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Pedro Leite da Silva Dias & Maria Assunção Faus: A good time for research

Married meteorologists discuss how studies on the atmosphere in the Amazon have strengthened Brazilian climate science and warn about the challenges ahead

Léo Ramos Chaves / Revista Pesquisa FAPESP

Meteorologists Pedro Leite da Silva Dias and Maria Assunção Faus da Silva Dias have been married for 50 years. They divide their time between their home in the city of São Paulo and a coffee farm in Arceburgo, a town of 9,000 inhabitants in southwestern Minas Gerais, just across the state border from Mococa, São Paulo. A professor at the Institute of Astronomy, Geophysics, and Atmospheric Sciences of the University of São Paulo (IAG-USP), Pedro spends most of the week in the São Paulo state capital. Since retiring from IAG in 2015 when she became a senior professor at the university, Assunção, as Pedro calls her, has spent more time at their rural property.

Pedro Leite da Silva Dias
Field of expertise
Large-scale dynamics of meteorology and atmospheric modeling
University of São Paulo (USP)
Educational background
Undergraduate degree in applied mathematics from USP (1974), master’s degree (1977) and PhD (1979) in atmospheric sciences from Colorado State University in Fort Collins, USA

Maria Assunção Faus
Field of expertise
Rainfall in tropical systems and interactions between the biosphere and atmosphere, with a focus on the Amazon
University of São Paulo (USP)
Educational background
Undergraduate degree in applied mathematics from USP (1974), master’s degree (1977) and PhD (1979) in atmospheric sciences from Colorado State University in Fort Collins, USA

Like Pedro, Assunção continues to be active in academic research, albeit at a slower pace than in the past, and she has started providing climate consultancy services to companies. “The difference now is that I have to share his office,” jokes Assunção, who no longer has a permanent space of her own at IAG. Both continue to supervise graduate students and work on the research that has made them so well-known among their peers in Brazil and abroad. Pedro is a specialist in tropical climate modeling and Assunção studies how the climate, especially rainfall, interacts with the Amazon rainforest and wildfires.

The pair, both aged 71, spent almost their entire academic careers at USP, where they also held management positions. Both spent periods away from the São Paulo university, at other research institutions around the country and abroad. Between 1988 and 1990, Pedro headed the then newly created Center for Weather Forecasting and Climate Studies at the Brazilian National Institute for Space Research (CPTEC-INPE). Between 2007 and 2015, he directed the National Laboratory for Scientific Computing (LNCC). Assunção also headed CPTEC for six years, from 2003 to 2009.

In this interview, given at the IAG office now shared by the two researchers, Pedro and Assunção talk about their shared career paths, their research, and climate change.

You graduated in mathematics together at USP. Did you already know each other before university?
Pedro: Yes, since we were 15 years old. But we weren’t dating.
Assunção: Before USP, we went to the same school—Colégio Bandeirantes, in São Paulo. We were in the same class of 50 students, of which only five were girls.

What was it like to meet again at USP?
A: In 1971, Pedro enrolled at the Polytechnic School [Poli] and I started at the Physics Institute. He then switched to the applied mathematics course, and a year later I did the same.
P: When I started at Poli, I was already having second thoughts about studying engineering. I wanted to do something related to Earth sciences, and meteorology was already on the list. But at that time the only degrees available were in geology. I excluded this course because back then, mathematics and computing were not fundamental in the teaching of geology.

Why didn’t you choose to major in mathematics right from the start?
A: Initially, the course was just pure mathematics, there was no applied part, which was what we wanted.
P: My father [mathematician Candido Lima da Silva Dias (1913–1998), the first director of the Institute of Mathematics and Statistics at USP] told me the university would soon have an applied mathematics course. But I couldn’t wait for that to happen. I chose Poli, from which I could transfer to another exact sciences course. By the end of the first year, I had realized that engineering was not for me. Luckily, the applied mathematics course was approved soon after and slated to begin in 1972. I waited until the end of my first year and transferred to mathematics.
A: I wanted to do astronomy. Since there was no such course yet, I had to take physics. One day I saw a poster in a corridor of the Physics Institute offering scholarships in marine meteorology at USP’s Institute of Oceanography [IO]. I also wasn’t convinced that astronomy was what I really wanted to do. I went to the Institute of Oceanography and they accepted me. I told Pedro and I think the next day he went there and got the same scholarship. That’s how we started working in meteorological research, both with a two-year undergraduate research scholarship from FAPESP.

So let me get this straight… You had already transferred to mathematics, but you were doing a scholarship at the Institute of Oceanography?
A: Yes. While studying applied mathematics, we were allowed to take optional courses at other USP schools and departments. We took meteorology electives at IAG and the internship at IO.

Personal archivePedro and Assunção in Fort Collins in July 1976, while studying for their master’s degrees at Colorado State UniversityPersonal archive

At that time, were you already dating?
P: We dated for a year and got married in February 1973, during our third year of university. In October 1974, Professor Giorgio Giacaglia, who was IAG director at the time, was looking for young people willing to help set up a Department of Meteorology.
A: He came to talk to us about it at the recommendation of professors Paulo Marques dos Santos and Paulo Benevides, and told us that he was hiring two American meteorologists and three from Taiwan who had worked in the USA and Canada, but that he also had to recruit Brazilians, because he did not want to rely solely on foreigners to teach undergraduate and graduate courses. He knew we were set to graduate at the end of 1974 and made us an offer. He would hire us if we both completed a master’s and PhD in meteorology in the USA. We didn’t even hesitate. We immediately accepted the offer.

He had a specific path laid out for you?
P: Yes, and he explained why. We had thought about doing master’s degrees at INPE, where there were some researchers who had done PhDs in meteorology abroad, and a graduate course in meteorology at INPE already existed. Because it was difficult to get a scholarship to do a master’s degree abroad, our plan was to try for PhD scholarships abroad after doing our master’s degrees at INPE. But Giacaglia said that it would be important for IAG for us to have received a different education. He said USP needed independent thinkers. He was very specific. We had to go to the USA, not to France or England, which would have been other natural options at that time, because graduate training in Europe was very specialized and focused on the topic of the thesis. In America, they took a more open approach, which would be more useful for us when we returned to Brazil, where we would have to help set up USP’s Meteorology Department.

Did Giacaglia also choose where you would do your graduate studies in the US?
P: No. But we knew we had to go somewhere that offered tropical meteorology, which is not particularly common in the USA.
A: We made a list of potential places of interest and applied to four programs. We were accepted into three, and ultimately, we chose Colorado State University (CSU) in Fort Collins. At CSU’s Department of Atmospheric Sciences, established in the early 1960s, there were several professors with experience in large-scale meteorological experiments involving oceanographic expeditions and surface stations to explore the Equatorial Atlantic region. This played a big part in our decision. In May 1975 we were hired as teaching assistants at USP, and in August we went to Colorado. It all happened very quickly. Our first child—we have three—was born there in 1977. We completed our master’s degrees at the beginning of 1977 and our PhDs in May 1979, then we resumed our duties at IAG at the end of that month.

What did you study in the United States?
A: Pedro has always looked more at the large-scale dynamics of meteorology, which involves observing the behavior of the continents and oceans. I focused on storms and rainfall. During my master’s degree, I studied rainfall in Venezuela. My advisor, Alan Betts, had a really good set of data on this topic. During my PhD, I worked on modeling rainfall systems in the tropics. Rain is a really fascinating phenomenon. Many processes occur during a severe storm, such as wind, ice, and heavy rain. Improving our understanding of rainfall has a major impact on weather forecasting, which affects people’s lives and the economy.
P: I worked with Professor Wayne Schubert, who was already well known at that time for his studies on the dynamics of the tropical atmosphere. I did essentially theoretical research on the dynamics of the relationship between wind and temperature near the Equator, a topic that still challenges meteorologists today.
A: When we came back to Brazil, we invited several former professors to visit IAG, as we intended to start field research.
P: This created a culture of using field experiments to collect data and understand the lifecycle of meteorological phenomena.

We are far short of what is needed to reduce greenhouse gas emissions, says Pedro

What was the first experiment that you organized in Brazil?
P: It was RADASP, with funding from FAPESP and using Bauru’s meteorological radar.
A: I had to take a bold approach. I applied for the project in the early 1980s and it was approved. When the funding was released, I asked Alan Betts if he could spend a month here to help me, and he agreed. He presented a compact graduate course and passed some of his vast experience onto us.

Can you tell us more about the experiment?
A: The general objective was to study the role of local atmospheric circulations, produced by the topography, sea breezes, and lakes, in the formation of rainfall in regions monitored by meteorological radar in São Paulo. We set up equipment on the ground to record radiation, temperature, humidity, winds, and other parameters, and we released weather balloons every three hours to measure the vertical structure of the atmosphere. It was the first data with high temporal resolution collected at altitude in Brazil.

Was there any discussion about climate change in the 1980s, when you were starting your career?
P: It was the 1983 El Niño [until then, the strongest example of this climate phenomenon recorded in the twentieth century] that sparked greater interest in this issue. Its global economic and social impact was enormous. I had learned in graduate school what climate change was. Since as far back as the nineteenth century, there had been a notion that increasing concentrations of carbon dioxide in the atmosphere could have an impact on the climate.
A: It shouldn’t be forgotten that El Niño is not strictly classified as climate change—it is a natural climate variation. But since then, an entire climate research system has been created, with global scope.P: The question was to distinguish whether what was happening to the climate was due to rising concentrations of greenhouse gases or
natural variability. The World Meteorological Organization initiated the process, and with support from the United Nations [UN], the IPCC [Intergovernmental Panel on Climate Change] was formed in 1988. The first climate research review was published in 1990. I participated in the second report, in 1995, and the fourth, in 2007.
A: I was involved in the fifth one, in 2013.

Which of your own scientific contributions would you like to highlight?
P: For me, I think it is my work on tropical dynamics. Particularly how the energy associated with rainfall is dispersed in the atmosphere, causing the tropics to influence climate at higher latitudes. I also study how tropical phenomena with a small spatial scale and high temporal frequency can influence the formation of large-scale systems. This is more theoretical research that has led to solid explanations to support observations of the meteorological and climate time scale.

Are these processes different from those that occur in a temperate zone?
P: There are significant differences. This line of research began during my PhD at CSU and is frequently applied in the development of global atmospheric models. The topic is linked to studies on dynamic systems in mathematics. In the tropics, the effect of rainfall as a whole, not just individual isolated episodes, is very important. This knowledge is now used to improve weather forecast models in the tropics.
A: I am best known for my studies on rainfall interactions in the Amazon biosphere. I’ve done a lot of work on the interaction between the climate and the rainforest, pasture areas, and wildfire outcomes, as well as how these elements alter meteorological processes and how storms form and evolve in the tropical environment. The effect of fire pollution on the climate still keeps me up at night. In certain circumstances, pollution appears to inhibit rainfall, but in others, it can transform what appears to be typical, mild summer rain cloud in the Amazon into a more concerning weather system, with strong winds, lots of rain, and ice. In the Amazon, hail occurs mainly in spring, when the air is extremely polluted by fires. There is no consensus on this issue: is it pollution that causes the hail, or is it another meteorological parameter? More research is needed. This field of study started in the 1980s and was expanded greatly with the LBA [Large-Scale Biosphere-Atmosphere Experiment in Amazonia, which began in the mid-1990s], achieving great international exposure. We knew almost nothing about these processes a few decades ago, and Brazil has made a significant contribution to the research.

We now know that climate change is already taking place, says Assunção

The LBA was the first major climate experiment in the Amazon with tripartite funding from Brazil, the USA, and Europe.
P: The LBA was set up with people who already had a lot of experience in field experiments in the 1980s, including myself, Assunção, Carlos Nobre, Paulo Artaxo, Reynaldo Victoria, and others. First, we held a meeting just for us here in Brazil. Then we invited our foreign colleagues to a large meeting at which we defined the general objectives of the research program and the relationship between the Brazilian team and the groups from abroad. We were wary after previous experiments with heavy foreign participation had been marred by poorly resolved partnerships. In some studies, Brazil’s involvement was insignificant in terms of generating new knowledge and little science was carried out collaboratively.
A: The LBA was created with another idea in mind. We made a great effort to obtain funding from Brazilian agencies for fieldwork and research. It was a success: we were always considered effective partners. We could never compete financially with NASA [the North American Space Agency, which invested heavily in the LBA], of course, but with our funding, we were able to put our teams on an equal footing with the foreign researchers.
P: At the LBA, from the beginning, we stipulated certain conditions for forming partnerships with groups from abroad. Any foreign groups wishing to participate had to agree to offer scholarships to graduate students.
A: A large number of young people, mainly from the Amazonian community, were thus able to do PhDs overseas. They grew professionally, became researchers, and are now working across Brazil.

What is your opinion on the current level of meteorology and climate research in Brazil?
P: Nowadays there are people doing high-level research all over Brazil. That’s the big difference. That wasn’t the case 40 years ago, when there were very few of us and very limited areas of research. In the 1970s, we marveled at the working conditions of the laboratories at Colorado State University compared to our own. But it’s not like that anymore.
A: They still have more funding and more people though.
P: Yes, but the science done by our colleagues here now is not vastly different from what they do there. Most Brazilian researchers are at an international level.

Is our weather forecasting and climate modeling now at the same level as the best international centers?
P: I think that 15 or 20 years ago, we had greater international prominence in operational terms. We were among the 10 best weather forecasters in the world.

Why have we been left behind?
A: We had a more competitive computer and teams working on topics in which we were also competitive. For multiple reasons, the number of groups working on numerical forecasting has decreased. There was a fragmentation of trained specialists and many people in academia were lost.
P: Mainly to institutions abroad and the private sector.

Is our climate modeling out of date?
P: First of all, to be competitive, we would have to have a supercomputer around 50 times faster than the one CPTEC currently has. Another issue is that our science lacks direction. To solve bigger problems that have an impact on society at large, you need focus. This is a serious problem in Brazil. During my eight years as director of the LNCC, I saw six Ministers of Science and Technology come and go, each with a different idea of what the institution should do.

The IPCC has highlighted that strong tropical cyclones are becoming more frequent, says Pedro

Wasn’t the creation of the Brazilian Center for Natural Disaster Monitoring (CEMADEN) in 2012, practically INPE’s baby, a good thing for the country?
A: Having such an institution is important. But perhaps it could have been created in coordination with INPE and state agencies that deal with natural disasters.
P: There was a spillover process from CPTEC, which compromised its mission.
A: For example, the weather forecasting operation was duplicated.
P: We could have established a center that was better linked to existing initiatives around Brazil. Research groups from other states that were doing good work, such as in Santa Catarina, were left feeling like their efforts were not appreciated. Now, CPTEC doesn’t have the number of people needed to incorporate advances in climate modeling. Two years ago, with the aim of reversing this situation, INPE began an institutional program, funded by the MCTI [Ministry of Science, Technology, and Innovation], to develop a new Brazilian community model of the Earth system, known as MONAN.
A: It stands for Model for Ocean-laNd-Atmosphere predictioN.
P: MONAN has a coordinator from INPE, Saulo Ribeiro de Freitas, and an external coordinator, which is me. More than 50 scientists from all over Brazil are involved. In Tupi, Monan is the name of the god that created the world, the heavens, and living beings. In Brazil, the project is now spread across several universities, each with its own mission. We need everyone to contribute to this national demand. And our capacity for high-quality predictions is high.

Is it still possible to reduce greenhouse gas emissions enough to stop global warming exceeding 1.5 ºC, as per the objective of the Paris Agreement?
A: A significant change in emissions would already have to be taking place. The climate’s response time is slow. It’s not like you cut emissions, and global warming immediately ends.
P: My impression is that the necessary actions will only be taken when the “economic pain” becomes unbearable. It’s clear that there has been some progress, with a series of international treaties, such as the Kyoto Protocol and the Paris Agreement. But we are still a long way short of what is needed in terms of commitments to reducing greenhouse gas emissions worldwide.
A: Science has advanced a lot, and we now know that climate change is already occurring. But society is facing some major dilemmas, such as how to balance environmental impacts and the economy. This issue has never been discussed as much as it is today.

Is there evidence that extratropical cyclones, like the one that recently hit Rio Grande do Sul, are becoming more frequent or stronger in Brazil?
P: The IPCC has highlighted that climate change is increasing the frequency of more intense cyclones and typhoons. In my classes on the topic, I often tell a story about why cyclones form. From a thermodynamic perspective, they stabilize the atmosphere, transporting heat from below to above and thus preventing excessive heat at the Earth’s surface. Convective clouds, the big vertical ones that form on very hot days, also have the same effect. Global warming caused by the increased level of greenhouse gases has the opposite impact—it tends to destabilize the atmosphere, making it warmer close to the ground and cooler higher up. So to stabilize the temperature on this hotter planet, the atmosphere has to “make a decision:” either produce more isolated convective clouds or more intense cyclonic systems to resolve the thermodynamic instability. From a practical point of view, if the winds are favorable, it is more efficient to produce intense cyclones than isolated clouds. And cyclones solve the problem of thermodynamic instability more quickly. The atmosphere “makes decisions” based on the laws of conservation that control air movements, especially the law of conservation of thermodynamic energy.

Do you talk a lot about the climate and meteorology at home?
P: From the moment we started university we studied together. We were always exchanging ideas about science and teaching. Sometimes our children even asked us to stop talking about work so much.
A: I think the fact that we exchanged ideas on research-related issues was beneficial for both of us. Having young children was a very difficult phase of my life. Reconciling work with taking care of them wasn’t easy. I even thought about reducing my workload at the university, but Pedro said it was just a phase, that it would pass. I ended up not making any changes.