TIDES UP

[puurri]

TIDE'S UP

Tomorrow the BoM predicts the highest tide NSW for 18 years at 2.08M.

Factor in the north coast storm surge and flooding rivers and houses are predicted to go under permanently, particularly at Ballina.

What are your predictions and do you care about greedy developers and their gullible clients getting done?

[wanto]

well the swell/storm surge might be a little more extreme on the north coast, but the tide isn't. bom is calling 1.91 for yamba.

[oldman]

I was going to point that out also puurri.

Can't work out why ther BOM would call for 1.91 at yamba, and yet 2.08 for Port Jackson (at 8.38 pm or so). Both places receive the full effects of tide, so shouldn't be different. Someone will tell me that is wrong. I am going to find that hard to believe.

Are you looking at the right tide info wanto, or has the smh just lost the plot.

See http://www.smh.com.au/news/environment/ ... 41699.html

They are saying highest tide for 16 years. I thought that very interesting.

Norha Head, Wamberal, and a whole lot of other beaches and clifftops are looking a little nervous as we speak. Heavy rains with it make it worse for Norah Head also.

[wanto]

i'm no tide expert, but as i understand it they vary between locations and 1000km is a fair distance.

my source = bom website. i don't think the bom are more likely to be incorrect for yamba and not for sydney, than incorrect for sydney and not for yamba .. ?

still it's a big tide, and decent storm .. waves shouldn't top 6-8 foot though, so i think we've weathered worse situations in the last few years.

[oldman]

i'm no tide expert, but as i understand it they vary between locations and 1000km is a fair distance.

my source = bom website. i don't think the bom are more likely to be incorrect for yamba and not for sydney, than incorrect for sydney and not for yamba .. ?

still it's a big tide, and decent storm .. waves shouldn't top 6-8 foot though, so i think we've weathered worse situations in the last few years.

Yeah, I was thinking about it and the actual heights recorded would be relative to itself only, i.e. comparisons between the heights at yamba and sydney aren't comparable because they are just markings on a stick, and the stick may not be at the same relative height.

I remember with incredulity on a trip up Qld way once how one of the towns up there, I think it was Mackay, claimed to be 'the first mainland place the tides hit.' I found this at the time, and since, as quite a ridiculous claim, but there it was, and I didn't dream it.

Having said all that, I would think that if Sydney was getting it's highest tide in 16 years it is likely that yamba should also (their highest being 1.91, our highest being 2.08, or thereabouts.)

I take your point about yamba being a long way away, but compared to the moon, which is pulling the tides, yamba would be a freckle further away from the moon than Sydney, and the land mass shouldn't excessively impede the flow of the tides.

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

[2nd Reef]

The difference could be due to things such as local geography.

Tides are affected by the continental shelf, bays, headlands and estuaries. Sydney is measured at Fort Denison so the height will be influenced by the tide moving up the harbour.

That's all I've got to offer....

[Buff_Brad]

The variances, or squared standard errors, of estimates of tidal harmonic constants from analyses of a month or a year of tide-gauge data are analysed in terms of spectral properties of their noise continuum, modelled as exponential cuspsE 1 superimposed on a smoothly monotonic non-tidal spectrumE 0. Taking 5 representative stations, each with 19 years of data,E 0 is evaluated from the inter-species noise levels, andE 1 from the ratio of the variances from monthly and yearly analyses. It is shown that the cusps surrounding the diurnal tides are dominated byE 0, whereas the more important semi-diurnal and higher species cusps are fitted by an exponential form forE 1 with bandwidth of a few cycles per year. The variance ratios (monthly: yearly analyses) for diurnal harmonics are somewhat greater than the value expected for white noise, partly because of residual tidal lines in the monthly analyses which cannot be related to the major constituents. The corresponding ratios for semi-diurnal and higher species harmonics are less than the white noise value, on account of the cusps. The standard errors of yearly estimates of the larger tidal constituents may be predicted as proportional to their mean amplitude, as a very rough guide, in the approximate ratio of 11 mm/m.

Simply put.......there's a "noise" factor fellas. Like the noise factor in listening to radio waves.

[Trev]

Mackay's height tonight is 6.26 m
and on the point of the "different" stick, their preceeding low is 0.36 m.
Which means a tidal rise of 5.9 meters
Imagine that at The Bower or Maroubra or The Island.

[mustkillmulloway]

The variances, or squared standard errors, of estimates of tidal harmonic constants from analyses of a month or a year of tide-gauge data are analysed in terms of spectral properties of their noise continuum, modelled as exponential cuspsE 1 superimposed on a smoothly monotonic non-tidal spectrumE 0. Taking 5 representative stations, each with 19 years of data,E 0 is evaluated from the inter-species noise levels, andE 1 from the ratio of the variances from monthly and yearly analyses. It is shown that the cusps surrounding the diurnal tides are dominated byE 0, whereas the more important semi-diurnal and higher species cusps are fitted by an exponential form forE 1 with bandwidth of a few cycles per year. The variance ratios (monthly: yearly analyses) for diurnal harmonics are somewhat greater than the value expected for white noise, partly because of residual tidal lines in the monthly analyses which cannot be related to the major constituents. The corresponding ratios for semi-diurnal and higher species harmonics are less than the white noise value, on account of the cusps. The standard errors of yearly estimates of the larger tidal constituents may be predicted as proportional to their mean amplitude, as a very rough guide, in the approximate ratio of 11 mm/m.

.

but basicly u agree with wat i've been saying for ages

tide charts are a load crap

they are so incorrect....there not even close the right times 98% the time

[thermalben]

The variances, or squared standard errors, of estimates of tidal harmonic constants from analyses of a month or a year of tide-gauge data are analysed in terms of spectral properties of their noise continuum, modelled as exponential cuspsE 1 superimposed on a smoothly monotonic non-tidal spectrumE 0. Taking 5 representative stations, each with 19 years of data,E 0 is evaluated from the inter-species noise levels, andE 1 from the ratio of the variances from monthly and yearly analyses. It is shown that the cusps surrounding the diurnal tides are dominated byE 0, whereas the more important semi-diurnal and higher species cusps are fitted by an exponential form forE 1 with bandwidth of a few cycles per year. The variance ratios (monthly: yearly analyses) for diurnal harmonics are somewhat greater than the value expected for white noise, partly because of residual tidal lines in the monthly analyses which cannot be related to the major constituents. The corresponding ratios for semi-diurnal and higher species harmonics are less than the white noise value, on account of the cusps. The standard errors of yearly estimates of the larger tidal constituents may be predicted as proportional to their mean amplitude, as a very rough guide, in the approximate ratio of 11 mm/m.

Simply put.......there's a "noise" factor fellas. Like the noise factor in listening to radio waves.

C'mon Brad, if you're gonna rip stuff straight off the web - at least quote your source! (apologies in advance if you're either David E. Cartwright or Muhammad Amin, and worked at the Institute of Oceanographic Sciences, Bidston in 1986).

[puurri]

Consider my paras 2 and 3; Potential future storm and tide events compared with the State "planning" processes for coastal "development" .

Topic covered in prior posts.

[daryl]

The variances, or squared standard errors, of estimates of tidal harmonic constants from analyses of a month or a year of tide-gauge data are analysed in terms of spectral properties of their noise continuum, modelled as exponential cuspsE 1 superimposed on a smoothly monotonic non-tidal spectrumE 0. Taking 5 representative stations, each with 19 years of data,E 0 is evaluated from the inter-species noise levels, andE 1 from the ratio of the variances from monthly and yearly analyses. It is shown that the cusps surrounding the diurnal tides are dominated byE 0, whereas the more important semi-diurnal and higher species cusps are fitted by an exponential form forE 1 with bandwidth of a few cycles per year. The variance ratios (monthly: yearly analyses) for diurnal harmonics are somewhat greater than the value expected for white noise, partly because of residual tidal lines in the monthly analyses which cannot be related to the major constituents. The corresponding ratios for semi-diurnal and higher species harmonics are less than the white noise value, on account of the cusps. The standard errors of yearly estimates of the larger tidal constituents may be predicted as proportional to their mean amplitude, as a very rough guide, in the approximate ratio of 11 mm/m.

Simply put.......there's a "noise" factor fellas. Like the noise factor in listening to radio waves.

This does not explain why the tide is different from one place to another, the noise if such be is everywhere. What a lot of fluff.

[mustkillmulloway]

sorry for my off topic post
stupid bull.shi.t fictional flinders uni s.a guide too bull.s.hit tides thats never right bull.sh.it uni students don't know shit couldn't frockin do anything right

i doubt any houses will permantly go under :?

some will get wet....some people will scream terror

the developers will laugh and say buyer beware and local councilors will duck and get reelected via glossy ad's finaced by either the developers or the national party ( sunk at federal and state levels..pouring there funds into staying alive via councils)

so...same as it's always been

[SAsurfa]

Firstly tides are created by the different gravitational pulls of the sun and moon.

Now the moon, earth and sun are always changing positons around each other so the gravitational pull increases and decreases depending on the sum of all the forces.

If we now have the Earth rotation included as well as local bathymetries and constantly changing coastlines with gulfs/inlets and estuaries, we have more factors which influence the tide in an area.

So the tidal range, the difference between highest tide and lowest tide, changes along the coast depending on all of the abopve forces.

If we have a long inlet or gulf, such as Spencer Gulf here in SA, the tide can resonante and we get larger tidal ranges the more you travel up the gulf.

So nearly every location along the coast will have a different tidal range than a location around the corner

Tides are quite a complicated phenomena to get your head around but they can be predicted fairly easily for every location around the world.

And Fong, the tidal charts areant a load of crap at all you might be reading them wrong

[SAsurfa]

[stupid bull.shi.t fictional flinders uni s.a guide too bull.s.hit tides thats never right bull.sh.it uni students don't know shit couldn't frockin do anything right

When and where have you run into trouble with tidal predictions

[Trev]

Firstly tides are created by the different gravitational pulls of the sun and moon.

Now the moon, earth and sun are always changing positons around each other so the gravitational pull increases and decreases depending on the sum of all the forces.

If we now have the Earth rotation included as well as local bathymetries and constantly changing coastlines with gulfs/inlets and estuaries, we have more factors which influence the tide in an area.

So the tidal range, the difference between highest tide and lowest tide, changes along the coast depending on all of the abopve forces.

If we have a long inlet or gulf, such as Spencer Gulf here in SA, the tide can resonante and we get larger tidal ranges the more you travel up the gulf.

So nearly every location along the coast will have a different tidal range than a location around the corner

Tides are quite a complicated phenomena to get your head around but they can be predicted fairly easily for every location around the world.

And Fong, the tidal charts areant a load of crap at all you might be reading them wrong

OK. So why the large tidal changes in NQ - Mackay for instance is pretty open. Can't be because it's nearer the Equator as that wouldn't explain the even more massive tides in Britain.

[mustkillmulloway]

[stupid bull.shi.t fictional flinders uni s.a guide too bull.s.hit tides thats never right bull.sh.it uni students don't know shit couldn't frockin do anything right

When and where have you run into trouble with tidal predictions

shall i start with the latest

tiger whinging about the charts saying the run in should started a hour ago in my tinnie in noosa river as the tide pushed out for the next 4

he was cursing...but than again he'd just made a great cast into a tree

december standing in foot deep water retrivng a trap @ a time the charts had offically said was a 1.3 mtr high

mate...tide charts are CRAP....THEY FAIL TOO PREDICT THE TIDES OVER A YEAR

THEY COULD BE OK IF GIVEN FOR A MONTH...BUT REALLY...the people at bom or flinders...have no idea...less time figuring more time experncing would help

[Trev]

The variances, or squared standard errors, of estimates of tidal harmonic constants from analyses of a month or a year of tide-gauge data are analysed in terms of spectral properties of their noise continuum, modelled as exponential cuspsE 1 superimposed on a smoothly monotonic non-tidal spectrumE 0. Taking 5 representative stations, each with 19 years of data,E 0 is evaluated from the inter-species noise levels, andE 1 from the ratio of the variances from monthly and yearly analyses. It is shown that the cusps surrounding the diurnal tides are dominated byE 0, whereas the more important semi-diurnal and higher species cusps are fitted by an exponential form forE 1 with bandwidth of a few cycles per year. The variance ratios (monthly: yearly analyses) for diurnal harmonics are somewhat greater than the value expected for white noise, partly because of residual tidal lines in the monthly analyses which cannot be related to the major constituents. The corresponding ratios for semi-diurnal and higher species harmonics are less than the white noise value, on account of the cusps. The standard errors of yearly estimates of the larger tidal constituents may be predicted as proportional to their mean amplitude, as a very rough guide, in the approximate ratio of 11 mm/m.

Simply put.......there's a "noise" factor fellas. Like the noise factor in listening to radio waves.

C'mon Brad, if you're gonna rip stuff straight off the web - at least quote your source! (apologies in advance if you're either David E. Cartwright or Muhammad Amin, and worked at the Institute of Oceanographic Sciences, Bidston in 1986).

Good grief! And I thought BB was just hitting the keyboard with his eyes closed. as usual