Another visitor ... [*]

Had the unusual pleasure of a visiting student this week, one JH from Stockholm University. I'd hosted her PhD. supervisor, JN, for a Friday Seminar last year (on a somewhat arcane physical oceanographic subject), and at the time he mentioned a new student he had who was moving into what, for him, was new research territory: the carbon cycle. Anyway, said student finally came to NOC this past week, and TT and I tried to pass on some of our hard-earned "knowledge" on the topic.

Actually, it was travelling at least as much in the other direction at times. Building upon some rather theoretical work one of her PhD. co-supervisors did in the 1990s, J's work was largely based on a clever re-framing of the ocean's carbon cycle that throws out DIC and alkalinity, and replaces them with acidic-carbon (^aC) and basic-carbon (^bC). This originates, in part, from the somewhat strange nature of alkalinity as a concept, which sees it regulating DIC concentrations at the ocean's surface while itself being composed of a number of ionic species including bicarbonate and carbonate. I've never really liked its definition, and always struggle with it when I think of what changes to it result in.

A key upshot of J's model is that the organic carbon portion of the biological pump drives ^aC, while the inorganic portion drives ^bC, which nicely separates processes. It also makes the changes driven by riverine carbonate (to ^bC) and anthropogenic CO₂ (to ^aC) more straightforward to follow. Which, for her work on oceanic CO₂ storage, is pretty handy. To be honest, I didn't follow it at first, and I'm still not quite sure I've got the full measure of it yet, but I now see that it's a pretty clever way of framing things (rather than very strange as I first thought).

The rationale for J's work is to create a simplified ocean carbon submodel that can slot nicely and cheaply into an integrated assessment model (IAM) and outperform the existing decay term that's currently used. From what she showed us, her model's a definite improvement on this front - though it will now make the behaviour of this IAM a bit more complicated and time-dependent (the price of quasi-realism). And it'll hopefully make for a nice publication for her to boot.

Anyway, considering the rather narrow focus of this rationale, as well as the simplicity of her model's ocean biogeochemistry, I was pretty impressed at J's knowledge and grasp of wider issues in marine biology (DOM, acidification, PFTs, ect.). She pressed me pretty hard on most angles, and I found myself in arm-waving territory on more than one occasion. She even got me on the defensive and playing my "until-there's-a-complete-description,-I-refuse-to-add-your-process-to-my-model" card. Usually I manage to fob people off long before they get there.

I'm now half-thinking about trying to apply her model in my own work, though I'm less sure that it'll make quite as interesting an exercise as I first thought. Squeezing ^aC and ^bC out of my DIC and alkalinity terms is easy because of the assumptions involved, but that may also make it less interesting. Still, to demonstrate the utility of this approach in more complex, 3D frameworks, it's probably worth having a go. I just have to pull my finger out to find and plug the holes in MEDUSA's leaky oxygen cycle ...

Anyway, aside from the science, J was nice enough to chat about Swedish crime fiction (obviously), the highlights of Southampton, intra-UK politics, desirable conference destinations, nationalist parties in Sweden and the UK, Jane Austen and blue plaques, etc. I say "chat", but I'm not sure she got a word in edgeways. (Note to self: more listening, less pontificating)

---

^[*] ... stay awhile, stay forever