iiinova — where your digital self keeps evolving

Aslak Grinsted @glaciology.net · 21/12/2025

Quite happy about this assignment for my inverse problems course (heavily based on material I inherited from Klaus Mosegaard). It is a gravity inversion problem using old IPY data.

130

Aslak Grinsted @glaciology.net · 22/05/2025

I have built a cool little prototype ML algo that can estimate population density in 20m resolution from S2 imagery. Here are 5 examples. Row1: Sentinel-2. (input data) Row2: population density from eurostat. (input data) Row3: ML model population density. (output data)

5 random places in EU . Shows how my ML model 'guesses' where people live.

2101

Aslak Grinsted @glaciology.net · 21/05/2025

Why do these 2 numpy lines not give the same result? Aaargh! data[range(1,3),range(1,3)].shape -> (2,) data[1:3,1:3].shape -> (2,2) I don't want the diagonal!

110

Aslak Grinsted @glaciology.net · 19/05/2025

Bedrock reached at the Ice coring on Müller ice cap (Axel Heiberg Island). I bet that we would reach at 611m --- pretty close to the final 613m. (Bo guessed 612m so i didn't win).

Group photo of the ice coring crew at Müller ice cap posing with the bottom part of the ice core. A sign says "Müller ice cap 613m"

1120

Aslak Grinsted @glaciology.net · 14/05/2025

They got the EGRIP camp weather data flowing out of camp. alice.egrip.camp

screenshot of the EGRIP weather web page.

010

Aslak Grinsted @glaciology.net · 13/04/2025

I need a new circular saw and would like the batteries to be compatible with my other DeWalt tools. But i am wondering if i should jump ship to some non-US brand. Also - they apparently have extra high exposure to the tariff situation.

000

Aslak Grinsted @glaciology.net · 02/04/2025

Scandinavia in March vs April #modis

060

Aslak Grinsted @glaciology.net · 10/02/2025

Loewe 1936: "... there is a strong evidence that the Greenlandic ice cap is not quickly decreasing today but in a nearly stationary condition". Pretty impressive statement considering the sparse data at the time. I'd love a pdf of that paper. Anybody? www.buchfreund.de/de/d/p/79453...

screenshot of the first page of Loewe 1936.

100

Aslak Grinsted @glaciology.net · 27/01/2025

End of an era. The final Symposium of the EastGRIP project.

People sitting in an opulent room listening to talks.

0111

Aslak Grinsted @glaciology.net · 09/01/2025

Here, I've exaggerated the contrast of a Sentinel-2 median image from the same region (Sharffenbergbotnen). Notice the clear layering. The youngest blue-ice appear more brownish. I wonder why? We believe this valley to be mostly holocene ice.

000

Aslak Grinsted @glaciology.net · 08/01/2025

Blue ice areas are a source of ancient ice. So, you can potentially use them to get a horizontal ice core. Here's a photo of a very clear layer that i interpret as an isochrone. Maybe this layer was caused by volcanic eruption. The challenge is how to date the ice.

150

Aslak Grinsted @glaciology.net · 08/01/2025

Many electrical wood working tools work great on ice. I've used band saws, circular saws, chainsaws, hand drills, router, and planer. Here's me 20years ago. Cutting a blue ice sample with a chainsaw.

Aslak cutting a blue ice sample using a chainsaw.

330

Aslak Grinsted @glaciology.net · 03/01/2025

Organizing some old fieldwork photos using immich. Here's a nice black "dragon" shaped stripe in Scharffenbergbotnen, Heimefrontfjella, Antarctica.

A black stripe in a mountain shaped like the dragon head of a viking ship

051

Aslak Grinsted @glaciology.net · 12/12/2024

In other images we can see sediments being flushed into the fjord. Soon after we can see sea ice forming. Probably because fresh water freezes more easily. Later it spreads out and fills almost the entire fjord.

Sea ice in the fjord. Is that the fresh water freezing more easily?

171

Aslak Grinsted @glaciology.net · 12/12/2024

Here's some additional media. A timelapse of the lake level dropping as seen in S2. new press release: science.ku.dk/english/pres... +a video of the past events published in 2017: www.youtube.com/watch?v=xDH5... 5/

150

Aslak Grinsted @glaciology.net · 12/12/2024

ICESat-2 gave us a nice record of the lake filling prior the recent outburst flood. We know the longer historical context from a 2017 study. There were no good images of the prior GLOFs as they occurred during the polar night. So, this is the first time we can estimate the discharge. 4/x

blue is data from icesat2, red is estimated levels based on S2 images.

Longer record of Catalina lake level from Grinsted et al. 2017.

140

Aslak Grinsted @glaciology.net · 12/12/2024

The peak discharge corresponds to 7200 m3/s. That is ~2.5x Niagara falls in the tourist season. There is a big potential energy release as the water runs to sea level. The max daily release was ~46 GW. 3/x

121

Aslak Grinsted @glaciology.net · 12/12/2024

From sentinel-2 images and an elevation model I estimate the daily lake level. New satellites and good weather made that possible. V= 3.4km3 (for comparison the annual water consumption of Denmark is ~1km3, and the total volume of all humans is about 0.5km3) 2/x

sentinel2 - Before vs After animated gif.

130

Aslak Grinsted @glaciology.net · 12/12/2024

A new gigantic outburst flood from Catalina lake in East Greenland [Catalinadal, Renland, Scoresbysund]. total volume: 3.4 km3 peak discharge: ~7200 m3/s top-10 #GLOF in terms of both numbers. previous outburst 2013 I'm sending out a press release today about it. 🧪❄️ 🥼❄️ 1/x

610441

Aslak Grinsted @glaciology.net · 10/12/2024

Digging a particularly deep toilet hole at EGRIP.

031

Aslak Grinsted @glaciology.net · 07/11/2024

Remote sensing sea ice experts: Is this fresh sea ice? (It was a plume of sediment rich freshwater a few days prior)

Sea ice and icebergs in a sentinel 2 image

010

Aslak Grinsted @glaciology.net · 03/11/2024

Trying to show the scale of a lake using blender + blendergis + sentinel2 + arcticdem and a model of the eiffeltower. Steep learning curve - but fun. I am considering using the golden gate bridge or the statue of liberty instead.

040

Aslak Grinsted @glaciology.net · 22/10/2024

Half of all voters need to read some scifi dystopias to learn about which futures to avoid. -maybe Octavia E. Butlers Parable of the Sower.

021

Aslak Grinsted @glaciology.net · 09/10/2024

The latest forecast has shifted the track and the surge a little north. Better for Rotunda cera.coastalrisk.live

020

Aslak Grinsted @glaciology.net · 24/09/2024

It would be great if Jupyter notebooks had a cell type for tabular data. I'd like something better than this...

010

Aslak Grinsted @glaciology.net · 10/09/2024

Ramseier, René O. 1974 "Oil on Ice: How to Melt the Arctic and Warm the World." Environment: Science and Policy for Sustainable Development 16.4 (1974): 6-14. www.tandfonline.com/doi/pdf/10.1... Stumbled across this when looking for his 1972 phd thesis.

Ramseier wrote in 1974 "Oil on Ice: How to Melt the Arctic and Warm the World." in the journal Environment: Science and Policy for Sustainable Development

000