Inside COP29

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Thea Stevens – thea.stevens@pgr.reading.ac.uk

Juan Garcia Valencia – j.p.garciavalencia@pgr.reading.ac.uk

Introduction

Hi there! We are Thea (3rd year PhD) and Juan (2nd year PhD), and we had the privilege to attend Week 2 of COP29 at the end of last year. We thought it would be a good idea to write a blog as an accumulation of answers to the main questions we’ve encountered since coming back – we hope you enjoy reading about it and that it’s hopefully useful to anyone thinking of applying for this amazing opportunity next year! 

Picture 1, Entrance to COP29. Picture 2, Emmanuel Essah, Thea Stevens and Juan Garcia Valencia in COP29

Pre-COP 

What is COP29? 

COP29, the 29th Conference of the Parties, is the annual United Nations climate change conference and serves as the primary decision-making event under the United Nations Framework Convention on Climate Change (UNFCCC). Established by the treaty signed in 1992, COP brings together representatives from all UN member states and the European Union to address global climate challenges. This year, COP29 was held in November in Baku, Azerbaijan, drawing over 65,000 delegates from around the world, including diplomats, climate scientists, trade union leaders, and environmental activists. The event aims to negotiate effective strategies to combat the root causes of climate change. In essence, it’s the world’s largest and most significant gathering dedicated to climate action.

What were the expectations going into COP29?

Even before the summit began, COP29 was widely referred to as the “Finance COP” due to the prominence of one particular issue: climate finance. This term highlights the obligation of developed nations to provide financial resources to developing countries. These funds are intended to help nations build clean-energy systems, adapt to a warming world, and recover from disasters exacerbated by climate change. A significant focus of the negotiations and media coverage was the New Collective Quantified Goal (NCQG), a proposed climate finance target aimed at channelling resources to developing nations to combat climate change effectively.

However, discussions were also expected to extend beyond finance, addressing crucial topics such as Article 6 of the Paris Agreement, as well as strategies for adaptation and mitigation. We had the incredible opportunity to attend the second week of COP29—a pivotal stage of the process when ministers usually tackle the intricate details of agreements crafted in the first week, working to reach consensus. Heading into the conference, we anticipated hearing much more about the NCQG and its potential connections to other pressing climate issues.

Why did we apply to go?

“I decided to apply to attend COP29 due to the significance of geopolitical progress in ensuring that countries act in accordance with science. I think it is easy for us to forget the magnitude of what we study as meteorologists and climate scientists. To be able to follow how our scientific understanding shapes what actions are taken on a political scale feels important in order to put our work into context. I have also been following the progress of COPs for a long time – I was that geeky teenager in geography class who got a bit obsessed with the developments made there. So, on a more personal level, it also felt like a really exciting opportunity.” – Thea 

“My decision to apply for COP29 stemmed from a deep interest in the science-policy interface. As a PhD student researching monsoons and their variability with climate change, my work primarily involves analysing large datasets with the aim of crafting papers that can inform decision-making. While this scientific foundation is critical, I was eager to move beyond the confines of my computer screen and engage directly with the global climate community. This experience promised not only professional growth but also the chance to see firsthand how research and advocacy converge on the global stage so I knew I had to give it a go!” – Juan

What did we do in preparation? 

Having closely followed previous COPs and participated in COPCAS, we were familiar with the structure and nature of these conferences, which gave us a sense of what to expect. However, we knew that attending in person would be a completely different experience. In preparation, we undertook extensive training and courses. The Walker Institute’s help was invaluable, as they provided numerous opportunities to upskill and address our questions. They even arranged security training, given that we were heading to a politically sensitive region. Additionally, the IISD webinars were incredibly helpful in providing up-to-date insights on negotiation progress and key facts. Staying informed through these resources and keeping up with current news allowed us to approach the conference well-prepared and confident.

During COP 

What was the schedule like? 

The daily schedule at COP29 was intense. With only one week to make the most of the experience, our days were packed with meetings from 9:00AM – 6:00PM. We started each morning with the RINGO (Research and Independent Non-Governmental Organisations) meeting, which brought together members of the observer scientific community. These sessions provided a valuable space to discuss key themes and points of interest for the day, while also offering great networking opportunities.

The rest of the day was a whirlwind of press conferences, negotiations, and side events hosted by a wide range of organisations. Most events were open to all attendees, though some, particularly negotiations in the second week and high-profile press conferences (such as those featuring Antonio Guterres, Secretary-General of the UN!), were closed-door.

Another key aspect of our responsibilities was meeting twice daily with our team back at the Walker Institute. These sessions were a great chance to share our findings, report on the atmosphere on the ground, and receive valuable recommendations for upcoming events. More often than not, these check-ins also provided a much-needed energy and mood boost to keep us going through the busy days!

How did we decide on what to attend? 

Understanding the true scope of events and talks at COP took a while to get your head around. There is so much going on, and so much you could be going to it always felt like you were missing something. It was helpful to be able to think of the types of events you could go to into three different categories: the negotiations, the side events and the pavilion events. Each one of these had quite a different atmosphere, which was helpful to consider when deciding what to go to. 

The pavilions were basically a full conference on their own, with every country and NGO having their own elaborately decorated area. Talks here were slightly more informal and there was a wide diversity of topics. If you wanted to get some information on a more specific topic and also have time to talk with the people presenting this was the place to be. 

The side events were often more specific to the ongoing negotiations and included panel discussions and press conferences. These were often really exciting opportunities to get an update on the negotiations that we might not have been allowed to sit in on, and they often provided a more candid and emotive response to the developments. 

Lastly were the negotiations themselves. These were very slow and bureaucratic, but despite this, they were really fascinating to watch. It was what was going on in these negotiation rooms that really mattered to the outcome of COP! We had been given very good advice before we went to properly follow just one of the negotiation pieces so that you could understand how it was being shaped over time. However, as we attended the second week, the negotiations occurring behind closed doors increased more and more, and the agenda for these was constantly changing. We found it best to just jump on any opportunity there was to attend one of these as they became increasingly difficult to access. 

Having an overview of the different potential experiences in each of these parts of COP made it easier to asses what to go to and what might be interesting at any given time. 

Picture 3, 4, and 5 show various events that happened in COP29, including a press conference, a science pavilion event and a plenary.

Who was someone interesting you met?

“While waiting in a queue to get into a negotiation, I met a delegate from an NGO based in South Africa. Through links to local religious groups, she helped guide communities to access climate-related financial aid. We discussed how amendments being made during different negotiations were having a direct impact on the accessibility of these funds. This provided a powerful reminder of how the negotiations had an impact on some of the most vulnerable communities not only in South Africa but all over the world. Having her watching and voicing opinions to negotiators between events provided a channel for these voices to be heard.” – Thea 

“Among the many incredible individuals I met, my interaction with two indigenous women from Chile left a profound impact. Their presentation on the consequences of lithium extraction in the Atacama Desert was both heartbreaking and inspiring. They spoke passionately about the devastating effects of privatized water and mineral resources, which have left their communities struggling with water scarcity and ecological exhaustion. Their unwavering determination to fight for their rights and protect their environment, despite significant challenges, was a powerful reminder of the human cost of unsustainable practices. Their story underscored the importance of amplifying marginalized voices in global climate discussions” – Juan

What is the role of the host country and how much influence do they have?

Hosting a COP entails significant responsibilities, including providing the facilities, security, and leadership required to ensure the summit’s success. In many ways, we were impressed by Azerbaijan’s efforts as the COP29 presidency. The facilities were well-prepared, and the transportation system was particularly noteworthy—clear, organised, and highly efficient, running seamlessly throughout the two weeks to help delegates commute to and from the conference centre with ease.

However, Azerbaijan’s selection as host sparked controversy from the moment it was announced at the end of COP28 in Dubai. One of the reasons was this it marked the third consecutive year that a petrostate was appointed to host the climate summit, raising concerns about potential conflicts of interest. This issue became a recurring theme throughout the conference, dominating discussions and even prompting high-profile criticisms. For example, Christiana Figueres, former UN climate chief, wrote an open letter during the first week, asserting that the COP process had become “no longer fit for purpose.”

By the second week, questions about the presidency’s ability to guide negotiations effectively were widespread. As the host country, Azerbaijan was expected to lead efforts to foster consensus among governments and non-Party stakeholders, particularly on critical issues like the NCQG and draft texts. Yet, progress was slow, and negotiations stretched into Saturday, further fuelling doubts about the presidency’s capacity to align its leadership with COP’s overarching goals.

Post-COP

What surprised you the most? 

“One of the most exciting and surprising things about COP was how accessible everything felt. As someone who wasn’t there for more than just to communicate what was happening to students at COPCAS, it felt really incredible that we were given access to the negotiations and all the plenary sessions. I obviously knew this was going to be the case before we went, but it was only really sitting when in on these events did I realise how unique of an opportunity this was.” – Thea

“One of the most striking aspects for me of attending last year’s COP was the incredible diversity of attendees, showcasing the universal impact of climate change and the essential need for broad representation in climate discussions. Among the most inspiring aspects was the strong presence of young people and activists, whose energy and commitment highlighted the vital role of the next generation in driving meaningful climate action” – Juan 

What do we think of the COP process? 

Going to COP and sitting in on the negotiations made the enormity of ambition and geopolitical complexity of bilateral agreements evident. Countries – with vastly different agendas and core beliefs – coming around a table trying to agree on something is an absurdly ambitious arrangement. Reducing fossil fuel consumption is unlike any another problem we face; their presence is pervasive in all of our lives. Fossil fuels are a bedrock of wealth and power in our global political economy. Despite alternative energies booming, and 2024 confirmed as the warmest year on record, this makes fossil fuels hard for the world to walk away from at the speed we need to do so. 

Whilst COP can be critiqued for being slow and disappointing, there remains hope in the vision of these bilateral negotiations. Given the increase in conflict and geopolitical instability these past few years, I left COP with an appreciation for the fact that there is still a negotiating table.

However, attending COP also brought to light how important it is to have ambitious domestic policies. COP will never really be the space where radical or big change will happen; this is instead the space where countries are all brought onto the same page. I think we left with more conviction that local politics and policies are where these larger changes need to happen.

Picture 6, Powerful presentation by Enkhuun Byambadorji on Transforming Climate Narratives for Healthy. Picture 7, Organised protests by activists inside the Blue Zone.

Environments

What tips would you give to someone who is hoping to attend next year? 

  • Apply!! It’s an amazing opportunity both professionally and personally and it shouldn’t be missed. 
  • Wear comfortable yet formal attire. You will be walking around for most of the day but also meeting important and really cool people, so you definitely still want to look the part. 
  • Have business cards for networking 
  • Bring a power bank 
  • Practice your elevator pitch- in case you stumble across somebody interested in your research. 
  • Take lots of pictures!

Conclusion 

We wanted to end this blog by saying a massive thank you to the Walker Institute for their support in making this experience possible. Attending COP29 was a transformative journey that deepened our commitment to climate action and inspired us to continue advocating for a sustainable future.

Preparing for the assimilation of future ocean-current measurements

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By Laura Risley

Ocean data assimilation (DA) is vital. Firstly, it is essential to improving forecasts of ocean variables. Not only that, the interaction between the ocean and atmosphere is key to numerical weather prediction (NWP) as coupled ocean-atmosphere DA schemes are used operationally.  

At present, observations of the ocean currents are not assimilated operationally. This is all set to change, as satellites are being proposed to measure these ocean currents directly. Unfortunately, the operational DA systems are not yet equipped to handle these observations due to some of the assumptions made about the velocities. In my work, we propose the use of alternative velocity variables to prepare for these future ocean current measurements. These will reduce the number of assumptions made about the velocities and is expected to improve the NWP forecasts.

What is DA? 

DA combines observations and a numerical model to give a best estimate of the state of our system – which we call our analysis. This will lead to a better forecast. To quote my lunchtime seminar ‘Everything is better with DA!’. 

Our model state usually comes from a prior estimate which we refer to as the background. A key component of data assimilation is that the errors present in both sets of data are taken into consideration. These uncertainties are represented by covariance matrices. 

I am particularly interested in variational data assimilation, which formulates the DA problem into a least squares problem. Within variational data assimilation the analysis is performed with a set of variables that differ from the original model variables, called the control variables. After the analysis is found in this new control space, there is a transformation back to the model space. What is the purpose of this transformation? The control variables are chosen such that they can be assumed approximately uncorrelated, reducing the complexity of the data assimilation problem.

Velocity variables in the ocean 

My work is focused on the treatment of the velocities in NEMOVAR. This is the data assimilation software used by the NEMO ocean model, used operationally at the Met Office and ECMWF. In NEMOVAR the velocities are transformed to their unbalanced components, and these are then used as control variables. The unbalanced components of the velocities are highly correlated, therefore contradicting the assumption made about control variables. This would result in suboptimal assimilation of future surface current measurements – therefore we seek alternative velocity control variables. 

The alternative velocity control variables we propose for NEMOVAR are unbalanced streamfunction and velocity potential. This would involve transforming the current control variables, the unbalanced velocities, to these alternative variables using Helmholtz Theorem. This splits a velocity field into its nondivergent (streamfunction) and irrotational (velocity potential) parts. These parts have been suggested by Daley (1993) as more suitable control variables than the velocities themselves. 

Numerical Implications of alternative variables 

We have performed the transformation to these proposed control variables using the shallow water equations (SWEs) on a 𝛽-plane. To do so we discretised the variables on the Arakawa-C grid. The traditional placement of streamfunction on this grid causes issues with the boundary conditions. Therefore, Li et al. (2006) proposed placing streamfunction in the centre of the grid, as shown in Figure 1. This circumvents the need to impose explicit boundary conditions on streamfunction. However, using this grid configuration leads to numerical issues when transforming from the unbalanced velocities to unbalanced streamfunction and velocity potential. We have analysed these theoretically and here we show some numerical results.

Figure 1: The left figure shows the traditional Arakawa-C configuration (Lynch (1989), Watterson (2001)) whereby streamfunction is in the corner of each grid cell. The right figure shows the Arakawa-C configuration proposed by Li et al. (2006) where streamfunction is in the centre of the grid cell. The green shaded region represents land. 

Issue 1: The checkerboard effect 

The transformation from the unbalanced velocities to unbalanced streamfunction and velocity potential involves averaging derivatives, due to the location of streamfunction in the grid cell. This process causes a checkerboard effect – whereby we have numerical noise entering the variable fields due to a loss of information. This is clear to see numerically using the SWEs. We use the shallow water model to generate a velocity field. This is transformed to its unbalanced components and then to unbalanced streamfunction and velocity potential. Using Helmholtz Theorem, the unbalanced velocities are reconstructed. Figure 2 shows the checkboard effect clearly in the velocity error.

Figure 2: The difference between the original ageostrophic velocity increments, calculated using the SWEs, and the reconstructed ageostrophic velocity increments. These are reconstructed using Helmholtz Theorem, from the ageostrophic streamfunction and velocity potential increments. On the left we have the zonal velocity increment error and on the right the meridional velocity increment error. 

Issue 2: Challenges in satisfying the Helmholtz Theorem 

Helmholtz theorem splits the velocity into its nondivergent and irrotational components. We discovered that although streamfunction should be nondivergent and velocity potential should be irrotational, this is not the case at the boundaries, as can be seen in figure 3. This implies the proposed control variables are able to influence each other on the boundary. This would lead to them being strongly coupled and therefore correlated near the boundaries. This directly conflicts the assumption made that our control variables are uncorrelated. 

Figure 3: Issues with Helmholtz Theorem near the boundaries. The left shows the divergence of the velocity field generated by streamfunction. The right shows the vorticity of the velocity field generated by velocity potential. 

Overall, in my work we propose the use of alternative velocity control variables in NEMOVAR, namely unbalanced streamfunction and velocity potential. The use of these variables however leads to several numerical issues that we have identified and discussed. A paper on this work is in preparation, where we discuss some of the potential solutions. Our next work will further this investigation to a more complex domain and assess our proposed control variables in assimilation experiments. 

References: 

Daley, R. (1993) Atmospheric data analysis. No. 2. Cambridge university press. 

Li, Z., Chao, Y. and McWilliams, J. C. (2006) Computation of the streamfunction and velocity potential for limited and irregular domains. Monthly weather review, 134, 3384–3394. 

Lynch, P. (1989) Partitioning the wind in a limited domain. Monthly weather review, 117, 1492–1500. 

Watterson, I. (2001) Decomposition of global ocean currents using a simple iterative method. Journal of Atmospheric and Oceanic Technology, 18, 691–703

Nature vs Nurture in Convective-Scale Ensemble Spread

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By Adam Gainford

Quantifying the uncertainty of upcoming weather is now a common procedure thanks to the widespread use of ensemble forecasting. Unlike deterministic forecasts, which show only a single realisation of the upcoming weather, ensemble forecasts predict a range of possible scenarios given the current knowledge of the atmospheric state. This approach allows forecasters to estimate the likelihood of upcoming weather events by simply looking at the frequency of event occurrence within all ensemble members. Additionally, by sampling a greater range of events, this approach highlights plausible worst-case scenarios, which is of particular interest for forecasts of extreme weather. Understanding the realistic range of outcomes is crucial for forecasters to provide informed guidance, and helps us avoid the kind of costly and embarrassing mistakes that are commonly associated with the forecast of “The Great Storm of 1987”*.

To have trust that our ensembles are providing an appropriate range of outputs, we need some method of verifying ensemble spread. We do this by calculating the spread-skill relationship, which essentially just compares the difference between member values to the skill of the ensemble as a whole. If the spread-skill relationship is appropriate, spread and skill scores should be comparable when averaged over many forecasts. If the ensemble shows a tendency to produce larger spread scores than skill scores, there is too much spread and not enough confidence in the ensemble given its accuracy: i.e., the ensemble is overspread. Conversely, if spread scores are smaller than skill scores, the ensemble is too confident and is underspread. 

Figure 1: Postage stamp plots showing three-hourly precipitation accumulation valid for 2023-07-08 09Z at leadtime T+15 h. There is reasonable spread within both the frontal rain band effecting areas of SW England and Wales, and the convective features ahead of this front.

My PhD work has focussed on understanding the spread-skill relationship in convective-scale ensembles. Unlike medium range ensembles that are used to estimate the uncertainty of synoptic-scale weather at daily-to-weekly leadtimes, convective-scale ensembles quantify the uncertainty of smaller-scale weather at hourly-to-daily leadtimes. To do this, convective-scale ensembles must be run at higher resolutions than medium-range ensembles, with grid spacings smaller than 4 km. These higher resolutions allows the ensemble to explicitly represent convective storms, which has been repeatedly shown to produce more accurate forecasts compared coarser-resolution forecasts that must instead rely on convective parametrizations. However, running models at such high resolutions is too computationally expensive to be done over the entire Earth, so they are typically nested inside a lower-resolution “parent” ensemble which provides initial and boundary conditions. Despite this, researchers often report that convective-scale ensembles are underspread, and the range of outputs is too narrow given the ensemble skill. This is corroborated by operational forecasters, who report that the ensemble members often stay too close to the unperturbed control member. 

To provide the necessary context for understanding the underspread problem, many studies have examined the different sources and behaviours of spread within convective-scale ensembles. In general, spread can be produced through three different mechanisms: firstly, through differences in each member’s initial conditions; secondly, through differences in the lateral boundary conditions provided to each member; and thirdly, through the different internal processes used to evolve the state. This last source is really the combination of many different model-specific factors (e.g., stochastic physics schemes, random parameter schemes etc.), but for our purposes this represents the ways in which the convective-scale ensemble produces its own spread. This contrasts with the other two sources of spread, which are directly linked to the spread of the parent ensemble.  

The evolution of each of these three spread sources is shown in Fig. 2. At the start of a forecast, the ensemble spread is entirely dictated by differences in the initial conditions provided to each ensemble member. As we integrate forward in time, though, this initial information is removed from the domain by the prevailing winds and replaced by information arriving through the boundaries. At the same time, internal model processes start spinning up additional detail within each ensemble member. For a UK-sized domain, it takes roughly 12 hours for the initial information to have fully left the domain, though this is of course highly dependent on the strength of the prevailing winds. After this time, spread in the ensemble is partitioned between internal processes and boundary condition differences.  

Figure 2: Attribution of spread within a convective-scale ensemble by leadtime. 

While the exact partitioning in this schematic shouldn’t be taken too literally, it does highlight the important role that the parent ensemble plays in determining spread in the child ensemble. Most studies which try to improve spread target the child ensemble itself, but this schematic shows that these improvements may have quite a limited impact. After all, if the spread of information arriving from the parent ensemble is not sufficient, this may mask or even overwhelm any improvements introduced to the child ensemble.  

However, there are situations where we might expect internal processes to show a more dominant spread contribution. Forecasts of convective storms, for instance, typically show larger spread than forecasts of other types of weather, and are driven more by local processes than larger-scale, external factors.

This is where our “nature” and “nurture” analogy becomes relevant. Given the similarities of this relationship to the common parent-child theory in behavioural psychology, we thought it would be a fun and useful gimmick to also use this terminology here. So, in the “nature” scenario, each child member shows large similarity to the corresponding parent member, which is due to the dominating influence of genetics (initial and boundary conditions). Conversely, in the “nurture” scenario, spread in the child ensemble is produced more by its response to the environment (internal processes), and as such, we see larger differences between each parent-child pair.  

While the nature and nurture attribution is well understood for most variables, few studies have examined the parent-child relationship for precipitation patterns, which are an important output for guidance production and require the use of neighbourhood-based metrics for robust evaluation. Given that this is already quite a long post, I won’t go into too much detail of our results looking at nature vs nurture for precipitation patterns. Instead, I will give a quick summary of what we found: 

  • Nurture provides a larger than average influence on the spread in two situations: during short leadtimes**, and when forecasting convective events driven by continental plume setups. 
  • In the nurture scenarios, spread is consistently larger in the child ensemble than the parent ensemble. 
  • In contrast to the nurture scenarios, nature provides larger than average spread at medium-to-long leadtimes and under mobile regimes, which is consistent with the boundary arguments mentioned previously. 
  • Spread is very similar between the child and parent ensembles in the nurture scenarios.  

If you would like to read more about this work, we will be submitting a draft to QJRMS very soon.  

To conclude, if we want to improve the spread of precipitation patterns in convective-scale ensembles, we should direct more attention to the role of the driving ensemble. It is clear that the exact nesting configuration used has a strong impact on the quality of the spread. This factor is especially important to consider given recent experiments with hectometric-scale ensembles which are themselves nested within convective-scale ensembles. With multiple layers of nesting, the coupling between each ensemble layer is likely to be complex. Our study provides the foundation for investigating these complex interactions in more detail. 

* This storm was actually well forecast by the Met Office. The infamous Michael Fish weather update in which he said there was no hurricane on the way was referring to a different system which indeed did not impact the UK. Nevertheless, this remains a good example of the importance of accurately predicting (and communicating) extreme weather events.  

** While this appears to be inconsistent with Fig. 2, the ensemble we used does not solely take initial conditions from the driving ensemble. Instead, the ensemble uses a separate, high-resolution data assimilation scheme to the parent ensemble. Each ensemble is produced in a way which makes the influence of the data assimilation more influential to the spread than the initial condition perturbations. 

The 5th ICTP Summer School on Modelling of Climate Dynamics: Convection and Clouds, and Conference on Convective Organisation (WCO4)

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By Juan Garcia Valencia

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!

Overall, this summer school far surpassed my expectations. I wholeheartedly recommend attending a summer school if given the chance. I learned immensely from the lectures, group work, conversations with professors and students, and presenting my work. I’ve returned with a wealth of ideas to explore in my research, new skills, and new friends working in this field.

Starting Your PhD Journey: Tips for Success

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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!”. 

From the department’s PhDs students to you! 

Written by Juan Garcia Valencia 

Met Ball 2024!

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Sarah Watson – s.r.watson@pgr.reading.ac.uk

Thea Stevens – thea.stevens@pgr.reading.ac.uk

Isabelle Gorst – i.r.gorst@pgr.reading.ac.uk

Another year, another Met Ball!

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.

The Mystery of Coarse Dust Transport in Observations and Models​

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Natalie Ratcliffe – n.ratcliffe@pgr.reading.ac.uk

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:

  1. The model underestimates coarse mass at emission and the underestimation is exacerbated with westwards transport.
  2. 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.
  3. 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 importance of anticyclonic synoptic eddies for atmospheric block persistence and forecasts

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Charlie Suitters – c.c.suitters@pgr.reading.ac.uk

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.