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Datums for 9460150, ATTU, MASSACRE BAY AK


9460150, Massacre Bay, Attu Island Station 9460150 Massacre Bay, Attu Island is a historic station with tidal harmonic constants and tidal datums based upon a 06/1943 - 06/1944 installation. Due to the remote nature of this area, there are no plans to collect updated water level values in the vicinity of Attu Island, AK. During the 1943-1944 installation of this station NOAA was able to obtain and compute a full suite of harmonic constants. Therefore, this station is used as a control station for predictions at other subordinate harmonic stations in the far western Aleutian Islands.

In order to provide tidal predictions (http://tidesandcurrents.noaa.gov/tide_predictions.shtml) for this station and its subordinate stations, it is necessary to provide the separation between Mean Sea Level (MSL) and Mean Lower Low Water (MLLW) only.

Therefore, MSL has been held fixed as station datum and MLLW referenced to MSL in order to remove any reference to the terrestrial system. The removal of a terrestrial reference frame enables the relationship between MSL and MLLW to remain consistent over time and not require a periodic National Tidal Datum Epoch (NTDE) update to accountant for sea level rise.

Elevations on Station Datum

Station: 9460150, ATTU, MASSACRE BAY, AK
Status: Accepted (Nov 27 2012)
Units: Feet
T.M.: 150
Epoch: Special
Datum: STND
DatumValueDescription
MHHWMean Higher-High Water
MHWMean High Water
MTLMean Tide Level
MSL0.00Mean Sea Level
DTLMean Diurnal Tide Level
MLWMean Low Water
MLLW-1.94Mean Lower-Low Water
NAVD88
STND0.00Station Datum
GTGreat Diurnal Range
MNMean Range of Tide
DHQMean Diurnal High Water Inequality
DLQMean Diurnal Low Water Inequality
HWIGreenwich High Water Interval (in hours)
LWIGreenwich Low Water Interval (in hours)
MaximumHighest Observed Water Level
Max Date & Time Highest Observed Water Level Date and Time
MinimumLowest Observed Water Level
Min Date & Time Lowest Observed Water Level Date and Time
HATHighest Astronomical Tide
HAT Date & Time HAT Date and Time
LATLowest Astronomical Tide
LAT Date & Time LAT Date and Time
Tidal Datum Analysis Periods
06/01/1943 - 05/31/1944




Products available at 9460150 ATTU, MASSACRE BAY, AK

Revised: 10/15/2013
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services