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What tidal current predictions and observed current data are available?
The availability of tidal current predictions and observed current data is limited compared to the availability of tide data. Continuous measurements of currents were not possible until recently. Short deployments of current meters at various estuaries have been carried out for over 100 years. Archived data sets are available but data quality can vary considerably based on the age of the data and location of the measurements. Data from the last 30 years is in digital form; older data exists as paper transcripts. Inquiries about specific locations to ascertain if data exists, its quality and availability will be answered by our office. You can contact our office at (301) 713-2815 between 7AM-3PM Eastern Time. You may also submit an inquiry to our e-mail address at: Tide.Predictions@noaa.gov
Recent current observations exist where a National Ocean Service (NOS) PORTS is installed, for example, Houston/Galveston, Tampa Bay, San Francisco Bay, New York/New Jersey Harbor, and Narragansett Bay. Data collect since May 1999, can be accessed and downloaded from the INFOHUB . Historical PORTS data prior to 1999 are available by special request as described above.
NOS tidal current predictions are available in various bays, harbors, estuaries, and within rivers and channels. Inquiries and requests for tidal current predictions should be sent to our office as described above.
Currents are spatially variable, thus predictions should NOT be extrapolated even to near-by locations. Interpolation between two near-by locations should NOT be attempted. Use of such extrapolations can be hazardous.
How can I get predictions of tidal currents
Short term tidal current predictions for a single calendar month can be obtained via e-mail from: Tide.Predictions@noaa.gov. Subsequent requests for additional months will be subject to the fee for custom predictions described below.
Long term tidal current predictions (more than 1 month) are not available through the WWW, internet, or e-mail from our office. You can obtain long term tidal current predictions on a calendar year basis by calling our office at (301) 713-2815 between 7AM-3PM Eastern Time. You may also obtain tide predictions by submitting a request to our e-mail address at: Tide.Predictions@noaa.gov If you elect to submit your request via e-mail, please include the following information.
Your Full Name
Your Full Mailing Address (NOT E-mail)
Your Phone Number (Including Area Code)
The Location(s) for which you want predictions
The Format and Options you want included (see next question below)
- With or Without Daylight Savings Time
- Standard, International, or Manuscript Format
Since Standard and Manuscript formats can be provided on hard-copy (paper) or on diskette, when requesting either of these formats please indicate which media you want provided. If no preference is listed, a paper copy will be provided.
The tidal current predictions will be sent to the mailing address you provide.
***** PLEASE NOTE *****
There is a fee for long term tidal
current predictions. This fee is normally $35 for a calendar year of predictions at one
location. Each additional year or location is $10.
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What formats are tidal current predictions available in?
Tidal current predictions are available in several different formats.
International Format - This format is an electronic ASCII file which provides time and speed of current for a single location in a column delimited format. This format is most suitable for importing into a database, plotting, or other computer program. The following example for ADMIRALTY INLET, WA, April, 1997 shows the predictions in Pacific Standard Time using 24-hour notation. Tidal current predictions are only available in Local Standard Time using 24-hour notation.
06030 1 4979999 254 -1.7 650 824 0.4 9551434 -2.618232129 1.999999999 99.9 1 06030 2 497 43 403 -1.9 756 943 0.611281548 -2.619292233 2.199999999 99.9 2 06030 3 497 140 503 -2.3 8471055 1.013011658 -2.820302330 2.299999999 99.9 3 06030 4 497 230 555 -2.8 9321157 1.514211801 -3.021279999 99.999999999 99.9 4 06030 5 4979999 22 2.4 314 642 -3.210151252 2.015291857 -3.122209999 99.9 5 06030 6 4979999 109 2.4 356 727 -3.510581343 2.416311950 -3.223119999 99.9 6 06030 7 4979999 154 2.3 435 809 -3.811411431 2.717282041 -3.199999999 99.9 7 06030 8 497 2 238 2.1 512 851 -3.912241519 2.918222131 -3.099999999 99.9 8 06030 9 497 52 322 1.9 548 933 -3.813081606 2.919152221 -2.799999999 99.9 9 0603010 497 144 406 1.5 6231016 -3.613541655 2.720072312 -2.499999999 99.9 10 0603011 497 240 451 1.2 6591101 -3.314431745 2.421019999 99.999999999 99.9 11 0603012 4979999 7 -2.1 344 541 0.8 7351149 -3.015351838 2.121569999 99.9 12 0603013 4979999 107 -1.9 458 637 0.5 8151243 -2.616321936 1.922539999 99.9 13 0603014 4979999 212 -1.8 624 745 0.3 9051345 -2.317342038 1.623509999 99.9 14 0603015 4979999 319 -1.8 741 900 0.310191454 -2.018382140 1.599999999 99.9 15
Standard Format - This format is available in hardcopy and as an electronic ASCII file which provides time and speed of current for a single location in a page readable format. The following example for ADMIRALTY INLET, WA, April, 1997 shows the predictions in Pacific Standard Time using 24-hour notation. Tidal current predictions are only available using 24-hour notation, but can be adjusted to reflect Daylight Savings Time.
Admiralty Inlet, Wash. T.M. 120 W.
Predicted Tidal Current April, 1997
Flood Direction, 180 True. Ebb (-)Direction, 5 True.
NOAA, National Ocean Service
Slack Maximum Slack Maximum Slack Maximum Slack Maximum Slack Maximum
Water Current Water Current Water Current Water Current Water Current
Day Time Time Veloc Time Time Veloc Time Time Veloc Time Time Veloc Time Time Veloc
h.m. h.m. Knots h.m. h.m. Knots h.m. h.m. Knots h.m. h.m. Knots h.m. h.m. Knots
1 9999 254 -1.7 650 824 0.4 955 1434 -2.6 1823 2129 1.9
2 43 403 -1.9 756 943 0.6 1128 1548 -2.6 1929 2233 2.1
3 140 503 -2.3 847 1055 1.0 1301 1658 -2.8 2030 2330 2.2
4 230 555 -2.8 932 1157 1.5 1421 1801 -3.0 2127 9999 99.9
5 9999 22 2.4 314 642 -3.2 1015 1252 2.0 1529 1857 -3.1 2220 9999 99.9
6 9999 109 2.4 356 727 -3.5 1058 1343 2.4 1631 1950 -3.2 2311 9999 99.9
7 9999 154 2.3 435 809 -3.8 1141 1431 2.7 1728 2041 -3.1
8 2 238 2.1 512 851 -3.9 1224 1519 2.9 1822 2131 -3.0
9 52 322 1.9 548 933 -3.8 1308 1606 2.9 1915 2221 -2.7
10 144 406 1.5 623 1016 -3.6 1354 1655 2.7 2007 2312 -2.4
11 240 451 1.2 659 1101 -3.3 1443 1745 2.4 2101 9999 99.9
12 9999 7 -2.1 344 541 0.8 735 1149 -3.0 1535 1838 2.1 2156 9999 99.9
13 9999 107 -1.9 458 637 0.5 815 1243 -2.6 1632 1936 1.9 2253 9999 99.9
14 9999 212 -1.8 624 745 0.3 905 1345 -2.3 1734 2038 1.6 2350 9999 99.9
15 9999 319 -1.8 741 900 0.3 1019 1454 -2.0 1838 2140 1.5
Manuscript Format - This format is available in hardcopy and as an electronic PostScript file, which provides time and speed of current for a single location in a 3-month per page format. This format includes additional information such as the day of week and phases of the moon. Tidal current predictions are only available using 24-hour notation, but can be adjusted to reflect Daylight Savings Time.
Example for ADMIRALTY INLET, April-June, 1997 .
Where can I get information on the Gulf Stream?
The Gulf Stream is an ocean current in the western North Atlantic Ocean that is a major component of the circulation of the water in this ocean basin. It flows generally northward along the east coast of the U.S. from Florida to North Carolina. The current turns toward the northeast, away from the coast of the U.S. in the area of Cape Hatteras, NC.
Knowledge of the position of the Gulf Stream is important to fishermen, weather forecasters, Coast Guard search and rescue operations, and many others. Changes in the position and speed of the Gulf Stream are mostly caused by environmental rather than astronomical effects. NOS does not have observations or predictions available for the Gulf Stream. Gulf Stream analysis and position information is available from a variety of private vendors and other sites on the WWW; including the:
Marine Remote Sensing Lab at Rutgers University
Naval Atlantic Meteorology and Oceanographic Center
John Hopkins University Applied Physics Lab
University of Miami School of Marine and Atmospheric Science
Where can I get information on currents in the oceans?
Our office is responsible for information on Tidal Currents. Tidal Currents are the currents caused by the rise and fall of the tides into and out of bays, estuaries, and harbors. We do not have information on currents in the open ocean. The following web site may have information that you are looking for:
Marine Remote Sensing Lab at Rutgers University
Naval Atlantic Meteorology and Oceanographic Center
John Hopkins University Applied Physics Lab
University of Miami School of Marine and Atmospheric Science
Woods Hole Oceanographic Institute
University of Hawaii
Scripps Institute Data Services Directory
How can I get a copy of the program that you use to make tidal current predictions?
Our office does offer copies of the program that we use to make predictions for the NOS Tidal Current Reference Stations. Our office is not in the business of software development and distribution. The program we use was developed for our use and is not user friendly. The program is written in FORTRAN and requires the use of a separate control file for each location that predictions are being made for. This control file must be altered each time you want to make tidal current predictions for different time periods. A copy of the tidal current prediction program is available from our office by calling (301) 713-2815 between 7AM-3PM Eastern Time. You can also submit a request for a copy of the program by sending e-mail to our address:Tide.Predictions@noaa.gov. If you elect to submit your request via e-mail, please include the following information:
Your Full Name
Your Full Mailing Address (NOT E-mail)
Your Phone Number (Including Area Code)
Note in your message that you want the tidal current prediction program
The Location(s) you want control files for.
***** PLEASE NOTE *****
There is a fee for a copy of this
program. This fee is $39. The program comes with the control file for one NOS
Tidal Current Reference Station of your choice. Additional stations are
available at a cost of $10 each.
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I want to develop my own program to predict tidal
currents.
What information can you provide me with which will help me do
this?
There are a number of products/services that we can offer you.
1) "Our Restless Tides" - A booklet which describes the astronomical forces which cause the tides in terms that can be understood by a lay person. (cost $5)
2) Manual of Harmonic Analysis and Prediction of Tides (Special Pub 98) - This book describes the process of tidal analysis and the mathematics behind tidal predictions. The material covered in the book is fairly detailed; with illustrations, graphs, and tables to provide additional information. (cost $22)
3) "Computer Applications to Tides in the National Ocean Service (Supplement to Special Pub 98)" - A booklet which describes the methods of predicting tides that are used by NOS. The booklet contains sample algorithms for tidal data analysis and tidal predictions. (cost $15)
4) Tidal Current Prediction Package - The predictions package includes a copy of items 2 and 3 listed above. The package also includes a limited copy of the tidal current prediction program (NCP2) used by NOS to generate tidal current predictions. The program is a FORTRAN program and is not very user friendly. The program requires the use of a control file containing the harmonic constants for each location that tidal currents are to be generated for. This control file has to be altered each time that tidal currents are being predicted for a different time period. Copies of the compiled and source code for the program are provided. The program only works for locations that harmonic constants are available for; the NOS tidal current reference stations. The package comes with a control file (harmonic constants) for one Tidal Current Reference Station of your choice. (cost $39)
5) Tidal Current Harmonic Constants - copies of the tidal current
harmonic constants, provided in hardcopy or in NCP2 control file format, are
available for 40 Tidal Current Reference Stations.
(cost $36 each)
6) Tidal Current Table-2 Files - These are a list of the NOS
secondary stations whose tidal current predictions are generated by applying
time and speed corrections to each of the four tidal current phases. There are
two Table-2 files for the U.S.:
- Tidal Current tables for the Atlantic Coast
- Tidal Current
tables for the Pacific Coast
(cost $88 each)
*** PLEASE NOTE ***
As the bays and estuaries change due to
natural and artificial processes (shoaling, erosion, dredging, construction) the
tidal currents for the area can be effected. The tide and tidal current
harmonic constants and Table-2 corrections can change as more recent data is
received and analyzed.
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You can discuss your request or obtain any of the products listed above by calling our office at (301) 713-2815 between 7AM-3PM Eastern Time. You may also request these products by submitting a request to our e-mail address at Tide.Predictions@noaa.gov
If you elect to submit your request via e-mail, please include the following information:
Your Full Name
Your Full Mailing Address (NOT E-mail)
Your Phone Number (Including Area Code)
The Information you want.
The information requested will be sent to the mailing address you provide along with an invoice for payment.
