Animated Images of Arctic Sea Ice Extent Decline

This post shows how to download and animate a series of Arctic Sea Ice Extent images using R and the animation package.

In my previous post, I showed how to download the daily arctic sea ice extent  data and generate an animation of the time series plots. In this post I show how to animate the monthly images provided by NOAA’s Nation Snow and Ice Data Center.

###### RClimate Script: NSIDC_Monthly_Sea_Ice_Extent_Images.R
## Download and process 1981 to 2012 Monthly Arctic SIE Images
## Sept. 5, 2012: http://chartsgraphs.wordpress.com; DK O'Day
##############################################################
  library(animation)
## Establish work dir to place downloaded images and gif file
  setwd(getwd())
  where <- getwd()

## Monthly NSIDC Extent Immage Link
# ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/Aug/N_198108_extn.png
  part_1 <- "ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/Aug/N_"
  part_3 <- "08_extn.png"

# Specify month number for animation
  m <- "08"

# Loop through years to create link and download images
  for (y in 1981:2012) {
     file_name <- paste(part_1, y, part_3, sep="")
     copy_name <- paste(where, "//asie",y,m,".png",sep="")
     download.file(file_name, copy_name, mode="wb")
     }

## copy last file c times to extend gif animation
    for (c in 1:2)
    {
     file_name <- paste("asie2012",c, ".png",sep="")
     file.copy(from= copy_name, to = file_name, overwrite=T)
    }

## Use animation package to generate gif file
  ani.options(convert=shQuote('C:\\Program Files (x86)\\ImageMagick-6.7.9-Q16\\convert.exe'))
  ani.options(outdir = getwd()) # direct gif output file to working dir
  ani.options(interval= 0.70)
  im.convert("asie*.png", "asie_image_animation.gif")

Here is a link to the R script file.

R Script to Build Animation of Arctic Sea Ice Extent – Update 9/3/12

In my previous post I showed an animation of Arctic Sea Ice Extent from the 1980′s through August, 2012 (link).  In this post, I show how to build this Arctic Sea ice Extent  animated chart.

Source Data

The Arctic Ice Sea Monitor (link)   updates their daily csv file with the latest satellite based arctic sea ice measurements.  Here is the daily csv file link.

R script

To develop my animation of the daily Arctic Sea Ice extent, I decided to produce a plot for each year that showed the current year in red and the previous years in grey.  I go this idea from Tamino at Open Mind.

Here is my R script: link.

Once I have the individual png files for each year, I use Photoshop Elements to generate my animation.

After getting Pierre’s comment about using the animation package, I gave it another try. The 2nd time,  I got it to work with ease.

I can now update the daily ASIE plot automatically without any Photoshop Elements involvement.

Thanks Pierre.

Arctic Update

I have restarted updating my Arctic Update Page which went into hibernation in late September, 2010 after the Sea Ice minimum was reached. I continue to be concerned about the rapid Arctic Sea ice decline, I see it as one of many threads of evidence on the serious consequences of global warming.

1/16/11 Update

After a break, I have restarted daily updates to my Arctic Update page.  I will start slowly,with just 4 charts and limited discussion.  I will be adding additional charts and analysis as the year unfolds.

Arctic SIE Trend for Latest Month

December, 2010 showed the lowest SIE in the1979-2010 period.