Sunday, 22 December 2013

New PIOMAS Gridded Data: November 2013

New PIOMAS gridded data (effective thickness fields) has been released up to November, hat-tip to Wipneus for letting me know. So I've interrupted my blogging holiday to post on the new data which gives a great view of 2013 from the point of view of PIOMAS.

The regional PIOMAS derived data I have previously released, and which is used throughout this post, has now been updated through to November 2013, it is available in CSV files here. Thickness calculations have not been updated for 2013 because they need concentration which has not been released.

Once again, thanks to Dr Jinlun Zhang and colleagues at the Polar Science Centre for making the gridded PIOMAS data publicly available.

Tuesday, 17 December 2013

Go on, say something outrageous...

I've been having problems with the Tang et al paper about summer mid latitude impacts of sea ice loss. Basically I've been so focused on sea ice that I've a stack of papers I need to re-read on atmospheric impacts, and every time I've tried to 'put pen to paper' regarding Tang et al I find myself needing to re-read several other papers. Unfortunately I've already started to wind down for a Christmas break from work and blogging, so I find that I haven't the motivation.

So I've decided that the final post of 2013 will be a look at percentage open water formation, and a clarification of what I think is a tipping point revealed by the PIOMAS data. Regular readers may already have grasped what I've been getting at before, but now is the time to stop hinting (i.e. 'non-linear') and say exactly what I mean.

EDIT 23/7/14 - after months of consideration and 2014 April data, I have concluded that the effect outlined here will be countered by winter ice growth. More here.

Monday, 16 December 2013

Improved Grid Box Area Calculation

I will be posting properly in the New Year once I have a reply from Dr Zhang. However after one final post of 2013, to be posted tomorrow, I will not be blogging until 2014. I wanted to provide the massive improvement to my sea ice data so that those who want to can use the data.

Grid box areas for each grid box in the PIOMAS domain have been recalculated following advice from Dr Zhang. The error from the PIOMAS monthly series is shown below.

Click on it to enlarge, but basically I was running with a -0.6% error with respect to PIOMAS monthly data, now the error is considerably less (green plot).

  • Previous data: -0.614% average error.
  • New data: +0.002% average error.

For those who want to use the data it is now at a stage where further improvements will be less than the difference between the PIOMAS monthly series, and monthly averages derived from the daily series. I have updated all three CSV files linked to in the previous post presenting PIOMAS gridded data broken down into regions as used by Cryosphere Today.

The data can be found here.

Saturday, 14 December 2013

Early freeze season volume gain.

I've accidentally deleted this post while deleting a post in progress about the recent Tang paper, having decided to relegate that to a mid monthly miscellanea post. So this is a quick re-write of the post that was deleted.

Tuesday, 3 December 2013

Regional PIOMAS Volume Data

I've been busy recently getting the code I use to handle the PIOMAS gridded data into a more tidy state, it was getting the situation where I, the author, was having trouble remembering where the heck I'd coded what. As part of this I've finally dealt with the issue of making a matching set of PIOMAS data broken down into the same regions Cryosphere Today uses. I have also improved the grid box area calculation with help from Dr Zhang.