Atmospheric Sciences

Dasaraden Mauree

Dasaraden Mauree is a post-doctoral research fellow at the EPFL. He has a Ph. D. in Earth and Universe Sciences from Université de Strasbourg. His uses computer models for his research work which is now focused on urban climate, building energy simulation, energy efficiency at the urban scale and urban energy systems. He still has a strong interest in climate modeling particularly with respect to land use changes. He strongly believes in open research and in supporting outreach programmes. Dasaraden tweets at @D_Mauree.

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.

Do you want to establish a career in the atmospheric sciences? Interview with the Presidents of the AMS and the EGU-AS Division.

Establishing a career in the atmospheric sciences can be challenging. There are many paths to take and open questions. Fortunately, those paths and questions have been thoroughly explored by members of our community and their experiences can provide guidance. In light of this, in September 2016 Ali Hoshyaripour [Early Career Scientists (ECS) representative of the European Geoscience Union’s Atmospheric Sciences division (EGU-AS)] and Monique Kuglitsch [Senior International Outreach/Communications Specialist at the American Meteorological Society (AMS)] collaborated on a virtual interview of the presidents of our organizations: Annica Ekmann (AE) and Fred Carr (FC), respectively, with questions provided by early career scientists. You can find below a summary of the different questions and answers.

On education

Red Latinoamericana de estudiantes en Ciencias Atmosféricas y Meteorología (RedLAtM) opened the interview series by asking AE and FC, “did something important mark your life?”

AE: I can’t think of any specific event that changed my life, but spending some time abroad as a Post-Doc and visiting scientist has been very important to me. Both from a professional point of view, to learn from a new environment, but also on a personal level.

FC: I didn’t have a major life-changing moment but several very important ones. In 1969, after I received my B.S. degree, 100% of college graduates were drafted into the military (this was at the height of the Vietnam War). However, because I had a slight hearing deficit, I was ineligible for military service, and I was able to begin graduate school. Had I served in the military, my career path would have been much different. Later, after receiving my PhD and while working as a post-doc for Dr. Lance Bosart at SUNY-Albany, I began applying for faculty positions. I eventually had to decide between an offer from the University of Oklahoma (OU) and waiting for another university to decide among several candidates. I chose the “bird-in-the-hand” option, and joined the School of Meteorology at OU, which at that time had only 6 full-time faculty and was housed in the oldest building on campus. Now we have over 20 faculty and are housed in the magnificent National Weather Center, so that was a fortunate decision. And, of course, getting married to my wonderful wife Meg in 1972, and the birth of my son Brett in 1985 were very positive milestones in my life.

RedLAtM followed-up by asking AE and FC, “why did you both decide to pursue a career in atmospheric sciences?”

AE: My path into science in general, and atmospheric science in particular, was not straight-forward. I’ve always liked math and started my undergraduate education in math and physics. I soon found myself a bit “lost in theory” and wanted concrete problems where I could apply the knowledge. That was how I was drawn towards a Master’s program in meteorology. I was sure my future career would be as a weather forecaster until I started working on my degree project. I really enjoyed this first experience working as a scientist; learning about the problem, developing a tool to study the problem (in my case a numerical model), analyzing the results and then summarizing and presenting the results. So after my degree project I applied for a PhD student position. Then one thing just followed after another… I really enjoy working as scientist, I like the challenges it brings and also that I constantly learn new things from students and colleagues.

FC: I developed a strong interest in atmospheric science because of my love of skiing (which I started at age 5) and subsequent love of snowstorms. I grew up on the Massachusetts coast just northeast of Boston (Beverly) which meant that we were near the rain–snow line of almost every winter storm that passed over the northeast U.S. Thus I followed the weather forecasts and snow observations extremely closely, and decided I wanted to be a meteorologist. My interest in atmospheric science has increased ever since and today, at age 69, I am still skiing and still vicariously following closely all U.S. snowstorms and snow amount reports!

RedLAtM also wanted to know from AE and FC, “how should a young person guide his/her path as student and scientist in order to reach those institutions like the ones you lead?”

AE: A solid PhD education followed by a Postdoctoral position in a good lab is of course important. But I also think it’s essential to be in an environment where you personally and professionally feel appreciated and get good support, otherwise it’s easy to lose the enthusiasm when things turn difficult—which they will at some point. After a Post-Doc, other characteristics than your scientific skills will also become more and more important; project management skills, time management skills, leadership skills, administration skills, etc. If there are opportunities to learn these skills on the way, even at a small scale, it’s a good idea to take them.

FC: My advice will be targeted toward becoming involved in the American Meteorological Society (AMS). One can begin as an undergraduate student by attending scientific meetings, especially the AMS Annual Meeting that has so many activities (Career Fair, Student Conference, Exhibit Hall, etc.) from which they can benefit. As a graduate student, one can begin giving oral and poster presentations at the many conferences/symposia the AMS sponsors every year. The AMS also has meetings that are attractive to the private sector as well (Broadcast; Weather and Forecasting; Washington Forum, etc.), so you can remain involved in the AMS no matter what your career path is. The AMS has over 100 Boards and Committees addressing a wide spectrum of issues, many of which are listed here: and nearly all of them desire to have 1–2 student members. For early career scientists seeking more involvement in the AMS, I recommend joining one of the 30 Scientific and Technological Activities Commission (STAC) committees in the discipline that matches your interest. Also note the “Student Opportunities” link on the STAC website ( The Commissions on Professional Affairs and on the Weather, Water and Climate Enterprise have many volunteer opportunities for those in the private and public sectors (see first URL above). As your career proceeds, you can become more involved in the leadership of the various commissions, boards and committees, and eventually to major leadership positions in the Society.

RedLAtM posed their next question to FC, “which universities are the best for doing postgraduate studies in Tropical/Subtropical Dynamic applied in numerical weather prediction for tropical cyclone forecasting? I’m from Mexico and we have systems coming from two basins: the Atlantic and the Northeast Pacific.”

FC: By “postgraduate studies”, I will assume that you mean research opportunities as a recent PhD recipient. First, your PhD advisor may know of post-doctoral opportunities in his/her own research group or in tropical research groups at other institutions such as the Universities of Miami or Hawaii. In the U.S., it is possible for almost every doctoral program in atmospheric sciences to have 1–2 experts in tropical meteorology, so one could look over these program for research topics in your areas of interest (the following web site provides a list of these doctoral institutions: The National Research Council has postdoctoral research opportunities at several organizations such as NOAA, Naval Research Lab, etc. that perform tropical research; the list of these organizations is at Finally, I will mention NCAR’s Advanced Study Program Postdoctoral Program (at in which accepted candidates can work with any NCAR scientist they wish, a few of which do study tropical cyclones.

On career

Under the topic of career, Anonymous asked AE and FC “have you experienced ‘impostor syndrome’ and do you have advice for early career researchers who have it?”

AE: I have often felt that I’m not “good enough” and that everybody else is so much smarter and better than I. Personally, what I tended to do was to put all the good characteristics of a number of other people into one ideal person, and then I compared myself with that ideal person, which of course never was a very favorable comparison…. So I’ve stopped doing that J. From a general perspective, I think a good mentor can be very helpful.

FC: I believe I may have experienced a mild form of this syndrome when I first became a professor and I didn’t see myself at the same level as the distinguished professors at Florida State University where I was a student. However, I was getting papers published and receiving research grants, so I must have been doing something right. Eventually I learned that all scientists, being human, have their strengths and weaknesses, and that one can become a colleague of your distinguished peers by recognizing your own strengths and making contributions in these areas. My advice for those who may have impostor syndrome is to talk with people who you admire (one should always try to find mentors wherever you work), as they may have also experienced similar feelings. Also, develop a strong support system among your friends and colleagues, and look at your resume every once in a while to see all the wonderful things you have accomplished!

RedLAtM wanted to know from AE, “do you consider you had to sacrifice more than your male colleagues in order to achieve what have you done as a scientist in atmospheric sciences?”

AE: I don’t feel that I have made specific sacrifices to be a scientist. It’s been challenging sometimes, like many others I do have problems balancing work and private life. But I don’t think it’s a problem that’s unique for academia. It’s unfortunate that the role model of a successful scientist tends to be a person that works day and night, I wish we could change this image. Personally, I would like to see more research groups that do not rely upon, or are focused around, one single person.

RedLAtM wanted to know about FC’s experiences at the National Centers for Environmental (NCEP) and his experiences with models, asking “what has been your experience in the [NCEP]? I mean, what are the challenges that models have nowadays?” and “what are the biggest challenges in modeling?”

FC: Early in my career, I realized that my modeling research efforts would be more worthwhile if the models I worked on were the U.S. operational models used by NCEP. I became one of the few university scientists who spent a sabbatical at NCEP (as well as many visits later on) and was fortunate to be able to make some major improvements to the precipitation forecasts in the NAM and GFS models. It was a wonderful experience working with the NCEP scientists and I encourage all NWP experts to spend time there at some point in their careers. The NWP models today still have room for improvement, which is a good thing since it means that forecasts are still going to get better in the future as we address the current challenges. Some of the major challenges include improving data assimilation (i.e., the way we use data from new observing systems such as dual-pol radar, current and new satellite sensors, pressure data from cell phones, etc.), improving the physics in the models, and how best to design an ensemble of convection-resolving models.

Some of the biggest challenges [in modeling] include: (1) Predictability—at both climate and convective time and space scales. That is, we need to know what the theoretical predictability of the climate system is to know how much room for improvement there is in our climate projections. We need to understand convective predictability to know how long a high-resolution forecast (e.g., 1 km) will successfully evolve convective phenomena. (2) Observations: We now have even operational models forecasting at resolutions much finer than the observational network that provides their initial conditions. We need measurements that, in general, provide higher time and space resolution than we have now, and also those that eliminate the gaps we have such as lower-tropospheric thermodynamic profiling. (3) Data Assimilation: This was mentioned above, and despite the sophistication of today’s assimilation methods, there are still many issues that need research, such as assimilation for convection-resolving models. (4) Physics: We still need to improve our representation of microphysical processes (which are rarely verified), boundary layer turbulence, and surface processes under different wind, stability and vegetation regimes, to name a few. (5) Coupled modeling: Climate models and also medium-range forecasting models need to be coupled with, e.g., ocean models, sea ice models, and land-surface and hydrologic models. So, lots of research opportunities for everyone!

Nadine Borduas asked AE and FC, “is it better to focus on one aspect of [atmospheric sciences] or do a little of all three?”

AE: Difficult question, but I think we need both types in science. We need people that dig into the nitty-gritty details but also the ones that perhaps have a bit more superficial knowledge but are able to connect different subfields. In the beginning of a career, I would say that a relatively narrow focus is better so that you really become a specialist in a topic, method etc. But thereafter, I think it’s good to branch out more and more. Many of the interesting new discoveries today occur in the intersections between different disciplines or sub-disciplines.

FC: If “all three” means physical, dynamic and synoptic (observational) meteorology, then I would recommend that all atmospheric scientists have some knowledge of all three. Dynamicists and modelers still need to know what the observed structure of the atmosphere is, while observationalists (and modelers) need to know how to physically interpret observed (or modelled) behavior of the atmosphere. However, in order to do original research, one must focus on just 1–2 sub-specialty topics within these broad areas in order to achieve the depth one needs to advance the science.

Nadine Borduas also sought advice on developing a research group from AE and FC, asking “when establishing a research group in [atmospheric sciences] how much field/lab/model work to you incorporate in your proposals?”

AE: I assume you mean how much of each one of these components I would incorporate in a proposal? I’m a modeler myself, but collaborate strongly with people doing lab or field work. In most proposals, I therefore either have an experimentalist as a co-applicant and/or refer to specific people that can provide the necessary complementary data and expertise.

FC: If one were to form a new atmospheric research group, it probably would have to concentrate primary on one of two areas: climate and/or mesoscale modeling, or research using new observational tools. It would be difficult to have major expertise in both areas unless you had a very large group (such as at a national laboratory). A few research groups might be formed to do theoretical studies or pure experimental labs (e.g., wind tunnels, fluids laboratory) but these are not as well-funded these days. For a modeling research group, no field or lab work would be needed in the proposals. If you are designing/testing new radars, UAS or thermodynamic profiling systems, considerable field work is required, as well as some laboratory work to refine the instruments. If you were concentrating on measurements from space, then you have no local field or lab work to do (except perhaps some ground-truth validation studies), and your efforts would be concentrated on data processing, data analysis, and product development. Thus the answer depends on the primary purpose of the research group.

RedLAtM wanted to know from FC, “what inspired the foundation of the COMET program?”

FC: The National Weather Service, as it was implementing the “modernization” effort in radars, satellites and workstations in the 1990’s, realized that most forecasters at the time were not well-trained in interpretation of the observations from these systems, nor in convective and mesoscale observations and dynamics, nor in new data analysis software. They wanted a training program much more rigorous than typically given by NWS training courses and thus asked UCAR for assistance. Since each of the NWS Forecast Offices (FO) had a new position known as a Science Operations Officer (SOO), the idea was to train the SOOs at COMET with graduate-level course material, and the SOOs would then be the training focal point at each of the 120 NWS FOs. The instructors for each SOO course would be both university professors and veteran NWS forecasters. I was one of the first COMET instructors of the SOO course, and it was one of the most intense and rewarding teaching experiences I have ever had.

On the role as president of EGU-AS (AE) or AMS (FC)

In regards to her role as President of EGU AS, RedLAtM asked AE, “from your point of view, what is the biggest challenge for women in Atmospheric Sciences? What we have to face in order to leader organizations like EGU AS? Do we have the same opportunities as men have?”

AE: I think that on paper, women and men have the same opportunities to do a career in atmospheric sciences. Still, it’s a fact that more women than men leave science after their PhD or Post-Doc, and you don’t see them as often in leadership positions as men. This problem needs to be fixed, but there is no single and easy solution. I think supporting networks and role models are important, we need to see as big diversity in this respect among women as among men.

RedLAtM also asked AE “what are the youth programs you have supported since you’ve been elected president of EGU AS?”

AE: During the last year we were looking for a new ECS representative for the AS Division and eventually Ali Hoshyaripour was elected for the position. But we had such a large number of really good candidates, so together with Ali, we decided to form an AS Division ECS group that together could come up with activities and help spread information relevant for the AS ECS community. I’m really happy about this initiative, and think it will be a great resource for the AS Division as a whole. In addition, I have of course participated in activities organized by the EGU for early career scientists to meet Division Presidents and other more senior people.

From FC, RedLAtM wanted to know “how we can set up an AMS student chapter in Latin-America?”

FC: I will keep this answer short. The following website explains exactly what is needed to start a Local or Student Chapter of the AMS: I hope you will do so!

Oghenechovwen Christopher Oghenekevwe asked FC about Memoranda of Understanding. Specifically, “does an MoU exist between AMS and any Pan-African institution that allows undergraduate students Meteorology and Climate Science further their career with access to mentorship?”

FC: I don’t believe any MOU currently exists between the AMS and any African countries or organizations. The AMS does have agreements with the meteorological societies in Canada, Australia, India and China, and we will be glad to consider others. Since you mentioned students, you might investigate possible collaborations with the AMS Education Program ( and see if some of the teacher training programs could be adapted to student mentoring programs. The head of the Education Program is Wendy Abshire ( and I recommend that you contact her.

Finally, Chrysanctus Onyeanusi asked FC, “does this society have any scholarship scheme for young meteorology students like me?”

FC: The AMS has Freshman and Minority Scholarships for college freshman and sophomores, and Named Scholarships for seniors. Information about them is at However, I note that one must be a U.S. citizen or have permanent resident status to be eligible, so if you are an international student, we do not yet have a program for such students. However, it seems to me that we should have one, so I will pass this suggestion to our Centennial Committee, which is thinking about new activities the AMS can engage in as we celebrate our 100th Anniversary in 2019.

AnnikaAnnica Ekman is the President of the Atmospheric Sciences Division (AS) of the European Geosciences Union (EGU) and a Professor of Atmospheric Sciences at Stockholm University, Sweden.

She obtained her PhD in Atmospheric Sciences from Stockholm University in 2001, and was a PostDoc at Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts. Afterward, she returned to Stockholm University as a research scientist, becoming an Associate Professor in Atmospheric Sciences in 2009 and a Full Professor in 2015. Ekman’s research interests include cloud–aerosol interactions and the various ways that aerosol particles influence weather, atmospheric circulation, and the climate system. She is also the editor of Tellus B and co-leads the research areas of aerosols, clouds, turbulence and climate in Bolin Centre for Climate Research, Stockholm.

Since her appointment as the President of EGU AS in 2015, she has strongly supported new ideas to stimulate inter- and cross-disciplinary collaborations.


FredAmerican Meteorological Society (AMS) President and Professor of Meteorology, Fred Carr, hails from Beverly, Massachusetts. Carr studied meteorology at Florida State University in Tallahassee, Florida, and was a PostDoc at SUNY-Albany in Albany, New York.

Since 1979, he has been a faculty member at the University of Oklahoma in Norman, Oklahoma. From 1996 to 2010, he was the Director of the School of Meteorology, playing a key role in the expansion of the School and the creation of international exchange programs. Alongside his activities at the University of Oklahoma, he helped found the COMET Program at the University Corporation for Atmospheric Research (UCAR) and has been involved in many professional committees. He recently completed two terms on the UCAR Board of Trustees and is co-Chair of the UCAR Community Modeling Advisory Committee for the National Centers for Environmental Prediction (NCEP). Carr’s research topics include synoptic-, tropical, and mesoscale meteorology; numerical weather prediction; data assimilation; and observational systems.

Throughout his career, Carr has contributed to the AMS in multiple ways, including: a longtime AMS member; Fellow of the AMS; member of AMS Council; Chair of the AMS Board on Higher Education; and editor of Monthly Weather Review, associate editor of Weather and Forecasting, and member of the Editorial Board for the Bulletin of the American Meteorological Society (BAMS).

When cooling causes heating

When cooling causes heating














Following the Montreal Protocol in the late 1980s, CFC (chlorofluorocarbon) were replaced by hydrofluorocarbons (HFC) as a refrigerant. Unfortunately, the HFC’s have a global warming potential (GWP) far greater than the well-known greenhouse gas (GHG), carbon dioxide. Apart from the fact that this was not known until the mid-1990’s, climate-change due to GHG was not an emergency back then.

Rapid and urgent actions had to be undertaken in order to decrease the risk of temperature rise due to GHG. The COP21 held in Paris last year and the ratification by a majority of countries (and GHG emitters) has been followed by a landmark deal to eliminate HFC’s. It was concluded mid-October in Kigali where 197 states were meeting on the occasion of the 28th Montreal Protocol meeting.

But, why do GHG emissions matters, anyway? GHG warm the Earth by absorbing energy and by reducing the amount that escapes in space. This is more commonly known as the greenhouse effect. Due to the naturally present GHGs, the Earth’s air temperature is on average around 15°C. However, the burning of fossil fuels as well as the emission of other GHG’s from human activities are increasing this effect and causing a significant increase in the temperature (see Figure 1).

Figure 1: Left: Global CO2 emissions (US DoE) and  Right: Global land and ocean temperature anomalies (NOAA)

Figure 1: Left: Global carbon emissions (US DoE) and Right: Global land and ocean temperature anomalies (NOAA)

Going back to the HFC’s, scientists have argued that with the current rate of installation of air conditioning systems, there will be an overall 1.6 Billion units installed by 2050. With their booming economy, developing countries, like China or India, have experienced in the recent years a dramatic increase in such installation.

The deal that has been struck last week will have developed countries gradually decrease their HFC emissions as from 2019 while developing countries will start to decrease their emissions by 2024 (2028 for others). It has been argued that these emissions would have been responsible of 0.5°C rise air temperature by the end of 2100 (Xu et al., 2013). This is a significant contribution to the 1.5°C target set by the COP21.

A conversation with Didier Hauglustaine from the LSCE, France, however, highlighted the fact that there is no ideal replacement. One of the most promising one is the HFO. It looks like a variety of solutions will have to be developed depending on their usage. Giving some time to companies and states to adapt and develop new technologies that could replace HFC is hence a necessity.

All of this finally raises the question of the impact of man and new technologies on the atmosphere. It seems that we have created yet another problem while trying to resorb the ozone hole with the replacement of CFC by HFC’s. More importantly, the increase in air temperature, rapid urbanization as well as the higher probability of heat waves in the future, calls for an increased understanding of the urban environment. Human comfort (indoor and outdoor) in these areas should be assessed carefully at the design stage in order to develop new urban paradigms that could limit the use of air conditioning units.

Why should we care about a building’s energy consumption?

Why should we care about a building’s energy consumption?

From the 9th to the 11th of September the Solar Energy and Buildings Physics laboratory is hosting the CISBAT conference. This international meeting is seen as a leading platform for interdisciplinary dialog in the field of sustainability in the built environment. More than 250 scientists and people from the industry will be at EPFL in Lausanne to talk about topics from solar nanotechnologies to the metabolism in urban districts.

But how is this related to Atmospheric Science really? As you might know, this year the United Nations Climate Change Conference COP21 meeting will be held in Paris and the focus is to try to limit the global temperature increase to 2ºC. Switzerland has already submitted its proposal regarding its future emission and aims at reducing it by 50% by 2030. Many other countries have done the same, but NGO’s are saying that the most important greenhouse gas (GHG) emitters are not going far enough in their proposals to limit the temperature increase.

So what are the sectors where we can decrease our energy consumption, improve the efficiency and decrease our GHG emissions? If we look at France for example, the building sectors consumes about 44% of the final energy use. From these 44%, around 70% is used only for the thermal comfort on the occupants.


inbuildings Energy use for each sector (top) and inside buildings (bottom) adapted from French Environmental Energy Agency (Image credit: D. Mauree, 2014)

This conference is also an official presentation platform for the Swiss Competence Center for Energy Research “Future Energy Efficient Buildings & Districts” (FEEB&D). This project aims is to reduce the end energy demand of the Swiss building stock by a factor of five during the next decades thanks to efficient, intelligent and interlinked buildings.

From the figures above we have seen that there is here a huge potential to decrease our energy consumption. First we can improve the insulation of the buildings to enhance their efficiency. Several countries have implemented financial incentives to incite renovation but have also introduced tighter thermal regulations to decrease energy use in new and refurbished buildings.

In this conference, we will also be talking about the integration of renewable energies (RE) (solar PV, thermal, algae, wind, …). The idea of course is to improve the penetration of RE in urban areas so as to decrease our dependency on fossil fuels and hence of course reduce our GHG emissions. In order to reach this objective, it is then necessary to optimize their installations in order to see how we can reach the greatest autonomy possible with RE and the usage of storage solutions.

Among other subjects that will be presented during this meeting are model predictive control and daylighting and electric lighting. We will also address some issues related to urban simulation (you can have a look at a former blog post on this subject) / ecology and metabolism. Have a look at the CISBAT website and follow us on Twitter. I will also try to LT the conference with #cisbat15.

Urban Climate

Urban Climate

The 9th International Conference on Urban Climate and the 12th Urban Environment Symposium are taking place this week in the “Pink City” Toulouse. With the 21st Conference of Parties (COP21) which will be held in December in Paris, the obvious focus topic for the urban climate conference is the mitigation and adaptation to climate change in urban environment.

But, first of all, why should we even care about the urban climate and environment? One of the most important phenomena related to the urban climate that was first described by Luke Howard (1833) is the Urban Heat Island. This effect is caused by the accumulation of heat due to the various construction materials (asphalts, tiles, bricks…) used in urban areas. At night the urban areas hence cool less than in a natural environment and this leads to a higher temperature than the surrounding rural areas (see Figure). The difference in temperature can be up ot 8 degrees for some cities and for particular period during the year. Besides the presence of buildings also cause a modification of the wind pattern in cities.

One “simple” example of the significant impact of these effects is for example change the heating /cooling use in cities. Building energy demand is directly correlated with the outside air temperature but also to the wind speed. Thus, as the temperature is higher in urban areas, there is a greater need for cooling demand in temperate or arid climate. However, even in moderate climate, during long heat wave (and this is expected to become more frequent with climate change!) it can be expected that the cooling energy demand will increase.

Since 2010, over 50% of the world population lives in urban areas and this figure is expected to rise to 75% in 2050 (UN, 20121). As more people live in cities, this means that the cities need to grow to accommodate for the additional population. Urban expansion and densification as well as the decrease in agricultural land are crucial development issues that need to be addressed.

This means that we have to understand the various processes influencing the meteorological parameters in these areas. Model and simulation tools are ways to understand these complex problems and can be very useful tools for decision makers as it is an easier way to analyse different planning scenarios. Many scientists are also working on monitoring and measuring various meteorological parameters with traditional equipment but also with newer methods using mobile phones and other sensors.

The combined effects mentioned above can raise a number of questions:

  1. With climate change in mind, how do we build more buildings consuming less energy to accommodate for the increasing population?
  1. We have seen, for ex. in the summer 2003, that a long heat wave can increase significantly the number of deaths among vulnerable urban population (elder and younger people as well as people with respiratory problems). How do we then make sure that the thermal comfort of the inhabitants is satisfied in cities?
  1. Finally, how do we make sure that we build, design and plan more sustainable cities to decrease the impact of air pollution, to integrate more green and vegetated spaces…

All of these questions are very difficult to answer as they are a combination of scientific research questions but also of policy and planning decision. Scientists and planners should hence work together to build more sustainable cities and to provide meaningful implementation of the different research solutions.

1UN. World Urbanization Prospects: The 2011 Revision, CD-ROM Edition. Technical report, Department of Economic and Social A_airs, Population Division, 2012.

An unlikely choice between a gasoline or diesel car…

An unlikely choice between a gasoline or diesel car…

I have recently been confronted with the choice of buying a “new” car and this has proved to be a very tedious task with all the diversity of car that exists on the market today. However, one of my primary concerns was, of course, to find the least polluting car based on my usage (roughly 15000km/year).

Cars (or I should say motor vehicles) pollution is one of the major sources of air pollution (particulate matter, soot, NOx, …) in urban areas. These often cause, during both winter and summer seasons, long and prolonged exposition to ozone or PMs which can have significant effect on the health of urban population. Besides, vehicles are also one of the most important sources of greenhouse gases emissions (around 30%). Extensive research in various areas (air pollution and monitoring in urban areas, efficiency of motor vehicles, mobility and public transportation, urban planning,…) are thus being conducted to help reduce the exposition to dangerous pollutants and emissions of GHG.

Manufacturers have been more and more constrained by new regulations to decrease the pollutant emissions (with EURO6 norm now in the EU) and the increase the efficiency of motor vehicles. Governments around the world and more particularly in Europe, after the financial crisis of 2007/2008 have introduced new subsidies to incite people to buy new more energy efficient vehicles. One of the main issues here is that often the more efficient vehicles are not necessarily the less polluting vehicles. Policies have been based on GHG emissions from vehicle consumption without consideration of the full life cycle cost and analysis and also on other pollutants emissions.

Thus if we take for example an electric car, the GHG emissions (and also other pollutants) are pretty low or close to zero as there are none released by the car itself. But we also need to evaluate the emissions from the electricity power plant (most likely to be a centralized one based on either fossil fuel or nuclear energy). Furthermore if the life cycle cost of the battery in such cars, are taken into consideration, the picture is not so black and white anymore as it has been pointed out by numerous studies (ADEME – sorry for the French link!). Besides electric vehicle remain quite expensive and not really adapted to all usage.

If we compare both diesel and gasoline cars, then it becomes a bit more tedious. Diesel engines consumes generally less than gasoline one. However their PM emissions, for example, can be quite high and hence they need really efficient filters to get rid of these pollutants. More stringent regulations have forced manufacturers to improve significantly the quality of the air coming out of their diesel engines but still remain on average more polluting than gasoline cars. Countries, like France, that have strongly subsidized the use of diesel in the past, are now finding it quite difficult to phase out these types of cars. And besides they are more efficient and hence emits lets GHG.

Coming back to my choice of cars then… The choice for me in the end was then between the long term or short term benefits. Using a gasoline car or an electric car (in a country where the energy is coming from renewables!) would be more ecologically sound if we drive mostly in urban areas. However if you are thinking about the long term benefits (with climate change) then you should probably opt for a more efficient diesel car.

All of this, points out that research still need to be conducted and new innovative ideas are really needed (like Elon Musk’s battery, maybe?) so as to bridge the enormous gap between having an efficient car, the life cycle analysis and living in a pollution-free urban environment. But of course…, the best solution is to use public transport or bikes… well this is not always possible!

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

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!


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