Wheres the weather app gone?

So global weather is a pretty killer app

It seems to have disappeared from https://librarian.outernet.is/en/files/ What’s the status of this? Abandoned? Back burner?



The reason it was abandoned is openweather map has a terrible and unreliable API. For L-band it won’t be feasible either because of the ultra-low bandwidth.

I seem to remember you were doing a lot of cities before? Would it be feasible to do the capital city per country, plus some info for sailors?

Paris: Windy and rainy, wind north 6.
x 196 countries
= 3.6 kb per day.

I realise they’ll be a bit more overhead than that, but it looks perfectly feasible.

All the wind files here: amount to 3.6 Mb & could just be grabbed with wget every five days? http://www.globalmarinenet.com/free-grib-file-downloads/ Sailors would buy lanterns and it would save lives…

Well, if you encode it as binary data, it could be much much smaller. E.g., 16 bits for city code, (making this up) 8 bits for weather code, 4 bits for wind direction, 8 bit temp…

That still leaves us with a problem of finding a reliable API that would allow us to keep the data fresh.

As for broadcasting wind files, that’s simple. However, putting 3.6MB of data on L-band does require a substantial market.

Yes I guess it is a chunk of data.

Thinking about it it’s really the offshore areas you want, when you’re close to land there are other methods of getting weather (VHF)

134kb [wind][wave] Pacific Pacific Region Forecast Data (includes Gulf of Alaska data)
116 kb [wind][wave] Atlantic Region Forecast Data
105 kb[wind][wave] East Atlantic East Atlantic Region Forecast Data
100 kb [wind][wave] Central North Pacific Central North Pacific Region Forecast Data
129 kb [wind][wave] Central South Pacific Central South Pacific Region Forecast Data
100kb [wind][wave] Central Pacific Central Pacific Region Forecast Data
79 kb [wind][wave] West Pacific West Pacific Region Forecast Data
114kb [wind][wave] South Atlantic South Atlantic Region Forecast Data
78 kb [wind][wave] Central Atlantic Central Atlantic Region Forecast Data
128 kb [wind][wave] Indian Ocean Indian Ocean Forecast Data
30 kb [wind][wave] North Indian Ocean North Indian Ocean Forecast Data

Would reduce to 896kb, Say you did them every three days, would equal about 300kb a day on average. What do you think of that?

Size-wise it’s doable. 300kb would take probably about 30 minutes to download (provided ideal conditions). Of course, the smaller the better, esp on a moving vessel.

How often does this data update?

“These forecasts are generated daily at 0015, 0615, 1215, 1815 GMT for every region of the world.” http://www.globalmarinenet.com/free-grib-file-downloads/

but you could just grab whatever’s there on a three day rotation?

once every three days would be good enough for sailors?

Well it’s not ideal, daily would be much better. It’s a seven-day forecast. It’s considerably better than nothing. If you’re seriously considering it i’ll check out those maps, there may be overlap and duplication.

I’ll also see if I can find a three day forecast which would reduce the size…

As long as payload is <0.5MB, I don’t see any reason not to put it on air.

Should be possible to comply with these terms? https://developer.worldweatheronline.com/api/free-api-terms.aspx

Yes, and I think we’ve already looked at it before, just never had the time to implement an app based on it.

The API is much much more reliable than openweathermap.

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see below

OK so new proposal, you get land & sea maps daily from here

144kb wind five-day global forecast, retrieved daily

(Useful as longer term view for sailors, Disaster/ NGO planning, general planning)

264kb rain/pressure five-day global forecast, retrieved daily

(Useful as longer term view for sailors, Disaster/ NGO planning & harvest/ planting planning, general planning)

Plus the 48 hr pacific and Atlantic forecasts retrieved daily from here

44kb Pacific

(Useful mid-term for sailors)

52kb Atlantic

(useful mid-term for sailors)

= Grand total of 504 kb a day, for a global picture of weather, with enough info to navigate by.


If you’d let me stretch the 500kb limit i’d add in

Useful for NGO disaster planning, harvesting/ planting/ general.


Useful for NGO disaster planning, harvesting/ planting/ general.

But this would push it 379 kb over the 500kb limit…

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This definitely looks good. I’ll keep this in mind when we start broadcasting files on L-band.

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@sam_uk is right. Weather-related information is probably the most impactful, small payload service we can offer in the short term.

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So it seems all those image URLs stay the same, they just update the image file.

So a daily

wget http://pamola.um.maine.edu/fcst_frames/GFS-025deg/5-day/GFS-025deg_WORLD-CED_WS10_5-day.png
wget http://pamola.um.maine.edu/fcst_frames/GFS-025deg/5-day/GFS-025deg_WORLD-CED_PRCP_ACC-TCLD-PMSL_5-day.png
wget http://www.opc.ncep.noaa.gov/shtml/P_48hrsfcbwug_mobile.gif
wget http://www.opc.ncep.noaa.gov/shtml/A_48hrsfcbwug_mobile.gif

These max/min temp maps are much smaller at 41kb a piece, than the ones I posted before shame they’re in fahrenheit, I guess you could include a small text file for reference?

wget http://images.intellicast.com/WxImages/MaxTemperature/world_day2.jpg
wget http://images.intellicast.com/WxImages/MinTemperature/world_day2.jpg

I’ll mail intellicast and see if we can broadcast them.

Text file:

-30 °C -22.0 °F
-20 °C -4.0 °F
-10 °C 14.0 °F
-9 °C 15.8 °F
-8 °C 17.6 °F
-7 °C 19.4 °F
-6 °C 21.2 °F
-5 °C 23.0 °F
-4 °C 24.8 °F
-3 °C 26.6 °F
-2 °C 28.4 °F
-1 °C 30.2 °F
0 °C 32.0 °F freezing/melting point of water
1 °C 33.8 °F
2 °C 35.6 °F
3 °C 37.4 °F
4 °C 39.2 °F
5 °C 41.0 °F
6 °C 42.8 °F
7 °C 44.6 °F
8 °C 46.4 °F
9 °C 48.2 °F
10 °C 50.0 °F
20 °C 68.0 °F
21 °C 69.8 °F room temperature
30 °C 86.0 °F
37 °C 98.6 °F average body temperature
40 °C 104.0 °F
50 °C 122.0 °F
60 °C 140.0 °F
70 °C 158.0 °F

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If we are talking about marine use, why not broadcast the bigger ones? I think we could squeeze in the additional 300KB if the data is really useful. The two big files look like they could be JPG compressed to save a few KB at the expense of quality/precision.

The original file is 179KB, and below are examples of JPG-compressed versions. Let me know if any of those are still usable.

As far as size goes, around 50% quality seems to be the sweet spot. Quality level of less than 50% does not provide any meaningful file size reduction while dramatically degrading the quality.

Example: 75% quality JPG - 161KB

Example: 60% quality JPG - 122KB

Example: 50% quality JPG - 106KB

Example: 40% quality JPG - 91KB

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Yes good plan…

The temp ones are less useful for marine, more for land based ‘are all the people in my refugee camp going to freeze this week’ or ‘Should I plant my wheat yet, or wait another week’



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