In the tropics, organised convective systems provide the majority of precipitation and are often responsible for extreme events. To understand these systems, researchers now use kilometre-resolution (k-scale) global and regional convection-permitting models, along with the latest satellite observations. Machine learning tools have also emerged as important supplements to our dynamical and thermodynamic understanding.
It’s crucial to understand these tools to address key questions such as:
How do deep and shallow convection organise in k-scale models?
Can energy budgets help explain their precipitation biases?
What are the recent advances in convective parameterisation?
These questions were the focus of the “5th Summer School on Theory, Mechanisms and Hierarchical Modelling of Climate Dynamics: Convection and Clouds,” which I had the privilege of attending from the 1st–19th of July 2024 at the International Centre for Theoretical Physics (ICTP) in Trieste, Italy.
Picture 1 and 2. First lecture and campus.
The program offered a mix of introductory and advanced lectures, hands-on data analysis through participant projects, and the chance to get involved in the “4th Workshop on Convective Organisation and Precipitation Extremes (WCO4).” The opportunity to attend arose because two of my supervisors, Chris Holloway and Lorenzo Tomassini, presented their work at the conference and taught some of the lectures in the course. As a PhD student researching monsoons using kilometre-scale simulations, I also felt like I had to attend!
The three-week schedule was intense, with most days running from 9 AM to 6 PM (thankfully with plenty of coffee breaks and a long lunch). A typical day began with lectures from leading experts like Simona Bordoni, Robert Pincus, and Courtney Schumacher. Topics ranged from convection and radiation to RCE, stochastic parameterisation, and observations. Afternoons were usually dedicated to computer lab sessions or group project work.
Picture 3. Attendees of the summer school.
The second week centred on the WCO4 conference, covering topics from convective self-aggregation in idealized experiments to precipitation extremes associated with organized convection and optimizing our use of observational data. Students had the opportunity to present posters on their research—an incredibly valuable experience for me as I received loads of useful feedback about my ideas and goals. This was also my first time presenting research at an international event, so it was great to show what I’ve been working on in front of all the attendees and meet so many people genuinely interested in my work.
The final week focused on hands-on projects. In groups of 4–5, we analysed numerical model data and presented our results to everyone. My group examined how precipitation extremes change in a warming world using NextGEMS data, but every group had different topics that they had chosen according to their interest and expertise. Many of the tasks and analyses we did were similar to my first-year work, so I left with a plenty of new ideas for my research!
Picture 4. End of group project presentation and poster presentation.
Being an international centre, the school and conference brought together staff and students from all corners of the globe—one of my favourite aspects of the course. Despite knowing no one beforehand, I quickly got to know other PhDs and post-docs from various institutions, all working on projects similar to mine. I felt at ease in this new environment, making friends and meeting potential future colleagues!
Another fantastic aspect of this summer school was its stunning location on Italy’s sunny, warm northern Adriatic coast. After each day’s activities, we were free to spend our evenings as we pleased. This was the perfect opportunity to relax by the sea, swim, and explore Trieste’s picturesque town centre. More often than not, we’d venture into town for pizza and, of course, gelato!
So, you’ve officially embarked on the exciting journey that is a PhD—congrats! You’ve reached a major milestone, and whether you’re feeling excited, overwhelmed, or a mix of both, just know you’ve signed up for an adventure like no other. A PhD is an incredible opportunity to dive headfirst into a subject you’re passionate about, build a toolkit of valuable skills, and—who knows?—maybe even make history in your field.
But let’s be real: it’s not all rainbows and groundbreaking discoveries. The PhD life can be challenging, sometimes feeling like a marathon through an obstacle course. You’ll have moments that test your patience, confidence, and sometimes, your sanity. That’s why here at Social Metwork, we’ve gathered some golden advice from seasoned PhD students to help you navigate these waters. Our goal? To make this transition into PhD life a little smoother, maybe even a little fun.
We’ll break these tips down into three areas: navigating day-to-day life as a PhD student, getting organized like a pro, and growing into the great scholar you’re destined to be. Ready? Let’s dive in!
1. Navigating Day-to-day Life as a PhD Student
Work-life balance
The first year of your PhD can feel overwhelming as you try to juggle research, coursework, and life. One key piece of advice? Don’t overwork yourself. As Laura Risley puts it, “Sometimes if you’re struggling with work, an afternoon off is more useful than staying up late and not taking a break.” It’s easy to get absorbed in your work, but stepping away to recharge can actually help you return with fresh perspectives.
Getting involved in activities outside your PhD is another great way to maintain balance (L. Risley, 2024). Whether it’s exploring more of Reading, participating in a hobby, or just getting outside for some fresh air, your brain will thank you for the break. Remember, “Your PhD is important, but so is your health,” so make sure to take care of yourself and make time for things that bring you joy: exercise, good food, and sleep!
Lastly, don’t underestimate the power of routine. Building a consistent schedule can help bring some stability to PhD life. Most importantly, be kind to yourself. The weight of expectations can be heavy so give yourself permission to not have it all figured out yet. You won’t understand everything right away, and that’s completely normal!
Socialising and Building a Support System
Your cohort is your lifeline. The people you start with are going through the same experiences, and they will be your greatest support system. Whether you’re attending department events, organizing a BBQ, or just grabbing a coffee, socializing with your peers is a great way to get through everything. At the end of the day, we are all in this together! As Rhiannon Biddiscombe wisely says, “Go for coffee with people, go to Sappo, enjoy the pub crawls, waste a night out at PT, take part in the panto, spend time in the department in-person” — so make sure you get involved!
If what you want is to meet new people, you could even help organise social events, like research groups or casual hangouts – feeling connected within your department can make all the difference when you’re having a tough week. And hey, if you’re looking for a fun group activity, “Market House in town has darts boards, ping pong tables, and shuffleboard (you slide little discs to the end of the board, it’s good fun!)”.
2. Getting Organised Like a Pro
Writing and Coding
Staying organised is critical for both your mental health and your research. Adam Gainford recommends you start by setting up a reference manager early on—trust us, you’ll thank yourself later. And if your research involves coding, learn version control tools like GitHub to keep your projects neat and manageable. As a fellow PhD student says “Keeping organised will help keep your future self sane (and it’s a good skill that will help you with employability and future group projects)”.
A golden rule for writing: write as you go. Don’t wait until the last minute to start putting your thoughts on paper. Whether it’s jotting down a few ideas, outlining a chapter, or even starting a draft, regular writing will save you from stress later on. Remember what Laura always says, “It’s never too early to start writing.”
Time Management
Managing your time as a PhD student is a balancing act. Plans will shift, deadlines will change, and real life will get in the way—it’s all part of the process. Instead of stressing over every slipped deadline, try to “go with the flow”. Your real deadlines are far down the road, and as long as you’re progressing steadily, you’re doing fine.
Being organised also doesn’t have to be complicated. Some find it helpful to create daily, weekly, or even monthly plans. Rhiannon recommends keeping a calendar is a great way to track meetings, seminars, and research group sessions – I myself could not agree more and find time-blocking is a great way to make sure everything gets done. Regarding your inbox, make sure you “stay on top of your emails but don’t look at them constantly. Set aside a few minutes a day to look at emails and sort them into folders, but don’t let them interrupt your work too much!”. Most importantly though, don’t forget to schedule breaks—even just five minutes of stepping away can help you reset (and of course, make sure you have some valuable holiday time off!).
3. Growing into the Scholar You’re Meant to Be
Asking for Help
This journey isn’t something you’re expected to do alone. Don’t be afraid to reach out for help from your friends, supervisors, or other PhD students. Asking questions is a sign of strength, not weakness. What’s great is that everyone has different backgrounds, and more often than not, someone will be able to help you navigate whatever you’re facing (trust me, as a geography graduate my office mates saved my life with atmospheric physics!). Whether you’re stuck on a tricky equation or need clarification on a concept, ask ask ask!
“You’ve got a whole year to milk the ‘I’m a first year’ excuse, but in all seriousness, its never too late to ask when you’re unsure!” – a fellow PhD student.
Navigating Supervisor Meetings
Your supervisors are there to guide you, but communication is key. Be honest with them, especially when you’re struggling or need more support. If something doesn’t make sense, speak up—don’t nod along and hope for the best, “they should always have your back” (it will also be very embarrassing if you go along with it and are caught out with questions…).
Also, “If you know some things you want to get out of your PhD, communicate that with your supervisors”. Open communication will help you build a stronger working relationship and ensure you get what you need from the process.
Dealing with Imposter Syndrome
Imposter syndrome can hit hard during a PhD, especially when you’re surrounded by brilliant people doing impressive work. But here’s the thing: don’t compare yourself to others. Everyone’s PhD is different—some projects lend themselves to quick results, while others take longer. Just because someone publishes early doesn’t mean your research is less valuable or that you’re behind – we are all on our own journeys.
And remember, no one expects you to know everything right away. “There might be a pressure, knowing that you’ve been ‘handpicked’ for a project, that you should know things already; be able to learn things more quickly than you’re managing; be able to immediately understand what your supervisor is talking about when they bring up XYZ concept that they’ve been working on for 20+ years. In reality, no reasonable person expects you to know everything or even much at all yet. You were hand-picked for the project because of your potential to eventually become an independent researcher in your field – A PhD is simply training you for that, so you need to finish the PhD to finish that training.”
If you’d struggling with imposter syndrome, or want to learn about ways to deal with it, I highly recommend attending the imposter syndrome RRDP.
A Few Final Words of Wisdom
The PhD rollercoaster is full of ups and downs, but remember, you’re doing fine. “If you’re supervisors are happy, then don’t worry! Everything works out in the end, even when it seems to not be working for a while! “– Laura Risley
It’s also super important to enjoy the process. You’ve chosen a topic you’re passionate about, and this is a rare opportunity to fully immerse yourself in it. Take advantage of that! Don’t shy away from opportunities to share your work. Whether it’s giving a talk, presenting a poster (or writing for the Social Metwork blog!!), practice makes perfect when it comes to communicating your research.
Embarking on a PhD is no small feat, but hopefully with these tips, you’ll have the tools to manage the challenges and enjoy the ride. And if all else fails, remember the most important advice of all: “Vote in the Big Biscuit Bracket—it’s the most important part of being a PhD student!”.
This year’s ball was held on Thursday 6th June in the Meadow Suite, which had been transformed into a fin-tastic underwater haven thanks to a collection of kids party balloons and Laura’s delightful dolphin collection (rumour has it she has been collecting these for 18 years specifically for Met Ball 2024).
The Met Ball is a yearly event, organised to raise money for the Reading San Francisco Libre Association. After months of emails, forms and ticket sales, the day had finally come. The evening started off with a delicious 3 course meal, followed by the raffle and auction and finished on the dancefloor. We were delighted to be joined by Paul Starkey who provided an introduction to the Reading San Francisco Libre Association as well as the information boards and leaflets. The Reading San Francisco Libre Association helps to support the people, development and environment of San Francisco Libre, Nicaragua, with many projects being set up, including a recent main roads and bridges project which aims to improve connections between San Francisco Libre and other regions.
After introducing the charity, Paul kindly kicked off the raffle which had a suspicious amount of tickets with high numbers. Despite this, the raffle and auction were a huge success (once Sarah and Thea had figured out how to do the calling), with a fantastic sea-lection of prizes. From Mr Met mugs and tea hampers to hotel stays and indoor sky–diving, the prizes up for grabs were certainly a hit! None more than the sought after Brain Hoskins signed photo, which seemed to cause a splash amongst the HHH crowd. Overall, we raised £1003 for the charity!
Following this excitement, there were some waves made on the dance floor, with a special rendition of Islands in the Stream which will never be forgotten, as well as a reminder of how much we all love Wendy. We weren’t the only ones having fun though, as it seemed that most of the photos from the Met Ball were of the seal and lobster balloons who appeared to have a photoshoot around the Meadow Suite (these gen-Z influencers can’t get enough of the camera these days).
Some people’s memories may be more hazy than others, but we have a very specific memory of Ankit and Melissa agreeing to organise Met Ball 2025…
Thanks to everyone who attended and donated prizes to the raffle and auction. We really enjoyed organising it and we were over-whale-med by your presence! Some final words of wisdome from us to the future organisers? Get Brian Hoskins to sign anything and add it to the auction.
On Tuesday 23rd April 2024, I presented my PhD work at the lunchtime seminar to the department. The work I presented incorporated a lot of the work I have achieved during the 3 and a half years of my PhD. This blog post will be a brief overview of the work discussed.
Every year, between 300 and 4000 million tons of mineral dust are lofted from the Earth’s surface (Huneeus et al., 2011; Shao et al., 2011). This dust can travel vast distances, affecting the Earth’s radiative budget, water and carbon cycles, fertilization of land and ocean surfaces, as well as aviation, among other impacts. Observations from recent field campaigns have revealed that we underestimate the amount of coarse particles (>5 um diameter) which are transported long distances (Ryder et al., 2019). Based on our understanding of gravitational settling, some of these particles should not physically be able to travel as far as they do. This results in an underestimation of these particles in climate models, as well as a bias towards modelling finer particles (Kok et al., 2023). Furthermore, fine particles have different impacts on the Earth than coarse particles, for example with the radiative budget at the top of the atmosphere; including more coarse particles in a model reduces the cooling effect that dust has on the Earth.
Thus, my PhD project was born! We wanted to try and peel back the layers of the dusty onion. How are these coarse particles travelling so far?
Comparing a Climate Model and Observations
First, we compared in-situ aircraft observations to a climate model simulation to assess the degree to which the model was struggling to represent coarse particle transport from the Sahara across the Atlantic to the Caribbean. Measuring particles up to 300 um in diameter, the Fennec, AER-D and SALTRACE campaigns provide observations at three stages of transport throughout the lifetime of dust in the atmosphere (near emission, moving over the ocean and at distance from the Sahara; Figure 1). Using these observations, we assess a Met Office Unified Model HadGEM3 configuration. This model has six dust size bins, ranging from 0.063-63.2 um diameter. This is a much larger upper bound than most climate models, which tend to have an upper bound at 10-20 um.
Figure 1: Map showing the location of the flight tracks which were taken when the observations were measured.
We found that the model significantly underestimates the total mass of mineral dust in the atmosphere, as well as the fraction of dust mass made up of coarse particles. This happens at all locations, including at the Sahara: firstly, this suggests that the model is not emitting enough coarse particles to begin with and secondly, the growing model underestimation with distance suggests that the coarse particles are being deposited too quickly. By looking further into the model, we found that the coarsest particles (20-63.2 um) were lost from the atmosphere very quickly, barely surpassing Cape Verde in their westwards transport. Whereas in the observations, these coarsest particles were still present at the Caribbean, representing ~20% of the total dust mass. We also found that the distribution of coarse particles tended to have a stronger dependence on altitude than in the observations, with fewer particles observed at higher altitudes. This work has been written up into a paper which is currently undergoing review, but can be seen in preprint; Ratcliffe et al., (preprint).
Sensitivity Testing of the Model
Now that we have confirmed that the model is struggling to retain coarse particles for long- range transport, we want to work out if any of the model processes involved in transport and deposition could be over- or under-active in coarse particle transport. This involved turning off individual processes one at a time and seeing what impact it has on the dust transport. As we wanted to focus on the impact to coarse particle transport, we needed to start with an improved emission distribution at the Sahara, so we tuned the model to better match the observations from the Fennec campaign.
In our first tests we decided to ‘turn off’ or reduce gravitational settling of dust particles in the model to see what happens if we eliminate the greatest removal mechanism for coarse particles. Figure 2 shows the volume size distribution of these gravitational settling model experiments against the observations. We found that completely removing gravitational settling increased the mass of coarse particles too much, while having little to no effect on the fine particles. We found that to bring the model into better agreement with the observations, sedimentation needs to be reduced by ~50% at the Sahara and more than 80% at the Caribbean.
Figure 2: Mean volume size distribution between 2500-3000 m in the Fennec (red), AER-D (orange) and SALTRACE (yellow) observations, the control mode simulation (black) and the reduced dust sedimentation experiments (blue shades).
We also tested the sensitivity of turbulent mixing, convective mixing and wet deposition on coarse dust transport; however, these experiments did not have as great of an impact on coarse transport as the sedimentation. We found that removing the mixing mechanisms resulted in decreased vertical transport of dust which tended to reduce the horizontal transport. We also carried out an experiment where we doubled the convective mixing, and this did show improved vertical and horizontal transport. Finally, when we removed wet deposition of dust, we found that it had a greater impact on the fine particles, less so on the coarse particles, suggesting that wet deposition is the main removal mechanism for the four finest size bins in the model.
Final Experiment
Now that we know our coarse particles are settling out too quickly and sit a bit too low in the atmosphere, we come to our final set of experiments. Let’s say that our coarse particles in the model and our dust scheme are actually set up perfectly, then could it be the meteorology in the model which is wrong? If the coarse particles were mixed higher up at the Sahara, then would they reach faster horizontal winds to travel further across the Atlantic? To test this theory, I hacked the files which the model uses to start a simulation, and I put all the dust over the Sahara up to the top of the dusty layer (~5 km). We found this increased the lifetime of the coarsest particles so that it took twice as long to lose 50% of the starting mass. This unfortunately only slightly improved transport distance as the particles were still lost relatively quickly. After checking the vertical winds in the model, we found that they were an order of magnitude smaller at the Sahara, Canaries and Cape Verde than the observations made during the field campaigns. This suggests that if the vertical winds were stronger, they could initially raise the dust higher and keep the coarse particles raised higher for longer, extending their atmospheric lifetime.
Summarised Conclusions
To summarise what I’ve found during my PhD:
The model underestimates coarse mass at emission and the underestimation is exacerbated with westwards transport.
Altering the settling velocity of dust in the model brings the model into better agreement with the observations.
a. Turbulent mixing, convective mixing and wet deposition have minimal impact on coarse transport.
Lofting the coarse particles higher initially improves transport minimally.
a. Vertical winds in the model are an order of magnitude too small.
So what’s next?
If we’ve found that the coarse particles are settling out the atmosphere too quickly (by potentially more than 80%), would that suggest that the deposition equations are wrong and are overestimating particle deposition? So, we change those and everything’s fixed, right? I wish. Unfortunately, the deposition equations are one of the things that we are more scientifically sure of, so our results mean that there’s something happening to the coarse particles that we aren’t modelling which is able to counteract their settling velocity by a very significant amount. Our finding that the vertical winds are too small could be a part of this. Other recent research suggests that processes such as particle asphericity, triboelectrification, vertical mixing and turbulent mixing (has been shown to help in a higher-resolution (not climate) model) in the atmosphere could enhance coarse particle transport.
Huneeus, N., Schulz, M., Balkanski, Y., Griesfeller, J., Prospero, J., Kinne, S., Bauer, S., Boucher, O., Chin, M., Dentener, F., Diehl, T., Easter, R., Fillmore, D., Ghan, S., Ginoux, P., Grini, A., Horowitz, L., Koch, D., Krol, M. C., Landing, W., Liu, X., Mahowald, N., Miller, R., Morcrette, J.-J., Myhre, G., Penner, J., Perlwitz, J., Stier, P., Takemura, T., and Zender, C. S. 2011. Global dust model intercomparison in AeroCom phase I. Atmospheric Chemistry and Physics. 11(15), pp. 7781-7816
Kok, J. F., Storelvmo, T., Karydis, V. A., Adebiyi, A. A., Mahowald, N. M., Evan, A. T., He, C., and Leung, D. M. Jan. 2023. Mineral dust aerosol impacts on global climate and climate change. Nature Reviews Earth Environment 2023, pp. 1–16. url: https://www.nature.com/articles/s43017-022-00379-5
RatcliLe, N. G., Ryder, C. L., Bellouin, N., Woodward, S., Jones, A., Johnson, B., Weinzierl, B., Wieland, L.-M., and Gasteiger, J.: Long range transport of coarse mineral dust: an evaluation of the Met Office Unified Model against aircraft observations, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2024-806, 2024
Ryder, C. L., Highwood, E. J., Walser, A., Seibert, P., Philipp, A., and Weinzierl, B. 2019. Coarse and giant particles are ubiquitous in Saharan dust export regions and are radiatively significant over the Sahara. Atmospheric Chemistry and Physics. 19(24), pp. 15353–15376
Shao, Y., Wyrwoll, K.-H., Chappell, A., Huang, J., Lin, Z., McTainsh, G. H., Mikami, M., Tanaka, T. Y., Wang, X., and Yoon, S. 2011. Dust cycle: An emerging core theme in Earth system science. Aeolian Research. 2(4), pp. 181–204
The Beast from the East, the record-breaking winter warmth of February 2020, the Canadian heat dome of 2022…what do these three events have in common? Well, many things I’m sure, but most relevantly for this blog post is that they all coincided with the same phenomenon – atmospheric blocking.
So what exactly is a block? An atmospheric block is a persistent, large-scale, quasi-stationary high-pressure system sometimes found in the mid-latitudes. The prolonged subsidence associated with the high pressure suppresses cloud formation, therefore blocks are often associated with clear, sunny skies, calm winds, and temperature extremes. Their impacts can be diverse, including both extreme heat and extreme cold, drought, poor air quality, and increased energy demand (Kautz et al., 2022).
Despite the range of hazards that blocking can bring, we still do not fully understand the dynamics that cause a block to start, maintain itself, and decay (Woollings et al., 2018). In reality, many different mechanisms are at play, but the importance of each process can vary between location, season, and individual block events (Miller and Wang, 2022). One process that is known to be important is the interaction between blocks and smaller synoptic-scale transient eddies (Shutts, 1983; Yamazaki and Itoh, 2013). By studying a 43-year climatology of atmospheric blocks and their anticyclonic eddies (both defined by regions of anomalously high 500 hPa geopotential height), I have found that on average, longer blocks absorb more synoptic anticyclones, which “tops up their anticyclonicness” and allows them to persist longer (Fig. 1).
Figure 1: average number of anticyclonic eddies per block for the Euro-Atlantic (left) and North Pacific (right). Block persistence is defined as the quartiles (Q1, Q2, Q3) of all blocks in winter (blue) and summer (red). From Suitters et al. (2023).
It’s great that we now know this relationship, however it would be beneficial to know if these interactions are forecasted well. If they are not, it might explain our shortcomings in predicting the longevity of a block event (Ferranti et al., 2015). I explore this with a case study from March 2021 using ensemble forecasts from MOGREPS-G. Fortunately, this block in March 2021 was not associated with any severe weather, but it was still not forecasted well. In Figure 2, I show normalised errors in the strength, size, and location of the block, at the time of block onset, for each ensemble member from a range of different initialisation times. In these plots, a negative (positive) value means that the block was forecast to be too weak (strong) or too small (large), and the larger the error in the location, the further away the forecast block was from reality. In general, the onset of this block was forecast to be to be too weak and too small, though there was considerable spread within the ensemble (Fig. 2). Certainty in the forecast was only achieved at relatively small lead times.
Figure 2: Normalised errors in the intensity (left), area (centre), and location of the block’s centre of mass (right), at a validity time of 2021-03-14 12 UTC (the time of onset). Each ensemble member’s error from a particular initialisation time is shown by the grey dots, and the ensemble mean is shown in black. When Z, A, or L are zero, the forecast has a “perfect” replication for this metric of the block (when compared to ERA5 reanalysis).
Now for the interesting bit – what causes the uncertainty in forecasting of the onset this European blocking event? To examine this, I grouped forecast members from an initialisation time of 8 March 2021 according to their ability to replicate the real block: the entire MOGREPS-G mean, members that either have no block or a very small block (Group G), members that perform best (Group H), and members that predict area well, but have the block in the wrong location (Group I). Then, I take the mean geopotential height anomalies () at each time step in each group, and compare these fields between groups to see if I can find a source of forecast error.
This is shown as an animation in Fig. 3. The animation starts at the time of block onset, and goes back in time to selected validity times, as shown at the top of the figure. The domain of the plot also changes in each frame, gradually moving westwards across the Atlantic. By looking at the ERA5 (the “real”) evolution of the block, we see that the onset of the European block was the result of an anticyclonic transient eddy breaking off from an upstream blocking event over North America. However, none of the aforementioned groups of members accurately simulate this vortex shedding from the North American block. In most cases, the eddy leaving the North American block is either too weak or non-existent (as shown by the blue shading, representing that the forecast is much weaker than in ERA5), which resulted in a lack of Eastern Atlantic blocking altogether. Only the group that modelled the block well (Group H) had a sizeable eddy breaking off from the upstream block, but even in this case it was too weak (paler blue shading). Therefore, the uncertain block onset in this case is directly related to the way in which an anticyclonic eddy was forecast to travel (or not) across the Atlantic, from a pre-existing block upstream. This is interesting because the North American block itself was modelled well, yet the eddy that broke off it was not, which was vital for the onset of the Euro-Atlantic block.
To conclude, this is an important finding because it shows the need to accurately model synoptic-scale features in the medium range in order to accurately predict blocking. If these eddies are absent in a forecast, a block might not even form (as I have shown), and therefore potentially hazardous weather conditions would not be forecast until much shorter lead times. My work shows the role of anticyclonic eddies towards the persistence and forecasting of blocks, which until now had not be considered in detail.
References
Kautz, L., Martius, O., Pfahl, S., Pinto, J.G., Ramos, A.M., Sousa, P.M., and Woollings, T., 2022. “Atmospheric blocking and weather extremes over the Euro-Atlantic sector–a review.” Weather and climate dynamics, 3(1), pp305-336.
Miller, D.E. and Wang, Z., 2022. Northern Hemisphere winter blocking: differing onset mechanisms across regions. Journal of the Atmospheric Sciences, 79(5), pp.1291-1309.
Shutts, G.J., 1983. The propagation of eddies in diffluent jetstreams: Eddy vorticity forcing of ‘blocking’ flow fields. Quarterly Journal of the Royal Meteorological Society, 109(462), pp.737-761.
Suitters, C.C., Martínez-Alvarado, O., Hodges, K.I., Schiemann, R.K. and Ackerley, D., 2023. Transient anticyclonic eddies and their relationship to atmospheric block persistence. Weather and Climate Dynamics, 4(3), pp.683-700.
Woollings, T., Barriopedro, D., Methven, J., Son, S.W., Martius, O., Harvey, B., Sillmann, J., Lupo, A.R. and Seneviratne, S., 2018. Blocking and its response to climate change. Current climate change reports, 4, pp.287-300.
Yamazaki, A. and Itoh, H., 2013. Vortex–vortex interactions for the maintenance of blocking. Part I: The selective absorption mechanism and a case study. Journal of the Atmospheric Sciences, 70(3), pp.725-742.
Differential reflectivity (ZDR) is the difference in measured backscatter from emitted radio waves in the horizontal and vertical polarisations. It is an observable available from dual-polarisation radars. Conventional single-polarisation radars usually offer reflectivity ZH only which is the intensity of backscatter in the horizontal polarization available from conventional radars. The addition of measuring ZDR allows for hydrometeor type classification. In other words, we could tell between large round tumbling hail which gives near zero ZDR from large oblate raindrops that give highly positive ZDR (Kumjian, 2013a). Strong updrafts contribute to severe convective development by lofting large hydrometeors like raindrops into higher parts of the storm, giving ZDR column signatures. A differential reflectivity (ZDR) column is defined as “a region of enhanced ZDR as situated above the 0◦C level” (Kumjian, 2013b) and are known to be useful in informing forecast warning decisions (e.g. Kuster et al., 2019, 2020).
The UK Met Office has fully upgraded all 15 C-band radars as of January 2018 to have dual-polarisation capabilities. The Met Office also composites data from this radar network to provide three-dimensional gridded products covering the entirety of the UK (Scovell and al-Sakka, 2016). Whereas a single radar would only be able to detect hydrometeors as high as its highest scan elevation, thus leaving the so-called “cone of silence” aloft closest to the radar, the composite permits nearby radars to fill in these regions of missing observations. To harness the greater spatial domain of the 3D radar composite constituting data from multiple overlapping radars, the composite was upgraded to include ZDR to investigate the operational potential of using ZDR columns. But, how do we know ZDR columns can be reliably detected within this 3D radar composite?
The work described in this post is to verify ZH and ZDR generated by the Met Office compositing process against range-height indicator (RHI) scans from Chilbolton Advanced Meteorological Radar (CAMRa), otherwise known as the world’s largest steerable meteorological research radar (see Figure 1). RHI scans are carried out by varying a radar antenna’s elevation angle but with the azimuth angle held constant. ZDR columns are often narrow features that may challenge the limited resolution (1km in the horizontal) of the radar composite.
Figure 1: The 25 m antenna of the Chilbolton Advanced Meteorological Radar (CAMRa) located at the Chilbolton Observatory.
CAMRa is a suitable truth owing to it being well-calibrated to within 0.1dB of ZDR, its extremely narrow beamwidth of 0.28◦, high range resolution of 75m and high resolution elevations of 0.11deg within RHIs. In contrast, the composite is made of operational radar data of lower resolution and the compositing process could further degrade the accuracy of the data. Thus its ZDR output has to be verified.
Vertical cross sections of the radar composite
Figures 2a and 2d are RHI scans carried out by CAMRa, covering elevations from 0.02 to 10.0◦. These two figures captured an evolving convective system on 7 June 2016 at 1651Z (Figure 2e) and on 1 October 2019 at 1526Z (Figure 2f). The fine range resolution of 75m captured multiple intense reflectivity cores exceeding 40 dBZ with accompanying overshooting tops.
Figures 2b and 2e are pseudo-RHIs produced from the compositing process of the Chenies and Thurnham operational C-band radars. Both radars were chosen for the compositing process as their overlapping sampling regions offered coverage for the convective system scanned by CAMRa. Instead of generating the usual 3D composite with 1 km and 500 m of horizontal and vertical grid spacing respectively, the compositing software was modified in this verification process to interpolate C-band radar data onto a 2D grid along the CAMRa scan azimuth with the same grid resolutions thus producing the so-called pseudo-RHI plots.
Figure 2: RHI plots of radar reflectivity ZH scanned by CAMRa (a,d) and corresponding pseudo-RHI plots derived from the original Met Office radar compositing process (b,e) and with azimuthal correction applied (c,f). The top and bottom rows each corresponds to observations on 07 June 2016 but at 1603Z and 1651Z respectively.
However, the preliminary inspection of the pseudo-RHI plots reveals a serious vertical discontinuity of interpolated data. Such an issue would disrupt the automatic detection of vertically extending signatures such as ZDR columns. This problem is seen at around 70 and 100km down range in Figure 1b and 90km down range in Figure 2e. The displacement observed here suggests that the spatial location of storms could be misrepresented on the order of 5 km. What could have caused this problem?
Correction of spatial location of radar beams in compositing software
Through scrutiny of the Met Office compositing software, I found an error with how radar azimuths were used in the compositing process. In the pre-exisiting compositing software, radar azimuths would be formulated as azimuthal equidistant projection coordinates relative to the radar site, then directly transformed onto British National Grid coordinates. However, it was overlooked that Met Office radar azimuths are recorded with respect to British National grid north, whereas azimuthal equidistant projection coordinates require azimuths to be relative to true north. The deviations of up to a few degrees between the norths can lead to a horizontal displacement of radar data of at least a few kilometres at a range of 100km from a radar site. Lesson learnt: Attention to small details can have a large impact later on!
To fix this problem, grid convergence (Ordnance Survey, 2018) is added to all radar azimuths such that radar azimuths are adjusted with respect to true north before undergoing transformation into British National Grid coordinates. The effect of implementing such a correction can be seen in Figures 1c and 1f, where reflectivity values interpolated from two separate C-band radars result in a vertically continuous intense reflectivity core. There could still be mismatches on a smaller scale owing to radar scans happening at different times while the storm was being advected. With the radar composite corrected, is ZDR well represented?
Visual comparison of ZDR
Both Chenies and Thurnham radars used for generating pseudo-RHIs were upgraded to have dual polarimetric capability since March 2013. This allows the generation of ZDR pseudo-RHI plots as shown in Figures 2c and 2b, which can be qualitatively compared with CAMRa scans in Figures 2a and 2d on 7 June 2016 at 165136Z and on 1 October 2019 at 152641Z respectively.
Figure 3: RHI plots of radar differential reflectivity ZDR scanned by CAMRa (a,b), corresponding pseudo-RHI plots derived from the radar composite (c,d) and MAXDBZ plan views in (e,f). In the plan views, the red cross marks the position of CAMRa. The black line is the azimuth of CAMRa for the RHI scan. Black dots are separated by 20km with the first and last black dot corresponding to the plotted range of the RHIs. The top and bottom rows each corresponds to observations on 07 June 2016 at 1651Z and 01 Oct 2019 at 1526Z respectively. The freezing height was 3.0 km in the June case and 2.2 km in the October case.
Considering the observed ZDR column is approximately 95 km down range from the radar, a displacement of 0.6◦ is 1km of distance in the horizontal. Such a distance corresponds to the sampling resolution of the radar composite. The C-band operational radars also have a wider beamwidth of 1.1◦ and are unable to observe fine details unless the ZDR column is situated close to one of the radars. Thus, the discrepancy in intensity and height in Figure 2 is expected, owing to the differences in sampling resolutions between CAMRa and the radar composite. The operational radar composite, which combines measurements from radars at various ranges, is capable of detecting ZDR column features at a coarser resolution, whereas CAMRa is used to study fine details of the column structures with high precision in individual case studies.
We have shown that outputs from CAMRa captured sub-kilometre features such as the width of ZDR columns and their horizontal structures within a cell are too fine to be resolved by the composite. Despite the resolution limitations of operational radars and having done other tests not mentioned in this post, we are confident that the radar composite can be exploited to reliably capture the presence of ZDR columns at a horizontal spatial resolution of 1 km alongside an indication of their maximum heights.
References
Kumjian, M. R. (2013a). “Principles and Applications of Dual-Polarization Weather Radar. Part I: Description of the Polarimetric Radar Variables”. Journal of Operational Meteorology 1.20, pp. 243–264. doi:10.15191/nwajom.2013.0120
Kumjian, M. R. (2013b). “Principles and applications of dual-polarization weather radar. Part II: Warm- and cold-season applications”. Journal of Operational Meteorology 1.20, pp. 243–264. doi:10.15191/nwajom.2013.0120
Kuster, C. M. et al. (2019). “Rapid-update radar observations of ZDR column depth and its use in the warning decision process”. Weather and Forecasting 34.4, pp. 1173–1188. doi: 10.1175/WAF-D-19-0024.1
Kuster, C. M. et al. (2020). “Using ZDR Columns in Forecaster Conceptual Models and Warning Decision Making”. Weather and Forecasting, pp. 1–43. doi: 10.1175/WAF- D-20-0083.1 Ordnance Survey (2018). A Guide to Coordinate Systems in Great Britain. Accessed: 16-1-2024
Scovell, R. and H. al-Sakka (2016). “A Point Cloud Method for Retrieval of High-Resolution 3D Gridded Reflectivity from Weather Radar Networks for Air Traffic Management”. Journal of Atmospheric and Oceanic Technology 33.3, pp. 461–479. doi: https://doi.org/10.1175/JTECH-D-15-0051.1
In January 2024, Isabel Smith and Hannah Croad attended the 104th American Meteorological Society (AMS) annual meeting in Baltimore, Maryland. As fourth-year PhD students this was something of a “last hurrah” of our PhDs (with the remainder of our project monies and carbon budgets being used up), representing a fantastic opportunity to see the latest research happening in meteorology, meet other scientists working in our respective fields, and present our own work to a large audience at this late stage in our projects.
We arrived in Baltimore on the Friday before the conference started, navigating the busy streets near the Inner Harbour in a thick fog to find our hotel. The many plumes of steam coming from vents in the street were somewhat disconcerting, but it turns out this is the result of an underground steam pipe system and is completely safe. As exciting as this was, Baltimore is slightly lacking in terms of other tourist attractions, so on the Saturday we chose to visit Washington DC, only a 1-hour train ride away. We had a great day wandering about the capital city, visiting the Smithsonian’s National Air and Space Museum, and seeing all the iconic monuments including the Capitol building and the White House. Back in Baltimore on the Sunday, there was a buzz about the city as Baltimore’s NFL Ravens team were hosting the Kansas City Chiefs. Although we did not attend the game, and the Ravens lost, it was a great honour to be within a mile radius of Taylor Swift.
Figure 1: Posing for a selfie in front of the Capitol building in Washington DC whilst the sun made a brief appearance.
The conference started on Sunday, with registration (where we picked up some cool lanyards), speeches from outgoing and incoming AMS presidents, student posters, and an interesting panel discussion about how the two sides of American politics must come together in the fight against climate change. It was also great to meet up with two first-year PhD students from the department, Karan Ruparell and Robby Marks, for who this was the first international conference of their PhD.
Figure 2: PhD students (from left to right: Karan, Hannah, Robby, Isabel) from the University of Reading at the AMS 2024 annual meeting with the climate-striped-inspired logo.
The main conference programme was scheduled from Monday to Thursday. The size of the conference was overwhelming, with up to 40 parallel sessions at any one time amongst the many different mini- conferences and symposia. Hence, it was important to research which sessions you wanted to go to in advance. We did this using the AMS app, although it was rather slow and buggy (AMS if you’re reading this, please improve for next year). Isabel attended the 4-day symposium on Aviation, Range and Aerospace meteorology (ARAM), being held in the same room of the conference center each day. In contrast, Hannah attended many different sessions and so was continuously moving between different rooms, with the highlights being the Daniel Keyser symposium on synoptic-dynamic meteorology on Monday and the Polar symposium on Thursday.
The biggest day of the conference for us was Thursday, as we were both going to be presenting our work. Starting bright and early, Isabel gave an oral presentation in the ARAM symposium, talking about her work on trends in aviation scale turbulence. In the afternoon, Hannah presented a poster in the Polar symposium, talking about her climatology of summer-time Arctic cyclones. We found it interesting to compare the two different presentation formats. For oral presentations your research is likely to reach more people as you have a captive audience for 12 minutes, but the format is more nerve-wracking and there is only limited time for questions and discussion. Less people are likely to visit a poster, but the 1.5 hour format allows for longer and more in-depth discussion with those who do approach you (assuming your poster survives the flight in your suitcase of course). Regardless of the format, we both really enjoyed sharing and discussing our work with other scientists and found the day to be thoroughly rewarding.
Figure 3: Isabel giving her presentation in the ARAM symposium.
Figure 4: Hannah (left) presenting her poster at the Polar symposium.
In summary, we both had a fantastic time at the AMS 2024 annual meeting. Not only did we enjoy and learn a lot from the conference talks and posters, it was also great to catch up with current and ex-students from the department, old friends and lecturers from our time at the University of Oklahoma as undergraduate students, and to make new contacts in our respective fields. Although large conferences like AMS can be daunting, attending gives you an appreciation of the wide variety of research happening all over the world, conducive to a stimulating and inspiring atmosphere. They also provide fantastic opportunities to network and to learn new things outside of your immediate research topic. Hence, we would both recommend attending a big conference like AMS if you get the chance to do so in your PhD!
The Parliamentary Office for Science and Technology (POST) is a research and knowledge exchange service at UK Parliament. POST uses the best available research evidence and information to inform the legislative process and scrutiny of Government. POST advisors and fellows create POSTnotes and POSTbriefs on hot topics of interest to MPs and peers (members of the House of Lords) that are published online. Members may use information from POST publications during committee meetings or debates in Parliament.
The POSTnote process
POST fellows work for three months on an assigned topic outside of their usual area of research. The research is rapid! Fellows quickly identify experts from Academia, NGOs, Industry, and Government departments to speak to, and try to think of insightful questions to ask.
I was assigned the topic of carbon offsetting – yay! I interviewed almost 40 people that varied from those working with Indigenous Peoples in Guyana to others working with farming communities on Biochar (the carbon rich remains of super-heated organic material) research in the UK.
What is carbon offsetting?
A carbon credit is a token representing the avoidance, reduction or removal of atmospheric greenhouse gases (GHG), measured in tonnes of carbon dioxide equivalent (tCO2e). There are three main outcomes for projects creating carbon credits: Avoided emissions, for example by preventing deforestation and forest degradation; Reduced emissions, for example by restoring peatlands; and Removal and storage of CO2, for example by direct air capture or restoring forests. Businesses and individuals can purchase credits on the voluntary carbon market and may use them to offset their own emissions.
After lots of reading and reference gathering, the impartial POSTnote is drafted at around 3500 words and includes 100+ references. Internal and (a monster) external review follow (the draft note is sent to all contributors for comment) before final publication.
Working at Parliament
It was great to be a part of a team of POSTies, some seconded to select committees such as the Environmental Audit Committee or the Library. Others worked on different POSTnote topics like Green skills, AI in education and The future of fertiliser use. Westminster Palace is beautiful, awe-inspiring and a motivating place to work. There are lots of opportunities to enter ballots for activities and events. I was fortunate to attend the State Opening of Parliament (from the pavement, the King definitely waved at me), visit the archive tower (I counted nearly 300 steps up 12 floors and saw the original Freedom of Information Act 2000), and sing Christmas carols in Mr Speakers House.
Summary
I applied for a POST fellowship to learn more about policy and how research can have an impact. I loved the learning process, and I will use it in my research going forwards. I would like to thank SCENARIO DTP for funding the opportunity.
) at each time step in each group, and compare these fields between groups to see if I can find a source of forecast error. 
The Social Metwork 