By January of this year a major chunk of my PhD work was winding to an end. I had spent a long while looking at the effect of stratospheric aerosol geoengineering on the circulation of the stratosphere, which will form the second (and probably biggest) of the three results chapters in my PhD thesis. At the start of my project I had spent a lot of time reading about stratospheric dynamics and it’s now a somewhat familiar area to me. Well, almost. I still find some chunks counter-intuitive, and sometimes downright baffling. But at least it’s baffling in a familiar way.
We are always reluctant to move away from the familiar. But the work for my final results chapter required that I take the plunge into material and theory that was very much unfamiliar. I was going to look at the impacts of geoengineering on the tropospheric circulation. I eased myself into it by thinking about the tropospheric jet streams first. I at least have some grounding in this area. The dynamics of the midlatitude jet streams is somewhat similar to the dynamics of the stratosphere, and my undergraduate degree in Meteorology has quite a heavy emphasis on the theoretical underpinning of it all. The work on the jet was a nice transition.
Recently (over the past month or so) I have been thinking about precipitation. Especially tropical precipitation. Now, the Earth’s Tropics are meteorologically very different from the midlatitudes. In the midlatitudes the Coriolis Force is a significant effect and weather is determined by large scale wavelike motions producing depressions and anticyclones. Rainfall is mostly frontal in nature. In the Tropics the Coriolis Force is negligible. As a consequence we don’t usually see very large horizontal temperature gradients. This means we don’t see large, rotating weather systems. Rain comes from convective storms, on a much smaller scale than midlatitude frontal depressions. There is so much moisture in the air in the Tropics that the vertical temperature profile pretty much everywhere shows evidence of the release of heat when water vapour condenses to form rain. This forms a characteristic moist adiabatic temperature profile (see image below). Without a strong Coriolis Force this temperature profile is spread over the Tropical belt, so we see it even outside the rain-producing regions.
In order to interpret my model results I had to learn to think differently. Intuitions learned from midlatitude dynamics don’t apply this close to the Equator.
Learning new theory can be pretty intimidating. It’s difficult to know which paper to read first. Sometimes I find myself feeling paralysed. I have a pile of things to read but keep having to refer to different sources to understand terminology, or to get to the bottom of some ‘obvious’ physical understanding not fully explained in one piece of research. Then I took a different tack. I went to see one of the hundreds of other people working in the Department of Meteorology.
This department has experts on any conceivable area, and now, when I’m learning new theory, this is becoming invaluable. In a single hour with a researcher in tropical meteorology I ‘got’ it. I understood the fundamental differences between tropical and midlatitude thinking. Now I can read those papers with confidence. Now I understand the terminology, and a little of the intuition as well. Self-teaching works well (and is entirely necessary for a PhD student) but spending a little time with an expert can help one learn how to teach oneself. This is much the same as, how, when learning a foreign language, you must first learn enough to communicate on a basic level. Once you have that, you can begin to immerse yourself, to learn from conversation with native speakers. The amount of learning that goes on increases exponentially with time. You learn far more from native speakers. But you need to do that initial bit of work to access this higher plane of learning.
Talking of foreign lands, I will soon be off to the 2013 EGU (European Geosciences Union) General Meeting in Vienna. It’s a colossal conference (nearly 12,000 people attended last year) and I’m sure the experience will be educational, entertaining, confusing and exhausting. I’m sure I could list adjectives forever on that one. I will try to write some blog posts and Tweets during the conference, reflecting on what it’s like for a naive young PhD student to be launched into one of the world’s biggest academic conferences.