I’ve been intrigued by climate measurements in Turkey since becoming aware of the large number of stations there (more than any other country in Europe, even in relation to its size) while evaluating the ‘Station Dropout Problem‘. E.M. Smith (Chiefio) posted an analysis of the temperature record in Turkey a few days ago and clearly found a step change the record, so I had to go back and do some digging myself. Here’s one of E.M. Smith’s graphs:
“dT/yr is the “average of the changes of temperature, month now vs the same month that last had valid data, for each year”. An anomaly process similar to First Differences. Then dT is the running total of those changes, or the total change, the “Delta Temperature” to date.”
The dT graph shows a flat trend up to 1901 then a cooling trend up to 1951. After that, flat for a few years, then a small step change upwards in 1961, then flat again until a major step up in 1995. So what happened in 1995 to create a sudden jump like that? What information is there about climate in Turkey?
One study  examined the 63-year period starting from 1930 to 1993 and used temperature records from 85 climate stations. It concluded that annual mean temperatures were generally dominated by a cooling tendency in Turkey and that 1933 and 1992 were the coldest years. The paper also notes that only Eastern Anatolia appeared to show similar behaviour to the global warming trends, except in the last 5 years. It seems that 1992/93 were particularly cold years in Turkey, attributed to the effect of the eruption of Mt Pinatubo .
Climate in Turkey has been closely linked to the NAO:
“During the positive phases of the North Atlantic Oscillation indices (NAOIs), northeasterly circulation increased, and thus spatially coherent and significant cold signals dominate over the majority of Turkey.” 
The NAO index is highly negative in 1990 (1.23) and 1992 (1.11), but transiently flips to positive in 1994-1996 (-0.61; -1.01; -0.18). It couldn’t be this simple, besides the record for Turkey stays warm after 1995/6. What else? Chiefio noted changes of modification flags in the station data files – anything to do with lost stations? Well – here’s the station count overlaid on his graph:
providing data in the GHCN v2.mean file.
Having done a bit of searching on line, it seems that there was a massive closure of climate stations in Turkey during 1990 – more than 600 stations were closed during the decade . OK that fits with what is in the record. Here’s what the loss of stations looks like on a map:
adjustment by GIStemp. (data from www.climateapplications.com/GISSMaps/)
In checking database records with the GISS site, I’ve found quite a few “Lazarus Thermometers” that stopped reporting into the GHCN file in 1990, but have recently started again. One of these, Yozgat, is shown below (Fig. 6). Note that gap – Yozgat has still not warmed – could the absence of it and similar records from anomalies since 1990 have resulted in a ‘lift’ of the anomaly value by warmer trending thermometers? Strangely this and four very similar others current for 2010 are now no longer available from the GISS Station Data page under “after homogeneity adjustment” and are only present as “after combining sources at same location”. Unless this is in error this would suggest they are also no longer in the “Adjusted data” file and therefore do not contribute to GIStemp anomaly calculation and gridding. Why?
(data from www.climateapplications.com/GISSMaps/)
E.M. Smith’s dT method, using the unadjusted GHCN input to GIStemp, shows cooling in Turkey, a trend that is confirmed by publications. However, the dT graph shows step changes that indicate a possible effect of variability in the thermometer record – first the addition and then loss of stations.
Looking at the overall pattern of stations and the data within them, the stations that remain seem badly served by GIStemp adjustments in relation to the raw data available.
These elements together seem to contribute to recent warming of anomaly values in Turkey.
- Türkeş, M, Sümer, U.M. and Kiliç S. (1995) Variations and trends in annual mean air temperatures in Turkey with respect to climatic variability. International Journal of Climatology 15(5): 557 – 569
- Tayanç, M., Im, U., Dogruel, M. and Karaca, M. (2009) Climate change in Turkey for the last half century. Climatic Change 94:483–502
- Türkeş, M. and Erlat. E. (2009) Winter mean temperature variability in Turkey associated with the North Atlantic Oscillation. Meteorology and Atmospheric Physics 105 (3-4): 211-225
- Türkeş, M. (2009) An Assessment on the Precipitation Data Recovery in Turkey. Presentation at Med-CLIVAR Workshop, Barcelona (link)