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Board » General Discussion » Weather - Brain Storm

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Posted by
Zorba777


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2020-06-06 08:22:54
2020-09-10 08:44:00 - Re: Weather - Brain Storm
Hi ij and Bonk,

The picture based on WRF definitely looks a lot better and more realistic than the course GFS based map. GFS is known to be very poor when it comes to the winds in coastal areas.

What do you think about using ECMWF, which is 0.5x0.5 and updates twice a day? It's global and I think as a non-profits they would let us use it on a free license if we ask.
Updating every 12 hours is also easier for a lot of SOLers with daytime jobs, or with wives that complain about their hobby that keeps them out of bed too often ;-)

The quality difference between GFS and ECMWF is easy to see on windy: https://www.windy.com/?-6.375,154.841,7,i:pressure,m:dwIakqh

The winds over and around the islands are much better in ECMWF.

Other global models like ICON or Arpege could be considered too. They are also updated every 12 hours, but higher resolution than GFS: https://opengribs.org/en/gribs

Posted by
Zorba777


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2020-09-10 08:46:02 - Re: Weather - Brain Storm
Windy has a great article on the pros and cons of the most widely used WX models: https://windy.app/blog/what-is-a-weather-forecast-model-guide-on-forecast-models-all-around-the-world.html
Posted by
ij


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2018-06-09 20:33:19
2020-09-10 20:03:13 - Re: Weather - Brain Storm
Many numbers you see on those lists are not correct. ECMWF updates 4 times per day but only to +90h on every second run (Similar to some other forecast runs with other models).

Also, they explicitly mention not-for-profits in their license selection guidance so you're just dreaming and there's little point in trying to ask anything from them.

--
i.
Posted by
ij


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2020-09-11 11:32:12 - Re: Weather - Brain Storm
Of the available forecasts, these regional ones certainly seem interesting for higher than GFS precision:
- ICON-EU
- AROME
- NAM conus & maybe caribbean nests

For global models, I don't think there are freely available alternatives with enough incentives to make it worth replacing GFS, and many have clear disincentives such as non-even forecast lengths for different times.

Without at least seriously trying out with GFS 0.25 x 0.25 first, I wouldn't spend too much effort on the other global models that are freely available. (ECMWF is not freely available, if it would be, it would certainly seem attractive enough).

In practice, the blocker for any high-res wx is the lack of tiled wx support which requires too large modifications before some other blockers are removed first so it's not going happen over a weekend (I've definitely made some progress towards that direction but it's a big task with rather limited help so far). Even the WRF weathers which we've not been able to use for some time were somewhat big data sizewise for anything else than those small sprints (but certainly made the races much more interesting, IMHO).

--
i.
Posted by
dtayls


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2020-09-27 00:57:45 - Re: Weather - Brain Storm
ij said @ 2020-09-10 20:03:13:
Also, they explicitly mention not-for-profits in their license selection guidance so you're just dreaming and there's little point in trying to ask anything from them.
--
i.

Is it possible to get access to the ECMWF model for internal use only on the server while using the GFS model in the gribs provided to users?

It seems to me that this would fit the licencing requirements for the not-for-profit use of the real-time ECMWF data.

It would also be closer to reality in that the underlying model used on the server would be different to the forecasts available to users.

There may also be a need for a new SOL rule that makes it illegal to use commercial paid-for products not available to all users for free.

I think this would make for some more interesting racing.
Posted by
VIbex


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2020-09-27 03:07:04 - Re: Weather - Brain Storm
Most IRL races certainly have a rule about data used having to be freely available to all once the race start. But that doesn't mean you can't use Expedition, for example. It means you can't use PredictWind routing, or other professional services. So, dtayls, what did you have in mind with the rule? Just cover for-pay weather services? I assume no one's using that now, but you think if the server was using something that was made unavailable through the rules, it would be more like real life? I'd agree. But, the counterargument is that we're not actually living on the boats so you need some measure of predictability.
Posted by
dtayls


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2020-09-29 00:27:13 - Re: Weather - Brain Storm
VIbex: The key to my idea is to use an underlying weather model for the simulation which powers our virtual boats that is different from the predictions available to SOL competitors.

I agree when you say "we're not actually living on the boats so you need some measure of predictability" but I don't think that means we need to be able to 100% predict the weather.

When the weather is very stable and highly predictable then the models will likely be very closely aligned. In those cases it might be safe to sail very close to a mark or an island, but when the weather is less stable you might choose a wider safety margin over absolute performance.

As for the question of using 'rules' to control which models can or can't be used, there is always going to be someone who wants to cheat.

Ideally, I like the idea of using something like a pre-release beta version of the ECMWF model not generally available except to researchers, if such a thing exists. Another alternative might be a psuedo-random merge of multiple model GRIBs ... This could be a fun project :-)
Posted by
VIbex


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2020-09-29 14:57:06 - Re: Weather - Brain Storm
dtayls:I like it!
Posted by
ij


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2020-09-29 19:25:31 - Re: Weather - Brain Storm
There's no differentiation for non-profits. The ECMWF licensing is using the very same conditions for non-profits and commercial. From https://www.ecmwf.int/en/forecasts/accessing-forecasts/licences-available:

"Provide a service using real-time ECMWF products

If you wish to provide a commercial, non-commercial, or not-for-profit service to third parties using ECMWF real-time products, you will need to accept the terms of the ECMWF Standard licence and pay for the associated data and handling costs."

I don't see any way around paying, regardless of non-for-profit or not (research, as expected, doesn't allow providing any services and it would be really twisting the rules anyway).

If a "secret" wx is desired, it's relatively easy to create one with WRF, just some parameter tweaks that remain secret are required. But then we will find out the WRF is volatile enough in itself so the secrecy loses its useful/meaning (one cannot plan long-term route with wrf even nearly as reliably as with gfs).

A "secret" wx would really just force people to sit in front of computer whole the time, especially in low TWS conditions, because twa steering becames a joke for racing purposes (or not to participate at all which is hardly useful goal to aim at ;-)). ...It gave me another idea though, maybe the platform should allow truly crewing the same boat with different usernames to share watches (different from private boat sharing that is of course possible even today). Then it would be a bit less solo mission to keep an eye on the wx.

--
i.

--- Last Edited by ij at 2020-09-29 19:48:35 ---
Posted by
dtayls


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2020-10-01 03:03:21 - Re: Weather - Brain Storm
While they do indeed say "you will need to accept the terms of the ECMWF Standard licence and pay for the associated data and handling costs." what if that cost was $0 or the equivalent in Euros? I think you will find that their licensing model depends very much on how the data is to be used. The fact that SOL is a not-for-profit, that the data would not be made available for download to end users, and that we would not require 24x7 support might all have a big impact on the quoted price. Maybe someone should contact them and request a quote.

As it stands in SOL we are given perfect weather information for each 6 hour window which is a little unrealistic. What's more, some people know the idiosyncrasies of how the SOL server interprets the data and are therefore able to use that knowledge to their advantage. Is this really fair? And given that we allow this and the use of routers then we'd might as well allow full autopilot control of our boats!

If there is instability in in the weather then I would expect the underlying weather to reflect that and probably differ from the predictions. Those who understand the weather the best will generally make the best decisions and may even have a chance at winning over those who can drive the tools to perfection.

Ideally the underlying weather model used in the SOL simulation is based on the most accurate available. But some people may have access to this unless we 'rule' it out. So maybe we could also introduce some variations in to areas where the model is unstable. Again, this could be fun :-)

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