Sea Ice Suite

Last update: 1/27/2021

This POD calculates maps of the sea ice concentration (SIC) for the period 1979-2014 for one ensemble member from a model compared to observations for the following quantities:

  • mean: the mean (obviously) by month \(\%\).

  • trend: the linear trend by month \(\% s^{-1}\).

  • standard deviation: the standard deviation by month \(\%\).

  • standard deviation after detrending: the standard deviation of detrended data by month \(\%\).

  • one-lag correlation: the correlation at a lag of one month and one year of detrended data by month \(\fraction\). For a one-month lag, the map for January shows the correlation of January and February. The map for February shows the correlation of February and March. And so forth. For a one-year lag, the map for January shows the correlation of January and January a year later. And so forth.

All calculated are maps shown for each month. Observations of sea ice concentration are from HadISST1.1 (Rayner et al, 2003).

Version & Contact info

  • Version 1 (1/26/2021)

  • PI (Cecilia Bitz, University of Washington,

  • Developer/point of contact (Cecilia Bitz, University of Washington,

  • Other contributors: Lettie Roach


The current package consists of two files:

  1. which loads data, calculates statistics, regrids to grid of observations and plots everything.

  2. contains functions for computing the linear regression and lagged correlation used in this POD and also our mixed-layer depth POD.

Required programming language and libraries

Python version 3, numpy, pandas, scipy, netCDF4, cftime, xarray, dask, esmpy, xesmf, matplotlib, cartopy

Required model output variables

Monthly mean sea ice concentration on the original model grid for 1979-2014 from a historical simulation.


  1. Roach, L., C.M. Bitz, et al. In preparation.

  2. Rayner, N. A.; Parker, D. E.; Horton, E. B.; Folland, C. K.; Alexander, L. V.; Rowell, D. P.; Kent, E. C.; Kaplan, A. (2003) Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century J. Geophys. Res.Vol. 108, No. D14, 4407 10.1029/2002JD002670 (pdf ~9Mb)