Plum Island Ecosystems LTER Database

Acceptance and utilization of LTER data requires that:

(1) The Principal Investigator be sent a notice stating reasons for acquiring any data and a description of the publication intentions.
(2) The Principal Investigator of the data set be sent a copy of the report or manuscript prior to submission and be adequately cited in any resultant publications.
(3) A copy of any resultant publications should be sent to:

Principal Investigator
Ecosystems Center
Marine Biological Laboratory
7 MBL St.
Woods Hole, MA 02543

Dataset URLs:METADATA: HTML, Rich Text, XML(EML compliant)
DATA: Comma Delimited, Excel file with Metadata and data
Dataset ID:MON-BO-SeaLevel-Monthly-MSL.05
Dataset Title:Monthly mean sea level data (1921-2015) relative to NAVD88 for Boston, Massachusetts, NOAA/NOS
Investigator 1: 
First Name:Anne
Last Name:Giblin
Address line 1:Ecosystems Center
Address line 2:MBL
Address line 3:7 MBLSt
City:Woods Hole
Zip Code:02543
Associate Investigators:Joe Vallino, Hap Garritt, Jim Morris, Samuel Kelsey
Keywords:PIE LTER, disturbance, Plum Island Ecosystems, Massachusetts, Boston, water level, sea level
Abstract:Monthly sea level data for NOAA/NOS station 8443970, Boston, Massachusetts. The tide station is located on the right side of the U.S. Coast Guard Building adjacent to Northern Avenue Bridge. NOAA/NOS Center for Operational Oceanographic Products and Services (CO-OPS)
Contact: Plum Island Ecosystems LTER Information Manager
The Ecosystems Center
Marine Biological Lab
7 MBL St
Woods Hole, MA 02543
Phone (508) 289 7485
Online URL:
Data File URL
Data File Name MON-BO-SeaLevel-Monthly-MSL
Beginning Date 1/1/1921
End Date 12/31/2015
Number of Data Records 1138
Other Files to Reference
Availability Status Type 1
Quality Control Information
Maintenance Description Annual updates
Log of Changes: Version 01 , March 13, 2008, Level 3+ EML, data relative to NAVD88 datum
Version 02, 2008-2009 data added, 18Jan2011
Version 03: January 26, 2012, updated data and metadata, 2010-2011. Used MarcrosExportEML_HTML (working)pie_excel2007.xlsm 1/18/12 4:51 PM for QA/QC to EML 2.1.0
Version 04: 11Sep2013, data update with metadata and data updated to comply with importation to Drupal and LTER PASTA. Used MarcrosExportEML_HTML (working)pie_excel2007_Sep2013.xlsm 9/10/13 12:02 PM for QA/QC to EML 2.1.0
Version 05: February 22, 2016, Data and metadata updates to comply with importation to Drupal and LTER PASTA. Used MarcrosExportEML_HTML (working)pie_excel2007_Jan2015.xlsm 1/15/15 4:26 PM for QA/QC to EML 2.1.0
Geographic Description NOAA/NOS Boston, MA sealevel Station 8443970  
Location Bounding Box    
West Bounding Coordinate    
East Bounding Coordinate    
North Bounding Coordinate    
South Bounding Coordinate    
OR if single point location    
Latitude 42.353333  
Longitude -71.053333  
Taxonomic Protocols
Organisms studied
Methods:NOTES AND COMMENTS: Mean Sea Level (MSL) is a tidal datum determined over a 19-year National Tidal Datum Epoch. It pertains to local mean sea level and should not be confused with the fixed datums of North American Vertical Datum of 1988 (NAVD 88). The National Oceanic and Atmospheric Administration, National Ocean Service (NOS) is updating the nation's tidal datums to a new National Tidal Datum Epoch (NTDE) to reflect changes in mean sea level along the nation's coast.

The new NTDE will provide up-to-date tidal datum information available for applications that are essential to support NOAA's strategic programs, as well as other Federal, State and private sector coastal zone activities. As a result of the update, more accurate tidal information will be made available for widespread application to hydrographic surveys and mapping programs, navigational safety (Physical Oceanographic Real Time Systems, PORTSŪ), wetland restoration, marine boundaries, coastal engineering, storm warnings and hazard mitigation, emergency management, and hydrodynamic modeling.

The (NTDE) is a specific 19-year period over which tide observations are taken to determine Mean Sea Level and other tidal datums such as Mean Lower Low Water and Mean High Water. This latest update will define the 19-year period as 1983-2001. A tidal datum is a vertical reference based on a specific stage of tide which serves as a baseline elevation to which sounding depths or topographic heights are referenced. The 19-year period includes an 18.6 year astronomical cycle that accounts for all significant variations in the moon and sun that cause slowly varying changes in the range of tide. The NTDE has been adopted so that tidal datum determinations throughout the United States will be based on one specific common reference period.

Relative mean sea level, which is a term used to denote the average height of the ocean relative to land, can vary by location and over time and is not the same at all locations. It is the policy of NOS to consider a revised NTDE every 20-25 years in order to take into account relative sea level changes caused by global sea level change and the effects of long term local land movement due to subsidence or glacial rebound. Previous tidal Epochs were determined for periods 1924-42, 1941-59, and 1960-78. Water level measurements taken by NOS over long periods of time are used to smooth out shorter term (daily, monthly, annual) variations which help reveal long term trends (see The NOS Center for Operational Oceanographic Products and Services (CO-OPS) has the responsibility for operating and maintaining the National Water Level Observation Network, comprised of 175 long term stations in the coastal ocean and Great Lakes. The tide stations are used as the primary reference for determination of tidal datums and bench mark elevations (permanent monuments with elevations referenced to tidal datums) for station locations listed on the CO-OPS web site. A significant number of these tidal bench mark information "sheets" will be made available on the 1983-2001 NTDE after April 21, 2003. The remaining stations, that meet NOS publication standards, will be continuously updated until the process is completed at the end of FY 2003.

For further information please contact Steve Gill at 301-713-2981 Extension 139, or
Boston Station Datum, PID MY0555

Data Retrieval site:

Datum site:

National Ocean Service (NOAA)
Station: 8443970 T.M.: 0 W
Name: Boston, MA Units: Meters
Status: Accepted (Apr 17 2003) Epoch: 1983-2001
Datum: STND

Datum Value Description
--------- -------- ----------------------------------------
MHHW 4.205 Mean Higher-High Water
MHW 4.071 Mean High Water
NAVD88 2.752 North American Vertical Datum of 1988
MSL 2.660 Mean Sea Level
DTL 2.640 Mean Diurnal Tide Level
MTL 2.624 Mean Tide Level
MLW 1.178 Mean Low Water
MLLW 1.074 Mean Lower-Low Water
STND 0.000 Station Datum

Data Table

Variable Name Variable Description Units Measurement Scale Code Information Number Type DateTime Format Missing Value Code Missing Value Code Explanation
Station unique seven character identifier for the station   nominal       NA NA = not available
Year year of the data yyyy   datetime     yyyy NA NA = not available
Month numerical month mm   datetime     mm NA NA = not available
Highest Highest Tide of the month (relative to NAVD88) meter interval   real   NA NA = not available
MHHW Mean Higher-High Water (relative to NAVD88) meter interval   real   NA NA = not available
MHW Mean High water (relative to NAVD88) meter interval   real   NA NA = not available
MSL Mean Sea Level (relative to NAVD88) meter interval   real   NA NA = not available
MTL Mean of MHW and MLW (relative to NAVD88) meter interval   real   NA NA = not available
MLW Mean Low Water (relative to NAVD88) meter interval   real   NA NA = not available
MLLW Mean Lower-Low Water (relative to NAVD88) meter interval   real   NA NA = not available
Lowest Lowest Tide of the Month (relative to NAVD88) meter interval   real   NA NA = not available