1st Met Office Training and Research Summer School

Email: carlo.cafaro@pgr.reading.ac.uk

From the last week of June until the 1st September I took part in the Met Office Training and Research (MOTR), as part of the Mathematics of Planet Earth CDT.

Inspired by the highly popular and successful Geophysical Fluid Dynamics Summer School at the Woods Hole Oceanographic Insitution in the USA, it is a 10 week-programme, hosted by Met Office in Exeter. The PhD students have the opportunity to handle an applied research topic outside the area of their PhD, diversify their portfolio and experience the working and social life at the Met Office.

In the first two weeks we participated in a summer school. In particular in the first week there was a lecture course on ”Regional Climate Variability and Change”. In the morning the lectures were given by David Karoly from University of Melbourne on “patterns of climate change”, starting from the basic concepts of the climate systems and then expanding to the climate change attribution. In the afternoon we had specialist lectures by Met Office and University of Exeter scientists about El Nino, modelling paleoclimates and attribution of extreme weather events. 

IMG-20170630-WA0001
David Karoly giving one of his lecture on attribution of regional climate change patterns.

In addition, in the afternoon we had to do lab work working in pairs, using Climate Explorer, choosing a specific continent of the world and investigating past climate and future climate projections for that area. My colleague and I selected South America and we gave a presentation about that.

During the second week we participated in the workshop ”Future opportunities to inform UK regional projections”, with a lecture given by Ed Hawkins, amongst  others, talking about sources of uncertainty.

From the third week onward each student started a research project in different Met Office research groups. A different colleague and I worked within the Atmospheric Processes and Parametrization group (APP), supervised by Gabriel Rooney. My project was on numerical simulations and theoretical aspects of colliding density currents. Other colleagues were placed within the Climate Science, Dynamics groups and Informatics Lab, a partner of Met Office.

A typical day for us at Met Office started at 9am, meeting almost every day with Gabriel at 9.45 am, coffee break at 10.30 for half an hour or so (where I also met Annelize, previously in Reading), 1 hour lunch break and then “working” again until 5.30 pm or so.

WP_20170710_19_20_06_Pro
Not quite our typical day at Met Office (found on a desk at Met Office)

Also, once a week we had the meeting with the smaller convection group, where everyone was asked to give an update of their own work. We also attended journal club sessions on Fridays and a brainstorming meeting on 21st July. It was nice to take part in these events, even being only summer interns. During the project phase we had also weekly advanced seminars by Glenn Shutts and Mike Cullen, mainly about large-scale dynamics and hierarchies of operational models used in NWP.

WP_20170721_10_34_41_Pro
Glenn Shutts giving a lecture on Rossby waves breaking.

Personally, it was a wonderful experience for several reasons. The Met Office is a very pleasant place to work, with very friendly and flexible people. Since I think my project was quite academic I did not find many differences with working at university itself. Nevertheless, interacting with new people in a new environment has provided me with new inspirations and insights. I had the chance to talk with several scientists and also a chief Meteorologist, since I was curious about the activities carried out in the Operational room and how much communication there is with the research side. There were some social and sports events organised by MOSSA (Met Office Social and Sports Association) which I really enjoyed (picnic and sports day), getting the chance to meet and to talk with people of other research divisions.

Finally, to top it off, I visited Exeter a lot and the area around, mainly during the weekends and the 5 days of holidays agreed at the beginning, even going to Cornwall for 2 days. 

In the end I would like to thank all of the organisers, my supervisor and all the people I talked with for giving me and my colleagues this very valuable opportunity which I will keep always in mind for my future career.

Thunderstorms and showers: an insight into UK operational radar rainfall estimation.

If there’s one thing you can count on in Britain it’s that at any given time someone, somewhere, is talking about rain.  Either it’s raining, or we want it to rain, or it absolutely mustn’t be raining today.  It’s just one of those things we love to complain about – and we do!

My work isn’t in forecasting rain, but observing it. It’s a little known fact that the rainfall map you see on the front page of the Met Office website doesn’t just come straight out of one giant weather radar, neatly packaged.  There’s a lot of work that has to happen before we can turn the “reflectivities” from many different radar echoes into a sensible estimate of how heavily it’s raining on your street.

The Met Office owns and manages a network of 15 weather radars across the UK, and receives data from three more, in Ireland and the Channel Islands.  We’ve now almost completed a major upgrade of the network, replacing key components of the old radars – some of which had been running operationally for over 30 years! – with new technology.  The dual polarisation and Doppler information we obtain from the upgraded radars improves our ability to distinguish between “rain” and “non-rain” echoes, and to measure how fast the rain is moving, feeding improvements in short range “nowcasts” and flood forecasting models. It can also help us estimate the quantity of rainfall and other types of precipitation in real time.

For my PhD, I’m looking at how to improve Met Office estimates of surface rain rates from radar measurements at long range.  When a radar measures weather, it does so with a beam of energy that spreads out with distance.  20 km from the radar, the echo received represents a volume of space around 600 m by 400 m by 400 m.  At 50 km, the volume is 600 m by 1 km squared.  By 100 km, the beam has spread out to be 2 km wide.  This effect is called “beam broadening”, and limits the spatial detail with which we can measure rainfall.

The other effect of range is the increasing height of the radar beam above the ground.  This means the radar isn’t always measuring liquid rain drops, but may be measuring frozen ice crystals or snow, high up in colder parts of the atmosphere, which will melt before they reach the surface.  Snow, melting snow and rain all have different reflectivities, so we have to correct for this “vertical profile” to calculate how much rain is falling at ground level.

The Met Office corrects for the vertical reflectivity profile (VPR) using an iterative scheme (Kitchen et al. 1994, Kitchen 1997).  We know roughly the VPR shape, and the amount of beam broadening at a given range, so we can scale this shape to the actual radar reflectivity measurement.  This allows us to correct for the impacts of melting snow, which causes a huge enhancement of the radar measurement and would – if uncorrected – lead to extreme overestimates of rainfall.  In the early days of weather radar, this caused rings of very high rain rates to appear in the image: an effect called “bright banding”.  VPR correction also compensates for the underestimation of rain rates at very long distances from the radar.

201410131416_stratiform_rhi
Vertical slice “range height indicator” scan of rain from October 2014.  There is a “bright band” at 2 km height due to melting snowflakes in the reflectivity and linear depolarisation ratio (LDR).

In my work, I’m using measurements from the upgraded dual polarisation radar network to choose between different VPR shapes in making this correction.  Specifically, I’m investigating the depolarising properties of different melting drops, to identify the rare situations where we don’t need to correct for “bright banding”.  The linear depolarisation ratio (LDR), which I’m using to identify the large melting snowflakes that cause radar bright bands, has to be measured using different scans from the ones used to collect reflectivities for rainfall rates, and the Met Office is one of very few meteorological services capable of measuring LDR operationally.  Using LDR in this way can improve rainfall estimates significantly in cases where there is no bright band (Smyth and Illingworth, 1998; Sandford et al., in press).

201507032220_convective_rhi
Vertical slice “range height indicator” scan of a convective shower from July 2015.  There is no bright band in reflectivity, and very little melting layer enhancement in LDR.

As a logical extension to this work, I’m also looking into new VPR shapes for “non-bright band” rain, using vertical slice “range height indicator” scans from our research radar at Wardon Hill.  Correction for bright band is well established in the radar literature, as this is the most common type of rain at high latitudes (where the freezing level is low enough to affect radar measurements), but other types of VPR (e.g. Fabry and Zawadzki, 1995) are rarely discussed.  With the improvements in classification achieved by the new LDR algorithm, a suitable VPR shape is needed to correct for underestimation far from the radar in cases without bright band.  I’ve recently developed a test profile shape for non-bright band VPRs, and demonstrated improvements to rain rates in localised convective case studies. The method is currently being trialled for use in the Met Office’s operational radar processing software.

In the future it’s hoped that the work I’m doing will further improve the accuracy of Met Office rainfall estimates, particularly in thunderstorms and convective showers. And when the weather is doing things like this, that’s good to know!

References

Fabry, F. and I. Zawadzki, 1995: Long-term radar observations of the melting layer of precipitation and their interpretation. Journal of the Atmospheric Sciences, 52, 838-851.

Kitchen, M., 1997: Towards improved radar estimates of surface precipitation rate at long range. Quarterly Journal of the Royal Meteorological Society, 123, 145-163.

Kitchen, M., R. Brown. and A. Davies, 1994: Real-time correction of weather radar data for the effects of bright band, range and orographic growth in widespread precipitation. Quarterly Journal of the Royal Meteorological Society, 120, 1231-1254.

Sandford, C., A. Illingworth, and R. Thompson, in press: The potential use of the linear depolarisation ratio to distinguish between convective and stratiform rainfall to improve radar rain rate estimates. Journal of Applied Meteorology and Climatology.

Smyth, T. and A. Illingworth, 1998: Radar estimates of rainfall rates at the ground in bright band and non-bright band events. Quarterly Journal of the Royal Meteorological Society, 124, 2417-2434.

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.