Friday, March 02, 2007

The Megamonsoons

The megamonsoon was something that I first encountered in the book I just finished reading. The megamonsoon seems to have come about as an explanation for the transition in observed river systems in the early Mesozoic. The basic concept was that there was a massive monsoonal cycle that encompassed large areas. I'm unsure based on what I've read whether or not the intent for calling it the 'megamonsoon' is because the effect was so wide spread - seems to have been at one time or another all to have had a major effect all over the coastal regions of Pangea - or if it was due to the nature of the monsoon's intensity.

To be honest, my mind keeps conjuring up massive seasonal innundations. Stuff that makes the cloud forests of the Andes seem like a dry place or Bangladesh's wetness not that bad. It would make for an interesting reason why the river systems changed so much from the Permian to the Triassic in many locales. In fact, it would also make sense that the areas seem somewhat sparse vegetation-wise because deeper root structures, iirc, didn't evolve until afterwards. Fraser in the book suggested that the uplands were rather different than the lowlands in the Triassic, perhaps even very well vegetated.

One of the interesting things about the Placerias Quarry is that it seems to be something of an anomaly. There were a lot of the dicynodont there and in stone types that seem to be rather atypical for the Triassic. Placerias isn't common in a lot of locales except as a single bone or so that seems to have been washed in (re most of the petrified forest). Some relatively recent work on the quarry suggests that it wasn't the classically described swamps, butan environment that was frequently drenched and then dried out. That becomes more consistant with the other locales of the same chronology. At least as I understand it.

If the dicynodonts were uplands critters that would be...interesting...especially with respect to Ward's Low O2 hypotheses. An uplands therapsid when sealevel was supposed to have the O2 content of 10k feet. huh. Even more interesting. it makes me wonder if part of the reason that the great Triassic experiment in forms had little to do with oxygen and more to do with the fact that the favourable habitat was more fractured. That fracturing here might be from PT Event and then the strengthening of the megamonsoon such that anything more than growth between the massive season flooding seems difficult. Then again...the petrified forest. hrm.

At any rate, I'm almost out of time here and the purpose of thinking about this megamonsoon was not the Ward atmospheric hypoxia stuff, but rather that it would seem to me - since there are some papers out there that suggest that the megamonsoon started prior the Permian even but reached its peakin the Triassic - that the Great Dying would definitely be effected by this. Consider that if you get your precipitation all in one go and its been hydrogen sulfide tainted...erm. bad stuff.

I think I need to figure out how to dedicate some time to model this. I'd love to collaborate on that, but the star in that field for the PT boundary sims was rather pissed at me last I checked due to a misunderstanding. I don't want to have to replicate the whole basic data, but...ugh. well. IDK. We'll see. I need to pull apart the coupler in CCSM anyways for something...and since the woman that wrote the puppy happens to ahve an office directly across from mine...BWAHAHAHAHA. ahem.

2 comments:

Carlos said...

I was rather fascinated to find out that the megamonsoon theory had some of its roots in weather simulations from the early 1970s! (Hahn and Manabe 1975, cited in Dubiel et al. 1991)

Grids with 250 km resolution -- must be around eight thousand cells. That's Civ2 size.

There are ludic possibilities here.

Will Baird said...

That is interesting. I'd like to see what the changes are when we apply modern weather modeling techniques to the problem. Very interesting. *strokes chin*

I'm looking at taking the code to pull apart the coupler in so,me spare time and make it multi-machine friendly. IE able to handle communication between multiple machines. The woman that wrote the coupler is across from me, so we'll see what I can do to pick her brains. She gets twitchy at the suggestion, but finds the idea interesting.

It would tie very nicely in with a paper that I've been working on for a while now off and on. We'll see.