Dispatches from Davos

This week, a huge number of polar scientists across many disciplines have descended on Davos, Switzerland to attend the #Polar 2018 joint SCAR/IASC (Scientific Committee on Antarctic Research/International Arctic Science Committee) conference. It’s the first time in many years where scientists working on polar science at opposite ends of the earth have been able to come together and exchange knowledge. I braved the French railway strikes to get to Davos last Monday by train (it was worth it just for the views)

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It’s been a great experience – presenting my research to scientists from all over the world, learning about what’s going on in the field, and making connections with people working on similar topics.

Here are the highlights.

DAY 1

After 10 hours of travelling the day before, I woke up on day 1 and had to jump straight into presentation mode, because my talk was in the first session of the first day. Even so, I couldn’t quite help noticing that this place is bloomin’ GORGEOUS.

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I was talking in the cloud and aerosol processes session, which had a huge diversity of topics. I spoke about the role of cloud microphysics in determining melt rates over the Larsen C ice shelf, using modelling, aircraft observations and weather station data. It’s hard to model cloud microphysics because models have a persistent problem whereby they overestimate the amount of ice in a cloud, and underestimate the amount of liquid. This has an important influence on the amount of radiation received at the surface because liquid clouds emit more longwave radiation, and prevent more incoming solar radiation from reaching the surface. This error can mess up our estimates of how much the ice shelf is melting, which as I’m sure you can imagine, is a problem!

I got some great feedback from members of the audience, and had some wicked conversations with scientists working in similar fields afterwards. It was a great experience, and nice to get my first presentation at a major international conference out of the way.

I stayed all day in the clouds and aerosol session, and heard some great talks. It was particularly interesting to hear Jean-Baptiste Madeleine talk aboout modelling ice supersaturation at Dome C, and Gary Lloyd present some of the work from the recent Abel et al. (2017) paper that I have been using for my latest work to improve UM simulations of cloud.

After a long day of talks, it was great to chat to some people about their posters, and catch up with colleagues from other institutes.

Also spotted: my favourite poster of the conference (may the pressure gradient force be with you)

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DAY 2

One thing you must know about #Polar2018 is that a mountain of croissants appears during every break. I swear to god, there must be about 2.3 croissants a day for each of the 2200 attendees – and they get put on a pastry pedestal. It’s crazy.

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Anyway, the second day was a day of rushing frenetically between sessions trying to catch talks in different rooms, including presentations from two other BAS PhD students: Becs and Zoe, who were talking about Arctic snow cover 2000-16 and reconstructing past ice shelves and ice streams on the West Antarctic Peninsula, respectively.

After that, a bunch of us attended the Women in Polar Science lunch. We spoke about the issues faced by women in science (from in-built prejudice to outright harassment and assualt) and how to get more women involved in science, while still getting more supportive men involved along the way. It was great, but nothing new – and of course only addresses one angle of diversity in STEM. The conference so far has been overwhelmingly white and dominated by people from wealthy countries who can afford to send delegates to Switzerland, so we’ve still got to consider those issues as a scientific community. On a more positive note though, Polar Pride had its inauguration at the conference – follow @PridePolar for updates from the new network of LGBTQ+ people and allies in the polar science community.

DAY 3

Day 3 was one of the most engaging and exciting for me for sure. I was particularly interested in Patrick Taylor’s talk on using satellite-based cloud products like CERES to examine the radiative effect of polar clouds in CMIP5 models. This is akin to what I’m doing with the UM, but using much coarser resolution, larger scale models, so I was intrigued to see how well they did. Generally, he says, they get the inter-annual patterns right, but clouds do not warm the surface enough in winter, and they cool it too much in summer, i.e. they cause a cold bias. However, these models have a limited representation of the other fluxes in the surface energy budget, such as the sensible heat flux, which can play an important role in determining the overall heat budget. Plus, meteorology and atmospheric stability can have a strong effect on the radiative effect of clouds, which is difficult to model even in high resolution models, let alone global models. Patrick was talking about how sea ice regimes can affect the stability of the atmosphere (essentially how temperature changes with height) in different seasons, something I had not really considered before.

Constantino Listowski’s talk was another one I really liked. Tino used to work at BAS and I got a chance to grill him in a bit more depth afterwards too. He was talking about the interplay between sea ice and cloud microphysics using a combined Lidar/Radar satellite product called DARDAR. He was saying that Antarctic cloud microphysics are strongly sensitive to orography (something I know from my own work) and also to sea ice concentrations. While the seasonal cycle in the number of clouds composed exclusively of supercooled liquid closely follows that of temperature, mixed phase clouds are influenced by multiple factors acting together. Particularly, there appears to be a close connection between the break-up of sea ice and the evolution of supercooled liquid clouds into mixed-phase clouds. That’s because sea ice break-up exposes open ocean to the atmosphere, which is a huge source of heat and aerosols that can act as ice nucleating particles (INP). This can trigger the partial glaciation (conversion from liquid to ice) of clouds. They can’t completely glaciate though, because INP are so rare (1 in a million aerosol particles can be INP), meaning you get mixed phase clouds.

Another lunchtime meeting, this time with the producers of the new BBC Attenborough documentary series, Frozen Planet II. Sounds like they have some great ideas to inspire the public about polar science. Coming soon to a screen near you…

A couple more talks made me think hard about the representation of atmospheric stability in my modelling – it seems to be even more important than I had previously thought. Etienne Vignon’s talk about modelling Antarctic stable boundary layers (the bit of the atmosphere closest to the surface, strongly influenced by cooling of the surface when stable) sparked a lot of thought, and talking to him afterwards gave me lots of ideas about how to potentially improve the cold surface temperature bias in my own runs. It was a common theme, also touched on by Niehls Souverijns’ talk about using the COSMO model to run a long hindcast simulation over 30 years. I was interested to hear about this because one of the aims of my own work is to produce a high-resolution climatology of Larsen C (eventually). However, it’s important to be confident that your model is getting the physics of the atmosphere right, otherwise there’s no point! Niehls spoke about the importance of getting the atmospheric stability and cloud microphysics right – both things I have also found in my work, which is encouraging.

During the poster session I also had some useful conversations with researchers working on cloud modelling across scales (embedding cloud-resolving models within each grid cell of the NCAR global model) and a new non-iterative method for calculating atmospheric stability profiles in stable polar conditions (are you sensing a theme yet?).

DAY 4

Day 4 was great, but much less manic – I heard a lot more about polar meteorology (a lot about foehn winds, something I was working on a lot until recently, and their applicability elsewhere) and lots more about the Arctic, which was quite refreshing. I was reminded of my MSc research during Jan Lenaerts’ talk about the role of ozone depletion and greenhouse gas forcing on the surface mass balance of Antarctica: these forcings modulate precipitation via the influence on the Southern Annular Mode, the dominant pattern of atmospheric variability in the Southern hemisphere.

DAY 5

The final day was a short one, as most of the sessions I was interested in were over. But I did manage to hear Andy Elvidge talking about his work relating foehn winds to melting over Larsen C. They’ve found that melting is less pronounced in jet regions because air is drawn from lower altitudes (the jets are created by gap flows, where the wind flows through mountain passes) and is therefore cooler. That was published in Elvidge et al. (2015), but the new stuff is the relationship to the total surface energy budget that Andy presented. He showed that the turbulent fluxes are really important during foehn – which I was pleased to hear because I’ve found the same result using the UM at the same resolution in the same region!

 

And that’s a wrap! Now to enjoy some of the mountains before I head back to get working on all of the new ideas I’ve had whilst here.

 

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