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OT: Tide prediction anomalies in 2016
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N_Cook
Jan 27, 2016, 9:21:27 AM1/27/16
to
Anyone here take a close interest in tides , in particular disparities
between predicted and actual, in both storm and calm situations?
The UK Hydrographic Office seems to be predicting erroneous tides times
and or heights. Anyone else noticing this?
Obviously there is a danger to shipping if this most basic of tide data
is plain wrong, maybe get progressively worse through the year.
Dependendent on whether you use UKHO or NTSLF derived astronomic tide
data, the NTSLF prediction of surges is reasonably correct or unusually
way off, in our area of Bornemouth ,Southampton , Portsmouth.
eg
http://www.ntslf.org/storm-surges/latest-surge-forecast?port=Bournemouth
The non-storm condition astronomic tide prediction is also seemingly out
of kilter.
Allied evidence is that even the printed 2016 tide books for
Southampton, from UKHO data, has these sorts of errors, never seen
before (when it was Her Majesty's Hydrographic Office, coincidence?)
eg for Southampton
12/01/2016
High Water 00:02 4.7
Second Tide 02:07 4.5
Low Water 05:44 0.7
High Water 12:16 4.7
Second Tide 12:16 4.7
Low Water 18:05 0.5
13/01/2016
High Water 00:42 4.7
Second Tide 02:58 4.5
Low Water 06:26 0.7
High Water 12:58 4.7
Second Tide 15:16 4.3
Low Water 18:47 0.5
12/01/2016 has an obvious error in that there is always a first and
second tide in Southampton of different times certainly, sometimes same
height.
About 20 such errors in the 2016 tide book.
Obviusly the following could be just an "internet thing"
but could someone else confirm , that with their browser, the tides
returned for the next 7 days in
http://www.ukho.gov.uk/easytide/EasyTide/ShowPrediction.aspx?PortID=0065&PredictionLength=7
for Portsmouth and Southampton show exactly the same data? wheras pompey
should be half hour or so later times and slightly higher heights for
any given day
between predicted and actual, in both storm and calm situations?
The UK Hydrographic Office seems to be predicting erroneous tides times
and or heights. Anyone else noticing this?
Obviously there is a danger to shipping if this most basic of tide data
is plain wrong, maybe get progressively worse through the year.
Dependendent on whether you use UKHO or NTSLF derived astronomic tide
data, the NTSLF prediction of surges is reasonably correct or unusually
way off, in our area of Bornemouth ,Southampton , Portsmouth.
eg
http://www.ntslf.org/storm-surges/latest-surge-forecast?port=Bournemouth
The non-storm condition astronomic tide prediction is also seemingly out
of kilter.
Allied evidence is that even the printed 2016 tide books for
Southampton, from UKHO data, has these sorts of errors, never seen
before (when it was Her Majesty's Hydrographic Office, coincidence?)
eg for Southampton
12/01/2016
High Water 00:02 4.7
Second Tide 02:07 4.5
Low Water 05:44 0.7
High Water 12:16 4.7
Second Tide 12:16 4.7
Low Water 18:05 0.5
13/01/2016
High Water 00:42 4.7
Second Tide 02:58 4.5
Low Water 06:26 0.7
High Water 12:58 4.7
Second Tide 15:16 4.3
Low Water 18:47 0.5
12/01/2016 has an obvious error in that there is always a first and
second tide in Southampton of different times certainly, sometimes same
height.
About 20 such errors in the 2016 tide book.
Obviusly the following could be just an "internet thing"
but could someone else confirm , that with their browser, the tides
returned for the next 7 days in
http://www.ukho.gov.uk/easytide/EasyTide/ShowPrediction.aspx?PortID=0065&PredictionLength=7
for Portsmouth and Southampton show exactly the same data? wheras pompey
should be half hour or so later times and slightly higher heights for
any given day
Martin Brown
Jan 27, 2016, 10:21:54 AM1/27/16
to
On 27/01/2016 14:21, N_Cook wrote:
> Anyone here take a close interest in tides , in particular disparities
> between predicted and actual, in both storm and calm situations?
> The UK Hydrographic Office seems to be predicting erroneous tides times
> and or heights. Anyone else noticing this?
> Anyone here take a close interest in tides , in particular disparities
> between predicted and actual, in both storm and calm situations?
> The UK Hydrographic Office seems to be predicting erroneous tides times
> and or heights. Anyone else noticing this?
> Obviusly the following could be just an "internet thing"
> but could someone else confirm , that with their browser, the tides
> returned for the next 7 days in
> http://www.ukho.gov.uk/easytide/EasyTide/ShowPrediction.aspx?PortID=0065&PredictionLength=7
>
> for Portsmouth and Southampton show exactly the same data? wheras pompey
> should be half hour or so later times and slightly higher heights for
> any given day
Similar peak data with Southampton about 01m lower and leading
> but could someone else confirm , that with their browser, the tides
> returned for the next 7 days in
> http://www.ukho.gov.uk/easytide/EasyTide/ShowPrediction.aspx?PortID=0065&PredictionLength=7
>
> for Portsmouth and Southampton show exactly the same data? wheras pompey
> should be half hour or so later times and slightly higher heights for
> any given day
Portsmouth by about 5 mins but the shaded curves are radically different
with Southampton showing a pronounced inflection at height 2.4m mid tide
and a flat topped peak with first or second tide obvious.
I had a quick poke about predictions along the S coast too.
Newhaven looks a bit too ideal to me - perhaps it really is?
--
Regards,
Martin Brown
N_Cook
Jan 27, 2016, 10:47:20 AM1/27/16
to
The inflection is called young flood stand and is quite usual, the
general tide curves are quite different for the 2 ports.
Cross-comparing the returned data there is very little difference in
timing at the moment, which AFAIK does not happen as 20 miles separation
, but by 02 Feb the half-hour difference between pompey single tide peak
and Soton first tide peak, returns. Or it would seem to but for more
mangled data, Soton should be LW, HW(1), HW(2), LW etc .
Pompey can sometimes have a double high tide so nothing suspicious there.
Pompey
HW HW LW HW HW LW
04:46 06:41 10:38 17:08 19:28 23:13
3.8 m 3.7 m 1.9 m 3.6 m 3.5 m 2.0 m
Soton
Tue 2 Feb
HW HW HW HW HW LW
04:09 07:04 12:51 16:31 19:56 23:04
3.7 m 3.6 m 2.4 m 3.5 m 3.4 m 2.1 m
N_Cook
Jan 27, 2016, 11:21:52 AM1/27/16
to
I think its time to contact port operations, as a shipping hazard
from the UKHO site
Southampton
http://www.southamptonvts.co.uk/Live_Information/Tides_and_Weather/High_and_Low_Tide_Times/
using the same UKHO data, their www site shows this mangling for the
same day
02/02/2016
High Water 04:29 3.8
Second Tide 06:34 3.8
Low Water 6 10:30 2
High Water 16:56 3.6
Second Tide 19:11 3.6
Low Water 23:04 2.1
Low waters in Pompey and Soton cannot be over 2 hours time difference.
from the UKHO site
Southampton
Tue 2 Feb
HW HW HW HW HW LW
04:09 07:04 12:51 16:31 19:56 23:04
3.7 m 3.6 m 2.4 m 3.5 m 3.4 m 2.1 m
and the local VTS port operations site,
HW HW HW HW HW LW
04:09 07:04 12:51 16:31 19:56 23:04
3.7 m 3.6 m 2.4 m 3.5 m 3.4 m 2.1 m
http://www.southamptonvts.co.uk/Live_Information/Tides_and_Weather/High_and_Low_Tide_Times/
using the same UKHO data, their www site shows this mangling for the
same day
02/02/2016
High Water 04:29 3.8
Second Tide 06:34 3.8
Low Water 6 10:30 2
High Water 16:56 3.6
Second Tide 19:11 3.6
Low Water 23:04 2.1
Low waters in Pompey and Soton cannot be over 2 hours time difference.
Alastair
Jan 27, 2016, 3:20:10 PM1/27/16
to
http://www.southamptonweather.co.uk/doubletides.php
Alastair
Jan 27, 2016, 3:35:53 PM1/27/16
to
On Wednesday, 27 January 2016 16:21:52 UTC, N_Cook wrote:
HTH,
Cheers, Alastair
N_Cook
Jan 27, 2016, 4:36:27 PM1/27/16
to
compared to the Solent, some way away from the IoW
Message has been deleted
Weatherlawyer
Jan 27, 2016, 4:41:18 PM1/27/16
to
On Wednesday, 27 January 2016 21:39:45 UTC, Weatherlawyer wrote:
http://weatherlawyer.altervista.org/an-invitation-to-the-dance/
Alastair
Jan 27, 2016, 5:24:59 PM1/27/16
to
Vidcapper
Jan 28, 2016, 2:28:38 AM1/28/16
to
On 27/01/2016 20:20, Alastair wrote:
>
> Others may not be aware that there is a double tide in the Solent, which, strangely, is not caused by the Isle of Wight.
> http://www.southamptonweather.co.uk/doubletides.php
>
I knew there was a double tide there, but always assumed it *was* caused
>
> Others may not be aware that there is a double tide in the Solent, which, strangely, is not caused by the Isle of Wight.
> http://www.southamptonweather.co.uk/doubletides.php
>
by the IoW!
--
Paul Hyett, Cheltenham
Weatherlawyer
Jan 28, 2016, 9:15:26 AM1/28/16
to
Dover and Liverpool (Dublin too) are on the same co-tidal lines. Hull and Bristol oppose them; around Western Ireland it is less dramatic but still observable.
The Cavendish Experiment should show a scientist that both New and Full moons can not be responsible for both Spring Tides if any schoolboy mathematician couldn't first advise the experts here that water can not be distracted from its attraction to the centre of the earth by a less constant moon some 1/81st its size and five thousand times further away and save the imbeciles the difficulty of thinking.
(Thought being a process not highly favoured by many geophysicists, as can easily be proven by their explanation for the regular appearances of low Tides over the ocean chasms far out at sea.)
Sorry about that gentlemen but better I bang the drum than I bang your heads. If you are not to giddy, you might care to peruse the following:
http://weatherlawyer.altervista.org/winter-in-its-passing/#comment-53/youareallprobablyfartoodimtohandleanyofthissobewarned
N_Cook
Jan 30, 2016, 6:06:02 AM1/30/16
to
It looks as though Southampton is going through a period of 3 high
waters, so both VTS and UKHO can both be right depending on how you
define First High Water, as the earliest or the highest.
I don't know which of the harmonics is causing this effect though.
They are referring to it as typo errors, as the presentational forms
only allow for 2 high waters per tide cycle for Soton
waters, so both VTS and UKHO can both be right depending on how you
define First High Water, as the earliest or the highest.
I don't know which of the harmonics is causing this effect though.
They are referring to it as typo errors, as the presentational forms
only allow for 2 high waters per tide cycle for Soton
Alastair
Jan 30, 2016, 6:44:55 AM1/30/16
to
N_Cook
Jan 30, 2016, 8:15:15 AM1/30/16
to
http://www.sotonmet.co.uk/%28S%28a10m5a55ajku4z55q3fjug45%29%29/default.aspx
it looks as though we are going through a period of 3 high waters
13:41 (UKHO), 13:56(VTS),16:16 for yesterday , so VTS and UKHO were both
technically correct, depending on how you define first high water.
They are all likely maxima of the cosine summations to 2 decimal places,
with peaks surprisingly in reality showing up on the tide gauge at those
times. Surprising as 20kn wind around , although NTSLF pompey and
Bournemouth, and lymington gauges were showing close to zero residuals
for the first 2 high tide times and neutral 1012mB air pressure.
So VTS was going for the highest of the 2 "first " tides and UKHO going
for the earliest.
Then only 4 fields available in HTML presentation pages, into which 6
blocks of data was trying to be fitted, must be giving the "typos".
It looks as there are many months in 2016 where this 3 high tide events
are occuring.
N_Cook
Feb 16, 2016, 11:20:51 AM2/16/16
to
week, imagine the broohah ,if this 150,000 tonne ship had grounded due
to the local use of inaccurate tide data?
http://www.newsmaritime.com/2016/ultra-large-container-ship-apl-vanda-grounded-off-cowes-uk/
https://www.vesselfinder.com/news/5343-Container-Ship-APL-Vanda-Runs-Aground-Off-Cowes-UK
Weatherlawyer
Apr 5, 2016, 12:47:54 PM4/5/16
to
Nothing over 5.4 until: 2016/04/05 08:29 5.7 M. Talaud Islands, Indonesia
It looks like the reaction is a Tropical Storm (only just) with its path over the epicentre of the first one and the energy value governed by the magnitude of the second one based on their time difference and a relationship with Froude Numbers and the Beaufort Scale.
Now how do I convince you and do I wish to?
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