Arctic Amplification – November, 2013: Updated 12/20/13

Updated (bold italic) 12/20/13 to reflect comments from David. 

NASA’s GISS temperature anomaly map (link) for November, 2013 is reproduced  below. It uses a 2×2 degree grid cell for the globe. 

GISS_anom_map_11_13

The November, 2013 GISS temperature anomaly shows the critical global pattern that is important to recognize because it is fundamental to understanding why global warming is so dangerous.

First, the overall global anomaly for November, 2013 was 0.77 degrees C.  The 2 degree latitude zone mean anomaly varied from a low of 0.068 to a high of 2.33. So the mean global anomaly does not tell the full story, we need to look at the geographical distribution to really understand the global warming pattern.

As we examine the geographical distribution of the November, 2013 anomalies, we see that they tend to increase as we move from the equator toward the poles.  This pattern,  called polar amplification, means that the polar regions, particularly the Arctic region, warms much more rapidly than the overall global mean.

I developed this chart in R to display the mean zonal anomalies by 2 degree latitude zones to help me visualize the November, 2013 anomaly patterns.

art_amp

Here is the R Script that I used to produce the chart.
#### GISS Temperature Anomaly - Zonal mean by 2 degree latitude
##K O'Day, Dec. 18, 2013
##############################################################################################################################
 link <- c("http://data.giss.nasa.gov/tmp/gistemp/NMAPS/tmp_GHCN_GISS_ERSST_1200km_Anom11_2013_2013_1951_1980/nmaps_zonal.txt")
 mon <- "November, 2013"
 title <- paste("Mean Temperature Anomaly by 2 Degree Latitude Zones\n", mon, sep="" )
 note_1 <- "GISS Temperature Anomaly\n (1951-1980 base period)"
 df <- read.table(link, skip=4)
 par(las=1, oma=c(3,1,1,1), mar=c(5,5,3,1), ps=11)
 names(df)<- c("Zone", "Anom")
 #png(file="C://R_Home//Charts & Graphs Blog//RClimateTools//a_Revised_Blog//art_amp.png", bg="white")

 plot(df$Anom, df$Zone, xlim=c(0,3), ylim=c(-90,90), type="l", axes=F, xlab="Mean Anomaly for Zone - C",
      ylab = "Latitude",  xaxs="i", yaxs = "i", main=title)
   axis(1, at=NULL)
   axis(2, at=c(-90,-60,-30,0,30,60,90))
   abline(h=40, col="green")
   abline(h=0, col="darkgrey")
   abline(v=0.77,col = "black" )
   abline(h=64, col="blue")
   text(2.5, 43.5, "Philadelphia, Pa.", cex=0.7)
   text(2.7, 67, "Reykjavík, Iceland", cex=0.7)
   text(2.25, -20, note_1, cex=0.75, adj=0)
   rect(0.6,-65,0.85 , -50, col = "white", border = "white")
   text(0.77, -60, "Global Mean @ \n0.77 C", cex=0.7)
 mtext("D Kelly O'Day - http://chartsgraphs.wordpress.com", 1,1, adj = 0, cex = 0.8, outer=T)
 mtext(format(Sys.time(), "%m/%d/ %Y"), 1, 1, adj = 1, cex = 0.8, outer=T)
# dev.off()
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5 responses to “Arctic Amplification – November, 2013: Updated 12/20/13

  1. Thanks for sharing codes. The GISS dataset website link now seems to be broken. But after I fixed the link, still getting error after the code: “df <- read.table(link, skip=4)" as below. Appreciate if you can comment on where I am going wrong.(Do I need to install some package?)

    Error in file(file, "rt") : cannot open the connection
    In addition: Warning message:
    In file(file, "rt") : cannot open: HTTP status was '403 Forbidden'

  2. Pingback: Arctic Amplification – November, 2013: Updated 12/20/13 - R Project Aggregate

    • Prad – Good question. The issue arises because the NASA web site generates a file for the map based on user requests. You will need to do th efollowing:

      1. Go to NASA site, submit request for map: http://data.giss.nasa.gov/gistemp/maps/
      I use 1200 KM smoothing and Eqirectangular projection. You can select Nov or any other month

      2. When you press Make Map, the requested map is generated.

      3. Scroll down below the map and you will see Downloads. If you right click on text you will get NASA’s current web link for the generated map.

      4. Replace the link address in my R script with NASA’s current web link. It should work.

      Please note that NASA’s web link is temporary so you need to run script within a day or so after you generate map.

  3. I’m not sure I understand this map correctly. You state that the minimum anomaly is 0.068 degrees, yet the map shows areas (especially in northern America) where the anomaly, according to the legend, is negative. Did i get something wrong?

    • David

      Good question. The map shows temperature anomalies for 2×2 degree grid cells of the globe.

      The chart shows the zonal mean for 2 degree latitude bands.

      So you are correct, there are 2×2 grid cells that are below 0.0. However, there all 2 latitude degree zones mean values are above 0.0

      Kelly

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