The data set provided deals with world temperatures and comes from NASA: http://data.giss.nasa.gov/gistemp/, in particular: from “Table Data: Global and Hemispheric Monthly Means and Zonal Annual Means.”.
The original data set was modified by choosing only 4 variables:
The graph illustrates anomalies in temperatures from 1880 to 2015, measured globally and for Nothern and Southern hemispheres. In this version it shows moving average for 10 subsequent years for each dependent variable. This value can be easily changed through interaction (see below the information about possible interactions.)
The anomalies in temperatures (Axis Y) indicate how much higher or lower was the temperature than it was normal for a given place and time. Here normal means the average temperature over the period from 1951-1980 (here referred as “Benchmark”). The units used here are Celsius degrees multiplied by 100.
The Axis X shows year in which the anomaly was measured.
For more details about GISTEMP see FAQ
The graph is interactive. You may:
Hover over lines to see series highlighted and values displayed in the legend field
Change time series scope by using the range selector below the chart
Set number of years over which to calculate moving average (currently set to 10) in the box placed in the left-bottom corner of the graph. To see the orinal data from the database set the number to 1.
Zoom in by clicking and holding mouse button inside the chart; double click resets the zoom
Enjoy!
The detailed discussion of results is out of scope of this programming assignment. However, some observations can be listed:
In general, the average deviation increase in time in direction of higher warmth
For the last 30 years this trend is stronger for the Nothern Hemisphere
The graph was created in R using dygraphs for R package. Other packages used: xts, dplyr, knitr. If you are interested how exactly this was done, visit my rbubs page after the grading deadline; it’s likely I will publish the version with the source code disclosed.
GISS Surface Temperature Analysis (GISTEMP). NASA Goddard Institute for Space Studies. Dataset accessed on 2015-07-31 from Data Visualisation MOOC