On the Environment Canada climate site there is a nice interactive map that allows you to zoom in by region (e.g. map right) and then click on stations to get data. I downloaded the data as CSV files and used the pivot table function in Excel to aid conversion to annual data (D-N). Up-to-date GHCN/GISS data was downloaded from the GISS station data site (Unadjusted i.e.”after combining sources at the same location” and Adjusted “after homogeneity adjustment”).
On the quality of data, Environment Canada’s statement is here:
“Data collection, processing, quality control checks and procedures have evolved and changed over the years since the earliest data was observed in 1840. Changes have been particular rapid in recent years. For example, the advent of automatic weather observing stations established a new set of challenges for quality control.
The vast majority of observational data is accurate but the database contains some incorrect values, which show up from time to time. Environment Canada continues to review quality control procedures, both as current data is observed and incorporated into the database, and retrospectively for historical data. Be aware that data can be erroneous and that some values may change over time as quality control procedures identify and deal with doubtful data.”
So, an immediate surprise – the data from Environment Canada matched neither versions of the GISS data. Not only that, but the GISS unadjusted data was warmer in the past than the EC data but was adjusted to be cooler. This is an example of “wrong way” correction for urban growth and urban heat island effects within the GIStemp program and seems to happen when surrounding rural stations have a greater rate of warming than the station being adjusted (Prince Albert has ‘semi-urban’ status: population 31,000).
Hmm, there is a 0.5-1 deg C difference in some of those temperatures – why? Which set is right? Who do you believe? And is this repeated for other stations, which I’ll come to in a moment?
I was inspired to look at high latitude stations by a post (Infilling the True Hypothetical Cow) a week or so back in which Boballab downloaded data for Alert in the Canadian Arctic and looked at the effect at grid square level of adding back in data that is no longer being reported into the GHCN datafile. He did this at grid square level. Now he found good agreement between Environment Canada and GISS adjusted data when the data was anomalized with a 1951-1980 baseline.
I wanted to to look at additional high latitude stations and I listed (from GHCN v2.mean) those that had at least 20 years of data up to 1988 or later and were above 60N in latitude: 37 stations in total. Of these I found 18 on the EC site, although 3 (Hall Beach, Inuvik and Fort Simpson) had so little data that it was not worth using. The 15 that were in common with the GHCN/GISS data are shown and named on the map below; the GHCN/GISS Stations not on the EC site are marked but not named.
Four: Alert, Eureka Resolute and Tuktoyaktuk are above the Arctic Circle; together all the stations cover the three Canadian Provinces Territories of Nunavit, Northwest Territories and Yukon Territory.
On comparison the stations fall roughly into three categories (for which only the latter two are mutually exclusive):
- Those in which there is a historical record from GHCN/GISS, which ceases typically around 1989-90, but for which Environment Canada has more recent data. The GISS series may restart in the last few years: Alert , Burwash, Dawson, Hay River, Mayo, Tuktoyaktuk, Watson Lake, Yellowknife
- Those for which the GHCN/GISS data typically runs “warmer” than the Environment Canada data: Alert, Baker Lake, Burwash, Coral Harbour, Eureka, Tuktoyaktuk, Whitehorse, Yellowknife
- Those for which the GHCN/GISS data typically runs “cooler” than the Environment Canada data: Fort Smith, Hay River, Mayo, Norman Wells, Resolute, Watson Lake