Calculation of the PIG speeds from the data on the site:

http://www.cpom.ucl.ac.uk/csopr/iv/index.php?glacier_number=3 for the months of June and December, from December 2014 to December 2020.

Averages used:

To avoid problems related to doubtful variations in the measurements provided between close points along the transect for the same period and between close intervals for the same position along the transect I calculated the average of the existing measurements for :

> the same interval of points along the transect: 20-30 km, 30-40 km, ..., 120-130 km (I considered that the measurements of the other intervals: > 130, did not provide sufficiently reliable measurements)

> 5 periods for each month of June and December. For the month of December 2016 and for all months starting in December 2017 we have files that calculate the speeds from intervals of 6 days that follow each other regularly (which makes a global interval of 36 days).This is no longer true for the months prior to December 2016 and for the month of June 2017; in these cases I took the 5 periods closer to the month of calculation, with, as a result, an overall interval between 42 and 108 days and with overlaps between the periods used for the velocity calculations. Moreover for the months of June 2015 and 2016, for one of the chosen intervals I find no valuation of the speed and for these two months I calculate the speed using in reality only 4 intervals. For the month of December 2015 I find no valuation for the points between 20 and 30 km.

Sources of speed valuations along the transect:

> for the period 2014-2019 I based myself on the text files containing the valuations per point and per period, files contained in the global zip that I downloaded.

> For the month of June 2020 I am based on the individually downloaded text files.

> for the month of December 2020 no text files are available and I based on the image of the downloaded diagram to value the speeds by interval: 20-30 km up to 60-70 km and I dropped the other intervals for which a reliable valuation was not possible (in the

** first image** I give an example of the images used for my valuations)

Results :

> The measures found are presented in the

**second image** and it can be seen that they are consistent with each other.

> There is indeed a more or less constant acceleration from June 2018. To bring it out more clearly I calculated the averages for the 20-70 km interval that I show in the

**third image**.

**Click to enlarge****ADD** :

*In the third image it is the average over the interval 20-70, the values for the interval 20-30 are higher, e.g. for December 2020 there are 4.816!*