7 Responses to “Stormy weather ahead? at @ScienceLondon SciBar”

  1. omnologos Says:

    You could have told readers about your talk beforehand! 😎

    • andyrussell Says:

      Yes, good point. I’ve not been very active on the blog and twitter recently (and haven’t even got round to finishing the post about why I’ve not been very active!)

  2. jim McQuaid Says:

    That is a great illustration of resolution…..

  3. Malte Says:

    Cool. Could you be a bit more specific in which cases which resolutions would be used? Like the usual weatherforecasting company would use Lego or Duplo? (I could, for example, imagnine, that the Lego model would need too long to calculate, so that weather forecasters would use Duplo, but that research and leading edge fluid dynamicists would use a model of small Lego bricks.)

    • andyrussell Says:

      Hi there

      Thanks for the comment! A bit of a health warning about the following answer: there are some pretty big assumptions made at each stage!

      So, if we look to the CMIP5 suite of global climate models that are being run for the IPCC then I think that the highest resolution of those is about 100km. I can lay an approximate 100x100km grid over a satellite image of the cloud that is pictured in the post, see below. So in this case the the big cube is a pretty good representation in that it sees no detail.

      Climate model resolution

      So, if the cube is 100km res then the lego might represent a 10km resolution model and the duplo a 20km model. I think that the Met Office weather forecast model is (pseudo?) operational at about 1km or 1.5km (or it might still be 4km, I’ve not been following this much lately!) so the lego representation of this cloud is about a factor of 10 too crude when compared to one of the leading modelling certers.

  4. Jg Says:

    Delightful analogy. Thanks. I know a few Lego experts I’ll be sharing this with.

  5. [removed - AR] Says:

    [Wow, how good is this spam?!? It’s a section of the Nature Soapbox Science bit I wrote that I link to in the article. Is this automated? It’s very clever if it is! – AR]

    The second problem is that some important things – like severe storms, tornados and regional and local changes such as river catchment area precipitation changes – are too small for climate models to represent or resolve. The reason for this is that these computer models split the atmosphere (and oceans) into a 3D array of boxes. The important equations are solved in each box and then they pass information to neighbouring boxes as appropriate at each model time step. These boxes usually have horizontal dimensions of around 100-400 km to allow for a convenient computational time. However, storms and tornados work on scales of significantly less than 100 km so there’s no way that the models can tell us anything about these things. This problem is particularly acute in relation to the IPCC SREX as this analysis used a suite of climate model data from a project called CMIP3, which was completed in 2006 for the last IPCC assessment and, therefore, does not use the most up-to-date and highest resolution model data. (The data currently being prepared for the next IPCC Assessment Report called CMIP5 is, however, not yet complete so perhaps this criticism is a bit unfair.) Is this good enough?

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