A Guest Post by Peter Morcombe
I started out with the aim of understanding “Global Warming” by analyzing raw data for myself rather than accepting whatever the “consensus” might be. This meant that the data had to be digestible by a laptop rather than a super-computer. My main data source is NOAA/NCDC v2 ground stations, and the GISP2 ice core data. While there are several alternative sources of data the NOAA information is wide open to the general public, free of charge or fuss.
One of the problems with “Climate Change” is that we are trying to measure long term changes of a few tenths of a degree Kelvin in measurements that have huge variations from night to day and from winter to summer. Observations show that temperature changes are magnified at high latitudes, leading to an improved SNR (Signal to Noise Ratio). Consequently, I decided to concentrate on arctic Canada, Greenland and Russia.
This approach soon ran into problems because the number of high latitude stations reported in the GHCN v2 data set dropped like a stone after 1975. This issue was discussed in some depth here in January 2010. A few months later the issue was picked up by D’Aleo & Watts and the furor spread to live TV. It was suggested that stations were being discarded from the GHCN to create a “Warm” bias.
It puzzled me at the time that nobody seemed interested in what NOAA had to say so I was curious to visit Asheville to ask about this and other issues. It proved to be easy to set up a meeting but my business in North Carolina was postponed several months so the meeting took place late in October.
I was expecting to find a small group of scientists located in a dusty annex but instead there was a modern six-story building of at least 150,000 square feet. My next thought was that NOAA would be a minor tenant of some other government department. Wrong again! NOAA is the “landlord” with over 400 staffers.
The “Station Drop Off Problem” has been known to the professionals since Peterson & Vose, 1997, so amateurs such as myself have arrived at the scene of the crime a little late. The trouble with the P&V paper is that while it explains “What?”, it does not explain “Why?”
Having spent a dozen years living off Department of Defense research grants it was easy for me to relate to NOAA researchers. The folks I met in Asheville were scientists rather than politicians, yet they have to respond to the folks who control the purse strings. While the general public would like to think it a simple matter to collect every bit of data from every surface weather station there will never be enough resources to do it. The “Station Drop Off Problem” is not something that was deliberately planned to create a “Warm” bias; it just happened owing to shifting priorities, changing arrangements with other countries and budget restraints.
Let’s see how this applies to one of my pet projects. There are more than a dozen surface weather stations that meet WMO standards in the Canadian arctic but only two of them (Alert and Resolute) can be found in recent GHCN v2 records. It turns out that there was a shake up at Environment Canada (I confirmed this by contacting the Canadians) that took years to work itself out. The good news is that the hiatus is over so the number of stations reported is trending up again.
Then I asked about the GISP2 ice core records which cover the last 50,000 years with decadal resolution. Are there any station records at NCDC that could be used to connect the GISP data which ends in 1905 to the present day? The answer was an unequivocal “No” but there was some good news. There are several sources of station data for Greenland other than the GHCN v2.
Several automatic stations were set up close to the GISP drilling site. These are known as Barber, Cathy, Julie, Kenton, Klinck and Matt. Data from these stations can be found at: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/climate/climate.txt
Unfortunately, this data only covers 1988 to 1994 so it was not suited to the task of bridging the gap from 1905 to the present day. Over their brief period of activity the mean temperature recorded in central Greenland was -29oC compared to -7oC for the coastal stations, owing to the altitude of the central stations (72.6N, 38.5W and 3,205m).
In spite of the large difference in mean temperature there is a good correlation in temperature anomalies between the coastal stations and the GISP stations. It should therefore be reasonable to use anomalies calculated for coastal stations to extend the GISP2 temperature record from 1905 to the present. To be continued…