Datums for 9460150, ATTU, MASSACRE BAY

Historical Predictions and Datums A set of tidal harmonic constants based on data collected prior to 1960 have been calculated for use in generating tide predictions at this location. Due to the limitations of these historical observations, MSL is held fixed as the station datum and MLLW is referenced to MSL in order to remove any reference to the terrestrial system. The removal of the terrestrial reference enables the relationship between MSL and MLLW to remain consistent over time and not require periodic National Tidal Datum Epoch (NTDE) updates. Due to the remote nature of this location, there are no immediate plans to collect updated water levels data in the area. If you require additional assistance, please contact CO-PS Customer Service via email at Tide.Predictions@noaa.gov.
NOTICE: All data values are relative to the MLLW.

Elevations on Mean Lower Low Water

Station: 9460150, ATTU, MASSACRE BAY
Status: Accepted (Nov 27 2012)
Units: Feet
Control Station: 9461380 Adak Island, AK
T.M.: 150
Epoch: Special
Datum: MLLW
MHHWMean Higher-High Water
MHWMean High Water
MTLMean Tide Level
MSL1.94Mean Sea Level
DTLMean Diurnal Tide Level
MLWMean Low Water
MLLW0.00Mean Lower-Low Water
STND1.94Station 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)
Max TideHighest Observed Tide
Max Tide Date & Time Highest Observed Tide Date & Time
Min TideLowest Observed Tide
Min Tide Date & Time Lowest Observed Tide Date & Time
HAT5.00Highest Astronomical Tide
HAT Date & Time01/01/2026 01:00HAT Date and Time
LAT-1.85Lowest Astronomical Tide
LAT Date & Time05/28/2025 00:48LAT Date and Time
Tidal Datum Analysis Periods
06/01/1943 - 05/31/1944

Products available at 9460150 ATTU, MASSACRE BAY,