Co-Tidal Chart Needed

[JumbleDuck]

For work I need a co-tidal chart showing an amphidromic point. I thought the UKHO did a North Sea one, but all I can find from them is NP214 for the Persian Gulf, which would do at a pinch. My Google-fu has failed to find anything useful online - can anybody point me at something, maybe from RYA training materials? At this stage a scan would be very useful too (PM for email address), and rights will be properly negotiated before anything goes public.

 

[Aeolus]

Googled to find out what is an Amphidromic Point, and found this. Any use?
Amphidromic point - Wikipedia

 

[JumbleDuck]

Googled to find out what is an Amphidromic Point, and found this. Any use?
Amphidromic point - Wikipedia

Thanks. I'm already using that - what I need now is a detailed chart of a smallish area so that students can do some calculations with it - "if high tide is Grimsby is 3.30pm, when is high tide in Copenhagen?", that sort of thing.

 

[tillergirl]

I would be surprised if there was a amphidromic point in the North Sea. I might be wrong though. There are co-tidal charts in the Thames Estuary which has a bit of fun because the Estuary is under the influence of two tides - North Sea and English Channel - and is not fully synchronised. The UKHO has such charts so would be copyright for me to copy but there is a Port of London co-tidal chart which I think is public domain. If you think it useful PM me an email address.

 

[westhinder]

I would be surprised if there was a amphidromic point in the North Sea. I might be wrong though. There are co-tidal charts in the Thames Estuary which has a bit of fun because the Estuary is under the influence of two tides - North Sea and English Channel - and is not fully synchronised. The UKHO has such charts so would be copyright for me to copy but there is a Port of London co-tidal chart which I think is public domain. If you think it useful PM me an email address.

Actually, Wikipedia tells me there are three amphidromic points in the North Sea: https://upload.wikimedia.org/wikipedia/commons/2/20/Amfidromieen.JPG

 

[tillergirl]

Well, well, well. I suppose there must be some of course on reflection. I am a little surprised No 1 is so south; the Channel influence 'dies' v quick. I thought the Baltic influence would occur but there is plenty of room on the East side of the North Sea.

 

[LadyInBed]

I have this one

 

[BabaYaga]

I thought the Baltic influence would occur

I think it's the other way around. The fact that there are two of these points 'guarding' the inlet to the Baltic ,explains why there is so very little tidal range further east.

 

[Roberto]

Thanks. I'm already using that - what I need now is a detailed chart of a smallish area so that students can do some calculations with it - "if high tide is Grimsby is 3.30pm, when is high tide in Copenhagen?", that sort of thing.

here you have phases too, nice exercise

 

[jdc]

I think you need the diurnal M2 co-tidal chart data

The link may have what you want! Co-tidal charts for the southern North Sea

Since you have I understand good academic contacts, what you need can probably be obtained from Prof. Dyke, Professor Philip Dyke - University of Plymouth whose 2007 paper is often cited.

And I stumbled on this which could be informative: The Scottish Shelf Model. Part 1: Shelf-Wide Domain - gov.scot

 

[BabaYaga]

"if high tide is Grimsby is 3.30pm, when is high tide in Copenhagen?", that sort of thing.

I realise that was probably just an example, but beware that the tidal range in Copenhagen is rarely over 0.2 metres and more often about 0.1 metres. Find your students a more exciting task...
https://www.dmi.dk/fileadmin/user_upload/Bruger_upload/Tidevand/2020/Kobenhavn.pdf

 

[Spirit (of Glenans)]

here you have phases too, nice exercise

I read a piece about this subject in YM or PBO some years ago and it mentioned that there was an amphidronic point on the Wexford coast, somewhere around Courtown I believe, but this chart doesn't seem to show it.

 

[Roberto]

Found this one too

 

[tillergirl]

I think it's the other way around. The fact that there are two of these points 'guarding' the inlet to the Baltic ,explains why there is so very little tidal range further east.

You mistake my English. I thought the Baltic influence would occur (and it does) but there is plenty of room on the East side of the North Sea (for it not to influence). Mustn't cut the words! I remain surprised by the the southern 'amph' point - not that I am suggestion there is anything wrong with that.

 

[LittleSister]

Some available here to download, free to use with Creative Commons Licence -

Figure 4. M2 co-tidal charts. (a) CO4, NEMO VN3.2. (b) CO5, NEMO VN3.4.

 

[BabaYaga]

You mistake my English. I thought the Baltic influence would occur (and it does) but there is plenty of room on the East side of the North Sea (for it not to influence). Mustn't cut the words! I remain surprised by the the southern 'amph' point - not that I am suggestion there is anything wrong with that.

Yes, maybe I misunderstood.
But if this slight thread drift might be permitted to continue – would you care to explain what you mean by 'Baltic influence'?
I took your remark to mean that the non existent tidal range of the Baltic would somehow reduce the range in neighboring waters. How would that work?

 

[Martin&Rene]

A well known yachting magazine, called "Yachting Monthly" did an excellent article on this subject in Dec 2014 and it even included the Islay-Machrihanish one. Jumbleduck, send us a private message. One of these days we may even meet you on Bute.

 

[JumbleDuck]

Thanks very much, people. I'm away being cultured for a few days, but will pick up the suggestions when I get back to work.