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Manual for Marine Forecast


Marine Forecast is designed with the intent that it should be:

  • Simple (just include the necessary functionality)
  • Intuitive (easy to use)
  • Responsive (fast to use)
  • Useful on everything from smartphones to desktop computers

Having said that, the interface complexity depends on how large a screen the user has.

The user interface will look different depending on the size of the browser window. When you have a large window there is room for more buttons, larger graphics, and more information.

On a small screen some of the lesser important buttons are removed and they are arranged slightly differently. The goal is to give a good user experience on all platforms.

This manual describes the use of Marine Forecast when you have a large browser window, but the functionality of the buttons on small screens is completely the same as on a large screen.

Language and navigation

At the top of the left side is a series of buttons. Their functionality is illustrated below.

Save settings

When you click on the "Save settings" button you will be informed how you save the current setup of Marine Forecast.

This is done simply by making a bookmark in the browser. With Internet Explorer the button will however try to create a bookmark directly.

Find my location

When you click on the "Find my location" button, your browser will on the first attempt ask whether to allow Marine Forecast to access your location.

If you choose not to allow this, nothing happens. Otherwise your browser will try to find out what your location is, put a marker at the location, and zoom the map to your location.

When it has found the location the button will turn orange. This means that Marine Forecast follows your location.

If you drag the map the color of the button will change to blue and Marine Forecast no longer follows changes in your position.

Search on place name

When you move the mouse over the "Search on place name" button, a text box will open.

Here you can enter a place name that you want to focus the map on.

If Marine Forecast can't find the place, nothing happens. Otherwise Marine Forecast zooms to the area and puts a blue marker on the location.

Type position

You can enter a position in this field. When you move the mouse over the button, two text fields, in which you can enter a latitude and a longitude, opens up.

Below you can see some examples of how you type a position in:

Example 1:
Latitude: 56 45 30.125 N
Longitude: 12 30 12.000 E

Example 2:
Latitude: 56 45 30 N
Longitude: 12 30 12 E

You enter them as "degrees minutes decimal seconds N/S/E/W".

Layer selector

In the top right corner of the map you will find the layer selector. It can be used to choose which background map you want to use and what other layers to be displayed.

Time selector

In the lower right corner the time selector can be seen.

It is used to select at which time the desired forecast is valid for.

You can choose the time with the drop-down time menu, slider, or the buttons below.

Additionally, you can choose whether you want to see the time in the browser's local time or UTC / GMT.

Add to home screen

We have made Marine Forecast so that it is "web app capable". This means that it can be saved as a so-called web app on iPhones, iPads, and Android devices.

It will give you a little more screen space as you avoid that the browser address bar fills the screen. And unlike ordinary apps you don't need to update the app.

iPhones and iPads

When using Safari as your browser on iPhones and iPads you can choose to add Marine Forecast for the home screen. The screens below show how it's done with an iPad:


On Android devices, you must use the Chrome browser to store Marine Forecast as a web app.

This is done as follows:

On Android, it is recommended to only save Marine Forecast on the desktop since they, unlike iOS devices, otherwise will "overwrite" each other's setup.


Once you have selected a forecast parameter in Marine Forecast where a legend appears (not arrows and wind barbs) you will be able to see where the forecast originate from.

In the picture below you can see a forecast of wind speed from DMI.

Below we will describe when you should use different forecasts as well as the advantages and disadvantages of them.

Short and medium range forecasts

You can divide forecasts up in short and medium range forecasts.

Short range forecasts are often more accurate than the medium range forecasts but only extends about two days ahead.

The medium range forecasts will go further in time (we show them 5 days ahead), but will often be less accurate on the short term than the short range forecasts.

It is recommended to use the short range forecasts whenever possible.

Short range forecasts

We have two sources of short range forecasts.

The first is two regional meteorological forecasting models run by DMI.

One is called K05 and covers a large area around Greenland, while the other is called SKA (or S03) and covers Northern Europe.

You can see areas covered by the two models here.

DMI's regional meteorological forecasts are calculated on a very fine grid. This means that they can simulate small scale processes that models with coarser grids can't simulate.

In general, the DMI meteorological forecasts are of high quality.

DMI's forecasts, however, only extends 54 hours ahead.

The second source of short range forecasts are FCOO.

We focus on making regional oceanographic forecasts of high quality.

We have therefore set up a wave model for the ocean around Greenland and the North and Baltic Seas.

In addition, we run an oceanographic model for the North Sea and the Baltic Sea that among other things provide forecasts of water levels, currents, salinity, and sea temperature.

The model includes tides and the length of the projections is as DMI's models 54 hours.

Medium range forecasts

FCOO retrieves and displays the medium range forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF).

Specifically, the meteorological forecasts and wave forecasts.

ECMWF produces some of the best global meteorological forecasts in the world and even for regional meteorological models it can be difficult to compete with the quality of their forecasts.

The meteorological forecasts we obtain from ECMWF contains data 10 days ahead.

ECMWF also produces global wave forecasts data 10 days ahead.

Both are used in Marine Forecast.

We show only the first approximately five days of forecasts.

Additionally, FCOO downloads and displays medium range oceanographic forecasts from the National Oceanic and Atmospheric Administration (NOAA) in the United States.

These Forecasts are also global. However, current forecasts from NOAA suffers from the disadvantage that they do not include tides. Forecasts are therefore of limited value in areas where there are tides.

We show NOAA oceanographic forecasts for all areas except Denmark.

The last source of medium range forecasts are the Naval Oceanographic Office (NAVO) which provides forecasts for the US Navy.

In Marine Forecast we currently show their sea ice forecasts for Greenland.

In addition, we are also working on showing their oceanographic forecasts for Greenland. NAVOs oceanographic forecasts includes tides.


Besides forecasts, we also present measurements in the Marine Forecast setups for Denmark and Greenland.


We show sea level measurements along with forecasts for a wide range of ports in Denmark.

We get measurements from DMI who collects them from their own gauges, Coastal Directorate gauges and locally owned gauges.

Water level forecasts are from FCOO's hydrodynamic model GETM.


In Greenland we show tide predictions for most ports.

These predictions are made by DMI and are based solely on measurements.

Navigational warnings

For Marine Forecast Denmark, there are two types of navigational warnings.

The first is the so called Maritime Safety Information and they are displayed on Marine Forecast as a pink circle designated MSI.

The second type of navigational warnings is firing warnings. They appear as a pink semi-transparent polygon.

Inactive shooting areas are shown with a pink dotted polygon. You can click both MSI's and firing warnings for detailed information.

The navigational warnings are updated every 10 minutes via a web service that is provided by the Danish Maritime Authority (DMA).

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Defence Centre for Operational Oceanography - Lautrupbjerg 1-5 - DK 2750 Ballerup  -