Calling all students…

I’m off to the UK next week for a workshop at Sheffield University where we will discuss the Surface Mass Balance of the Greenland Ice Sheet. The ISMASS workshop includes all the main modelling groups and observation groups who are involved in assessing surface mass balance in Greenland. I will be representing DMI’s Greenland SMB work there (not an easy task condensing it down to a 20 minute talk!).

In the course of preparing my presentation I have been making plots and figures and really investigating some exciting results. Sadly, I very rarely get the chance to spend time on this these days and I am keen to recruit students to assist in this work. Should any potentially interested students want to discuss this at Sheffield do let me know.

At the risk of spoilers in my presentation, here for example is one showing how different ways of characterising the surface snow pack affects our estimates for surface mass balance, and how the effects of the specific changes can be very different in different years.

Surface mass balance map plots of Greenland
Surface mass balance for the hydrological year (Sep -Aug) ending in 2012 and 2013 calculated using HIRHAM5 with 2 different surface schemes. The maps on the right show the difference between the 2.

As I mentioned I rarely get enough time to analyse the output from our runs and I would be very happy to hear from any students who are interested in doing a project on our simulations. We have lots of MSc and Bachelors projects already listed on our website at DMI but we are always happy to hear new ideas from students on related topics. I have terabytes of data from simulations I would like to be properly analysed and this could be very interesting given we are talking about Greenland and the Arctic in the present day and in the future. It’s a really nice opportunity to work with some cutting edge research. I am also happy to hear from students who would like to do a summer project and for the right candidate I would be able to look into a paid “studentmedarbejderhjælper” position for a few months, especially if you are already a trained computer science candidate….

If you are an undergraduate looking into an MSc, I urge you to consider Denmark. EU citizens usually qualify for generous support grants (rare these days!) as we have a shortage of candidates wanting to study in the sciences in Copenhagen. The research and teaching are world class and done in English at MSc level. The possibilities for projects in Greenland are literally endless.

If you want any more details or to talk about any of the possibilities, do get in touch!

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Changes in SW Greenland ice sheet melt

A paper my colleague Peter Langen wrote together with myself and various other collaborators and colleagues has just come out in the Journal of Climate. I notice that the Climate Lab Book regularly present summaries of their papers so here I try to give a quick overview of ours. The model output used in this run is available now for download.

The climate of Greenland has been changing over the last 20 or so years, especially in the south. In this paper we showed that the amount of melt and liquid water run off from the ice sheet in the south west has increased at the same time as the equilibrium line (roughly analogous to the snow line at the end of summer on the ice sheet) has started to move up the ice sheet. Unlike previous periods when we infer the same thing happened this can be attributed to warmer summers rather than drier winters.

Map showing area around Nuuk
The area we focus on in this study is in SW Greenland close to Nuuk, the capital. White shows glaciers, blue is sea, brown is land not covered by ice.

We focused on the area close to Nuuk, the capital of Greenland, as we had access to a rather useful but unusual (in Greenland) dataset gathered by Asiaq the Greenland survey. They have been measuring the run off from a lake near the margin of the ice sheet for some years and made this available to us in order to test the model predictions. This kind of measurement is particularly useful as it integrates melt and run-off from a wider area than the usual point measurements. As our model is run at 5.5 km resolution, one grid cell has to approximate all the properties of a 5.5 km grid cell. Imagine your house and how much land varies in type, shape and use in a 5.5 km square centred on your house and you begin to appreciate the problems of using a single point observation to assess what is essentially an area simulation! This is even more difficult in mountainous areas close to the sea, like the fjords of Norway or err, around south west Greenland (see below).

Represent this in a 5.5km grid cell, include glacier, sea and mountain...  Godthåbsfjord near Nuuk in August
The beautiful fjords near Nuuk. Represent this in a 5.5km grid cell…

The HIRHAM5 model is one of very few regional climate models that are run at sufficiently high resolution to start to clearly see the climate influences of mountains, fjords etc in Greenland, which meant we didn’t need to do additional statistical downscaling to see results that matched quite closely the measured discharge from the lake.

Graph comparing modelled versus measured discharge as a daily mean from Lake Tasersuaq near Nuuk, Greenland. The model output was summed over the Tasersuaq drainage basin and smoothed by averaging over the previous 7 days. This is because the model does not have a meltwater routing scheme so we estimated how long it takes for melt and run-off fromt he ice sheet to reach this point.
Graph comparing modelled versus measured discharge as a daily mean from Lake Tasersuaq near Nuuk, Greenland. The model output was summed over the Tasersuaq drainage basin and smoothed by averaging over the previous 7 days. This is because the model does not have a meltwater routing scheme so we estimated how long it takes for melt and run-off from the ice sheet to reach this point.

We were pretty happy to see that HIRHAM5 manages to reproduce this record well. There’s tons of other interesting stuff in the paper including a nice comparison of the first decade of the simulation with the last decade of the simulation, showing that the two look quite different with much more melt, and a lower surface mass balance (the amount of snowfall minus the amount of melt and run – off) per year in recent years.

Red shows where more snow and ice melts than falls and blue shows where more snow falls than is melted on average each year.
Red shows where more snow and ice melts than falls and blue shows where more snow falls than is melted on average each year.

Now, as we work at DMI, we have access to lots of climate records for Greenland. (Actually everyone does, the data is open access and can be downloaded). This means we can compare the measurements in the nearest location, Nuuk, for a bit more than a century. Statistically we can see the last few years have been particularly warm, maybe even warmer than the well known warm spell in the 1920s – 1940s  in Greenland.

Graphs comparing and extending the model simulation back in time with Nuuk observations
Graphs comparing and extending the model simulation back in time with Nuuk observations

There is lots more to be said about this paper, we confirm for example the role of increasing incoming solar radiation (largely a consequence of large scale atmospheric flow leading to clearer skies) and we show some nice results which show how the model is able to reproduce observations at the surface, so I urge you to read it (pdf here) but hopefully this summary has given a decent overview of our model simulations and what we can use them for.

I may get to the future projections next time…

The Present Day and Future Climate of Greenland

Regional Climate Model Data from HIRHAM5 for Greenland

In this post I am linking to a dataset I have made available for the climate of Greenland. In my day job I run a Regional Climate Model (RCM) over Greenland called HIRHAM5 . I will write a simple post soon to explain what that means in less technical terms but for now I just wanted to post a link to a dataset I have prepared based on output from an earlier simulation.

Mean annual 2m  temperature over Greenland (1989 - 2012) from HIRHAM5 forced by ERA-Interim on the boundaries
Mean annual 2m temperature over Greenland at 5km resolution (1989 – 2012) from HIRHAM5 forced by ERA-Interim on the boundaries [Yes I know it’s a rainbow scale. Sorry! it’s an old image – will update soon honest…]

This tar file gives the annual means for selected variables at 0.05degrees (5.5km) resolution over the Greenland/Iceland domain.

I am currently running a newly updated version of the model but the old run gave us pretty reasonable and could be used for lots of different purposes. I am very happy for other scientists to use it as they see fit, though do please acknowledge us, and we especially like co-authorships (we also have to justify our existence to funding agencies and governments!).

This is just a sample dataset we have lots of other variables and they are available at 3 hourly, daily, monthly, annual, decadal timescales so send me an email (rum [at] dmi [dot] dk) if you would like more/a subset/different/help with analysis of data. This one is for the period 1989 – 2012. I have now updated it to cover up to the end of 2014. The new run starts in 1979 and will continue to the present and has a significantly updated surface scheme plus different SST/sea ice forcing and a better ice mask.

I have also done some simulations of future climate change in Greenland at the same high resolution of 5km using the EC-Earth GCM at the boundaries for RCP4.5 and RCP8.5 scenarios which could be fun to play with if you are interested in climate change impacts in Greenland, Iceland and Arctic Canada.

Mean annual 2m temperature change between control period (1990 - 2010) and end of the century (2081 - 2100) under RCP45 from HIRHAM5 climate model runs forced by EC-Earth GCM at the boundaries
Mean annual 2m temperature change between control period (1990 – 2010) and end of the century (2081 – 2100) under RCP45 from HIRHAM5 climate model runs forced by EC-Earth GCM at the boundaries.  This plot shows the full domain I have data for in the simulations.

This run should be referenced with this paper:

Quantifying energy and mass fluxes controlling Godthåbsfjord freshwater input in a 5 km simulation (1991-2012), Langen, P. L., Mottram, R. H., Christensen, J. H., Boberg, F., Rodehacke, C. B., Stendel, M., van As, D., Ahlstrøm, A. P., Mortensen, J., Rysgaard, S., Petersen, D., Svendsen, K. H., Aðalgeirsdóttir, G.,Cappelen, J., Journal of Climate (2015)

http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-14-00271.1 

PDF here

Finally I should acknowledge that this work has been funded by a lot of different projects:

Picture4

Space for cycling

Golden bike sculpture on tower in Rådhusplads, Copenhagen
Copenhagen: A city that loves bikes so much it puts golden ones on the top of some buildings…

Warning! This post is positively evangelical about cycling…

I bike everywhere. I take the Sterna chicks cycling everywhere and it has got to the point I almost don’t know how to get around the city without my bike. This is not unusual in Copenhagen. Cycling culture is one of the things I love most about living here. The wider benefits of being in a biking city are far-reaching and far too many mention here (but check out Copenhagenize for an inspiring run-down).

I have always cycled everywhere, and in fact have never owned my own car, though I can drive and even enjoy it – albeit on congestion free roads such as you might find in the North of Scotland.  However, the vulnerability of cyclists in the UK has come to disturb me ever more. Especially since the very tragic death of Dr. Kat Giles, a polar scientist I had met a couple of times, under the wheels of an HGV in London on a route she had cycled for ten years or so back in 2013.

I am so accustomed to the safety of cycling in Copenhagen that I think I would find it hard to go back to cycling in the UK or anywhere else without good bike infrastructure (including separated bike lanes). I would certainly not let my 4 year old bike to the nursery as I do at present (and for which a poor child was threatened with having their bike confiscated recently in the UK, but I digress). Even my mother (hi Mum!) has been witnessed riding a bike in Copenhagen. I have video evidence.

Be that as it may, such are the benefits of biking that I feel the UK and in particular the mega-city that is London should really be doing A LOT more to facilitate normal people cycling everyday . So I was rather disappointed, but entirely unsurprised to see this pop up on twitter:

https://twitter.com/Hackneycyclist/status/592387246063538176

Hackneytwitter

Now, on my regular commuting route, the University of Copenhagen is building a brand new and very large building spanning both sides of a large dual carriageway that is one of the main routes into Copenhagen. Bear in mind that around 40% of commuters travel by bike in this city and this is a major route, so clearly the bike path cannot just be closed. Here are a few photos I took yesterday on the spur of the moment (with my fairphone in case you’re interested in cool ethical consumer electronics) showing what the builders have done:

2015-04-27 15.31.44 2015-04-27 15.31.47 2015-04-27 15.31.49 2015-04-27 15.31.53 2015-04-27 15.31.56 2015-04-27 15.32.01 2015-04-27 15.32.05 2015-04-27 15.32.10

The pavement and separated bike lane have been taken over by the construction, shielded by the link fence on the right; the near side lane on the road is now a shared bike/pedestrian route and the whole thing is smoothly transitioned in and out with the assistance of some blue paint and traffic bollards on the road and of course temporary tarmac ramps to help cyclists get over the kerb at both ends of the building works. The same is true on the other side, so the road has temporarily narrowed to a normal road before widening again to a dual carriageway.

You see, it really isn’t hard to do major building works and keep the bike traffic flowing.

The thing is, this isn’t a unique situation, even small building works where the bike lane and/or pavement is likely to be blocked is treated like this in Copenhagen. It’s about treating all people on the move with respect and it’s something a lot of cities, and countries could learn from when thinking about road safety, sustainable transport and above all quality of life for everyone.

This is what #spaceforcycling really looks like.

Climate and ice sheet modelling at DMI

I was very honoured to be asked to give a short talk last week to some students at the Danish Technical University. The subject was ice sheet modelling and climate at DMI where I work in the Research department, climate and Arctic section.
I thought this could be interesting for others to look at too, so I have uploaded the powerpoint presentation on my academia.edu page.

In the presentation I try to explain why we are interested in climate and ice sheets and then give a brief overview of our model systems and the projects we are currently working on. We are mainly interested in the Greenland ice sheet from the perspective of sea level rise. If we are to climate change we need to know how fast and how much of Greenland will melt and how this will change local and regional sea level. There are also studies showing that increased run-off from the ice sheet may change ocean circulation patterns and sea ice. There is lots more stuff to look at so feel free to download it.

I end up with a very brief overview of our biggest project at the moment, ice2ice. This is a large ERC funded project with the Niels Bohr Institute and partners in Bergen at the Bjerknes Climate Research Centre. I may write a brief post on ice2ice soon if I get chance. It’s a really interesting piece of work being focused on past glacial-interglacial climate change rather than present day or the future and I think we have potential to do some great science with it.

At the risk of seeming like I’m blowing the DMI trumpet (something rarely done or even really seen as socially acceptable in Denmark!), I think we at DMI have a lot to be proud of. We are a small group from a small country with limited resources but my colleagues have pioneered high resolution regional climate modelling of the Greenland ice sheet and the development of coupled climate and ice sheet models at both regional and global scales. I was brought in as a glaciologist to work on the interface between ice sheet and atmosphere, needless to say I have learnt a hell of lot here. It’s been an exhilarating few years.

If you have any questions, I will enable comments for this thread (but with moderation so it may take  a while for you to see it).

Finally, here is a little movie of calving icebergs

shot by Jason Amundson, University of Alaska Fairbanks at Jakobshavn Isbrae in West Greenland.

 

 

 

Planet Carbon

There are some really powerful visualisations in this short 4 minute video from Carbon Visuals about the sheer amount of energy, mostly from fossil fuels, that we have come to rely on. I think it really shows what a huge challenge we face in terms of both energy policy (we’re burning through it as if it will never run out) and climate change.

I am not really convinced by CCS (Carbon capture and storage) though, it seems to require a very large amount of energy just to make the CCS process work (around 30% of powerplant output if I recall correctly) burning through our fossil fuel supplies even faster. Several programmes I have seen recently (for example, the excellent Planet Oil from the BBC, now probably available on youtube, made by Professor Iain Stewart, head of the RSGS) make the point that our civilisation is basically burning through the easy energy.

If we don’t invest in developing other sources now, it will be so much harder in the future. Those other sources, realistically speaking, have to include nuclear. As Brian Cox points out in his beautifully filmed epic Human Universe, this will also have to include nuclear fusion.

I think the best resource I have found to think about some of these issues is Without Hot Air, an excellent book by David MacKay and available here for free download or you can buy a paper copy in the usual places.

 

 

 

 

Up Goer 5

I’m a bit late jumping on this bandwagon, but here is my first attempt to explain my research simply. The explanation behind this was a cartoon from the well-known web comic xkcddescribing the Saturn V moon rocket using only the ten hundred most commonly used words. It has since become something of a web phenomenon, especially amongst scientists (for example look up the #upgoer5 hashtag on twitter). To give due credit, I put this together using the text editor handily made available by Theo Sanderson.
 
 

I study the way ice and water are changing at the top of the world. My work uses a very big computer which makes lots of attempts to tell us what the world will be like in one or two hundred years at the top of the world. We want to know how much ice there will be, how much ice will turn into water and how warm the air will get and how quickly this will all happen so that we can be ready for changes in the water around the land.

One of the other things I have been working on is a picture of the ice in the place called green land, which is a piece of land near the top of the world. Every day this picture is changed to show how much ice has fallen from the sky and how much ice has changed into water.

You can see this picture here.

http://www.dmi.dk/dmi/index/gronland/indlandsisens_massebalance.htm

accumulatedmap