Grib files for Mariners transmitted by Outernet L-Band Satellite

Seasalt · August 30, 2016, 3:42am

Syed " What do you think would be the killer app, from a content perspective? Simply sending a comprehensive set of grib files? Or something else?"

For people that cross oceans then grib weather forecast files would be essential.

But sending a broadcast every 6 hrs or 12 hrs with a world wide grib file could be something like 1 - 2 mb every 6 hours Assuming you want to send out most of the world.

But if we broke the grib up into the 3 regions as defined by Inmarsat then it would be a lot less information. Mariners at sea are only interested in their geographic regions grib. Possibly this could break the grib down to .6 to 1 Mb per region or even less.

It might be possible to use a special compression algorithm and remove a lot of redundant information as the current system is sort of designed to be a one off, stand alone data file but you will be using apps that could handle date , spacing etc so this information could be removed from the data set.

It might be possible to remove grib data from a worldwide grib file where the wind data is over land. This might reduce the data size by a third.

I think this kind of thinking on reducing grib file size has been worked on. I am hoping some of the excellent mariner programmers from the Opencpn project will get behing the Outernet Grib project and possibly something like a Opencpn Outernt Grib plugin could be born.

The open source navigation project Opencpn already has a Grib plugin and a RTL-SDR dongle plugin.

It might be possible with the grib file forecast to have the first four 6 hour forecast and then just give 12 hour forecasts. So a 3 day forecast would have
4 X 6 hrs day one
2 X 12 hrs day two.
2 X 12 hrs day three.

This would still be very useful for mariners.

Seasalt · August 30, 2016, 7:21am

Here is a standard Zygrib Wind only grib file
Location India to Hawaii approx one third of the earth.
(approx Coverage equivalent Inmarsat 4F1)

Period of forecast 3 days
forecast 12 hours apart
resolution = 1 degree or 60Nautical miles.

Total size = 334KB including Wind data over land. which could be deleted.

I think Mariners will find this information very useful

Syed · August 31, 2016, 12:47am

We are looking into this now. This is high on the priority list.

Seasalt · October 13, 2016, 6:52am

Syed I am receiving a lot of the new Grib2 files. How do we open them.

I have tried my usual way which is to use Zygrib grib display program but it is starting to load and saying something like not compatible.

Seasalt · October 13, 2016, 11:51am

With the NOAA’s Weather and Climate Toolkit Java Linux toolkit I was able to display one of the GRIB2 files.

Its Just gets better and better.

Abhishek · October 13, 2016, 12:24pm

Is the built-in viewer working for you?

Seasalt · October 13, 2016, 1:11pm

No when I click on grib files it is trying to find a external program to display them,

Abhishek · October 13, 2016, 1:23pm

eh?

is there no /mnt/downloads/Weather/index.html?

It should have downloaded by now.

Abhishek · October 13, 2016, 1:37pm

which version are you running? Viewer only works in V3.1 of rxOS on chip or rpi3. Its currently not included in OuternetInABox or on the desktop installers.

If you have not upgraded to 3.1, please grab it from We Moved!
or We Moved!

Seasalt · October 13, 2016, 1:55pm

Here is a list of my directories.

Abhishek · October 13, 2016, 2:19pm

if you still have grib2 files in that directory that is highlighted you have not upgraded to v3.1.

Weather App is enabled if you click on the “Weather” folder - it will show a globe, but without v3.1 it will have no data.

Seasalt · October 13, 2016, 2:30pm

Here is a list of my directories.

Seasalt · October 13, 2016, 2:34pm

Ihave updated this morning to 3.1. I have grib2 files in the grib directory. It says at bottom left version 3,1 .

Abhishek · October 13, 2016, 2:37pm

how long has it been since you upgraded?

What happens when you click on the “Weather” folder?

Seasalt · October 13, 2016, 2:56pm

10 hrs since upgrade of CHIP and reboot.
I can get this weather world with Ocean data current to appear. But the others have no data.

Abhishek · October 13, 2016, 5:10pm

yesterdays data got downloaded before you upgraded, so it did not get processed. You just need to wait for new data which will go up at midnight utc.

Seasalt · October 14, 2016, 2:19am

Working great now. Very nice looking global weather app.

Abhishek · October 14, 2016, 11:48am

Note that the new gribs first download into the grib2 folder, but after processing get moved to the Weather/grib2 folder. So if you want to pull the files for use with desktop weather viewer software, you should pull from there. The naming of the files and subfolders in Weather/grib2 exactly mirrors the original NOAA naming.