Thursday, March 25, 2010

Where has all the data gone ?

As noted yesterday, the BoM temperature data for the "new" Cunderdin station (010286 - Cunderdin Airfield) begins at 1996, while the station record indicates that the station commenced in 1942.

Apparently, there are 52 years worth of data missing from the record for this "new" Cunderdin station.

Which begs the question - is this a unique occurence, resulting from the late-night changes at the BoM to substitute station 010286 for the inconvenient Cunderdin station 010035?

A look at the listing of RCS stations on the BoM site shows that there are 103 "high quality" stations in this network. They have notional station start dates ranging from 1860 through to 2003, with 65% of them having a notional start date prior to 1969. Overall, the average notional station start date is 1950.

However, when you look at the data start date, a different picture emerges. For openers, 32 of the stations (32%) have a data start date which is later than the station start date by more than a year, or have significant gaps in the data in the early years.

Some of these missing years of data are considerable - several are in the order of the 52 year gap noted for Cunderdin, above. For example:

008039 - Dalwallinu Comparison. [data] [graph]
Station date = 1912, Data date = 1955 (43 years missing)

010592 - Lake Grace PO. [data] [graph]
Station date = 1914, Data date = 1956 (42 years missing)

017031 - Marree Comparison. [data] [graph]
Station date = 1885, Data date = 1939 (54 years missing)

And several more in addition to these.
The net effect of all this missing data is that for these 103 stations, the oldest station data start date moves forward by 4 years (to 1864), while the average station data start date moves forward by 9 years (to 1959).
Where's the Beef?
Just how "high quality" are the stations in the RCS network? What is the overall impact on the derived climate record of all these missing years? With so much data from the early years missing, how can anyone make a valid long-term climate assessment? Is this RCS data of any practical value at all?

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