Defining lon-lat coords of 1000-metre isobath and extracting region around it

Hello everyone. I would like some help and advice with defining the 1000 m isobath around Antarctica and then using that as a location definer.

First, how do people go about defining the 1000 m isovath? Specifically, I am looking for a continuous set of long lat pairs that extend around Antarctica. Is there a set of coordinates that are used by the community?

Second, with those coordinates. I presume that it would be fairly easy to extract the region say 100 km either side of the isobath. I haven’t tried it yet, but my plan would be to: i) at each lat/long add and minus the latitudinal step I am interested in, ii) use something like this (Using a polygon (long, lat) to define and extract a region of the model output) to extract the gridded information.

Thank you in advance, Kathy

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Hi Kathy,

Is this to apply to ACCESS-OM2 output? There’s an example at the top of this cross-contour transport notebook on how to select out a single isobath contour.

Then in terms of finding points within 100 km of this contour, I would think this nearest neighbour notebook would do that for you.


This example uses the matplotlib contour. There is also a way in scipy to find contours : Contour finding — skimage 0.23.2 documentation, which from memory has slightly more control over the smoothing of the contour. The are probably based on very similar / the same algorithm though.

@adele157 and @anton
Thanks both for your suggestions. I will have a go, and put the solution back on here. Cheers, Kathy

(Note: it really helps if you add tags to a post you make. Makes it easy for others to find it if they happen to search for something similar. I took the liberty to add a few.)