Wind in the South Pacific?

[IslandHopper]

Originally Posted by Albro359

I have Cornell's book with me. It provides a lot more info than the website quoted above. I don't consider it a waste of money, rather the reverse.

Most of my voyage planning is done on the boat !

Here here....

[Andrew Troup]

Originally Posted by Littlechay

No need to waste money on Mr. Cornell's book. It's all available online Climatology of Global Ocean Winds - COGOW of course the book can be useful if you want to take the data with you but as most voyage planning is done at home most people have internet at that stage.

Thanks for that, Littlechay, that's a very valuable link.

I was a huge fan of QuikSCAT when it was in operation>

It's particularly valuable in my part of the world where the landmasses are small, and so do not block 'visibility' of weather inferred from seastates, from any given direction.

I hoped there would be a consolidation of the accumulated data from that era.

Great not to have to go hunting for it.

Shame it probably will become increasingly inapplicable, as climate change accelerates, but for now it's a goldmine.

[Andrew Troup]

Originally Posted by Albro359

I have Cornell's book with me. It provides a lot more info than the website quoted above. I don't consider it a waste of money, rather the reverse.

Most of my voyage planning is done on the boat !

I think you mean "different" info, rather than "more" - unless you didn't explore the website very thoroughly?

The quantity of info, which you mention, is admittedly a different question from the usefulness of the info, but the COGOW is surely beyond reproach when it comes to quantity.

The website gives easy access to averaged statistical and graphical data, twice a month, for every location on a half-degree grid for all the world's oceans apart from zones near the poles.

If the oceans occupy say 7/10 of the globe, the number of discrete physical locations covered by the website will be something approaching 180 x 2 x 360 x 2 x 0.7 = nearly two hundred thousand graphical plots like this one. Even allowing for the poles, and the fact that QuikSCAT does not work within 30km of long coastlines, that still has to be over 150,000 locations.

I don't see how a single book could possibly contain this much paper.

Here's a sample of a graphical plot, but bear in mind as well as this averaged data over ten years to 2009, the info is also available as tabulated data, and you can drill right down to the individual observations

By this I mean the mean wind-strength and wind direction ON THAT DAY, at that location, for every day over the entire period.

Note that this is not modelled data, this is data based on wind-strengths inferred from actual wave-front height, steepness and aspect, as measured from satellite using doppler radar.

Notice how remarkably 'variable' the wind direction is at the location I picked for the first sample plot, near Australia's East coast. I wonder if it's even possible to get much more balanced strength and direction than this. Conversely with the second plot, at a carefully selected location in the NE trades region of the Pacific.

[IslandHopper]

^^^ but of absolutely no use to you me without an internet connection, this is why a publication is of more use to me.....

[Albro359]

Originally Posted by Andrew Troup

I think you mean "different" info, rather than "more" - unless you didn't explore the website very thoroughly?

The quantity of info, which you mention, is admittedly a different question from the usefulness of the info, but the COGOW is surely beyond reproach when it comes to quantity.

The website gives easy access to averaged statistical and graphical data, twice a month, for every location on a half-degree grid for all the world's oceans apart from zones near the poles.

If the oceans occupy say 7/10 of the globe, the number of discrete physical locations covered by the website will be something approaching 180 x 2 x 360 x 2 x 0.7 = nearly two hundred thousand graphical plots like this one. Even allowing for the poles, and the fact that QuikSCAT does not work within 30km of long coastlines, that still has to be over 150,000 locations.

I don't see how a single book could possibly contain this much paper.

Here's a sample of a graphical plot, but bear in mind as well as this averaged data over ten years to 2009, the info is also available as tabulated data, and you can drill right down to the individual observations

By this I mean the mean wind-strength and wind direction ON THAT DAY, at that location, for every day over the entire period.

Note that this is not modelled data, this is data based on wind-strengths inferred from actual wave-front height, steepness and aspect, as measured from satellite using doppler radar.

Notice how remarkably 'variable' the wind direction is at the location I picked for the first sample plot, near Australia's East coast. I wonder if it's even possible to get much more balanced strength and direction than this. Conversely with the second plot, at a carefully selected location in the NE trades region of the Pacific.

Well yes, you're right...different info, not more....but more detail is more confusing...to me at least...
What I want is just an idea of how the winds are at different times of the year and the likelihood of gales / calms, which is what Cornell gives me in a very user friendly format
BUT the big problem with all this is that it is historic, it doesn't tell me what I'm going to get next week when on my way to the Australs.
The GRIB files change every day...that's not very helpful either ...you get what you get....any historic data may say 90% chance of fair winds but it doesn't foretell the future..now, where's that crystal ball ?

[Andrew Troup]

I'm sure Cornell has added a lot of value to the raw data, from a passage planning point of view.

I think the COGOW info is more likely to be useful to someone planning a short hop, or looking for the chances of a particular wind direction and strength in relation to (say) anchoring in a location far from any recognised cruising routes.

For purposes like this, being able to home into the historical data for just a couple of locations, rather than a broad-brush average, could be invaluable.

And being able to 'drill down' is particularly handy at the margins. For instance, there are wind arrows in the deep south which, when you drill down, prove to be based on a tiny fraction of the possible dates, presumably because they were right at the end of a satellite's sweep, and things like the tilt of the earth made them unavailable most of the time. Such readings, rather than appearing as "zero"s, are listed as NaN (Not a Number)

This is not evident from the graphical plots.

[Littlechay]

Originally Posted by Albro359

I have Cornell's book with me. It provides a lot more info than the website quoted above. I don't consider it a waste of money, rather the reverse.

Most of my voyage planning is done on the boat !

That was just one example of the info available on the web. It is all there, where do you think that Cornell got it from? He certainly didn't do any original work. His information is also old as the field of understanding the climate, winds, currents, etc. is evolving so rapidly.

As I said if you don't have internet access then it's fine, but way too expensive for what it is. If it was original work the cost would be justified but for rehash of freely available info it is expensive.

I still use the old "Ocean passages of the world (NP136)" and find it very good supplemented by the new information from the web. Buy an older edition with the charts.

Things have not really changed since the old guys did it so the old books are fine, the new information is more detailed so I use the web to fine tune. If I don't have fine tuning then it doesn't really matter once you set sail.

[Littlechay]

Originally Posted by Andrew Troup

Shame it probably will become increasingly inapplicable, as climate change accelerates, but for now it's a goldmine.

There data is still being accumulated by different satellites such as ASCAT The Advanced Scatterometer (ASCAT) Data Products

I don't have the time or the bandwidth to post other sources right now I'm afraid but it's all out there

[SV Windrush II]

This is one of the most informative threads I have read so far. Thanks all!

[Nicholson58]

Originally Posted by Littlechay

No need to waste money on Mr. Cornell's book. It's all available online Climatology of Global Ocean Winds - COGOW of course the book can be useful if you want to take the data with you but as most voyage planning is done at home most people have internet at that stage.

I bought his atlas from him personally. He signed & personalized it for us. Very nice fellow. I find his World Cruising Routs a great addition to the library.