TIDES UP

[oldman]

That map is a beauty SASurfa. If you just think about the tidal flow being affected by land mass you can see how many of these high flow areas would be generated.

Particularly the straits between Aust and Indo, with the entire Pacific Ocean trying to flow into the Indian and then receding. Such huge volumes of water through a narrow strait is easy to imagine.

Also helps to explain the high and increasing tidal range as you move up the east coast of Oz, as you have observed, and the high tidal range on the north west coast of Oz, around Broome etc. but lower tidal range on the southern oceans where water movement is both less affected by the lunar flow and the oceans are unimpeded.

Nice work!

[thermalben]

Here's a nice animated graphic for you oldman, showing the tidal range around New Zealand (courtesy ASR).

[thermalben]

( they can predict the tides a year in advance but daylight savings beyond them )

hehe.. always wondered that myself Fong!

[combatwombat]

nah way off, this topic is stupid.

All the at risk houses, don st etc at belongil are not even close.

Went to Sth wall today on a whim..... and south ballina looked soggy , but certainly not flooded.

Although it did prove what a try hard Buff Brad is!!

[oldman]

Here's a nice animated graphic for you oldman, showing the tidal range around New Zealand (courtesy ASR).

Geez Ben, I thought I was getting somewhere and then you show me that.

My head's spinning now, just like those tidal flows.

Cheers fellas

[doowdle]

Hay ben, that would be one of these amphidromic points, with the tide spinning around NZ.

heres a map with other points:



The whitelines show lines where the tide happens at the same time, 1 hour between lines.

for some reason, this point is an exception cos it spinning around the islands, so there is no point where the tide height is zero, but don't really get why.

[SAsurfa]

Great picture doowdle, that was what I was looking for

[Damage]

Come on pseudo moon boffins. I'm interested to hear your regurgitated and undigested learnings from wikipedia.

Ouch. That hurts.

[don.weather]

Qld's EPA post near-real time tide data, including actuals, predictions and residuals. So, you can see how "accurate" the tide forecast really is.

Interesting plot there Ben. Our marine designers use HAT all the time, and yet this plot clearly shows that both the predicted and actual tides are above HAT. I can understand the actual being greater (due to storm surge and other effects that have been discussed on here), but I'm a little concerned that the predicted is greater than HAT.....surely if they can predict tides greater than HAT, then HAT should equal the predicted tides?? Otherwise, what the hell is HAT?

[thermalben]

You're right Don.. HAT = Highest Astronomical Tide. Surely this means the highest predicted tide of the year? Might touch base with the EPA and see whether they inadvertently used a dodgy batch of data.

[doowdle]

I think the HAT is highest astronomical tide under average meterological conditions.

Does your graph show predicted high water factoring stuff like lower than average pressure or storm surge?

[Grooter]

Interestingly, stone henge is on one of those points, did the cave men know?

Probably not.

But considering the stones at Stone Henge are aligned to represent a giant calendar of where the points of the Moon's orbit intersects the plane of the Earth's orbit and the giant heel stone predicts the day of the summer solstice each year who knows? Maybe this particular point on the earth where it is built is very significant.

The Pyramids at Giza were built around the same time and I think they also align to one of these points, ditto the temples built in South America

Or so I've heard anyway...... I'm probably wrong!

[Revolution]

Anyone lost a house yet?