryland. This station is located at the northern end of Chesapeake Bay. Winds, which blow along the length of the bay, have been known to cause water levels to be 1-2 feet above or below the predicted tides. Stations in relatively shallow water, or with a small tidal range, are also highly susceptible to meteorological effects and thus difficult to accurately predict. At these stations, short-term weather events can completely mask the astronomical tides. Many of the stations along the western Gulf of Mexico fall into this category. An example is Galveston, Texas. This station is in a bay which is relatively shallow and has a small opening to the sea. At this station it is possible for meteorological events to delay or


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None
Use_Constraints:
Preliminary Data Preliminary data have not been subjected to the National Ocean Service's quality control or quality assurance procedures and do not meet the criteria and standards of official National Ocean Service data. They are released for limited public use as preliminary data to be used only with appropriate caution. Predicted Tidal Data The accuracy of the tide predictions is different for each location. Periodically we do a comparison of the predicted tides vs. the observed tides for a calendar year. The information generated is compiled in a Tide Prediction Accuracy Table. We work to insure that the predictions are as accurate as possible. However, we can only predict the astronomical tides, we cannot predict the effect that wind, rain, freshwater runoff, and other short-term meteorological events will have on the tides.

  1. Who distributes the data set? (Distributor 1 of 1)

    National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Center for Operational Oceanographic Products and Services (CO-OPS)
    1305 East West Highway N/OPS
    Silver Spring, MD 20190
    U.S.A.

    301-713-2981 (voice)
    301-713-4392 (FAX)
    co-ops.userservices@noaa.gov Hours: 0900 - 1700, Monday to Friday, EST

  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    Preliminary DataPreliminary data have not been subjected to the National Ocean Service's quality control or quality assurance procedures and do not meet the criteria and standards of official National Ocean Service data. They are released for limited public use as preliminary data to be used only with appropriate caution.Predicted Tidal DataThe accuracy of the tide predictions is different for each location. Periodically we do a comparison of the predicted tides vs the observed tides for a calendar year. The information generated is compiled in a Tide Prediction Accuracy Table. We work to insure that the predictions are as accurate as possible. However, we can only predict the astronomical tides, we cannot predict the effect that wind, rain, freshwater runoff, and other short-term meteorological events will have on the tides.In general, predictions for stations along the outer coast are more accurate than those for stations farther inland; along a river, or in a bay or other estuary. Inland stations tend to have a stronger non-tidal influence; that is, they are more susceptible to the effects of wind and other meteorological effects than stations along the outer coast. An example of an inland station which is difficult to predict is Baltimore, Maryland. This station is located at the northern end of Chesapeake Bay. Winds which blow along the length of the bay have been known to cause water levels to be 1-2 feet above or below the predicted tides.Stations in relatively shallow water, or with a small tidal range, are also highly susceptible to meteorological effects and thus difficult to accurately predict. At these stations, short-term weather events can completely mask the astronomical tides. Many of the stations along the western Gulf of Mexico fall into this category. An example is Galveston, Texas. This station is in a bay which is relatively shallow and has a small opening to the sea. At this station it is possible for meteorological events to delay or accelerate the arrival of the predicted tides by an hour or more.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 29-Oct-2013
Metadata author:
National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Center for Operational Oceanographic Products and Services (CO-OPS)
Chief, Products and Services Division (CO-OPS)
1305 East-West Highway N/OPS3
Silver Spring, MD 20910
U.S.A.

301-713-2981 (voice)
301-713-4392 (FAX)
co-ops.userservices@noaa.gov Hours: 0900 - 1700, Monday to Friday, EST

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)


Generated by mp version 2.9.13 on Sun Nov 23 10:43:49 2014