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1

General Discussion / Re: DEM for climate model

« on: December 06, 2013, 01:00:26 pm »

Hi all,
So, we 'published' our results in the end, using  DEM I created by tracing some of the Fonstad and Tolkien maps.  See here:
http://www.bristol.ac.uk/news/2013/10013.html
Hope it is of interest...the results are presented in detail in the pdf available from the link above.
cheers,
Dan

2

General Discussion / Re: DEM for climate model

« on: November 05, 2013, 02:44:11 am »

Hi,
Thanks very much for your reply - very useful!

The climate model I am using was developed at the UK Met Office.  It is essentially the same model that they use to produce weather forecasts, but running at a lower resolution.  It is computationally expensive (even at the low resolution I run at, it takes a week on a parallel supercomputer to simulate 50 years of weather - and several hundred years are needed to generate a meaningful climatology and to allow the model to 'spin-up' from the initial state of the atmosphere which is provided by the user).

Because the model is based on the fundamental equations of fluid mechanics and physics, the weather is all internally generated, and the only input file which the user supplies is the topography and bathymetry - everything else (temperature, precipitation, winds, clouds, humidity, pressure, vegetation....etc...etc) is predicted by the model. [actually, you also have to tell it some physical and geophysical constants like the acceleration due to gravity, molar gas constant, strength of the sun, amount of greenhouse gases in the atmosphere etc.]

So, yes, the resolution is low (and in fact the climate model runs at an even lower resolution than the 720x360 which is needed to generate the topography and bathymetry), but it is not dissimilar from other climate models which are run globally.

I wanted to start a test simulation, so I generated my own topography/bathymetry by tracing some of Fonstad's maps, and colour-coding for different heights, then converting to a bitmap and reading into some IDL code (which then adds some random noise, decreases bathymetry away from the coasts, and lowers rivers relative to the surrounding land).  The climate model is now running based on this topography, and is busy producing weather!  It is still early days, but the initial results look very interesting...I'll keep you posted!  It would be interesting to try a different input global map of heights/depths, so please do send me one if anyone has time to generate it!

Many thanks,
Dan

3

General Discussion / DEM for climate model

« on: October 24, 2013, 08:14:12 pm »

Hi all,
I am a climate scientist at the University of Bristol, UK, and a huge Tolkien fan since an early age!  For some outreach activities, I am interested in running a climate simulation of Tolkien's Middle Earth.  My 'normal' work involves setting up the climate model for many past time periods of the Earth when the continents were in different positions, so doing the same for Middle Earth / Arda is not a huge leap!  In order to do this, I need a DEM.  In particular, a DEM (topography and bathymetry) at a resolution of about 720 x 360 points covering the 'globe' (any resolution is actually OK, as I can regrid).  Most formats would be OK (e.g. zipped ascii/binary).  I could probably work with a native ArcGIS format as well.  I would obviously acknowledge the project appropriately if it was successful.
Looking forward to hearing from you - hope this is possible!
Thanks a lot,
Dan