AS
Atmospheric Sciences

atmospheric science

A simple model of convection to study the atmospheric surface layer

A simple model of convection to study the atmospheric surface layer

Since being immortalised in Hollywood film, “the butterfly effect” has become a commonplace concept, despite its obscure origins. Its name derives from an object known as the Lorenz attractor, which has the form of a pair of butterfly wings (Fig. 1). It is a portrait of chaos, the underlying principle hindering long-term weather prediction: just a small change in initial conditions leads to vastly different outcomes in the long run.


Figure 1: The Lorenz attractor.

The three-equation system that gives rise to the Lorenz attractor is often referred to as a simple model of atmospheric convection, yet amongst the atmospheric science community, attention is rarely paid to the original fluid flow that the Lorenz equations describe. Consisting of a fluid layer heated from below and cooled from above, Rayleigh-Bénard convection (Fig. 2) is a hallmark flow beloved by fluid dynamicists and mathematicians alike for its analytical tractability, yet rich behaviour. It is often cited as being of immediate relevance for many geophysical and astrophysical flows [1]. The success of turbulent Rayleigh-Bénard convection in leading to our understanding of chaos, as exemplified by the Lorenz attractor, suggests the enticing possibility of gaining other key conceptual insights into the behaviour of the Earth’s atmosphere through the use of this simple convective system.

 

Figure 2: Schematic of Rayleigh-Bénard convection.

In a recent study [2] we explored this potential by investigating to what extent turbulent Rayleigh-Bénard convection serves as an analogue of the daytime atmospheric boundary layer, also known as the convective boundary layer (CBL). In particular, we investigated whether statistical properties in the surface layer develop with height in a similar way in both systems. The surface layer is typically just a few tens of metres thick, but due to the strong turbulent mixing that takes place there, it is of primary importance for the development of the boundary layer. The surface boundary conditions of Rayleigh-Bénard convection and the CBL are the same, which might lead one to think that surface-layer properties should behave similarly in both cases. However, differences in the upper boundary conditions between the two systems modify the large-scale circulations that appear in both systems and this may have an impact in the surface layer.

Indeed, despite the much-heralded relevance of Rayleigh-Bénard convection to geophysical flows, we find that its cooled upper plate modifies the large-scale structures in such a way that it substantially alters the behaviour of near-surface properties compared to the CBL. In particular, the downdrafts in Rayleigh-Bénard convection are considerably stronger than in the CBL and their impingement into the surface layer changes how velocity and temperature statistics develop with height.

However, we also find that just an incremental change to the upper boundary condition of Rayleigh-Bénard convection is needed to closely match surface-layer statistics in the CBL. If instead of being cooled, the upper plate is made adiabatic, i.e. no heat is allowed to escape (Fig. 3), the influence of the strong, cold downdrafts is removed, resulting in surface-layer similarity between this modified version of Rayleigh-Bénard convection and the CBL. Rayleigh-Bénard convection with an adiabatic top lid has the advantage that it is a simpler experimental set-up than the CBL and provides a longer statistically steady state, allowing for greater statistical convergence to be achieved through long-time averaging.

Figure 3: Schematic of the modifed version of Rayleigh-Bénard convection with an adiabatic top lid.

In the long term, the classical Rayleigh-Bénard system will continue to serve as a paradigm for studies of natural convection, though we are increasingly beginning to see that its practical application to geophysical and astrophysical [3] flows may not be as straightforward as past literature seems to suggest.

 References

[1] A. Pandey, J. Scheel, and J. Schumacher.  Turbulent superstructures in Rayleigh-Bénard convection.Nature Communications, 9:2118, 2018.

[2] K.  Fodor,  JP  Mellado,  and  M.  Wilczek.   On the  Role  of  Large-Scale Updrafts and Downdrafts in Deviations From Monin-Obukhov Similarity Theory  in  Free  Convection. Boundary-Layer Meteorology,  2019.

[3] F. Wilczynski, D. Hughes, S. Van Loo, W. Arter, and F. Militello.  Stability  of  scrape-off  layer  plasma:  a  modified  Rayleigh-Bénard  problem. Physics of Plasmas, 26:022510, 2019.

Edited by Dasaraden Mauree


 Bettina DialloKatherine Fodor is a PhD. candidate at the Max Planck Institute for Meteorology in Hamburg, Germany. She uses very high resolution computer simulations to study turbulence in the atmosphere. In particular, her research concerns interactions between large-scale structures and small-scale turbulence. You can find her on Twitter @FodorKatherine where, in addition to science, she also tweets about cycling.”

 

 

The puzzle of high Arctic aerosols

The puzzle of high Arctic aerosols

Current Position: 86°24’ N, 13°29’E (17th September 2018)

The Arctic Ocean 2018 Expedition drifted for 33 days in the high Arctic and is now heading back south to Tromsø, Norway. With continuous aerosol observations, we hope to be able to add new pieces to the high Arctic aerosol puzzle to create a more complete picture that can help us to improve our understanding of the surface energy budget in the region.

Cruise track to the high Arctic with the 33 day drift period. (Credits: Ian Brooks)

In recent years, considerable efforts have been undertaken to study Arctic aerosol. However, there are many facets to Arctic aerosol so that different kinds of study designs are necessary to capture the full picture. Just to name a few efforts, during the International Polar Year in 2008, flight campaigns over the North American and western European Arctic studied the northward transport of pollution plumes in spring and summer time [1,2,3]. More survey-oriented flights (PAMARCMIP) have been carried out over several years and seasons [4] around the western Arctic coasts. The NETCARE campaigns [5] have studied summertime Canadian Arctic aerosol in the marginal ice zone. And the Arctic Monitoring and Assessment Programme (AMAP) has issued reports on the radiative forcing of anthropogenic aerosol in the Arctic [6,7].

These and many other studies have advanced our understanding of Arctic aerosol substantially. Since the 1950s we are aware of the Arctic Haze phenomenon that describes the accumulation of air pollution in the Arctic emitted from high latitude sources during winter and early spring. In these seasons, the Arctic atmosphere is very stratified, air masses are trapped under the so-called polar dome and atmospheric cleansing processes are minimal. In springtime, with sunlight, when the Arctic atmosphere becomes more dynamic, the Arctic Haze dissolves with air mass movement and precipitation. Then, long-range transport from the mid-latitudes can be a source of Arctic aerosol. This includes anthropogenic as well as forest fire emissions. The latest AMAP assessment report [6] has estimated that the direct radiative forcing of current global black and organic carbon as well as sulfur emissions leads to a total Arctic equilibrium surface temperature response of 0.35 °C. While black carbon has a warming effect, organic carbon and particulate sulfate cool. Hence, over the past decades the reductions in sulfur emissions from Europe and North America have led to less cooling from air pollution in the Arctic [8]. Currently, much effort is invested in understanding new Arctic emission sources that might contribute to the black carbon burden in the future, for example from oil and gas facilities or shipping [9, 10, 11].

These studies contribute to a more thorough understanding of direct radiative effects from anthropogenic aerosol and fire emissions transported to the Arctic. However, neither long-range transported aerosol nor emissions within the lower Arctic contribute substantially to the aerosol found in the boundary layer of the high Arctic [12]. These particles are emitted in locations with warmer temperatures and these air masses travel north along isentropes that rise in altitude the further north they go. The high Arctic boundary layer aerosol, however, is important because it modulates the radiative properties of the persistent Arctic low-level clouds that are decisive for the surface energy budget (see first Arctic Ocean blog in August 2018).

Currently, knowledge about sources and properties of high Arctic aerosol as well as their interactions with clouds is very limited, mainly because observations in the high Arctic are very rare. In principle, there are four main processes that shape the aerosol population in the high north: a) primary sea spray aerosol production from open water areas including open leads in the pack ice area, b) new particle formation, c) horizontal and vertical transport of natural and anthropogenic particles, and d) resuspension of particles from the snow and ice surface (snowflakes, frost flowers etc.). From previous studies, especially in the marginal ice zone and land-based Arctic observatories, we know that microbial emissions of dimethyl sulfide and volatile organic compounds are an important source of secondary aerosol species such as particulate sulfate or organics [13]. The marginal ice zone has also been identified as potential source region for new particle formation [14]. What is not known is to which degree these particles are transported further north. Several scavenging processes can occur during transport. These include coagulation of smaller particles to form larger particles, loss of smaller particles during cloud processing, precipitation of particles that acted as cloud condensation nuclei or ice nucleating particles, or sedimentation of large particles to the surface.

Further north in the pack ice, the biological activity is thought to be different compared to the marginal ice zone, because it is limited by the availability of nutrients and light under the ice. Hence, local natural emissions in the high Arctic are expected to be lower. Similarly, since open water areas are smaller, the contribution of primary marine aerosol is expected to be lower. In addition, the sources of compounds for new particle formation that far north are not very well researched.

To understand some of these sources and their relevance to cloud properties, an international team is currently measuring the aerosol chemical and microphysical properties in detail during the Arctic Ocean 2018 expedition on board the Swedish icebreaker Oden. It is the fifth expedition in a series of high Arctic field campaigns on the same icebreaker. Previous campaigns took place in 1991, 1996, 2001 and 2008 (see refs [15, 16, 17, 18] and references therein).

The picture below describes the various types of air inlets and cloud probes that are used to sample ambient aerosol particles and cloud droplets or ice crystals. A large suite of instrumentation is used to determine in high detail the particle number concentrations and size distribution of particles in the diameter range between 2 nm and 20 µm. Several aerosol mass spectrometers help us to identify the chemical composition of particles between 15 nm and 1 µm as well as the clusters and ions that contribute to new particle formation. Filter samples of particles smaller than 10 µm will allow a detailed determination of chemical components of coarse particles. They will also give a visual impression of the nature of particles through electron microscopy. Filter samples are also used for the determination of ice nucleation particles at different temperatures. Cloud condensation nuclei counters provide information on the ability of particles to form cloud droplets. A multi-parameter bioaerosol spectrometer measures the number, shape and fluorescence of particles. Further instruments such as black carbon and gas monitors help us to distinguish pristine air masses from long-range pollution transport as well as from the influence of the ship exhaust. We can distinguish and characterize the particle populations that do or do not influence low-level Arctic clouds and fogs in detail by using three different inlets: i) a total inlet, which samples all aerosol particles and cloud droplets/ice crystals, ii) an interstitial inlet, which selectively samples particles that do not form droplets when we are situated inside fog or clouds, and iii) a counterflow virtual impactor inlet (CVI), which samples only cloud droplets or ice crystals (neglecting non-activated aerosol particles). The cloud droplets or ice crystals sampled by the CVI inlet are then dried and thus only the cloud residuals (or cloud condensation nuclei) are characterized in the laboratory situated below.

Inlet and cloud probe set-up for aerosol and droplet measurements installed on the 4th deck on board the icebreaker Oden. From left to right: Inlets for particulate matter smaller 1 µm (PM1) and smaller 10 µm (PM10); forward scattering spectrometer probe (FSSP) for droplet size distribution measurements; counterflow virtual impactor inlet (CVI) for sampling cloud droplets and ice crystals; total inlet for sampling of all aerosol particles and cloud droplets/ice crystals; interstitial inlet for sampling non-activated particles; particle volume monitor (PVM) for the determination of cloud liquid water content and effective droplet radius. Newly formed , very small, particles are sampled with a different inlet (not shown in the picture) specifically designed to minimize diffusion losses. (Picture credit: Paul Zieger)

To gain more knowledge about the chemical composition and ice nucleating activity of particles in clouds, we also collect cloud and fog water on the uppermost deck of the ship and from clouds further aloft by using tethered balloon systems. When doing vertical profiles with two tethered balloons, also particle number concentration and size distribution information are obtained to understand in how far the boundary layer aerosol is mixed with the cloud level aerosol. Furthermore, a floating aerosol chamber is operated at an open lead near the ship to measure the fluxes of particles from the water to the atmosphere. It is still unknown whether open leads are a significant source of particles. For more details on the general set-up of the expedition see the first two blogs of the Arctic Ocean Expedition (here and here).

After 33 days of continuous measurements while drifting with the ice floe and after having experienced the partial freeze-up of the melt ponds and open water areas, it is now time for the expedition to head back south. We will use two stations in the marginal ice zone during the transit into and out of the pack ice as benchmarks for Arctic aerosol characteristics south of our 5-week ice floe station.

As Oden is working her way back through the ice and the expedition comes to an end, we recapitulate what we have measured in the past weeks. What was striking, especially for those who have spent already several summers in the pack ice, is that this time the weather was very variable. There were hardly two days in row with stable conditions. Instead, one low pressure system after the other passed over us, skies changed from bright blue to pale grey, calm winds to storms… On average, we have experienced the same number of days with fog, clouds and sunshine as previous expeditions, but the rhythm was clearly different. From an aerosol perspective these conditions meant that we were able to sample a wide variety characteristics including new particle formation, absence of cloud condensation nuclei with total number concentrations as low as 2 particles per cubic centimeter, coarse mode particles, and size distributions with a Hoppel-minimum that is typical for cloud processed particles.

Coming back home, we can hardly await to fully exploit our recorded datasets. Stay tuned!

Do not hesitate to contact us for any question regarding the expedition and measurements. Check out this blog for more details of life during the expedition and our project website which is part of the Arctic Ocean 2018 expedition.

Changing Arctic landscapes. From top to bottom: Upon arrival at the drift station there were many open leads. Storms pushed the floes together and partially closed leads. Mild and misty weather. Cold days and sunshine lead to freeze-up. (Credit: Julia Schmale)

Edited by Dasaraden Mauree


The authors from left to right: Andrea Baccarini, Julia Schmale, Paul Zieger

Julia Schmale is a scientist in the Laboratory of Atmospheric Chemistry at the Paul Scherrer Institute, Switzerland. She has been involved in Arctic aerosol research for the past 10 years.

Andrea Baccarini, is doing his PhD in the Laboratory of Atmospheric Chemistry at the Paul Scherrer Institute, Switzerland. He specializes in new particle formation in polar regions.

Paul Zieger, is an Assistant Professor in Atmospheric Sciences at the University of Stockholm, Sweden. He is specialized in experimental techniques for studying atmospheric aerosols and clouds at high latitudes.

The perfect ice floe

The perfect ice floe

Current position: 89°31.85 N, 62°0.45 E, drifting with a multi-year ice floe (24th August 2018)

With a little more than three weeks into the Arctic Ocean 2018 Expedition, the team has found the right ice floe and settled down to routine operations.

Finding the perfect ice floe for an interdisciplinary science cruise is not an easy task. The Arctic Ocean 2018 Expedition aims to understand the linkages between the sea, microbial life, the chemical composition of the lower atmosphere and clouds (see previous blog entry) in the high Arctic. This means that the “perfect floe” needs to serve a multitude of scientific activities that involve sampling from open water, drilling ice cores, setting up a meteorological tower, installing balloons, driving a remotely operated vehicle, measuring fluxes from open leads and sampling air uncontaminated from the expedition activities. The floe hence needs to be composed of multi-year ice, be thick enough to carry all installations but not too thick to allow for drilling through it. There should also be an open lead large enough for floating platforms and the shape of the floe needs to be such that the icebreaker can be moored against it on the port or starboard side facing all for cardinal directions depending on where the wind is coming from.

The search for the ice floe actually turned out to be more challenging than expected. The tricky task was not only to find a floe that would satisfy all scientific needs, but getting to it north of 89°N proved exceptionally difficult this year. After passing the marginal ice zone north of Svalbard, see blue line on the track (Figure 2), progress through the first year ice was relatively easy. Advancing with roughly 6 knots, that is about 12 km/h, we advanced quickly. After a couple of days however, the ice became unexpectedly thick with up to three meters. This made progress difficult and slow, even for Oden with her 24,500 horse powers. In such conditions the strategy is to send a helicopter ahead to scout for a convenient route through cracks and thinner ice. However, persistent fog kept the pilot from taking off which meant for the expedition to sit and wait in the same spot. For us aerosol scientists looking at aerosol-cloud interactions this was a welcome occasion to get hand on the first exciting data. In the meantime, strong winds from the east pushed the pack ice together even harder, producing ridges that are hard to overcome with the ship. But with a bit of patience and improved weather conditions, we progressed northwards keeping our eyes open for the floe.

Figure 2: Cruise track with drift. The light red line indicates the track to the ice floe, the dark red line indicates the drift with the floe. The thin blue line is the marginal ice zone from the beginning of August.

As it happened, we met unsurmountable ice conditions at 89°54’ N, 38°32’ E, just about 12 km from the North Pole – reason enough to celebrate the farthest North.

Figure 3: Expedition picture at the North Pole. (Credit: SPRS)

Going back South from there it just took a bit more than a day with helicopter flights and good visibility until we finally found ice conditions featuring multiple floes.

And here we are. After a week of intense mobilization on the floe, the four sites on the ice and the instrumentation on the ship are now in full operation and routine, if you stretch the meaning of the term a bit, has taken over. A normal day looks approximately like this:

7:45:  breakfast, meteorological briefing, information about plan of the day; 8:30 – 9:00: heavy lifting of material from the ship to the ice floe with the crane; 9:00 (or later): weather permitting, teams go to the their sites, CTDs are casted from the ship if the aft is not covered by ice; 11:45: lunch for all on board and pick-nick on the floe; 17:30: end of day activities on the ice, lifting of the gangway to prevent polar bear visits on the ship; 17:45: dinner; evening: science meetings, data crunching, lab work or recreation.

Figure 4: Sites on the floe, nearby the ship. (Credit: Mario Hoppmann)

At the balloon site, about 200 m from the ship, one balloon and one heli-kite are lifted alternately to take profiles of radiation, basic meteorological variables and aerosol concentrations. Other instruments are lifted up to sit over hours in and above clouds to sample cloud water and ice nucleating particles, respectively. At the met alley, a 15 m tall mast carries radiation and flux instrumentation to characterize heat fluxes in the boundary layer. The red tent at the remotely operated vehicle (ROV) site houses a pool through which the ROV dives under the flow to measure physical properties of the water. The longest walk, about 20 minutes, is to the open lead site, where a catamaran takes sea surface micro layer samples, a floating platform observes aerosol production and cameras image underwater bubbles. The ice core drilling team visits different sites on the floe to take samples for microbial and halogen analyses.

Open Lead site. (Credit: Julia Schmale)

Importantly, all activities on the ice need to be accompanied by bear guards. Everybody carries a radio and needs to report when they go off the ship and come back. If the visibility decreases, all need to come in for safety reasons. Lab work and continuous measurements on the ship happen throughout the day and night. More details on the ship-based aerosol laboratory follow in the next contribution.

Edited by Dasaraden Mauree


Julia Schmale is an atmospheric scientist at the Paul Scherrer Institute in Switzerland. Her research focuses on aerosol-cloud interactions in extreme environments. She is a member of the Atmosphere Working Group of the International Arctic Science Committee and a member of the Arctic Monitoring and Assessment Programme Expert Group on Short-lived Climate Forcers .

How can we use meteorological models to improve building energy simulations?

How can we use meteorological models to improve building energy simulations?

Climate change is calling for various and multiple approaches in the adaptation of cities and mitigation of the coming changes. Because buildings (residential and commercial) are responsible of about 40% of energy consumption, it is necessary to build more energy efficient ones, to decrease their contribution to greenhouse gas emissions.

But what is the relation with the atmosphere. It is two folds: firstly, in a previous post, I have already described what is the impact of the buildings / obstacles on the air flow and on the air temperature. Secondly, the fact that the climate or surrounding environment is influenced, there will be a significant change in the energy consumption of these buildings.  Currently, building energy simulation tool are using data usually gathered outside of the city and hence not representative of the local context. Thus it is crucial to be able to have necessary tools that capture both the dynamics of the atmosphere and also those of a building to design better and more sustainable urban areas.

In the present work, we have brought these two disciplines together by developing a multi-scale model. On the one side, a meteorological model, the Canopy Interface Model (CIM), was developed to obtain high resolution vertical profile of wind speed, direction and air temperature. On the other hand, an energy modelling tool, CitySim, is used to evaluate the energy use of the buildings as well as the irradiation reaching the buildings.

With this coupling methodology setup we have applied it on the EPFL campus, in Switzerland.  We have compared the modelling results with data collected on the EPFL campus for the year 2015. The results show that the coupling lead to a computation of the meteorological variables that are in very good agreement. However, we noted that for the wind speed at 2m, there is still some underestimation of the wind speed. One of the reason for this is that the wind speed close to the ground is very low and there is a higher variability at this height.

Comparison of the wind speed (left) and air temperature (right) at 2m (top) and 12m (bottom).

We intend to improve this by developing new parameterization in the future for the wind speed in an urban context by using data currently being acquired in the framework of the MoTUS project. One surprising result from this part of the study, is the appearance inside of an urban setup of a phenomena call Cold Air Pools which is very typical of valleys. The reason for this is the lack of irradiation reaching the surface inside of dense urban parts.

Furthermore, we have seen some interesting behaviour in the campus for some particular buildings such as the Rolex Learning Center. Buildings with different forms and configuration, reacted very differently with the local and standard dataset. We designed a series of additional simulation using multiple building configuration and conducted a sensitivity analysis in order to define which parameters between the wind speed and the air temperature had a more significant impact on the heating demand (see Figure 1). We showed that the impact of a reduction of 1°C was more important than a reduction of 1m s-1.

Figure 1. Heating demand of the five selected urban configurations (black dots), as function of the variation by +1°C (red dots) and -1°C (blue dots) of the air temperature, and by +1.5 m s-1 (violet dots) and -1.5 m s-1 (orange dots).

Finally, we also analysed the energy consumption of the whole EPFL campus. When using standard data, the difference between the simulated and measured demand was around 15%. If localized weather data was used, the difference was decreased to 8%. We have thus been able to reduce the uncertainty of the data by 2. The use of local data can hence improve the estimation of building energy use and will hence be quite important when building become more and more efficient.

Reference / datasets

The paper (Mauree et al., Multi-scale modelling to evaluate building energy consumption at the neighbourhood scale, PLOS One, 2017) can be accessed here and data needed to reproduce the experiment are also available on Zenodo.

How we might lose the battle against climate change … or against any other environmental problem?

How we might lose the battle against climate change … or against any other environmental problem?

This would not be a blog about atmospheric science if I did not talk about climate change. But I won’t be talking about the science of climate change… there are numerous blogs including here that will talk much better about this. The problem that will be addressed here does not only refer to the “battle” we are currently facing with climate but also numerous other environmental issues (smog, PM2.5 / PM10 pollution, endocrine/ hormone disruptors, pesticides…). For most of these environmental issues, extensive research is already conducted in Atmospheric sciences but these are also tackled in social and economic sciences as well. However, most of the policies in place right now fail to address these issues which are really urgent matter and humans (and other form of life as well) are losing million of hours of life expectancy and hence costing billion of euros to the community.

My point here is that there is a huge gap between what the scientific community understands (and is of course continuing to study) and what is perceive as a threat by the public. More and more scientists engage in outreach programmes and try to convey their findings about their research to the public. One of the other methods scientists use nowadays is more generally known as “open science” where researchers make their data and findings (for ex. with articles) freely available. However it seems that although these practices have been in place for a couple of years / decades, the gap still exists. Either the public has the perception that scientists are totally disconnected from their reality or they do not feel the urgency to take actions to address these issues (because most likely we do not “feel” or “see” the direct impact of the such pollution problems – in the case of climate change we are talking mostly about long term effect on sea level, biodiversity…).

The second issue lies with what kind of policy to put in place based on the findings from the scientific community. Although the aim of science is primarily to understand the “how” and the “why” of questions, it is crucial now for us to take a more firm stand on these issues. Several discussions have already been taking place within the scientific community to decide on whether it is the role of scientist to act as an advocate for a change in policy. For ex. if my research is on climate change and my findings show that human greenhouse gas (GHG) emissions are responsible for the current climate change, is it my role as a researcher to say “loud and clear” that I think we should decrease drastically our GHG emissions? Some scientists think that this is not our role, as we need to be impartial and hence we cannot engage in advocacy. I have to disagree here as we are indeed the most well placed persons to take such stands.

However, I think it is also now crucial for universities and research institutes, to develop new ways (or totally new separate departments) in order to engage with the public and share the knowledge. It is not possible, when the extent of knowledge is so vast, in so many topics, that there are still many areas on which the public / government and the scientific community are in such disagreement. Various situations, in the past, have caused tremendous suffering (for ex. high death and cancer rate in the case of asbestos) and could have been prevented, because the scientific knowledge was here but there was intense lobbying and a lack of political will to change things (it took about 50 years for France to officially ban asbestos after it has been recognized as the origin of pathological diseases).

In view of these situations, policy change will definitely come when the public “knows” and can hence ask for a change with their local / national / international governments. This bottom-up approach seems to be the most likely way with which we will be able to address these environmental issues in the future. The problem here is that we (scientists in general) have to ask ourselves why is it that our research influence so marginally policies that are put in place. Are we not engaging with the public enough? Should we share our results/findings differently? Are international organisations the best way to find consensus on such topics? I agree that scientists cannot solve all the problems of the world but the research community is one of the pillars of the society and should engage as such in the debates the society is facing. Although I started with a very bleak perspective (and for now this seems to be the case with many challenges we are facing) there is still some hope for the future. We will see, for ex., in the COP21 international meeting if an agreement will be reached on the climate change topic… but I have serious doubts about this being the case.

Welcome to the AS division blog

http://www.esa.int/spaceinimages/Images/2015/01/Ecosystem_Earth

Ecosystem Earth. Copyright ESA/NASA

 

The Atmospheric Sciences Division of the EGU is launching its new blog. This blog hopes to address a number of topics, as well as the major challenges, related to the atmospheric sciences. In this introductory post, I would like to present some of the topics we will address here and also some hurdles the scientific community is trying to overcome.

First, let’s agree on some definitions. Atmospheric science is a field which studies the various processes which are taking place in the fluid layer above the surface of a planet. This can include a a range of topics : Atmospheric Chemistry (“is the study of the composition of the atmosphere, the sources and fates of gases and particles in air, and changes induced by natural and anthropogenic processes”), Atmospheric Dynamics (“involves observational and theoretical analysis of all motion systems of meteorological significance, including such diverse phenomena as thunderstorms, tornadoes, gravity waves, tropical hurricanes, extratropical cyclones, jet streams, and global-scale circulations”), Atmospheric Physics (“is the application of the fundamental laws of physics to the systems and the phenomena hosted by the subtle thin layer of gases and vapors surrounding a planet”) and Climatology (“which represents the composite of day-to-day weather over a longer period of time”). Although these definitions might seem a tiny bit rudimentary they give a grasp of how vast this field can be. It is popular belief that atmospheric science is applied mainly to the Earth but extensive research isalso taking place on other celestial bodies.

Secondly, let’s take a look at the major research challenges that we are facing in this field. Data collection and assimilation are an inherent problem in all research but particularly important in this field. The amount of data to be collected and analysed is significant with regards to the systems (e.g. Earth’s atmosphere) we are looking at. Furthermore weather and climate processes are very complex to model due to the non-linear processes (e.g. fluid mechanics, feedbacks…). These models are crucial in understanding the phenomena and for an enhanced prediction for the future. Developing and developed countries alike, faces air pollution problems. Models have significantly improved in this aspect but still need to be improved to tackle the new challenges (e.g. indoor air-pollution, biomass burning, …). These are also very closely related to urban climate and boundary layer and small scale processes (turbulence…). I only mention a few tasks we need to address but of course there are a significant number of others (e.g. ozone layer, extreme events, cloud physics, …).

Finally, to conclude there is also one significant obstacle that we are also facing and this is policy making and application of some research programmes. Even if models and significant research exist in a certain field this does not mean that policy makers will base their decisions on the outcome of a research project. It is thus also vital to address societal complexity through research and also to use outreach as a means to reach a vast audience to promote the goals of our research programmes.

In the future, we hope to present some of the research programmes that are currently being done in this field and to show how we intend to address present and future challenges. Please feel free to comment below and we also welcome guest bloggers, so do not hesitate to contact us if you want to contribute. We look forward to having an amazing ride with you!