R Script to Build Animation of Arctic Sea Ice Extent – Update 12/20/13

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:
Be sure to set your working directory to appropriate location!!

library(animation)
  ani.options(convert=shQuote('C:\\Program Files (x86)\\ImageMagick-6.7.9-Q16\\convert.exe'))
## Use setwd() to specify directory where you want png images to be saved
  setwd("<strong>C:\\R_Home\\Charts & Graphs Blog\\RClimateTools\\Arctic_sea-ice_extent</strong><em>")
# use png_yn to toggle between plot output to png file or screen
  png_yn <- "y"
# Establish chart series patterns and colors to be able to distinguish current yr from previous years in plot
  pattern <- c(rep("dashed", 5), rep("solid", 12))
  ser_col <- c(rep("black",5),rep("grey",12))
# Establish chart annotations for date, chart title,
  what_date <- format(Sys.Date(), "%b %d, %Y")  # with month as a word
  title <- paste("IARC-JAXA Daily Arctic Sea Ice Extent*\n", what_date)
  note_1 <- "*Extent - Area of Ocean with at least 15% Sea Ice"
  par(oma=c(2,1,1,1)); par(mar=c(2,4,2,1))
#  Day of year axis setup
## Set up basic day of year vectors (mon_names, 1st day of mon)
  mon_names <- c("Jan", "Feb", "Mar", "April", "May", "June", "July", "Aug", "Sept", "Oct","Nov","Dec")
  mon_doy <- c(1,32,60,91,121,151,182,213,244,274,305,335,366)
  mon_pos <- c(16, 46, 75, 106,135, 165, 200, 228, 255, 289, 320, 355)
# Read JAXA Arctic Sea ice Extent csv file
# Data File: Month,Day,1980's Avg,1990's Avg,2000's Average,2002:2012
  link <- "http://www.ijis.iarc.uaf.edu/seaice/extent/plot.csv"
  j_data <- read.csv(link, header = F, skip=1, na.strings = c(-9999))
 series_id <-  c("mo", "day", "1980s", "1990s", "2000s","2002", "2003", "2004", "2005", "2006", "2007", "2008", "2009",
                "2010", "2011", "2012", "2013")
 colnames(j_data) <- series_id
# File has data for each day in 366 day year
# Establish Day of year
  for (i in 1:366)   j_data$yr_frac[i] <- i
    #convert ASIE to millions Km^2
   j_data[,c(3:17)] <- j_data[,c(3:17)]/1000000
# Loop through years
   for (j in 3:17)
  {
     png_name <- paste("asie",series_id[j],".png",sep="")
      if (png_yn =="y") png(filename=png_name)
      which_yr <- j
      no_yrs <- j
  # Calc min asie for year
    min_asie <- min(j_data[,j], na.rm = T)  # must remove na's to get valid answer
    lab_asie <- round(min_asie,3)
    min_r <- which(j_data[,j] == min_asie)
    min_d <- j_data[min_r,2]
    min_m <- j_data[min_r,1]
    min_date <- paste(min_m,"/",min_d,"/",series_id[j], sep="")
    plot(j_data[,17],  type="n", col = "grey",axes=F, xlab="",
       ylab="Arctic Sea Ice Extent - Millions Sq KM",
       ylim=c(0,15),xaxs="i", yaxs = "i",
       main=title)
    text(20, 1.5, note_1, cex = 0.8, adj=0, col = "black")
    text(20,1,"Data Source: http://www.ijis.iarc.uaf.edu/seaice/extent/plot.csv", cex = 0.8, adj=0,col = "black")
    mtext("D Kelly O'Day - http://chartsgraphs.wordpress.com", 1,0.5, adj = 0, cex = 0.8, outer=T)
  # custom x & y axes
    axis(side = 1, at=mon_doy, labels=F, xaxs="i")
    axis(side=1, at= mon_pos, labels=mon_names, tick=F, line=F, xaxs="i")
    axis(side=2,  yaxs="i", las=1)
    points(70, min_asie, col = "red",pch=19, cex = 2)
  # Add each previous yr data series as light grey line
  for (n in 3:no_yrs)
  {
    points(j_data[,18], j_data[,n], type="l",lwd=1,lty=pattern[j], col=ser_col[j])
    text(182,14,series_id[j], col = "red", cex = 1.1)
  }
  points(j_data[,18], j_data[,j], col="red", type="l",lwd=2.5)
  text(182,14,series_id[j], col = "red", cex = 1.1)
  text(120,min_asie+0.5, min_date, col="red", cex=0.9)
  text(120,min_asie, lab_asie, col="red", cex=0.9)
  if(png_yn == "y") dev.off()
}
## copy last png file 3 times to provide pause in animation
if(png_yn== "y")
{
  for (c in 1:2)
  {
    file_name <- paste("asie2012",c, ".png",sep="")
    file.copy(from= "asie2012.png", to = file_name, overwrite=T)
  }
  ani.options(outdir = getwd())    # direct gif output file to working dir
  ani.options(interval= 0.80)
  im.convert("asie*.png", "last_animation.gif")
}

Visualizing the Arctic Sea Ice Extent Decline

Understanding what is happening to Arctic sea ice is critical to recognizing the serious consequences of global warming. So I want to help people visualize the 30+ year trend in Arctic sea ice extent.

The source data file is here:  http://www.ijis.iarc.uaf.edu/seaice/extent/plot.csv

Global Sea Level Rise and El Nino – La Nina

Here is an informative interview with NASA’s Josh Willis about global sea level rise and El Nino – La Nina.  I first saw the video on Zeke Hausfather’s  YALE Forum on CLIMATE CHANGE & THE MEDIA

Comparison of UAH and RSS Time Series with Common Baseline

In this post I set both UAH 5.4 and RSS 3.3 global temperature anomaly series to a common baseline period (1981-2010)  to compare them. Since both the UAH 5.4 and RSS 3.3 series are satellite based , they exhibit striking similarities.

Common Baseline

In this previous post, I showed how to convert temperature anomaly time series from one baseline period to another period.  I then used this technique in this post to directly compare UAH 5.4 (baseline 1981-2010) and GISS.

In this post, I compare the satellite based UAH 5.4 (baseline 1981-2010) and RSS 3.3 (baseline 1979-1998) series.

The offsets are as follows:

  • UAH:  -0.000978
  • RSS:      0.098772

Since the UAH TLT 5.4 series is based on a 1981-2010 baseline, the offset is nearly zero (-0.00098 versus 0.0). The RSS offset changes the baseline from 1979-1998 to 1981-2010.

Users can reproduce my analysis on their own by downloading my CTS.csv file and applying the offsets to the UAH and RSS series.

Comparison of 1981-2010 Baseline Series

Here is a plot of UAH and RSS 12 month moving averages for 1979 to current: Click to Enlarge

Continue reading

Comparison of UAH and GISS Time Series with Common Baseline

In this post I set both UAH and GISS global temperature anomaly series to a common baseline period (1981-2010)  and compare them. Even though the UAH series is satellite based and GISS series is station based, the series exhibit striking similarities.

Common Baseline

In this previous post, I showed how to convert temperature anomaly time series from one baseline period to another period.  I use this technique in this post to directly compare UAH (baseline 1981-2010) and GISS (baseline 1951-1980) series.

The offsets are as follows:

  • UAH:  -0.000978
  • GISS: 0.34958

Since the UAH TLT 5.4 series is based on a 1981-2010 baseline, the offset is nearly zero (-0.00098 versus 0.0).

Users can reproduce my analysis on their own by downloading my CTS.csv file and applying the offsets to the UAH and GISS series.

Comparison of 1981-2010 Baseline Series

Here is a plot of UAH and GISS 12 month moving averages for 1979 to current: Click to Enlarge Continue reading

UAH Temperature Anomalies Following Predictable Pattern

In this post I show one simple  and 2 multiple regression models to assess the role of time, El Nino – La Nina SSTA and volcanic activity (SATO) on UAH global temperature anomaly trends. The 3rd model provides a reasonable  approximation of the actual UAH oscillations over the 1979 – Feb, 2011 period.

Click Image to Enlarge

This analysis is similar to previous temperature anomaly regressions (here, here, here) that I have done.

The simple trend line regression shows the overall trend is upward, however, there are several oscillations that the linear trend misses.  The yr_frac and Nino34 regression improves on the linear model, however, it undershoots in the early 1980s,  overshoots in the 1992-1994 period, periods following significant volcanic activity.

The yr_frac, Nino34 and SATO model improves the fit in the early 1980s and 1992-1994 period and is slightly better in the 1998 and 2010 El Nino periods.

The 3rd model matches the observed 2010 El Nino – La Nina oscillation pretty well so far, indicating that the 2010 – 2011 UAH anomalies are following a predictable pattern.

Comparison of UAH Anomalies During 1998 & 2010 El Nino – La Nina Oscillations

In this post, I show the UAH global temperature anomaly traces during the 1998 and 2010 El Nino – La Nina oscillations.

Click Image to Enlarge

UAH_NINO34_cyclesThe 1998 UAH anomalies were higher in the peak El Nino period than the comparable 2010 El Nino peak period.  The anomaly drop off from the peaks have been comparable so far.  It will be interesting to see how the current La Nina progresses compared to the  12 month depressed anomaly period following the 1998 El Nino.