On 28/11/2020 15:54, N_Cook wrote:
Global Sea Level rise from satellite altimetry from the latest
aviso.altimetry.fr data release,
from datafile at
ftp://ftp.aviso.altimetry.fr/pub/oceano/AVISO/indicators/msl/MSL_Serie_MERGED_Global_AVISO_GIA_Adjust_Filter2m. txt


Processing below is for my preferred time-span of 2003.0 to latest
2020.702868 (13 September 2020 ), output to the public this morning
,28 November 2020.
Using 651 datapoint subset, avoiding early Jason and Mount Pinatubo
problems and being able to choose x=0 for year 2000 and y is cm of
global SLR in Aviso terms.
The following curve-fits ranked in terms of R^2 goodness of fit and
curve-forms with, second differentials; zero acceleration, increasing
acceleration, constant acceleration and the indicial form with
decreasing acceleration again as the best fit.
Linear
r*r = 0.97374
y= 0.376521*x + 1.34
SLR to 2100= 40.0cm
In Aviso terms, 3.77mm/year of GSLR . Bear in mind that gradient is
based on 2003 to 2020 data. If/when Aviso sorts out the javascript
problem on their site, myself and others have enquired but no change for
months, I'll redo with the full dataset 1993 to 2020 . But without their
linear "fit", little point in me doing so, the previous such comparisons
of the gradient have agreed.

Exponential
r*r = 0.98464
y= 2.18 -4.808622*(1 - e^(x*0.045144) )
SLR to 2100 = 4.36m (sic, not cm)

Quadratic
r*r = 0.985125
y= 2.35 + 0.165837*x + 0.008889 * (x)^2
SLR to 2100 = 1.078m

Best fit as previous results, in the last 1.5 years, in the range 80 to
89 cm rise from 2000 to 2100
Indicial
r*r = 0.985384
y=2.61+ 0.066640 * (x)^1.533651
SLR to 2100 = 80.4cm

For anyone wishing to repeat this execise , the curve-fitter I use is
statpages.info/nonlin.html
once the source page is saved to disc, it's a stand alone javascript
coding routine.
As above, the full dataset linear processing has previously agreed to
Aviso to 2 decimal places of the gradient on their plots. The
cumbersome form of the exponential is more comfortable for converging
with that curve-fitter than the simpler transformation of it.

History , curve plots etc, of this exercise in sig below, otherwise a
summary he-
History of these results, ranking by R*R, goodness of fit, for best
curve type each time usually the indicial form and decreasing
acceleration , using 2003 to the latest datapoint to avoid the early
altimeter calibration problem and post-Pinatubo recovery SLR flattening
and including the 1993 to 2003 tranche does not actually make much
difference to projections, going by previos full and partial dataset
processing.
Initially melding together the separate J1,J2 and J3 plots and then
since 2019 using the Aviso Reference data as the small GIA component is
getting less and less significant and less and less confidence in the
mission cross-over/overlap data, going in and out of the filters.
SLR to year 2100 using Dec 2017 data of May2017 , J1+J2 only , 56.2cm
data to 25 May 2018 to 2100 , SLR 57.1 cm
data to 02 Aug 2018 to 2100 , SLR 50.5 cm
Update data to 01 Sep 2018, public output 07 Dec 2018
SLR to year 2100 , 49.0 cm
Update data to 01 Oct 2018, public output 18 Jan 2019
SLR to year 2100 , 50.9 cm
Update data to 29 Nov 2018, public output 02 Feb 2019
SLR to year 2100 , 77.4 cm
Update data to 26 June 2019, public output 07 September 2019
SLR to year 2100 , 80.2 cm

Update to 25 July 2019, 02 Nov 2019 public output,
SLR to 2100, 88.2cm

Update 11 January 2020
for data 2003.002659 to 2019.806999,
SLR to 2100 , 88cm

01 Dec 2019 output to the public 15 Feb 2020
SLR to 2100, 117cm (quadratic was the best fit that time, otherwise
indical was 89cm)

624 datapoints from year 2003.002659 to year 2019.9699
output to the public 29 Feb 2020.
SLR to 2100, 88.5cm

640 datapoints 2003.002659 to 2020.404245 website back working on
20 July 2020
SLR to 2100 = 82.9cm

644 datapoints 2003.002659 to 2020.512835 , output to the public
probably in Sep 2020, update here of 07 Oct 2020
Global SLR to year 2100 = 86.6cm


Aviso website has come back again, so I returned to the full dataset of
1018 datapoints
x=0 for year 1990, y is cm in Aviso terms
y= 0.342338*x -1.621
So gradient 0.342338 cm /year
Rounding to the latest Aviso graphic , dated 04 Dec 2020
https://www.aviso.altimetry.fr/en/data/products/ocean-indicators-products/mean-sea-level.html
to their gradient of 3.42mm/year

--
Global sea level rise to 2100 from curve-fitted existing altimetry data
http://diverse.4mg.com/slr.htm