World of Ham Radio 1997/WOHR97_AmSoft_(1997-02-01).iso/weather/wea_03/amsoft.iii

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                               TIDES.DOC

           DOCUMENTATION FOR TIDES - VERSION 2.00 - 1991 APR 14

                           Edward P. Wallner
                           32 Barney Hill Road
                           Wayland, MA 01778-3602
                           (508)-358-7938

            (Note: Recent changes and additions are underlined)

   This is a program for predicting the height of the tide or the strength of
   the tidal current at various stations. It runs on IBM compatible machines
   under MS-DOS or IBM-DOS. The method and format followed in the predictions
   are generally those used by the National Ocean Service (NOS) in the
   standard tide and current tables.

   This program may be freely copied and used for non-commercial purposes.
   If you find it useful a contribution of $15 is requested. In any case feel
   free to use the programs and pass them on without alteration and without
   charge.

   The author assumes no responsiblity for any errors in the program or the
   predictions.

   Detailed predictions are made for high and low water (or maximum ebb and
   flood) at reference stations for which the tidal constants have been
   derived from observations made over a long period of time. The tides for
   subordinate stations are found by making corrections to the times and
   heights (or speeds) at the reference stations. The predictions for
   subordinate stations are less accurate than for reference stations,
   particularly for the lower high and higher low water where tides are
   nearly diurnal. Current floods/ebbs at subordinate stations may also be
   less accurate. For stations where the current is rotary the current along
   the principal axis is predicted. The times and speeds of flood and ebb in
   these cases are approximate.

   The TIDES program predicts the height of the tide or strength of the
   current at any time. The values at reference stations are of the same
   order of accuracy at any time as for the high/low or flood/ebb values. The
   predictions for subordinate stations may be less accurate at intermediate
   times, the more so the larger the differences from the reference station

    REQUIREMENTS AND CHARACTERISTICS

   TIDES should run on any IBM machine or compatible with 128K of free memory
   and the text output should be OK on any printer. The plot of tide heights
   on the monitor works on the Color Graphics Adapter (CGA) board and on the
   printer uses codes for the EPSON (IBM extended ASCII.) Special codes to set
   up NEC pinwriter printers are also available. TIDES.EXE, the executable
   version of the prediction program, runs with or without an 80x87
   coprocessor.

   TIDES computes the highs and lows for Boston for a month in about 1½
   minutes on an IBM-XT with an 8087 coprocessor, and in about 38 minutes
   without an 8087. (An 8087 coprocessor can be bought for less than $100 and
   is a good investment if you do much number crunching, such as tidal
   predictions. For systems with a 80286 or higher chip the program is
   reasonably fast without a coprocessor.)

   Predictions for Boston and New York for 1986 agreed with the standard
   tables to the minute and tenth of a foot for most cases with some times off
   by 2 or 3 minutes and an occasional difference of .1 or .2  foot. Currents
   in Cape Cod Canal were generally within 0.1 knot. (If the tide level
   remains nearly constant for an extended period the predicted time of high
   of low can vary considerably but the height will still be accurate.)

   Predictions should be accurate for any era within a few centuries of the
   present unless the physical conditions at the station change. Accuracy
   increases very slightly using short prediction intervals. Intervals much
   greater than one year may lead to significant error and those greater than
   480 days are rejected.

   The source program TIDES.BAS is written in QuickBASIC. In order to fit a
   good selection of station constants on the distribution disk, the source
   program is omitted. It is available to contributors on request.

   PROGRAM OPERATION

   Just enter TIDES and follow the prompts exactly, filling in zeros if
   required by the prompt format. When TIDES is run the highs and lows for the
   next week are first computed for a chosen default station, then a menu is
   given. In general entering "Q" will stop any operation and return you to
   the menu.

   When the "CHANGE STATION" or "CHANGE DEFAULT STATION" option is executed a
   list of stations for which tidal constants have already been stored in the
   TIDES format is shown, including the file names under which they are kept.
   The first pages give all of the U.S. reference stations except those in
   Alaska. The following pages show a selected set of stations for a specific
   area.  The next page is shown when M is pressed and the list is restarted
   from the top when R is pressed.

   When the desired station is on the screen press S to stop paging. You will
   then be prompted to enter the station file name which is shown in
   parentheses after the station coordinates.

   The root directory can hold only 112 files so some disks include more files
   in an additional directory, e.g. /VIN FOR Martha's Vineyard and /KEYS for
   the Florida Keys. These directories include a list of the station files
   named STALIST.XXX which may be added to the STALIST.T_C used by the
   program.

   The list can be edited using EDLIN or any other text editing program. For
   example undesired stations can be eliminated and other station titles
   moved to the desired line.

   The station names and locations stored in file STALIST.T_C are displayed
   by the program as a reminder, but the name of any file of data in the TIDES
   format can be used whether it is on the screen or not. New stations for
   which no data file exists can be created using menu option H.

   The main menu gives options for computing and printing highs and lows, for
   computing and printing hourly heights, for plotting heights at a given
   interval (0.5 hours generally works well), for computing the height at
   specified dates and times, for changing the time interval and station, for
   changing the default station, for creating additional data files, for
   changing from metric to English units or vice-versa and for printing the
   astronomical and constituent factors entering the predictions (used mainly
   for verifying the program). The equivalent quantities are computed for
   tidal currents.

   The printed output can be redirected to a file instead of the printer. The
   output will be an ASCII file which can be edited using any text editor.

   CREATING ADDITIONAL DATA FILES

   Option H is used to generate data files for the TIDES program both for
   stations for which harmonic constants are available and for subordinate
   stations, for which only differences from a reference station are
   available.

   First a title and file name for the station are entered. The prompt for
   the title has places for the latitude and longitude of the station which
   are optional inputs for better identification and do not affect the
   computation. For stations for which harmonic constants are available you
   are then prompted to enter the type of station (tide, current, or
   hydraulic current) and the amplitude and epoch of each of 37 tidal
   constituents. The constants are entered in sequence from the NOS form 444
   of "Standard Harmonic Constants for Prediction", columns B (?.??xH) and D
   (k'). If there is no data in column  B, use column H (Amplitude). If the
   amplitude of a constituent is zero entering "0" or just a carriage return
   will enter 0 for both the amplitude and epoch. The modified epoch D (k')
   should be entered as a number from 0 to 360; ignore any minus sign in
   column D.

   Several minor constituents can optionally be inferred from the major
   constituents if they are not entered directly. This generally gives a
   slight improvement in accuracy at the cost of a slight increase in running
   time.

   For subordinate stations the corresponding reference station data must have
   been entered. The list of stations for which data is already stored is
   shown and the file name of the reference station entered. The time
   differences between the reference and subordinate stations at high and low
   (or maximum flood and ebb) are entered, then the height differences. In
   some cases the range of the tide at both stations is requested, as is the
   maximum flood and ebb for current stations. This data can be taken from
   Table 2 of the NOS tide or current tables.

   When Option H is run the title of the new station is added to the end of
   the STALIST.T_C file. This file must be edited if it is desired to place
   the station title in a different line.

   DATA SOURCES

   A list of places for which I currently have harmonic constants is given at
   the end of this document.

   The harmonic constants for various North American reference stations are
   published by:
      National Oceanographic and Atmospheric Administration
      National Ocean Service N/OMA132
      Rockville, Maryland 20852

   I have a complete set of this data for all U.S. reference stations, about
   76 other U.S. stations and many stations in British Columbia (see
   BCLIST.TXT for a list of these.) I will send a copy of a limited number of
   station constants and subordinate station corrections if you will let me
   know the area of interest and send a stamped self addressed 9¼"x4"
   envelope. The stations for which constants are available are listed below.

   The International Hydrographic Organization maintains a data bank of tidal
   constants for  4208 stations worldwide. If you wish constants for foreign
   locations send me the latitudes and longitudes (to the nearest minute) with
   a self addressed, stamped envelope and I will eventually send the constants
   for the closest station in the IHO data set. (The IHO data uses the symbols
   H for amplitude and G for phase in place of k'.)

   The tide tables published by the British Admiralty give data for use in
   their Simplified Harmonic Method of Tidal Prediction. This data is given
   for about 4400 tide and 148 current stations world wide. A PC program
   implementing this method is also distributed. Harmonic constants are given
   for M2, S2, K1 and O1 as well as data from which M4, M6, S4, S6, MS4, MSf,
   Sa and SSa can be computed. Predictions of about the same accuracy can be
   made with TIDES if inferred constants are included in the data file.

   Differences for tides and currents for subordinate U.S. locations are given
   in the annual tables published by the National Ocean Service. In 1989 the
   datum to which height of tide is referred was changed from mean low water
   to mean lower low water for all U.S. stations. Though the difference is
   generally only a couple of tenths of a foot or less, data should be taken
   from 1989 or later tables. The constants themselves do not change
   appreciably over many years so any later table can be used.

   The theory used in the TIDES program is given in:

      Manual of Harmonic Analysis and Prediction of Tides
      Paul Schureman
      Coast and Geodetic Survey Special Publication No.98
      U.S. Gov't. Printing Office, Washington D.C. 1941

   This book has been reprinted recently and is available from NOS for $5.00.

   A supplement to this document, "Computer Applications to Tides in the
   National Ocean Survey" is also available from NOS at no cost.

   MISCELLANEOUS

   The present version of the program does not give predictions of slack
   water at current stations and for rotary currents the north and east
   components of velocity must be predicted separately at hourly intervals
   and combined vectorially by the user. If there is a demand for these
   features I may get around to adding them sometime.

   Starting in the 1989 tables the datum was changed to mean lower low water
   for all U. S. ports, which meant a change of a few tenths of a foot in Z0
   (item 1, line 2 of -.TID data files) for ports on the Atlantic coast. The
   new values have been used in the data on this disk.

   New constants have also been used for Eastport starting in 1989.

   If you have any suggestions, comments or problems please let me know.

   HARMONIC CONSTANTS ARE AVAILABLE FOR THE STATIONS LISTED BELOW

   REFERENCE STATIONS COVERED BY NATIONAL OCEAN SURVEY

   TIDES - EAST COAST

   Albany, New York                     Punta Palmas, Venezuela
   Amuay, Venezuela                     Philadelphia, Pennsylvania
   Baltimore, Maryland                  Portland, Maine
   Boston, Massachusetts                Reedy Point, Delaware
   Breakwater Harbor, Delaware          St. Marks River Entrance, Florida

   Bridgeport, Connecticut              St. Petersburg, Florida
   Caleta Percy, Magellan Strait, Chile***
   Charleston, South Carolina           Sandy Hook, New Jersey
   Cristobal, Panama                    San Juan, Puerto Rico
   Eastport, Maine                      Savannah, Georgia

   Galveston, Texas                     Savannah River Entrance, Georgia
   Hampton Roads, Virginia              Suriname Rivier, Surinam
   Isla Zapara, Venezuela               Tampico Harbor, Mexico
   Key West, Florida                    Washington, D.C.
   Mayport, Florida                     Willets Point, New York

   Maimi Harbor Entrance, Florida       Wilmington, North Carolina
   Mobile, Alabama
   New London, Connecticut
   Newport, Rhode Island
   New York, New York

   Pensacola, Florida
   Punta Gorda, Venezuela

   TIDAL CURRENTS - EAST COAST

   Baltimore Harbor Approach, MD        Mobile Bay Entrance, FL
   Boston Harbor, MA                    Pollock Rip Channel, MA
   Cape Cod Canal, MA                   Portsmouth Harbor Entrance, NH
   Charleston Harbor, SC                St. Johns River Entrance, FL
   Chesapeake & Delaware Canal          Savannah River Entrance, GA
   Chesapeake Bay Entrance              Tampa Bay Entrance, FL
   Delaware Bay Entrance                The Narrows, New York Harbor, NY
   Galveston Bay Entrance, TX           The Race, Long Island Sound
   Hell Gate, East River, NY            Throgs Neck, Long Island Sound
   Key West, FL                         Vieques Passage, Puerto Rico
   Miami Harbor Entrance, FL

   TIDES - WEST COAST

   Aberdeen, Washington                 Matarani, Peru
   Anchorage, Alaska ***
   Astoria, Oregon
   Balboa, Panama                       Nikishka, Alaska
   Buenaventura, Columbia               Nushagak Bay, Alaska
   Callao, Peru                         Port Townsend, Washington
   Cordova, Alaska
   Dutch Harbor, Alaska                 Puntarenas, Costa Rica
   Guayaquil, Ecuador                   St. Michael, Alaska
   Guyamas, Mexico                      Salina Cruz, Mexico
   Honolulu, Hawaii                     San Diego, California
   Humboldt Bay, California             San Francisco, California
   Juneau, Alaska                       Seattle, Washington
   Ketchikan, Alaska                    Seldovia, Alaska
   Kodiak, Alaska                       Sitka, Alaska
   Kwajelein Atoll, Marshall Is.        Sweeper Cove, Alaska
   La Union, El Salvador
   Los Angeles, California              Talara, Peru
   Massacre Bay, Alaska                 Valdez, Alaska

   TIDAL CURRENTS - PACIFIC COAST

   Admiralty Inlet, WA                  Rosario Strait, WA
   Akutan Pass, Aleutian Islands        San Diego Bay Entrance, CA
   Ch'ang Chiang Entrance, China        San Francisco Bay Entrance, CA
   Deception Pass, WA                   San Juan Channel (S. Entrance), WA
   Grays Harbor Entrance, WA            Sergius Narrows, AK

   Huang P'u Chiang, China              Strait of Juan de Fuca Entrance
   Isanotski Strait, AK                 The Narrows, Puget Sound, WA
   Kvichak Bay, AK                      Unimak Pass, Aleutian Islands
   North Inian Pass, AK                 Wrangell Narrows, AK

   *** Complete prediction requires more than 37 constituents.


   OTHER TIDE STATIONS

   Alameda, CA                          Apalachicola, FL
   Apia, Samoa Islands
   Aquia Creek, Potomac River, VA       Aransas Channel, TX
   Arthur Harbor, Palmer Station, Antarctica
   Atlantic City (Steel Pier), NJ       Avon, NC

   Bar Harbor, ME                       Bayou Rigaud (Grand Isle), LA
   Bayshore, L.I., NY                   Bay St. Louis, MS
   Bears Bluff, N. Edisto R., SC        Block Island (Old Harbor), RI
   Boca Congrejos, Isla Verde, PR       Buzzards Bay Entr, Cape Cod Canal, MA
   Burntcoat Head, Nova Scotia          Canton Island, Phoenix Is., S. Pac.

   Cape Cod Canal, E. Entrance, MA      Cape Hatteras (Fishing Pier), NC
   Cape May (ferry terminal), NJ        Cape Steenboom, New Guinea
   Carlos Point, Estero Bay, FL         Charleston, OR
   Chesapeake Beach, MD                 Coconut Point, FL
   Colonial Beach, VA                   Constantine Harbor, AK

   Crescent City, CA                    Daytona Beach, Fl
   Daytona Beach Shores (Sunglow Pier), FL
   Elkhorn Slough, CA                   Esbjerg, Denmark
   Friday Harbor, San Juan Island, WA
   Galveston, Pleasure Pier, TX         Garibaldi, OR
   Guam (Apra Harbor), Marianas         Hirtshals, Denmark
   Indian River Inlet, DE

   Lewisetta, Potomac River, VA         Turkey Point, FL
   La Jolla, CA                         Eureka, CA
   Point of Pines, SC                   Port San Luis, CA.
   Neah  Bay, WA                        Cross Island, AK
   Nantucket, MA                        Malakal Harbor, Palau Is. Caroline Is.

   Matanzas Pass, Estero Island, FL     McMurdo Sound, Antarctica
   Mokuoloe Island, HI                  Montauk, Long Island, NY
   Monterey Harbor, CA                  Morehead City, NC
   Moss Landing, CA                     Myrtle Beach (Springmaid Pier), SC
   Naples, FL                           New Bedford, MA

   Newport Bay, CA                      Nikiska, Cook Inlet, AK
   Old Saybrook Point, CT               Padre Island (South End), TX
   Ponape Harbor, Caroline Islands      Port Aransas, TX
   President Channel, Orcas Is., WA     Providence, RI
   Puerto Soberania, Palmer Peninsula

   Punta Tunas, PR                      Reykjavik, Iceland
   Rincon Island, CA                    Rockland, ME
   Sabine Pass, TX                      Saint John, New Brunswick
   Seavey Island, ME                    Shell Point, FL
   Southbeach, OR                       Stamford, CT

   Tarawa, Gilbert Islands              Toke Point, WA
   Virginia Beach, VA                   Wachapreague, VA
   Wallops Island, VA                   Yakutat, AK

   INterNATIONAL HYDROGRAPHIC ORGANISATION DATA

   Banyuls, France                      Socoa, France
   Toulon, France                       Marseille, France
   Saint Servan, France                 Cherbourg, France
   Nice, France                         Venezia, Italy
   Grado, Italy                         Esbjerg, Denmark
   Aarhus, Denmark                      Hirtshals, Denmark

   Saint John, New Brunswick, Canada    Burntcoat Head, Canada
   Grand Turk, UK

   Cabo San Lucas, B.C.S., Mexico       La Paz, B.C.S., Mexico
   Magdalena Bay, Mexico                San Carlos, B.C.S., Mexico
   Topolobampo, Sin., Mexico            San Juanico Bay, Mexico
   Yavaros, Son., Mexico                Ballenas Bay, Mexico
   Guaymas, Som., Mexico                Isla Guadalupe, B.C., Mexico
   Bahia de los Angeles, B.C., Mexico   Puerto Penasco, Son., Mexico
   Ensenada, B.C., Mexico               Salina Cruz, Oax., Mexico

   Matavia, Tahiti, France              Motuoini, Tahiti, France
   Nuku'alofa, Tonga                    Urangan Jetty, Australia
   Brisbane Bar, Australia              Caloundra Heads, Australia
   Brisbane (W. Inner Bar), Australia   Snapper Rocks(Danger Point), Australia
   Ballina, Australia                   Iluka, Australia
   Victoria Dock, Singapore             Horsburgh Lighthouse, Singapore
   Tg. Segenting, Malaysia              Colombo, Sri Lanka
   Hong Kong, UK                        Kao-Hsiung, China
   Fujairah, Oman (U.A.E.)              Naha Ko, Japan
   Kobe, Japan                          Nagoya, Japan
   Sinko, Yokohama, Japan

   CANADIAN DATA

   Constants for all reference tide stations in the NOS tables for the East
   and West coasts are available as well as many stations in British Columbia.
   Tidal current constants for Grand Manan Channel (Bay of Fundy Entrance) are
   also on hand.

   Also see Notes.Ken