On 26/07/2018 18:45, N_Cook wrote:

They and other academics are still putting a linear "fit " to the curve.

Just to be clear, I do think the ice-melt, especially looking 30-50
years ahead, is potentially serious and absolutely needs careful
monitoring by academics and amateurs alike.

But I'd be pretty certain that the professionals are all too well aware
that sea level rise may be slowly but steadily accelerating beyond a
linear trend.

Their problem, however, is that of needing to stick to a simple (ie
linear) model until someone can suggest a credible alternative model
grounded in some physical processes. I dare say that there is a lot of
work going on to develop such a model as - presumably - recorded in the
recent literature (not something I've explored). But an arbitrary
mathematical fit, especially one involving some power terms, is just not
likely to give meaningful results, especially when used to extrapolate
several tens of years into the future.

I don't know your circumstances, but if you're interested and able, why
not go along to one of the sea level rise conferences. Looks like there
was one earlier this July in Liverpool, but others scheduled include:

https://waset.org/conference/2018/08/paris/ICSLRE/home

https://waset.org/conference/2018/08/amsterdam/ICSLRGC

Not looked in detail, but seems a little odd to have two highly related
meetings so close together. MAybe they're looking at different aspects
of the problem.

On 27/07/2018 13:11, JGD wrote:
On 26/07/2018 18:45, N_Cook wrote:

They and other academics are still putting a linear "fit " to the curve.

Just to be clear, I do think the ice-melt, especially looking 30-50
years ahead, is potentially serious and absolutely needs careful
monitoring by academics and amateurs alike.

But I'd be pretty certain that the professionals are all too well aware
that sea level rise may be slowly but steadily accelerating beyond a
linear trend.

Their problem, however, is that of needing to stick to a simple (ie
linear) model until someone can suggest a credible alternative model
grounded in some physical processes. I dare say that there is a lot of
work going on to develop such a model as - presumably - recorded in the
recent literature (not something I've explored). But an arbitrary
mathematical fit, especially one involving some power terms, is just not
likely to give meaningful results, especially when used to extrapolate
several tens of years into the future.

I don't know your circumstances, but if you're interested and able, why
not go along to one of the sea level rise conferences. Looks like there
was one earlier this July in Liverpool, but others scheduled include:

https://waset.org/conference/2018/08/paris/ICSLRE/home

https://waset.org/conference/2018/08/amsterdam/ICSLRGC

Not looked in detail, but seems a little odd to have two highly related
meetings so close together. MAybe they're looking at different aspects
of the problem.


I'm in regular contact with 2 international repute academics at the NOC/
Southampton, concerning newspaper archives for the historical context
of storm-induced depths of marine flooding onto land locally as there
are no useable high-frequency tide-gauge records to get a handle on that
aspect . Original gauge plots tend not to have survived , eg Lymington
ones were lost ,ironically , in a marine flood of 1989 and Southampton
ones for some odd reason were stored at the Ordnance Survey and were
bombed out of existance in WW2.
I've only asked one of them about questionable linear global sea level
rise and he considers a linear "curve" fit perfectly proper and then
quote the IPCC spread of beyond-linear guesstimates for SLR this century.
So I go my own way on that.

Y = year (minus 2000) , x is cm SLR in Aviso.Altimetry terms for Jason-3
output up to 25 May 2018, publically outputed approx 23 July 2018,
for various optimised curve fits and concattenated 54 datapoint data for
Jason1+2+3, ranked in terms of R*R

Linear
Y= 1.440160 + 0.332706 * x
R^R=0.981621
year Sea Level Rise , cm
2020 8.094
2050 18.075
2100 34.71

Exponential
Y = 1.885012 -8.885318*(1-Exp(0.027178*x))
r*r = 0.984062
year Sea Level Rise ,cm
2020 8.301
2050 27.58
2100 127.585

Quadratic
Y= 1.949468 +0.222901 * x +0.004728 * x^2
r*r = 0.984207
year Sea Level Rise , cm
2020 8.298
2050 24.914
2100 71.519


Best still on R*R goodness, Indicial
Y= 2.182871 +0.121504 * x^1.306716
r*r = 0.984447
still about 4/3 power, projection still falling
year Sea Level Rise , cm
2020 8.273
2050 22.35
2100 52.073



Y = year (minus 2000) , x is cm SLR in Aviso.Altimetry.fr terms for Jason-3
output up to 14 June 2018, publically outputed approx 08 August 2018,
for various optimised curve fits and concattenated 56 datapoint data for
Jason1+2+3, ranked in terms of R*R, each time requiring adjustment of
the immediately preceeding datapoints as they come out of the 6-month
filter and pass into the permanent Jason3 curve.
Still on downward cycle, perhaps next public output or successor will
return to upswing cycle and a bounded projected range.
So far the best curve fit range of SLR to year 2100 is between 61.164 cm
Y = 2.317755 + 0.089566*x^1.408787 ,output of 17 December 2017
and latest output to year 2100 is 50.521
Y= 2.154097 + 0.128932*x^1.287097 , output of 14 June 2018

for 14 June 2018 data
linear
Y = 1.445252 + 0.332125*x
R*R= 0.982125
year Sea Level Rise
2020 8.087
2050 18.051
2100 34.657
(note the 0.332125 gradient in cm terms is the same as 3.32 mm/year
for the Aviso Reference figure for 1993 to latest, for the linear "fit" ,
so my limited to 56 datapoint sampling , compared to hundreds of the
Aviso processing , gives confidence)
exponential
Y= 1.861540 -9.864524*(1-Exp(0.025029*x))
R*R= 0.984220
year Sea Level Rise
2020 8.27
2050 26.477
2100 112.52

quadratic
Y= 1.921280 + 0.230026*x + 0.004370*x^2
R*R = 0.984354
year Sea Level Rise
2020 8.269
2050 24.347
2100 68.623

Best still on R*R goodness, Indicial
Y= 2.154097 + 0.128932*x^1.287097
R*R= 0.984613
year Sea Level Rise
2020 8.248
2050 21.973
2100 50.521

On 18/08/2018 09:54, N_Cook wrote:

Y = year (minus 2000) , x is cm SLR in Aviso.Altimetry.fr terms for Jason-3
output up to 14 June 2018, publically outputed approx 08 August 2018,
for various optimised curve fits and concattenated 56 datapoint data for
Jason1+2+3, ranked in terms of R*R, each time requiring adjustment of
the immediately preceeding datapoints as they come out of the 6-month
filter and pass into the permanent Jason3 curve.
Still on downward cycle, perhaps next public output or successor will
return to upswing cycle and a bounded projected range.
So far the best curve fit range of SLR to year 2100 is between 61.164 cm
Y = 2.317755 + 0.089566*x^1.408787 ,output of 17 December 2017
and latest output to year 2100 is 50.521
Y= 2.154097 + 0.128932*x^1.287097 , output of 14 June 2018

for 14 June 2018 data
linear
Y = 1.445252 + 0.332125*x
R*R= 0.982125
year Sea Level Rise
2020 8.087
2050 18.051
2100 34.657
(note the 0.332125 gradient in cm terms is the same as 3.32 mm/year
for the Aviso Reference figure for 1993 to latest, for the linear "fit" ,
so my limited to 56 datapoint sampling , compared to hundreds of the
Aviso processing , gives confidence)
exponential
Y= 1.861540 -9.864524*(1-Exp(0.025029*x))
R*R= 0.984220
year Sea Level Rise
2020 8.27
2050 26.477
2100 112.52

quadratic
Y= 1.921280 + 0.230026*x + 0.004370*x^2
R*R = 0.984354
year Sea Level Rise
2020 8.269
2050 24.347
2100 68.623

Best still on R*R goodness, Indicial
Y= 2.154097 + 0.128932*x^1.287097
R*R= 0.984613
year Sea Level Rise
2020 8.248
2050 21.973
2100 50.521



I don't know why no updates on this Aviso site

https://www.aviso.altimetry.fr/index.php?

then navigation, as not too obvious

data/
products/
mean sea level

They were about every 6 week updates backdated a couple of months.
The last update was 08 August covering up to 24 June 2018.
Nothing since, 10 weeks, too abrupt an uptrend perhaps, but I'd expect
something to leak out if that was the case ?. A year ago I registered
for their email notifications but nothing ever received.

I don't know why no updates on this Aviso site

https://www.aviso.altimetry.fr/index.php?

then navigation, as not too obvious

data/
products/
mean sea level

They were about every 6 week updates backdated a couple of months.
The last update was 08 August covering up to 24 June 2018.
Nothing since, 10 weeks, too abrupt an uptrend perhaps, but I'd expect
something to leak out if that was the case ?. A year ago I registered
for their email notifications but nothing ever received.

A week ago I was talking to one of the top bods at the NOC, Southampton
and he volunteered to look into why no public Jason-3 update/s, but no
update from him in the last week.

On 30/11/2018 15:28, N_Cook wrote:

I don't know why no updates on this Aviso site

https://www.aviso.altimetry.fr/index.php?

then navigation, as not too obvious

data/
products/
mean sea level

They were about every 6 week updates backdated a couple of months.
The last update was 08 August covering up to 24 June 2018.
Nothing since, 10 weeks, too abrupt an uptrend perhaps, but I'd expect
something to leak out if that was the case ?. A year ago I registered
for their email notifications but nothing ever received.

A week ago I was talking to one of the top bods at the NOC, Southampton
and he volunteered to look into why no public Jason-3 update/s, but no
update from him in the last week.


Someone pressed a button or 2, update to 02 August out now
https://www.aviso.altimetry.fr/en/da...ts-images.html
now to find some time to number-crunch.
There may be another update in a week or 2 of course for catchup.

58 datapoints to 02 Aug 2018
updated on 01 Dec 2018
https://www.aviso.altimetry.fr/en/da...ts-images.html

Linear
Y= 1.449671 + 0.331635 * x
R*R = 0.982318
year Sea Level Rise (cm)
2020 8.082
2050 18.031
2100 34.613

(So linear "fit " gradient of 3.32 mm per year much as Aviso reference
value as a simple validity check on the relatively small set of datapoints )

Exponential
Y = 1.838701 -10.950351*(1-Exp(0.023025*x))
R*R = 0.984114
year Sea Level Rise (cm)
2020 8.243
2050 25.514
2100 100.382

Quadratic
Y= 1.894041+0.236818 * x +0.004035 * x^2
R^2 = 0.984237
year Sea Level Rise (cm)
2020 8.244
2050 23.822
2100 65.925

Best curvefit still by R*R goodness, by a whisker,
Indicial
Y= 2.125981+ 0.136320 * x^1.268834
R^2 = 0.984511
year Sea Level Rise (cm)
2020 8.226
2050 21.636
2100 49.14

Still on the downward trend

On Sunday, 18 February 2018 13:15:37 UTC, Norman Lynagh wrote:
An interesting read here

https://www.nasa.gov/feature/goddard...sea-level-rise
-accelerating


I suppose it's no great surprise but it certainly is very worrying and
is potentially far more important than all the political shenanigans
that fill the news media. I wonder if there's a backroom team somewhere
in Whitehall trying to devise a plan for an orderly abandonment of
Central London before the end of the century. It might eventually come
to that. There's only so much water that can be kept out. I won't be
around to see the potential problem becoming reality but my
grandchildren might well be.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
https://peakdistrictweather.org
Twitter: @TideswellWeathr

Yeah so worrying people are leaving in their droves Islamic acid attack London to live on the coast.

Another output last Friday on
https://www.aviso.altimetry.fr/en/da...ts-images.html
No wonder anti-climate change bods shout foul in such circumstances.
Usually with these updates, because of the 6-month filter and
seasonality, its a matter of revisiting some of the previous datapoints
as well as the update points.
This time the revisionists had been at work and the whole Jason-3 curve
has been "adjusted" , nothing seen about it in the accompanying notes,
presumably the reason for the paucity of data until the latest 2
updates. So had to revisit all
Jason-3 datapoints.
Creating a transparent masque of the latest data and rescaling+hovering
over an earlier Jason-3 output , it was impossible to align the early
sections of the curves. Also took the opportunity to make transparent
overlay masque of the pixel to time and height conversions plotted out ,
to check for any errors there on my part.

With the cross-over from J2 to J3 data, as used before, gave a linear "fit"
of 3.34 mm/year when rounded. Aviso reference figure is 3.33 now, not
3.32 . Undefined coming out and in of the filters for J2 and J3, over
the cross-over period,
betwixt and between. I'd previously used a mean for the heights in that
period.
Otherwise arbitrarily making the 2 datapoints both 1mm lower,
brought the liner "fit" here when rounded to 3.33 (gradient 0.333).
Retained as part of the suite
of now 68 datapoints for the remaining 3 curve-fit assesments.

Linear
Y = 1.434539 + 0.333266*x
r*r = 0.983702
year Sea Level Rise (cm)
2020 8.099
2050 18.097
2100 34.761

Exponential
Y = 1.86385 -9.780226*(1-e^(0.025191*x))
r*r = 0.985743
year Sea Level Rise (cm)
2020 8.27
2050 26.547
2100 113.528

Quadratic
Y = 1.92383 + 0.229431*x + 0.004391*x^2
r*r = 0.985864
year Sea Level Rise (cm)
2020 8.268
2050 24.372
2100 68.776

Best curvefit still by R*R goodness,
Indicial
Y = 2.15921 + 0.127719*x^1.289983
r*r = 0.986091
year Sea Level Rise (cm)
2020 8.248
2050 22.015
2100 50.712

upward trend again for the likely start of El Nino cycle

Resume of these projections from the Aviso Jason3 updates concattenated
to the Jason 1 and Jason 2 data,
for the best-fit of indicial power curves and global sea level rise for
the rest of the century.

year 2100 using Dec 2017 data , 56.15 cm
data to 05 Feb 2018 to 2100 , 60.7 cm
data to 25 May 2018 to 2100 , 52.1 cm
data to 02 Aug 2018 to 2100 , 49.1 cm
Update to 01 Sep 2018, public output 07 Dec 2018
to year 2100 , 50.7 cm
So between 49.1cm and 60.7cm SLR to 2100, is so far, my halfpennyworth
to this fundamental topic. Well above the 34.8cm of linear "fit".

On 09/12/2018 20:47, N_Cook wrote:

Linear
Y = 1.434539 + 0.333266*x
r*r = 0.983702
year Sea Level Rise (cm)
2020 8.099
2050 18.097
2100 34.761

Exponential
Y = 1.86385 -9.780226*(1-e^(0.025191*x))
r*r = 0.985743
year Sea Level Rise (cm)
2020 8.27
2050 26.547
2100 113.528

Quadratic
Y = 1.92383 + 0.229431*x + 0.004391*x^2
r*r = 0.985864
year Sea Level Rise (cm)
2020 8.268
2050 24.372
2100 68.776

Best curvefit still by R*R goodness,
Indicial
Y = 2.15921 + 0.127719*x^1.289983
r*r = 0.986091
year Sea Level Rise (cm)
2020 8.248
2050 22.015
2100 50.712

A more basic exponential curve, worse fit by R^2 but less projected rise
to 2100

Y = -8.243462 +10.097411 * 1.024902 ^x
r*r = 0.984998
year Sea Level Rise (cm)
2020 8.27
2050 26.296
2100 109.909