Weather on a planet with no continents

[Somes J]

Hi. I'm planning to use an all-ocean planet as a setting in a science fiction story, and I was wondering, what would the effect of an absence of continents be on the planet's weather?

The planet is something like 98% water-covered, its only land is a number of islands, mostly small, the largest are comparable to the major Japanese or Carribean islands. It's otherwise relatively Earth-like, although somewhat warmer (ice-free poles).

One thing I'm curious about, I've read speculation that an all-water planet might develop very powerful semi-permanent hurricanes, like you see on gas giants, since there's no land for them to break against. Don't hurricanes follow general large-scale atmospheric circulation patterns which eventually take them to higher lattitudes, where they dissipate because the water is cooler?

 

[klimatos]

Hi. I'm planning to use an all-ocean planet as a setting in a science fiction story, and I was wondering, what would the effect of an absence of continents be on the planet's weather?

The planet is something like 98% water-covered, its only land is a number of islands, mostly small, the largest are comparable to the major Japanese or Carribean islands. It's otherwise relatively Earth-like, although somewhat warmer (ice-free poles).

One thing I'm curious about, I've read speculation that an all-water planet might develop very powerful semi-permanent hurricanes, like you see on gas giants, since there's no land for them to break against. Don't hurricanes follow general large-scale atmospheric circulation patterns which eventually take them to higher lattitudes, where they dissipate because the water is cooler?

By the "planet's weather" I assume that you mean both weather and climate. Climate is a function of latitude, elevation, and continental position. By removing the latter two, you will have a strongly zonal climatic pattern based on latitude. Seasonality is a function of axial inclination relative to the plane of revolution, so you might want to give that some thought.

Weather on an all-water planet will be more moderate and less variable than on our own, because of the high specific heat of water compared to land. There will be less variation from day to night and from season to season.

Yes, hurricanes do dissipate as they move poleward, but not always. Just ask the British!

 

[Simfish]

The key phrase to use is "aquaplanet". Those are all-ocean GCM models that climate scientists have used to describe planets that are full of oceans.

http://scholar.google.com/scholar?q=aquaplanet&hl=en&btnG=Search&as_sdt=1,48&as_sdtp=on for more info.

Also, in one of my classes, we ran aquaplanet simulations. Check them out here: http://www.atmos.washington.edu/academics/classes/2011Q1/380/

(they're under week 4).

It's hard to make a conclusion though, since it REALLY varies on the solar influx you get (and also on factors like rotation rate and stuff - actually).[1] And maybe the climate model, since most climate models are only slab ocean models, and slab ocean models don't describe much of the ocean's complexity.

[1] Actually most of those are constants if you just care about Earth - I was just reading way too many papers on tidally-locked aquaplanets orbiting red dwarf stars.

 

[Ophiolite]

A complicating factor could be submarine topography that would impact upon oceanic circulation. That might give you some variety that would be useful for a plot twist.

 

[Xnn]

Kevin Costner already did that story with Waterworld.