Turbulent Arctic Ice NSIDC – Complete Video

I find the Arctic sea ice to be amazingly dynamic. Honestly, I used to think of it as something static and stationary, the same region meltinig and re-freezing for dozens or even hundreds of years – not that I put much thought into it either way. Shows you what I know.

This post is another set of Arctic ice plots and an amazing high speed video. The NSIDC NasaTeam data is presented in gridded binary matrices in downloadable form HERE.

The data is about 1.3Gb in size so it takes hours to download, I put it directly on my harddrive and worked from there. The code for extraction took a while to work out but was pretty simple in the end. This code ignores leap years. Formatting removed courtesy of WordPress.

filenames=list.files(path=”C:/agw/sea ice/north sea ice/nasateam daily/”, pattern = NULL, all.files = TRUE, full.names = FALSE, recursive = TRUE)
trend=array(0,dim=length(filenames)-1)
date=array(0,dim=length(filenames)-1)
masktrend=array(0,dim=length(filenames)-1)

for(i in 1:(length(filenames)-1))
{
fn=paste(“C:/agw/sea ice/north sea ice/nasateam daily/”,filenames[i],sep=””) #folder containing sea ice files

a=file(fn,”rb”)
header= readBin(a,n=102,what=integer(),size=1,endian=”little”,signed=FALSE)
year=readChar(a,n=6)
print(year)
day=readChar(a,n=6)
print(day)
header=readChar(a,n=300-114)
data=readBin(a,n=304*448,what=integer(),size=1,endian=”little”,signed=FALSE)
close(a)

if(as.integer(year)+1900<=2500)
{
date[i]=1900+as.integer(year)+as.integer(day)/365
}else
{
date[i]=as.integer(year)+as.integer(day)/365
}
if(i==1)
{
holemask= !(data==251)
}
datamask=data<251 & data>37 ## 15% of lower values masked out to match NSIDC

trend[i]=sum(data[(datamask*holemask)==1])/250*625
}

###mask out satellite F15
satname=substring(filenames,18,20)
satmask= satname==”f15″

newtrend=trend[!satmask]
newdate=date[!satmask]

After that there is some minor filtering done on 7 day windows to dampen some of the noise in the near real time data.

filtrend=array(0,dim=length(newtrend))
for(i in 1:(length(newtrend)))
{
sumdat=0
for(j in -3:3)
{
k=i+j
if(k<1)k=1
if(k>length(newtrend)-1)k=length(newtrend)-1
sumdat=sumdat+newtrend[k]
}
filtrend[i]=sumdat/7
}

So here is a plot of the filtered data:

Here is the current anomaly.

This compares well with the NSIDC and cryosphere plots. This anomaly is slightly different from some of my previous plots because it rejects data less than 15% sea-ice concentration. Cryosphere rejects data less than 10%. In either case the difference is very slight but since we’ve just learned that the satellites have died and are about 500,000km too low, my previous graph may be more correct. I hope the NSIDC get’s something working soon.

All of that is pretty exciting but the reason for this post is to show the COMPLETE history of the NSIDC arctic sea ice in a video. I used tinypic as a service for this 27mb file so don’t worry, you should be able to see it quite well on a high speed connection. It took my dual processor laptop computer more than 15 hours to calculate this movie, I hope it’s worth it. Brown is land, black is shoreline, blue is water except for the large blue dot in the center of the plot. The movie plays double speed at the beginning because the early satellite collected data every other day. You’ll see the large blue circle change in size flashing back and forth between the older and newer sat data just as the video slows down.

After staring at the graphs above you think you understand what is happening as ice gradually shrinks away. Well the high speed video shows a much more turbulent world with changing weather patterns in 2007 and 2008 summer blasting away at the south west corner of the ice. I’ve watched it 20 times at least, noticing cloud patterns (causing lower ice levels), winds, water currents and all kinds of different things. I’m not so sure anymore that we’re seeing a consistent decline to polarbear doom, with this kind of variance it might just be everyday noise.

Maybe I’m nuts, let me know what you see. Click on the image for the video.

30 Year Arctic Sea Ice - NSIDC NasaTeam Bootstrap - Click to Play