Show actual sea level vs. the projected sea level change curves
plainly and
Answer the question, "What rate of sea level change is currently being
observed at the selected gauge?"
There are five main sections to the Sea Level Tracker:
Data Entry Panel:
Here, the user selects the location and gauge to be analyzed, configuring the
visualization characteristics. This includes the gauge, measurement datum,
sea level curve rates, various smoothing curves of historical data, trend lines,
extreme water levels, and critical elevations for comparison.
Location Map:
The map shows the geographic location of the selected gauge. The Sea Level
Tracker also allows the user to select the desired gauge for analysis from the map.
Just click the location of interest, marked with blue icons.
Visualization Tab:
The generated visualization captures the historic hydrologic behavior for the
user-selected location, while taking into account historic trends in sea level
rise. The final output is configured by the user's selections in the User Interface.
Feasibility Study Report:
This tab allows users to generate a downloadable report that contains
the key outputs from the Sea Level Tracker as well as the inputs used to
create them.
Data Table(s) Tab:
For deeper inspection, the Sea Level Tracker allows the user to explore the raw
data. The tool allows for variable selection above the table, while also letting the
user filter the selected variables to ranges of interest.
Please acknowledge the US Army Corps of Engineers for producing this tool
and making it freely available as part of their progress in climate preparedness
and resilience.
Sea Level Tracker - Data Source(s):
Data used in calculations for Sea Level Change are pulled from the NOAA Center for
Operational Oceanographic Products and Services Application Programming Interface
(CO-OPS API). The CO-OPS Data API is a flexible retrieval mechanism for direct access
to CO-OPS' products, such as water levels, predictions, currents, meteorological
observations, and more. Users can retrieve output in multiple common formats. The
CO-OPS Metadata API can be used to retrieve information about CO-OPS' stations.
A request can be made to return information about a specific station, or information
about multiple stations can be returned. The types of information accessible via the
API are listed in detail under
Resource Types.
Information on how to use to query data through the CO-OPS API can be found
here.
Note:The tool does not predict future water levels. Rather, the tool offers smoothed
analysis of historic sea level behavior and the measured trends at a user selected
gauge.
To learn more about the tool, we strongly recommend reading
the user guide
(PDF version available
here).
Term Definitions
MHHW - Mean Higher High Water: The average of the higher high water
height of each tidal day observed over the National Tidal Datum Epoch. For stations with shorter
series, comparison of simultaneous observations with a control tide station is made in order to
derive the equivalent datum of the National Tidal Datum Epoch.
MHW - Mean High Water: The average of all the high water heights observed over the National
Tidal Datum Epoch. For stations with shorter series, comparison of simultaneous observations with a
control tide station is made in order to derive the equivalent datum of the National Tidal Datum Epoch.
MSL - Mean Sea Level: The arithmetic mean of hourly heights observed over the National Tidal
Datum Epoch. Shorter series are specified in the name; e.g. monthly mean sea level and yearly mean
sea level.
NAVD - North American Vertical Datum of 1988 (NAVD88): A fixed reference for elevations
determined by geodetic leveling. The datum was derived from a general adjustment of the first-order
terrestrial leveling nets of the United States, Canada, and Mexico. In the adjustment, only the
height of the primary tidal bench mark, referenced to the International Great Lakes Datum of 1985
(IGLD 85) local mean sea level height value, at Father Point, Rimouski, Quebec, Canada was held
fixed, thus providing minimum constraint. NAVD 88 and IGLD 85 are identical. However, NAVD 88
bench mark values are given in Helmert orthometric height units while IGLD 85 values are in
dynamic heights. See International Great Lakes Datum of 1985, National Geodetic Vertical Datum
of 1929, and geopotential difference. NAVD 88 should not be used as Mean Sea Level.
MLW - Mean Low Water: The average of all the low water heights observed over the National
Tidal Datum Epoch. For stations with shorter series, comparison of simultaneous observations with
a control tide station is made in order to derive the equivalent datum of the National Tidal Datum Epoch.
MLLW - Mean Lower Low Water: The average of the lower low water height of each tidal day
observed over the National Tidal Datum Epoch. For stations with shorter series, comparison of simultaneous
observations with a control tide station is made in order to derive the equivalent datum of the National
Tidal Datum Epoch.
EWL - Extreme Water Levels: The extreme levels measured by the CO-OPS tide gauges during
storms are called storm tides, which are a combination of the astronomical tide, the storm surge,
and limited wave setup caused by breaking waves. They do not include wave runup, the movement of
water up a slope. Therefore, the 1% annual exceedance probability levels shown do not necessarily
correspond to the Base Flood Elevations (BFE) defined by the Federal Emergency Management Administration
(FEMA), which are the basis for the National Flood Insurance Program.
NOAA's EWLs: For this product, the monthly extreme levels adjusted for relative sea level
trend, producing an unbiased data set from which the annual highest and lowest water levels are
derived. A Generalized Extreme Value (GEV) analysis is applied to this data set to determine the
expected frequency of extreme tides rising above or falling below any given level. The results are
a set of annual exceedance probability levels relative to the tidal datums for each station.
USACE's EWLs: Produced as is the NOAA EWLs using the statistical Percentile function rather
than GEV.
Linear Trend(s): The Sea Level Tracker fits a linear regression model for the monthly means
when requested by the user. The user has the choice to either fit a regression to the entire selected
period of record or a forty-year window. The values visible in the table and with the tooltips are the
value of the fit linear model for the selected date. The linear trend rates are visible via a module
that presents when the 'Trend Line Information' button below the plot is pressed.