5th WGNE workshop on systematic errors in weather and climate models

The 5th Working Group on Numerical Experimentation (WGNE) workshop on systematic errors in weather and climate models was held in Montréal, Canada from 19 to 23 June 2017. The principal goal of the workshop is to increase understanding of the nature and cause of errors in models used for weather and climate prediction, including intra-seasonal to inter-annual scales.

IMG_20170618_204314
Centre Mont-Royal, venue for the workshop

The workshop is held every four years. The 5th WGNE workshop focused on processes that models currently fail to represent accurately, based around six themes: atmosphere-land-ocean-cryosphere interactions, clouds and precipitation, resolution issues, teleconnections, metrics and diagnostics, and model errors in ensembles. For each of the themes, the workshop started off with talks from invited keynote speakers, followed by contributed oral presentations, a conclusion session and a poster session.

My PhD project studies mean-state precipitation biases over the Maritime Continent in CMIP5 atmosphere-only experiments, which aligns well with the “model errors in ensembles” workshop theme. I received a lot of constructive feedback and suggestions during the discussions in the poster session.

IMG_20170622_132821379
Lunch with experts. Photo courtesy of Ariane Frassoni
IMG_20170621_200054892
Pub night. Photo courtesy of Ariane Frassoni

A mixture of scientific and social activities were organized in this workshop dedicated to Early Career Scientists (ECS). We had the opportunity to be a session rapporteur and participate in a best poster competition. Then we were given the chance to get to know more established scientists during the more social ‘lunch-with-experts’ and ‘pub night’ activities. The lunch-with-experts was truly entertaining – with conversations about PhD life and challenges, future career path advice, variations between countries in PhD education systems and much more! ECS were also given the opportunity to become co-reviewer of a poster competition session where we work in pairs with an expert scientist to review posters in a session we are not competing in. By becoming the co-reviewer, we get to experience the review process and get in contact with expert scientists.

IMG_20170623_121858669
Session rapporteur presentation. Photo courtesy of Ariane Frassoni

On the last day, the session rapporteur presented a summary on the main issues discussed in each session, followed by a panel discussion and an overall conclusion to the workshop. I am very happy that my poster on ‘Maritime Continent seasonal climate biases in AMIP experiments of the CMIP5 multimodel ensemble’ was given the Best Poster Award, alongside with Falko Judt for his poster on ‘Effect of model error on the predictability of hurricane intensity’ and Danahé Paquin-Ricard for her poster on ‘The role and impact of a deep convective parameterization on Km-scale atmospheric forecasts’ during the closing session.

IMG_20170623_133016499
ECS group photo. Photo courtesy of Ariane Frassoni

Lastly, I also got to do some sightseeing while I was in Montréal after the workshop. From the amazing Notre-Dame Basilica, great views of the city from Mont Royal and the underground city to escape the weather, Montréal has so much to offer!

 

I am thankful to the World Meteorological Organization (WMO) for providing me the travel funding to attend the workshop and present my poster. Also many thanks go to Ariane Frassoni for organising the pub nights and facilitating the ECS activities, as well as for providing the photos for this post.

Two Weeks in Paris Learning about Fluid Dynamics and Sampling French Pastries

Email: r.frew@pgr.reading.ac.uk

The Fluid Dynamics of Sustainability and the Environment (FDSE) residential summer school runs every summer for two weeks, alternating between Cambridge University and Ecole polytechnique, which run the summer school in partnership. I attended this years hosted by Ecole polytechnique, situated to the South of Paris. 40 PhD students attended from institutes around the world, all working on a range of topics who want to learn more about environmental fluid dynamics.

logo-wake-green

The lectures covered topics on fundamentals of fluid dynamics, flow instabilities, environmental fluid dynamics, cryosphere, atmosphere, physical oceanography and renewable energy. The lectures went at a very fast pace (approximately triple speed!), aiming to familiarise us with as many concepts as possible in the two weeks, resulting in everyone taking home a large overflowing folder full of lecture notes to refer back to in the future.

We were kept very busy throughout the two weeks. Each day started with breakfast (coffee and croissants) between 7.30-8.20 am, followed by two back to back lectures 8.30-10.30 am. There was then half an hour for everyone to fuel their brain with coffee and (warm!) mini pastries before another hour lecture before lunch break. Lunch was roughly 12-1.30 pm, although typically there were so many interesting questions after each lecture that we ran progressively later relative to the schedule meaning that I think we only actually started lunch on time on the first day. There were also a number of guest speakers speaking on topics such as public engagement, climate policy, meteorology on mars and air quality.

After lunch we had the final lecture of the day, followed by a short break before numerical sessions and lab experiments, which ran until roughly 6 pm. These sessions gave us the chance to really learn about a particular topic in more detail and to have a more hands on experience with some of the material being lectured. My labs were on tidal energy where we explored the energy output and efficiency of tidal turbines, and Art and Science, which encouraged us to engage with Science in new and more playful ways and also to challenge us to look at it differently.

However the day didn’t end after the labs, the evenings were also jam packed! The first evening was a poster session, giving us all the opportunity to learn more about what all of the other students work on and to mingle. Other evenings consisted of learning to row sessions, visits to the observatory, movie nights and discussions about the ‘science’ in The Day After Tomorrow movie and barbeques enjoying the warm light evenings (definitely missing those now I’m back in Reading).

During the weekend sandwiched in the middle of the two weeks, we were all transferred to a hostel in the centre of Paris, setting us all up perfectly for some weekend sightseeing in Paris. On the Friday evening there was a boat party reception on the Siene, supplying us all with lots of wine, many difference French cheeses to sample and a lively dance floor.

The school ended on Friday July 14th, Bastille Day. After a morning presenting a few slides on the labs we had completed in groups to share what we had learnt, we travelled into the centre of Paris ready for an evening enjoying the spectacular Bastille Day fireworks around the Eiffel tower, ending the summer school with a bang.

Personally the main take away from the summer school was not to learn the entirety of the lecture content, but to become familiar with a wide range of topics gain more hands on experience of laboratory experiments and to have a (rather large) folder full of lecture notes to refer back to whenever I stumble across a particular concept again in the future. And of course, it was great having the opportunity to meet lots of other PhD students from around the world working on related topics and to be able to discuss, engage and get to know each other over the two weeks. I would like to thank all of the organisers and lecturers of the summer school for a really interesting and enjoyable two weeks!

 

Experiences of the NERC Atmospheric Pollution and Human Health Project.

Email: k.m.milczewska@pgr.reading.ac.uk

One of the most exciting opportunities of my PhD experience to date has been a research trip to Beijing in June, as part of the NERC Atmospheric Pollution and Human Health (APHH) project. This is a worldwide research collaboration with a focus on the way air pollution in developing megacities affects human health, and the meeting in Beijing served as the 3rd project update.

Industrialisation of these cities in the last couple of decades has caused air pollution to rise rapidly and regularly exceed levels deemed safe by the World Health Organisation (WHO).  China sees over 1,000,000 deaths annually due to particulate matter (PM), with 76 deaths per 100,000 capita. In comparison, the UK has just over 16,000 total deaths and 26 per capita. But not only do these two countries have very different climates and emissions; they are also at very different stages of industrial development. So in order to better understand the many various sources of pollution in developing megacities – be they from local transport, coal burning or advected from further afield – there is an increased need for developing robust air quality (AQ) monitoring measures.

The APHH programme exists as a means to try and overcome these challenges. My part in the meeting was to expand the cohort of NCAS / NERC students researching AQ in both the UK and China, attending a series of presentations in a conference-style environment and visiting two sites with AQ monitoring instruments. One is situated in the Beijing city centre while the other in the rural village of Pinggu, just NW of Beijing. Over 100 local villagers take part in a health study by carrying a personal monitor with them over a period of two weeks. Their general health is monitored at the Pinggu site, alongside analysis of the data collected about their personal exposure to pollutants each day, i.e. heatmaps of different pollutant species are created according to GPS tracking. Having all the instruments being explained to us by local researchers was incredibly useful, because since I work with models, I haven’t had a great deal of first hand exposure to pollutant data collection. It was beneficial to get an appreciation of the kind of work this involves!

IMG_8121

In between all our academic activities we also had the chance to take some cultural breaks – Beijing has a lot to offer! For example, our afternoon visit to the Pinggu rural site followed the morning climb up the Chinese Great Wall. Although the landscape was somewhat obscured by the pollution haze, this proved to be a positive thing as we didn’t have to suffer in the direct beam of the sun!


I would like to greatly thank NERC, NCAS and University of Leeds for the funding and organisation of this trip. It has been an incredible experience, and I am looking forward to observing the progess of these projects, hopefully using what I have learnt in some of my own work.

For more information, please visit the APHH student blog in which all the participants documented their experiences: https://www.ncas.ac.uk/en/introduction-to-atmospheric-science-home/18-news/2742-ncas-phd-students-visit-four-year-air-quality-fieldwork-project-in-beijing

Summer Barbecue and Ceilidh

Every year the Meteorology Department holds a summer barbecue and ceilidh to celebrate the end of the academic year. Organised by a couple of PhD students, work has been going on behind the scenes for a couple of months. There’s a surprising amount of things to do for an event like this, with health and safety forms and events licenses to fill in as well as booking the band, trying to find 200 bread rolls, and ticket design and selling.

After what seems like an age the day of the barbecue finally arrived! The first job was to collect all the meat – trying to fit 160 burgers and sausages into the communal fridge finally put my tetris skills to good use. A day of bread slicing and salad prep followed until 4:30 arrived and all the PhD students were rounded up to transform the lawn next to the department into a summer party paradise. What looked like an explosion in a bunting factory, one extremely innuendo ridden marquee erection later and with the BBQs lit everything was ready for the guests.

set_up_marquee
How many PhD students does it take to put up a marquee?

Primarily being a barbecue the food was of utmost importance. As the guests began to arrive the brilliant (or foolish) volunteers were hard at work keeping up with the demand for sausages and burgers. Fortunately the weather held out and we ended up with a rather glorious evening. It was lovely to be sat out on the sunny lawn with a glass of sangria surrounded by people enjoying an event that you’d put together. However we couldn’t just sit back and watch the clouds all evening, there was the Ceilidh to come.

Following rave reviews last year the Hogs Back Band made their triumphant return. For those not in the know a ceilidh is a party with folk music and traditional dances. I don’t know about you but I don’t have a repertoire of traditional folk dances memorised. Luckily for us the band came with a caller who explains all the dance, gives some interesting facts and helps pressure some ‘volunteers’ to get up and dance.

The first people on the dance floor were the kids and families, but after a couple of songs, some social pressure and a touch of dutch courage the students and staff started to get up. For a supposedly well educated group some of the dances caused us a bit of trouble; fortunately the band’s caller was on hand to put us to rights and publicly shame the group that were having the most trouble. Let me tell you dancing to a ceilidh is a proper work out! Good job there was a stack of desserts brought by some of meteorology’s excellent bakers to keep us going.

 

 

After the sun had set everyone was rounded up for the final dance, with a lot of galloping round a giant circle and spinning round we were almost done. Just tidying up and then back inside for the afterparty.

All in all it was a great event to get everyone together and get the students and staff to mix in a social setting. Watching your supervisor dancing a ceilidh with their children certainly helps you remember that they’re real people too. It’s so lovely to be part of such a sociable department and be reminded that there’s more to life than your PhD.

The ‘Roaring Forties’ and the Ozone Hole

Email: N.Byrne@pgr.reading.ac.uk

The ‘roaring forties’, often referred to as the ‘brave west winds’, are strong westerly winds in the Southern Hemisphere located between the latitudes of 40 and 50 degrees. These wild winds are some of the strongest on the planet and can traverse the globe at furious speeds, aided in part by the relative dearth of landmasses to serve as windbreaks. Their close companions, the ‘furious fifties’ and the ‘shrieking sixties’ represent regions of even stronger winds that affect the entire Southern Ocean. These strong and steady winds are the driving source of the primary Southern Ocean current (the Antarctic Circumpolar Current) and make it the largest ocean current on the planet.

nick-fig1
Figure 1: (Sourced from earth.nullschool.net.) Surface wind on 20-05-2017. Lighter colours represent regions of larger wind speeds.

The existence of these winds and ocean currents has long been known to sailors and in past centuries, they propelled ships at breakneck speed across the Pacific. In more recent times, vessels that will also travel this route include the British Antarctic Survey’s RRS Sir David Attenborough and the now infamous Boaty McBoatface! Research vessels such as these help contribute to our understanding of how the mid-latitude westerly winds interact with the Southern Ocean and the Antarctic climate, and whether there are any important feedbacks between these different components of the climate system. They are also an important source of evidence for how the climate is changing in one of the most remote places on Earth.

nick-fig2
Figure 2: (Sourced from BBC News.) Boaty McBoatface.

While the rapid increase in CO2 has received much attention for its role in surface climate change in many parts of the globe, in the Southern Hemisphere middle-high latitudes it is arguably ozone depletion (and the associated ozone hole) that has led to the largest changes in surface climate. This is primarily because of the recent discovery that there are important dynamical effects associated with the Antarctic ozone hole – namely a shift in the location of the ‘roaring forties’! This result was quite unexpected at the time of its discovery as it had previously been assumed that surface impacts associated with the Antarctic ozone hole were primarily radiative in nature. Much work in recent years has gone into improving our understanding of how these dynamical effects are transmitted to the surface and what might be the future implications for Southern Hemisphere climate (see references for more details). In any case, the observed impacts of the ozone hole on the westerly winds offer a sobering reminder of the potentially large (and unexpected!) changes that anthropogenic emissions can induce in our climate.

nick-fig3.jpg
Figure 3: (Sourced from Wikipedia.) Image of the largest Antarctic Ozone hole ever recorded over the Southern pole (September 2006).

References

Byrne, N. J., T. G. Shepherd, T. Woollings, and R. A. Plumb, (2017), Non-stationarity in Southern Hemisphere climate variability associated with the seasonal breakdown of the stratospheric polar vortex. J. Clim., in press. doi: 10.1175/jcli-d-17-0097.1.

Thompson, D. W. J., S. Solomon, P. J. Kushner, M. H. England, K. M. Grise, and D. J. Karoly, (2011), Signatures of the Antarctic ozone hole in Southern Hemisphere surface climate change. Nat. Geosci., 4: 741–749. doi:10.1038/ngeo1296.

Sting Jet: the poisonous (and windy) tail of some of the most intense UK storms

Email: a.volonte@pgr.reading.ac.uk

IDL TIFF file
Figure 1: Windstorm Tini (12 Feb 2014) passes over the British Isles bringing extreme winds. A Sting Jet has been identified in the storm. Image courtesy of NASA Earth Observatory

It was the morning of 16th October when South East England got battered by the Great Storm of 1987. Extreme winds occurred, with gusts of 70 knots or more recorded continually for three or four consecutive hours and maximum gusts up to 100 knots. The damage was huge across the country with 15 million trees blown down and 18 fatalities.

case_study_great_storm_fig011
Figure 2: Surface wind gusts in the Great Storm of 1987. Image courtesy of UK Met Office.

The forecast issued on the evening of 15th October failed to identify the incoming hazard but forecasters were not to blame as the strongest winds were actually due to a phenomenon that had yet to be discovered at the time: the Sting Jet. A new topic of weather-related research had started: what was the cause of the exceptionally strong winds in the Great Storm?

It was in Reading at the beginning of 21st century that scientists came up with the first formal description of those winds, using observations and model simulations. Following the intuitions of Norwegian forecasters they used the term Sting Jet, the ‘sting at the end of the tail’. Using some imagination we can see the resemblance of the bent-back cloud head with a scorpion’s tail: strong winds coming out from its tip and descending towards the surface can then be seen as the poisonous sting at the end of the tail.

Conceptual+model+of+storm+development
Figure 3: Conceptual model of a sting-jet extratropical cyclone, from Clark et al, 2005. As the cloud head bends back and the cold front moves ahead we can see the Sting Jet exiting from the cloud tip and descending into the opening frontal fracture.  WJ: Warm conveyor belt. CJ: Cold conveyor belt. SJ: Sting jet.

In the last decade sting-jet research progressed steadily with observational, modelling and climatological studies confirming that the strong winds can occur relatively often, that they form in intense extratropical cyclones with a particular shape and are caused by an additional airstream that is neither related to the Cold nor to the Warm Conveyor Belt. The key questions are currently focused on the dynamics of Sting Jets: how do they form and accelerate?

Works recently published (and others about to come out, stay tuned!) claim that although the Sting Jet occurs in an area in which fairly strong winds would already be expected given the morphology of the storm, a further mechanism of acceleration is needed to take into account its full strength. In fact, it is the onset of mesoscale instabilities and the occurrence of evaporative cooling on the airstream that enhances its descent and acceleration, generating a focused intense jet (see references for more details). It is thus necessary a synergy between the general dynamics of the storm and the local processes in the cloud head in order to produce what we call the Sting Jet .

plot_3D_sj ccb_short
Figure 4: Sting Jet (green) and Cold Conveyor Belt (blue) in the simulations of Windstorm Tini. The animation shows how the onset of the strongest winds is related to the descent of the Sting Jet. For further details on this animation and on the analysis of Windstorm Tini see here.

References:

http://www.metoffice.gov.uk/learning/learn-about-the-weather/weather-phenomena/case-studies/great-storm

Browning, K. A. (2004), The sting at the end of the tail: Damaging winds associated with extratropical cyclones. Q.J.R. Meteorol. Soc., 130: 375–399. doi:10.1256/qj.02.143

Clark, P. A., K. A. Browning, and C. Wang (2005), The sting at the end of the tail: Model diagnostics of fine-scale three-dimensional structure of the cloud head. Q.J.R. Meteorol. Soc., 131: 2263–2292. doi:10.1256/qj.04.36

Martínez-Alvarado, O., L.H. Baker, S.L. Gray, J. Methven, and R.S. Plant (2014), Distinguishing the Cold Conveyor Belt and Sting Jet Airstreams in an Intense Extratropical Cyclone. Mon. Wea. Rev., 142, 2571–2595, doi: 10.1175/MWR-D-13-00348.1.

Hart, N.G., S.L. Gray, and P.A. Clark, 0: Sting-jet windstorms over the North Atlantic: Climatology and contribution to extreme wind risk. J. Climate, 0, doi: 10.1175/JCLI-D-16-0791.1.

Volonté, A., P.A. Clark, S.L. Gray. The role of Mesoscale Instabilities in the Sting-Jet dynamics in Windstorm Tini. Poster presented at European Geosciences Union – General Assembly 2017, Dynamical Meteorology (General session)

Prof. Tapio Schneider – Our Distinguished PhD Visiting Scientist.

Email: j.f.talib@pgr.reading.ac.uk

Every year PhD students from the Department of Meteorology at the University of Reading welcome a distinguished scientist in the field of environmental sciences. Previous scientists include Richard Rotunno (UCAR), Isaac Held (GFDL) and Susan Solomon (NOAA). This year’s honoured visitor was Professor Tapio Schneider from the climate dynamics research group from California Institute of Technology (Caltech), the academic home of NASA’s Jet Propulsion Laboratory. Tapio is a well-known contributor to our understanding of global climate dynamics and it was a pleasure to welcome him to our department.

SAMSUNG CSC
Prof. Tapio Schneider with some of the current PhD cohort.

Our visiting scientist programme in the department is an opportunity for PhD students to share and explain their research to an external visitor. It allows for PhD research to be looked at from a completely new perspective which will hopefully improve the PhD studies. In a typical PhD visiting scientist week, the visiting scientist meets students one to one, attends departmental research groups and presents work in departmental seminars.

Tapio Schneider presented two departmental seminars during his time with us titled How low clouds respond to warming: Observational, numerical and physical constraints and Model hierachies: From advancing climate dynamics to improving predictions. The latter of these seminars encouraged a discussion to rethink how we approach advancing our modelling capabilities. Tapio argued that the atmospheric modelling community had not fully engaged in the benefits that observations offer. He suggested that our goal should be a heirarchical system that integrates both observational data and models. We should look into creating “machine-learning” models, those which use observational data to improve our modelling capabilities through altering parameterisation schemes and radiative balance calculations at the top of the atmosphere (as two examples).

As already mentioned, the visiting scientist also meets with students one-to-one and it was highly beneficial for my own project to have a meeting with Tapio Schneider. We discussed papers released by himself alongside his former PhD student Tobias Bischoff (for example, The Equatorial Energy Balance, ITCZ position and Double-ITCZ bifurications) which concentrate on creating a diagnostic framework with which we can estimate the location and structure of the Inter-Tropical Convergence Zone (ITCZ). We discussed conclusions reached from my own aquaplanet simulations and how they relate to the proposed diagnostic framework. Keep an eye on the blog for a post coming soon on the developments in my own PhD project, (titled, what determines the location and intensity of the ITCZ?).

To bring this blog post to a close I would like to thank Professor Tapio Schneider for his time, knowledge and wisdom that he shared with the PhD cohort whilst at Reading. Thank you also to those from the University of Reading who supported Tapio’s visit. Feedback from the PhD cohort is extremely positive and I would highly recommend a similar scheme for other scientific departments.

20170508_193056
PhD social with the distinguished visitor.