Presentation Open a Associations Parameters menu Validities menu |
Temperature Pressure Wind Waves Precipitation |
The information window Superimposition Animation Temporal interpolation Histogram |
Presentation |
- The Viewer offers a menu on the left displaying all of the elements composing a Grib file. Use the "Open" button to select a file and display its content. - Note the ![]() - On the right, the map displayed offers the same functions as the querier, i.e. the possibility to zoom in and out, displace the base map, and change the base map. - Above the map, you have a display of the geographic coordinates of the mouse, different base maps, and a menu to rapidly access a zone on the globe. - At the bottom of the window there is a location that contains information on the date, the validity, and the parameter(s) displayed. |
Open a Grib file |
- Click on the Open button to see the list of files available in the working directory. This is the dat directory contained in the software's installation directory, and it is recommended that you store all files received from Navimail in this directory (to avoid this step you can associate the Grib files with the Navimail program : see next chapter). You can navigate throughout the entire tree structure of your PC by clicking on ".." to display the parent directory, etc. - Then you simply select a file whose name is composed of the date and time it was created by the Navimail server. These files are proposed in reverse chronological order : the file on top of the list is the last one received. It should be noted that the software decodes Grib files (with the extension .grb) or files compressed with Gzip (extension .grb.gz) or Bzip2 (extension .grb.bz2). - Simply clicking on its name launches the decoding of a file, the dynamic generation of its contents in the menu on the left, and the display of the first range on the map with automatic positioning on the zone of interest. If you have several files it is therefore easy to select a file by rapidly viewing its content. - Underneath the map, the validity date and time for the product are indicated in UTC and local time (if your PC is properly configured). - Then there is a description of the parameter(s) displayed, - Followed by the reference date on which the forecasts were established and the name of the model. Locking : The padlock button to the right of the "Open" button indicates if activated (blue) that the map is locked (thus no more zooming or displacement is possible). This button is activated as soon as you open a file, since it allows you to display the zone of interest, where the Grib is located, and also allows you, when you have made a query with a displacement (course and speed), to have the base map be automatically displaced throughout the ranges. Of course you can unlock the map by clicking on this button, for example in order to zoom in on the data displayed. |
Associating Grib files with this program |
- Note that the program accepts the name of a Grib file as an argument (with the extensions .grb, .grb.gz or .grb.bz2). Once loading has been completed, the file is opened and the interface positioned on the first viewing tab. You can therefore associate these extensions with the navimail2.exe (under Windows) or navimail2 (under Linux and Mac) program and launch the interface from the E-mail client or a file manager by clicking with the right-hand mouse button on the attachment or file and choosing "Open with...". To associate Navimail2 with the Grib files under Windows Right click on a Grib file Renew these operations if necessary for the files with "BZ2" and "GZ" extensions A file opened using this process is first copied into the "dat" working directory, therefore it is not necessary to save the file into this directory. If the program is already running, the Grib file will be immediately displayed in the first unoccupied viewing tab (if they are all occupied, the 9th will always be used by new files). Therefore, whatever the location of the Grib files, they can be very rapidly viewed. You can thus submit queries and view the results without exiting the interface. |
The parameter menu |
- Once a file has been opened, a dynamic menu is created that represents the contents of the Grib file exactly. One button is displayed for each parameter present under the title Parameters. ![]() ![]() ![]() Warning : with the three main colors and the alpha channel, the transparency uses 4 bytes per pixel, so you need a display configuration that uses all of the colors (Optimum : 32bits) |
The Validities (or ranges) menu |
- Similarly to the parameters, a dynamic menu is created with all of the ranges contained in the Grib file. In this Validities menu one button is displayed per validity (range), one line per day. Underneath, several fairly self-evident buttons (with associated help balloons) make it possible to run through or carry out frontward or backward animation for the different ranges, the "Pause" button lets you interrupt an animation underneath, and finally a ruler lets you modify animation speed. |
Temperature |
- The sea and ground temperature parameter, expressed in degrees Celsius, is displayed in colored isoranges and isolines. The display increment step can be modified by choosing a value in the T menu under the list of parameters. You can also modify the default threshold (between the colors blue and red) at will by clicking with the middle mouse wheel on a location on the map, giving a better view of a specific temperature. You can zoom in on this display, once you have unlocked the map (see "Opening a file" above) while still preserving an optimum image. - Click on the right-hand mouse button to open up an information window that will give you the exact value of the parameters under the mouse pointer. This window is displaced with the mouse. Click again on this right-hand button to make the window disappear. Note that in superimposition mode all the parameters are displayed. |
Pressure |
- The pressure parameter at sea level, expressed in hectopascals, is displayed in colored isoranges and isolines or isobars. The display increment step can be modified by choosing a value in the P menu under the list of parameters. You can also modify the default threshold (between the colors blue and red) at will by clicking with the middle mouse wheel on a location on the map, giving a better view of a low pressure area. You can zoom in on or displace the image displayed, once you have unlocked the map (see "Opening a file" above), while still preserving an optimum image. - Click on the right-hand mouse button to open up an information window that will give you the exact value of the parameters under the mouse pointer. This window is displaced with the mouse. Click again on this right-hand button to make the window disappear. Note that in superimposition mode all the parameters will be displayed. |
Wind |
- The wind parameter at 10 meters, expressed in degrees for direction and in knots for speed, is displayed according to convention using weather symbols in the form of an arrow indicating the direction of the wind (the point of the arrow is exactly on the point of the grid) and then of a certain number of "barbs" according to the wind speed, in 5-knot multiples. A small barb indicates 5 knots, a large barb indicates 10 knots and a triangle indicates 50 knots. Thus a symbol with 3 large barbs and one small one indicates a wind of 35 knots (actually between 32.5 and 37.5 knots, with the latter limit excluded). - Color is set according to convention in this software program, and can be found using the tab "Help" -> Beaufort. - This wind can also be displayed in the form of directional vectors and isoranges and isolines depending on wind speed. To do so click on the ![]() You can also modify the display increment step of the isolines with the F button under the list of parameters. Note the possibility to choose the Beaufort scale, in which case each isoline distinguishes a different Beaufort force. -You can also modify the default threshold (between the colors blue and red) at will by clicking with the middle mouse wheel on a location on the map, giving a better view of an area of strong wind. You can zoom in on or displace the image displayed, once you have unlocked the map (see "Opening a file" above), while still preserving an optimum image. - Click on the right-hand mouse button to open up an information window that will give you the exact value of the parameters under the mouse pointer. This window is displaced with the mouse. Click again on this right-hand button to make the window disappear. Note that in superimposition mode all the parameters will be displayed. WARNING : The wind indicated is an average model wind, and even if models are increasingly close to observed reality, there may still be some differences between the wind observed and the forecasted wind, notably near coastlines where local effects are not always fully taken into account, but above all the air flow is turbulent in the lower layers of the atmosphere and the wind speed therefore actually fluctuates around this average value, while the maximum observed value of the gusts can reach or even exceed this average value by 50%. Thus an average wind value of 30 knots will lead to gusts of 45 knots. |
Waves |
- The wave parameter is composed of three parameters : direction expressed in degrees, height expressed in meters, and period expressed in seconds. - These parameters are displayed using directional vectors whose length is proportional to their height, and the period is displayed in the form of colored isoranges and isolines. - Color is set according to convention in this software program, and can be found using the tab "Help" -> Sea state. - You can also display the wave parameters in the form of directional vectors and wave height isolines and isoranges. To do so click on the ![]() -You can also modify the default threshold (between the colors blue and red) at will by clicking with the middle mouse wheel on a location on the map, giving a better view of a sensitive area. You can zoom in on or displace the image displayed, once you have unlocked the map (see "Opening a file" above), while still preserving an optimum image. - Click on the right-hand mouse button to open up an information window that will give you the exact value of the parameters under the mouse pointer. This window is displaced with the mouse. Click again on this right-hand button to make the window disappear. Note that in superimposition mode all the parameters will be displayed. WARNING : The wave height indicated is the H1/3 or average of the third of the highest waves, with the most probable maximum height situated between 1.6 and twice the H1/3. For an H1/3 value of 6 meters, the most probable maximum value is situated between 10 and 12 meters, with one out of every 100 waves on average exceeding 10m. |
Precipitation |
- The precipitation parameter, expressed in millimeters, is displayed in colored isoranges and isolines.![]() The display increment step can be modified by choosing a value in the menu R under the list of parameters. You can also modify the default threshold (between the colors blue and red) at will by clicking with the middle mouse wheel on a location on the map, giving a better view of an area with heavy precipitation. You can zoom in on or displace the image displayed, once you have unlocked the map (see "Opening a file" above), while still preserving an optimum image. - Click on the right-hand mouse button to open up an information window that will give you the exact value of the parameters under the mouse pointer. This window is displaced with the mouse. Click again on this right-hand button to make the window disappear. Note that in superimposition mode all the parameters will be displayed. |
The information window |
- When you right click on the weather map displayed, a little window opens up and displays the exact values under the mouse pointer. If symbols are displayed (barbs and vectors), the values displayed are those of the closest point on the grid. In the case of colored isoranges and isolines, it is the closest interpolated value. - In the event of superimposition, all of the values superimposed on one point are displayed, and therefore even if the fields displayed are no longer very legible, you can rapidly and precisely see all of the values displayed for a given point and for a given range. - This window is also available during an animation. In this case it shows you the temporal variation of the parameters at a given point. |
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- If several parameters are available, you can superimpose them during display. For example the wind can be superimposed on the pressure. Press on the S button under the list of parameters to activate this function, and press again to deactivate it. - You can also superimpose two or more "image" fields even if this somewhat reduces legibility. Note : you can play with the transparency of these images by moving the ruler located just under the list of parameters. This adjustment goes from complete transparency, maintaining only the isolines which in this case are colored, up to complete opacity where only the last image field is visible, as well as a veiled coast line. |
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- If several ranges are available you can launch an animation and go through the ranges, forward or backward with the two end buttons located just above the list of ranges. The middle button allows you to interrupt the animation. - This animation is then controlled by an independent process, which means that you still have the possibility to change parameters, change the increment step, change the threshold, zoom, displace the base map, and even if it is less useful, load a new file that will automatically become animated in turn. |
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The button temporal interpolation to create a local Grib containing hourly interpolated grib from the original received Grib Navimail (Grib that is created on the fly in memory of your computer and is not recorded).
- This allows to the weather situation hourly and in animation mode to have a smoother viewing. CAUTION The result is a simple linear interpolation and can not therefore claim to replace missing deadlines. This interpolation should be used with maturities spaced 3 hours for a grib of 2 on 2 and 6 am for a grib 5 of 5 ° or more. Interpolation will not or only partially, if no time is or becomes greater than 6 hours or greater than 3 hours with a grid of less than 4 degrees in longitude and latitude |
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This button, to the right of the padlock button, make active the display of a histogram.
This histogram displays the weather forecast, for the grid point that mouse over top, of the Grib file. Clicking the right mouse button on the map displays the histogram. Moving the mouse constantly upgrading the histogram. A new click the right mouse button freezes the histogram to the current position. This is also true if the mouse leaves the area or displayed map. If the histogram window is hidden use the window menu (top right) to display it at foreground : ![]() If the superposition is active ![]() If only one parameter is selected the histogram will be more complete with for example the time evolution of the wind direction, of the average force and gusts (knots and KPH). You can open a window histogram per tab in the viewer, 9 at most. NOTES : You can move the window containing the histogram and also resize the width to improve readability. |