Estimating the Effects of Vertical Wind Shear on Orographic Gravity Wave Drag

Orographic gravity waves occur when air flows over mountains in stably stratified conditions. The flow of air creates a pressure imbalance across the mountain, so a force is exerted on the mountain in the same direction as the flow. An equal and opposite force is exerted back on the atmosphere, and this is gravity wave drag (GWD).

GWD must be parametrized in Global Circulation Models (GCMs), as it is important for large-scale flow. The first parametrization was formulated by Palmer et al. (1986) to reduce a systematic westerly bias. The current parametrization was formulated by Lott and Miller (1997) and partitions the calculation into 2 parts (see figure 1):

  1. The mountain waves. This is calculated by averaging the wind, Brunt-Väisälä frequency and fluid density in a layer between 1 and 2 standard deviations of the subgrid-scale orography above the mean orography.
  2. The blocked flow. This is based on an interpretation of the non-dimensional mountain height.
Fig 1
Figure from Lott and Miller (1997).

The parametrization does not include the effects of wind shear. Wind shear is a change in the wind with height and it alters the vertical wave length of gravity waves and so alters the drag. It has been shown (Teixeira et al., 2004; Teixeira and Miranda, 2006) that a uniform shear profile (i.e. a change in the magnitude of the wind with height) decreases the drag whereas a profile in which the wind turns with height increases the drag. This effect was seen by Miranda et al. (2009) to have the greatest impact over Antarctica, where drag enhancement was seen to occur all year with a peak of ~50% during JJA. Figure 2 shows this.

Fig 2
Figure 2: Annual mean linear GWD stress (1992-2001). Vectors show the surface stress with shear. Shading indicates the anomaly of the modulus of the surface stress due to shear. Computed from ERA-40 data. Taken from Miranda et al. (2009).

The aim of this work is to test the impact of the inclusion of shear effects on the parametrization. The first stage of this is to test the sensitivity of the shear correction to the height in the atmosphere at which the necessary derivatives are approximated. We carry out calculations using 2 different reference heights:

  1. The top of the boundary layer (BLH). This allows us to avoid the effects of boundary layer turbulence, which are not important in this case as they are unrelated to the dynamics of mountain waves.
  2. The middle of the layer between 1 and 2 standard deviations of the sub-grid scale orography (SDH). This is the nominal height used in previous studies and in the parametrization.

All figures shown below focus on Antarctica and are averaged over all JJAs for the decade 2006-2015. We are interested in Antarctica and the JJA season for the reasons highlighted above. All calculations are carried out using ERA-Interim reanalysis data.

We first consider the enhancement assuming axisymmetric orography. The advantage of this is that it considerably simplifies the correction due to terms related to the anisotropy becoming constant (see Teixeira et al, 2004). Figure 3 shows this correction calculated using both reference heights. We can see that the enhancement is greater when the SDH is used.

Fig 3
Figure 3: Drag enhancement over Antarctica with shear corrections computed at the BLH (left) and SDH (right), during JJAs for the decade 2006-2015, using axisymmetric orography.

We now consider the enhancement using mountains with an elliptical horizontal cross-section. This is how the real orography is represented in the parametrization. Again, we see that the enhancement is greater when the SDH is used (figure 4).

Fig 4
Figure 4: Drag enhancement (left) and enhancement of drag stress (in Pa) (right) over Antarctica with shear corrections calculated at the BLH (top) and SDH (bottom), during JJAs for the decade 2006-2015, using orography with an elliptical horizontal cross-section.

It is interesting to note that at both heights the enhancement is greater when axisymmetric orography is used. This occurs because, in the case of elliptical mountains, the shear vector is predominantly aligned along the orography, resulting is weaker enhancement (see figure 5).

Fig 5
Figure 5: Histograms of the orientation of the shear vector relative to the short axis of the orography over Antarctica for JJAs during the decade 2006-2015, using the BLH (left) and SDH (right).

We also investigate the fraction of times at which the terms related to wind profile curvature (i.e. those containing second derivatives) dominate the drag correction. This tells us the fraction of time for which curvature matters for the drag. We see that second derivatives dominate over much of Antarctica for a high proportion of the time (see figure 6).

Fig 6
Figure 6: Fraction of the time at which terms with second derivatives dominate the drag correction relative to terms with first derivatives over orography with an elliptical horizontal cross-section, for JJAs during the decade 2006-2015, calculated using the BLH (left) and SDH (right).

In summary, the main findings are as follows:

  • The drag is quantitatively robust to changes in calculation height, with the geographical distribution, seasonality and sign essentially the same.
  • The drag is considerably enhanced when the SDH is used rather than the BLH.
  • Investigation of the relative magnitudes of terms containing first and second derivatives in the drag correction indicates that second derivatives (i.e. curvature terms) dominate in a large proportion of Antarctica for a large fraction of time. This leads to an average enhancement of the drag which is larger over shorter time intervals.
  • Use of an axisymmetric orography profile causes considerable overestimation of the shear effects. This is due to the shear vector being predominantly aligned along the mountains in the case of the orography with an elliptical horizontal cross-section.

These results highlight the need to ‘tune’ the calculation by identifying the optimum height in the atmosphere at which to approximate the derivatives. This work is ongoing. We expect the optimum height to be that at which the shear has the greatest impact on the surface drag.

References:

Lott F. and Miller M., 1997, A new subgrid-scale orographic drag parametrization: Its formulation and testing, Quart. J. Roy. Meteor. Soc., 123: 101–127.

Miranda P., Martins J. and Teixeira M., 2009, Assessing wind profile effects on the global atmospheric torque, Quart. J. Roy. Meteor. Soc., 135: 807–814.

Teixeira M. and Miranda P., 2006, A linear model of gravity wave drag for hydrostatic sheared flow over elliptical mountains, Quart. J. Roy. Meteor. Soc., 132: 2439–2458.

Teixeira M., Miranda P. and Valente M., 2004, An analytical model of mountain wave drag for wind profiles with shear and curvature, J. Atmos. Sci., 61: 1040–1054.

Visiting Scientist 2018

With thanks to Kaja Milczewska

Every year the PhD students in the Meteorology Department invite a distinguished scientist to spend a few days with us. This year, the students voted for the Visiting Scientist to be Prof. Olivia Romppainnen-Martius, who came to the Department from 4th-7th June 2018.

Prof. Romppainen-Martius is based at the University of Bern, in Switzerland, as an Associate Professor researching climate impacts.

Olivia’s research interests broadly covers mid-latitude atmospheric dynamics, with topics from how blocking events are precursors Sudden Stratospheric Warming events, to more impact based work on heavy Alpine precipitation and extreme hail in and around Switzerland. Her main research areas can be summarised as dynamics of short-term climate variation, forecasting and statistics of high-impact weather events and mid-latitude weather systems. More about her research and publications can be found here.

As is usual for the start of our distinguished visitor’s stay, Prof. Romppainen-Martius’s visit began with an introduction from Prof. Sue Gray during the coffee reception. This was immediately followed by a special seminar, titled “Recent hail research in Switzerland – the challenges and delights of complex orography and crowd-sourced data”. Her talk covered various probabilistic measures for predicting hail in the mountainous region that is Switzerland and how the climatology of these identified events is strongly linked with these mountainous areas. Verification of these predictions has recently been achieved through observer reports via the MeteoSwiss app, where observers record the time, location, and size of the hail they have observed.

The day was rounded off with a social at Zero Degrees, with Olivia and many PhD students engaging in fruitful conversation over pizza and beer.

After a busy first day, the second day of her visit included individual meetings with both research staff and students, and attending the Mesoscale and HHH (Hoskins-Half-Hour) research groups. On Wednesday 5th July, some PhD students presented their research to Olivia to showcase the breadth of topics covered in the Meteorology department. Interestingly, one of the talks ‘reliably’ informed us that Arctic sea-ice melting meant it was now possible to go on holiday cruises to see penguins. Clearly these penguins are on holiday too…

Slide1

At the weekly PhD Group meeting, Prof. Romppainen-Martius gave some useful advice on careers in academic research and the pathway to her current position – which of course includes lots of skiing. Additionally, she advertised some post-doctoral funding opportunities in Switzerland and Germany, which was sure to encourage the keen skiers in the crowd. This was an engaging open discussion about the realities of research life, and attendance was made all the better by biscuits from the group leaders Beth and Liam.

On the last day of her visit (Thursday 8th June), Olivia gave her second departmental seminar titled “Periods of recurrent synoptic-scale Rossby waves and associated persistent moderate temperature extremes”. The seminar was followed by a well-attended leaving reception, which concluded Olivia’s visit to our department. The students prepared a photo frame and other England themed items as a gift, to thank our distinguished scientist for accepting the invitation to spend an inspiring week with us.  Unfortunately, Olivia could not stay for the ‘world-renowned’ annual Met BBQ and Barn Dance on the Friday, but nonetheless we hope that she enjoyed her visit as much as we did!

Olivia

Top websites for weather enthusiasts!

If you’re searching for some weather-related procrastination, then look no further – we’ve got just what you need! Here’s our top picks for your coffee break-browsing:

  • Want a cool animated globe that shows you wind, temperature and aerosols, amongst other things? Null School is for you!

nullschool

  • Severe Weather Europe has photos and videos of awesome hailstorms, supercells and more.
  • If you’re wanting wind maps – then Windy.com is the place to go.

windy

  • Space weather more your thing? Then help with some research and find Solar Storms. Read more about the science in Shannon’s blog.
  • If you’ve been following all the recent thunderstorms, then check out the locations of all the lightning, updated in near real-time at Blitzortung.

lightning

  • The Met Office website has forecasts and pollen counts, but also cool things like podcasts about the weather.
  • Real-time satellite imagery is available at sat24 for the UK and Europe.

Sat24

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  • For articles on climate change and environmental science, Carbon Brief  is the answer.

 

Hierarchies of Models

With thanks to Inna Polichtchouk.

General circulation models (GCMs) of varying complexity are used in atmospheric and oceanic sciences to study different atmospheric processes and to simulate response of climate to climate change and other forcings.

However, Held (2005) warned the climate community that the gap between understanding and simulating atmospheric and oceanic processes is becoming wider. He stressed the use of model hierarchies for improved understanding of the atmosphere and oceans (Fig. 1). Often at the bottom of the hierarchy lie the well-understood, idealized, one- or two-layer models.  In the middle of the hierarchy lie multi-layer models, which omit certain processes such as land-ocean-atmosphere interactions or moist physics. And finally, at the top of the hierarchy lie fully coupled atmosphere-ocean general circulation models that are used for climate projections. Such model hierarchies are already well developed in other sciences (Held 2005), such as molecular biology, where studying less complex animals (e.g. mice) infers something about the more complex humans (through evolution).

Model_hierarchies_Shaw_etal2016
Figure 1: Model hierarchy of midlatitude atmosphere (as used for studying storm tracks). The simplest models are on the left and the most complex models are on the right. Bottom panels show eddy kinetic energy (EKE, contours) and precipitation (shading) with increase in model hierarchy (left-to-right): No precipitation in a dry core model (left), zonally homogeneous EKE and precipitation in an aquaplanet model (middle), and zonally varying EKE and precipitation in the most complex model (right). Source: Shaw et al. (2016), Fig. B2.

Model hierarchies have now become an important research tool to further our understanding of the climate system [see, e.g., Polvani et al. (2017), Jeevanjee et al. (2017), Vallis et al. (2018)]. This approach allows us to delineate most important processes responsible for circulation response to climate change (e.g., mid-latitude storm track shift, widening of tropical belt etc.), to perform hypothesis testing, and to assess robustness of results in different configurations.

In my PhD, I have extensively used the model hierarchies concept to understand mid-latitude tropospheric dynamics (Fig. 1). One-layer barotropic and two-layer quasi-geostrophic models are often used as a first step to understand large-scale dynamics and to establish the importance of barotropic and baroclinic processes (also discussed in my previous blog post). Subsequently, more realistic “dry” non-linear multi-layer models with simple treatment for boundary layer and radiation [the so-called “Held & Suarez” setup, first introduced in Held and Suarez (1994)] can be used to study zonally homogeneous mid-latitude dynamics without complicating the setup with physical parametrisations (e.g. moist processes), or the full range of ocean-land-ice-atmosphere interactions. For example, I have successfully used the Held & Suarez setup to test the robustness of the annular mode variability (see my previous blog post) to different model climatologies (Boljka et al., 2018). I found that baroclinic annular mode timescale and its link to the barotropic annular mode is sensitive to model climatology. This can have an impact on climate variability in a changing climate.

Additional complexity can be introduced to the multi-layer dry models by adding moist processes and physical parametrisations in the so-called “aquaplanet” setup [e.g. Neale and Hoskins (2000)]. The aquaplanet setup allows us to elucidate the role of moist processes and parametrisations on zonally homogeneous dynamics. For example, mid-latitude cyclones tend to be stronger in moist atmospheres.

To study effects of zonal asymmetries on the mid-latitude dynamics, localized heating or topography can be further introduced to the aquaplanet and Held & Suarez setup to force large-scale stationary waves, reproducing the south-west to north-east tilts in the Northern Hemisphere storm tracks (bottom left panel in Fig. 1). This setup has helped me elucidate the differences between the zonally homogeneous and zonally inhomogeneous atmospheres, where the planetary scale (stationary) waves and their interplay with the synoptic eddies (cyclones) become increasingly important for the mid-latitude storm track dynamics and variability on different temporal and spatial scales.

Even further complexity can be achieved by coupling atmospheric models to the dynamic ocean and/or land and ice models (coupled atmosphere-ocean or atmosphere only GCMs, in Fig. 1), all of which bring the model closer to reality. However, interpreting results from such complex models is very difficult without having first studied the hierarchy of models as too many processes are acting simultaneously in such fully coupled models.  Further insights can also be gained by improving the theoretical (mathematical) understanding of the atmospheric processes by using a similar hierarchical approach [see e.g. Boljka and Shepherd (2018)].

References:

Boljka, L. and T.G. Shepherd, 2018: A multiscale asymptotic theory of extratropical wave–mean flow interaction. J. Atmos. Sci., 75, 1833–1852, https://doi.org/10.1175/JAS-D-17-0307.1 .

Boljka, L., T.G. Shepherd, and M. Blackburn, 2018: On the boupling between barotropic and baroclinic modes of extratropical atmospheric variability. J. Atmos. Sci., 75, 1853–1871, https://doi.org/10.1175/JAS-D-17-0370.1 .

Held, I. M., 2005: The gap between simulation and understanding in climate modeling. Bull. Am. Meteorol. Soc., 86, 1609 – 1614.

Held, I. M. and M. J. Suarez, 1994: A proposal for the intercomparison of the dynamical cores of atmospheric general circulation models. Bull. Amer. Meteor. Soc., 75, 1825–1830.

Jeevanjee, N., Hassanzadeh, P., Hill, S., Sheshadri, A., 2017: A perspective on climate model hierarchies. JAMES9, 1760-1771.

Neale, R. B., and B. J. Hoskins, 2000: A standard test for AGCMs including their physical parametrizations: I: the proposal. Atmosph. Sci. Lett., 1, 101–107.

Polvani, L. M., A. C. Clement, B. Medeiros, J. J. Benedict, and I. R. Simpson (2017), When less is more: Opening the door to simpler climate models. EOS, 98.

Shaw, T. A., M. Baldwin, E. A. Barnes, R. Caballero, C. I. Garfinkel, Y-T. Hwang, C. Li, P. A. O’Gorman, G. Riviere, I R. Simpson, and A. Voigt, 2016: Storm track processes and the opposing influences of climate change. Nature Geoscience, 9, 656–664.

Vallis, G. K., Colyer, G., Geen, R., Gerber, E., Jucker, M., Maher, P., Paterson, A., Pietschnig, M., Penn, J., and Thomson, S. I., 2018: Isca, v1.0: a framework for the global modelling of the atmospheres of Earth and other planets at varying levels of complexity. Geosci. Model Dev., 11, 843-859.

Polar Prediction School 2018

From 17th-27th April three Reading students trekked to the to the far north to attend the APECS Polar Prediction School at the Abisko Research Station. The aims of this course were to provide a general education in the Polar climates, from ocean and ice to atmosphere to help the participants understand the issues of prediction in polar regions and contribute to the current academic push to improve our understanding and forecasting skill of these regions.

 

 

 

Abisko research station is situated 68°N on the banks of lake Torneträsk, the sixth longest lake in Sweden. Frozen from approximately December to June the lake provided a great base for experiencing taking observations of the poles. On the first full day we put up a met mast which we then used data from to explore boundary layer turbulence. Drilling the holes for the guy ropes to find the ice was still a metre thick was rather reassuring after people had stripped down to t-shirts in the sun.

Throughout the week we also launched multiple radiosondes which was another excellent excuse to spend some time drinking in the scenery. This caused a stir when there was an ice-fishing competition on the lake, so several local school children ended up assisting with the launch.

 

 

 

 

After a week packed full of lectures, from sea-ice dynamics to observations from an ice breaker, on the Sunday in the middle of the school we had the day off. Most people took this as a chance to explore a bit further afield. A few of us rented snowshoes which turned out to be an excellent idea as there were plenty of places where the snow was still a meter thick. However difficult the terrain the scenery was 100% worth it, and the kanelbullar in our packed lunches certainly helped keep us going.

 

 

This was followed by another week of lectures, covering boundary layers, clouds and much more. We also spent time working on our science communication, both to other scientists and the general public. This culminated with everyone giving a 1 minute “Frostbyte” presentation of their work.

The course was a great chance to learn about the polar climate more broadly which has been helpful in putting my PhD work in context. It’s also great to be able to say I have been to the Arctic when people ask in the future!

PPS2018_group

A big thank you to APECS, APPLICATE and the Polar Prediction Project for supporting the course as well as all the staff who gave their time to speak. More details about the course can be found here.

The Test MIST Special Meeting, Southampton, March 26-28th, 2018

Email: t.bloch@pgr.reading.ac.uk

MIST Logo_small_0
In its own words MIST is “the community of Magnetosphere, Ionosphere and Solar-Terrestrial researchers working in the United Kingdom. We represent the interests of MIST scientists and hold meetings to showcase MIST science twice a year”.

It is a group which focuses on Space Science, both theoretically and empirically, covering everything from Solar physics [see Shannon’s work] to Planetary Atmospheres, incorporating data from many space-missions, ground-based measurements (for Earth) and models which underpin our current understanding.

MIST holds two meetings a year: Autumn MIST, a one-day meeting; and Spring MIST, a longer 2.5 day meeting (unfortunately these names lead to a lot of pictures of dewy mornings when using Google…).

Each Spring MIST meeting is given a name based on a local geographical feature, this year we were at Southampton University near the River Test. The “Special” is to honour MIST’s 50th anniversary. Less obvious to me was why people kept laughing when the name was mentioned. The only clue was “Any similarity to low frequency emissions on 198 kHz is purely coincidental”. If you like cricket, this may be obvious… but for the rest of us, it’s a reference to the cricket ‘Test Match Special’ radio broadcast. Good thing we’re scientists and not comedians.

This year, it’s safe to say that the Reading delegation took over the meeting. With 9 of us attending (6 presenting!) the Reading Space group was definitely very well represented. Mike Lockwood gave an excellent speech at the conference dinner on the importance of MIST to the community and how he has seen it evolve over the years. See below to read about what everyone presented.

The bi-annual meetings are excellent for keeping up with the current state of the UK’s space-science research as well as maintaining a more informal atmosphere due to the small nature of the community (there were around 60 people at Spring MIST ’18). I find that this all comes together to form a very inviting platform for those of us just starting out in research.

SpringMist18
This year’s spring MIST group photo

Shannon Jones presented a poster, “Solar Stormwatch: Using citizen science to investigate CME distortions”.

Coronal mass ejections (CMEs) are the main drivers of hazardous space weather. We are using a novel dataset, created with the help of many citizen scientists through the Solar Stormwatch project, to investigate the effect of the solar wind on these storms. Participants track the shape of CMEs in images from the heliospheric imagers on board the twin STEREO spacecraft, providing an unprecedented level of detail (Barnard et al., 2017). We intend to use this data to extend the work of Savani et al. (2010), looking at how CMEs are distorted under varying solar wind conditions. 


Sarah Bentley gave a talk, “A solar wind-parameterised, probabilistic model of ground-measured ULF waves in Earth’s magnetosphere”.

Large scale ultra-low frequency (1-15 mHz) plasma waves in the magnetosphere are involved in the energisation and transport of radiation belt electrons, a hazardous environment for the satellites underpinning our everyday life. We can construct a statistical model predicting when and where we see these waves in the magnetosphere solely using causally correlated solar wind properties [Bentley et al., 2018]. Unlike existing models, this can be used probabilistically, so that instead of outputting a single value for the power in these waves at each location we can use a probability distribution. Sampling from these distributions turns out to be the best way of predicting total power over a longer event while using the mean values is the best way of predicting the power in the oncoming hour. Using these predicted power values we will eventually be able to predict the effect of these waves on radiation belt particles more precisely over a larger range of the magnetosphere.

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Oliver Allanson gave a talk, “Particle-in-cell models of diffusion due to whistler mode waves: comparing quasi-monochromatic to broadband waves”.

The momentum space diffusion of electrons due to whistler mode waves is a cornerstone of our current theoretical framework of acceleration (and loss) in Earth’s outer radiation belt. The quasilinear theory of wave-particle interactions provides us with a tractable method to estimate the amount of momentum space diffusion that occurs for a range of wave and ambient plasma conditions. Underlying quasilinear theory is the assumption that waves are broadband, incoherent, and of small amplitude. The right-handed whistler mode manifests in different ways throughout the outer belt: structured chorus, incoherent hiss, near monochromatic transmitter waves, lightning generated whistlers, and large amplitude nonlinear wave packets. It is possible that incoherent hiss is the only example that satisfies all of the formal requirements of quasilinear theory. We use particle-in-cell simulations (the EPOCH code) to model different cases, i.e. from near monochromatic to unstructured broadband, and from small amplitude to large. Through the use of various diagnostics, we explore whether the quasilinear diffusion description is a reasonable description of each case.


Clare Watt gave a talk, “The origin of the whistler-mode spectral “gap” at half electron gyro-frequency in the magnetosphere”.

Near-Earth space contains high-energy electrons, high-energy protons, and a host of different electromagnetic waves that exist over a wide-range of frequencies. Because of the Earth’s magnetic field, and the presence of the high-energy charged particles, the electromagnetic waves do not behave exactly like light in a vacuum, rather they are guided along and across the magnetic field, and interact with the electrons and protons to transport energy and momentum throughout the system. One type of waves are known as whistler-mode waves. They have frequencies of roughly 100-1000Hz and interact with the high-energy electrons in the outer radiation belt. These interactions are thought to be responsible for the energisation of the outer radiation belt. But the waves themselves have many fascinating and mysterious features. Decades of in-situ observations of the waves reveal a persistent frequency gap. Many theories have been put forward to explain the gap, but most rely upon special circumstances that are not guaranteed throughout space. Our recent physics-based simulations reveal a ubiquitous process that can explain the frequency gap, and what’s more, we have identified an independent observational test for the process. Our simulations revealed this new process because advances in computing and simulations allow us to use higher resolution than before – previous work had missed the important fine details of the interaction. At MIST, we reported not only on our simulation results, but also on the recently-published evidence from NASA Van Allen Probes and NASA Magnetosphere Multi-Scale that confirms our independent observational test.


Mike Lockwood gave a talk, “A homogenous aa index”.

Originally complied for 1868-1968 by Mayaud, and extended to the present day by ISGI (International Service for Geomagnetic Indices), the aa geomagnetic index has been a vital resource for studying space climate change over the past 150 years. However, there have been debates about the intercalibration of data from the different measuring stations. In addition, the effect of drift in geomagnetic latitude of the stations, caused by the secular change in the Earth’s field, has not been allowed for. As a result, the components of the aa index for the southern and northern hemispheres have drifted apart. We have corrected for these effects and also for the time-of-day and time-of-year sensitivity of the stations. The resulting indices for the northern and southern hemisphere now agree very closely and the aa index for all years shows a time-of-day and time-of-year “equinoctial” response pattern, as seen in the am index which has been compiled by ISGI from a much larger network of stations since 1959.


Chris Scott gave a talk, “The ionospheric response to intense bombing during World War II”.

There is an increasing number of case studies that demonstrate that the ionosphere can be perturbed from below. The explosion of the chemical plant at Flixborough in 1974 was sufficiently energetic that its effects were detected in the ionosphere (Jones and Spracklen, 1974), lightning has been shown to enhance ionospheric sporadic-E layer electron concentrations (Davis and Johnson, 2005) and there is much interest in the impact of earthquakes on the ionosphere (e.g. Astafyeva et al, 2013). The influence of the troposphere was also cited as the source of unknown variability in modelling work by Rishbeth and Muller-Wodarg (2006). Throughout the second-world war, routine measurements of the Earth’s ionosphere were made at Slough, UK. In this study we will use these data to investigate the impact on theionosphere of various bombing campaigns in order to determine the threshold above which such explosions can be detected in the upper atmosphere.

Presenting in Ponte Vedra, Florida – 33rd Conference on Hurricanes and Tropical Meteorology

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

You’ve watched many speak before you. You’ve practised your presentation repeatedly. You’ve spent hours, days, months, and sometimes years, understanding your scientific work. Yet, no matter the audience’s size or specialism, the nerves always creep in before a presentation. It’s especially no different at your first international conference!

IMG_20180420_133234

Between the 16th and 20th April 2018, me, Jonathan Beverley and Bethan Harris were fortunate enough to attend and present at the American Meteorological Society 33rd Conference on Hurricanes and Tropical Meteorology in Ponte Vedra, Florida. For each of us, our first international conference!

Being a regular user of Instagram through the conference, especially the Instagram Story function, I was regularly asked by my friends back home, “what actually happens at a scientific conference”? Very simple really – scientists from around the world, from different departments, universities, and countries, come to share their work, in the hope of progressing the scientific field, to learn from one another, and network with future collaborators. For myself, it was an opportunity to present recently submitted work and to discuss with fellow researchers on the important questions that should be asked during the rest of my PhD. One outcome of my talk for example, was a two-hour discussion with a graduate student from Caltech, which not only improved my own work, but also helped me understand other research in global circulation.

Recordings of the presentations given by University of Reading PhD students can be found at:

Alongside presenting my own work, I had the opportunity to listen and learn from other scientific researchers. The conference had oral and poster presentations from a variety of tropical meteorology subject areas including hurricanes, global circulation, sub-seasonal forecasting, monsoons and Madden-Julian Oscillation. One of the things that I most enjoy at conferences is to hear from leading academics give an overview of certain topic or issue. For example, Kerry Emanuel spoke on the inferences that can be made from simple models of tropical convection. Through applying four key principles of tropical meteorology including the weak temperature gradient approximation and conservation of free-tropospheric moist static energy, we can understand tropical meteorology processes including the Intertropical Convergence Zone, Walker circulation and observed temperature and humidity profiles.

Of course, if you’re going to fly to the other side of the pond, you must take advantage of being in the USA. We saw a SPACEX rocket launch, (just at a distance of 150 miles away,) experienced travelling through a squall line, visited the launch sites of NASA’s first space programs, and explored the sunny streets of Miami. It was a great privilege to have the opportunity to present and attend the AMS 33rd Conference on Hurricanes and Tropical Meteorology, and I am hugely thankful to NERC SCENARIO DTP and the Department of Meteorology for funding my work and travel.