Century trends in Victorian temperatures

It is dif­fi­cult to vouch for the qual­i­ty of these records. The light­hous­es at Gabo Island, Wilson’s Promon­to­ry and Cape Ottway are iso­lat­ed loca­tions where there is no dan­ger of urban heat island dis­tor­tion. Oth­er records, such as that from Mary­bor­ough, have been made at sta­tions that once may have been locat­ed on the edge of a large town but are now engulfed by it. Still oth­ers, such as Bal­larat Aero­drome appear from satel­lite images to be in open spaces, but still on the mar­gins of a rur­al city.

It is also dif­fi­cult to tell from the records or the site infor­ma­tion pro­vid­ed by the BOM whether the records for each sta­tion are from a sin­gle loca­tion or a move­able loca­tion. Some—such as Bal­larat Aerodrome—seem like­ly to rep­re­sent a series cob­bled togeth­er from dif­fer­ent loca­tions over the course of a cen­tu­ry. Oth­ers, such as Gabo Island Light­house or Wilson’s Promon­to­ry Light­house could eas­i­ly be from a sin­gle location.

The full list of sta­tions, in the row-order of the graph­ic, is

  1. Bal­larat Aerodrome
  2. Cape Ottway Lighthouse
  3. Deniliquin (NSW)
  4. Dur­did­war­rah
  5. Gabo Island Lighthouse
  6. Hor­sham
  7. Kerang
  8. Longer­a­nong
  9. Mary­bor­ough
  10. Omeo
  11. Ruther­glen
  12. Wilson’s Promon­to­ry Lighthouse

I used the fol­low­ing sim­ple R script to graph the data from CSV files avail­able here

 # data from http://www.bom.gov.au/climate/data/weather-data.shtml
df - read.table(file, header=TRUE, sep=",", na.strings="null")
df - df[,3:4]
p-qplot(Year, Jan, data=df, main="Montly mean maximum temperature: Ballarat Aerodrome, Vic")
p + geom_point() + geom_smooth(method = "lm")

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