Station INPA

Questions for David Adams

How did you become a scientist/engineer?

As a child growing up in the deserts of Southern California, I was fascinated with the strong thunderstorms that occurred ocasionally in the summertime. I also always dreamed of being able to travel. Going to the university allowed me to travel for the first time and also to study the atmosphere and storms.

What is your job like?

I have a lot of freedom in my job. Before I was able to go to the university to study, I had to work for many years in a supermarket and as a house painter. In those jobs, I always had a boss and I was told what to do. Now, as a scientist in a university, I have no boss and no one tells me what to do. I do what I like to do, science, and I get paid for it. I work with people from all over the world and have had the opportunity to live in four different countries.

What are you hoping to learn from your research?

I am trying to understand how the storms in the tropics work, why they form and how they grow to become so large and powerful. The GPS technique that we use is totally new for these types of studies, so there is a lot to be done.

The Amazon Dense GPS Meteorological Network

The region of the Amazon Rainforest acts an engine for planet Earth's atmospheric circulation. Most of the sun's energy is absorbed at the surface over equatorial regions of the planet, such as the Amazon Rainforest. This solar energy is used to heat the surface and evaporate water vapor. All of this heat and water vapor at the surface causes the atmosphere to become unstable. When the atmosphere becomes sufficiently unstable, the moist, hot air begins to rise and very large storms are formed which can cause a lot of rainfall and lightning.

What these storms are really doing is transferring the excess energy at the surface to the atmosphere. Given that that these storms occur almost daily of the Amazon Rainforest, the energy that is transferred to the atmosphere then builds up so much that it is forced to to higher latitudes. This is why we say that the equatorial regions act like an engine for the Earth's atmosphere.

How the equatorial atmosphere actually becomes unstable is much more complicated than the basic picture described above. Sometimes, it appears that the atmosphere is very unstable, but it doesn't rain. Other times the atmosphere appears stable and very strong storms form. In order to understand why this happens, we need to carry out long-term (over several years), scientific studies, to be able to see under what conditions rainstorms do or do not form. This is the reason why we brought GPS meteorological stations to the Amazon Rainforest.

GPS Meteorological stations tells us how fast and how much water vapor is accumulating above the GPS antenna. When sufficient water vapor has accumulated above the antenna, clouds will begin to form. If the atmosphere is unstable, this clouds will grow taller and cause more water vapor to accumulate over the antenna. This process continues until large raindrops form in the clouds and begin to fall under the influence of gravity; that is, what we call rainfall. When the storm finishes the amount of water vapor decreases above the antenna (See Figure 3). When we look at how the water vapor measured by the GPS changes before and after the storm, this gives us an idea of how strong the storm was and how much energy is transferred to the atmosphere. We can also look at other variables such as how tall the clouds were. We use satellites in space to make these cloud measurements.

In the Amazon, because it rains so much, it is very difficult to find place to install scientific equipment. Most of the region is either the Amazon river or rainforest. For this reason, we had to install GPS Meteorological stations on people's houses (Figure 1) or on tall towers in the middle of the rainforest (Figure 2). Although the Amazon Dense Meteorological Network (20 stations, see Figure 4.) lasted just a little more than one year, a few of the stations remain will be used to continue to study rainstorms in the Amazon for many years to come.