( Revised 19 November 2017 with addition of Kandi and Tambacounda and the deletion of El Obeid )
Published data were used to analyse the long-term annual temperature trends at six locations located in northern Africa. Stations selected were located in Algeria, Benin, Mali and Senegal
The data used were all from the website of KNMI (the Royal Netherlands Meteorological Institute). Only raw data were used (ie as originally recorded, without any adjustments). Data were only used from stations located in rural areas or in small towns so as to avoid the possible influence of urbanisation on the temperatures.
The periods of the data ranged from 47 years to 116 years of complete annual data. The earliest record, at Dar el Beida, commenced in 1856.
The plots shown below are of the annual mean temperatures at each of the six locations. On each plot a polynomial “best fit” trendline has been added. It should be noted that the trendlines near each extremity (ie near the start and end of the records) are quite sensitive to individual data points, whereas trendlines within the main body of the record are much more stable and reliable.
COMPARISON OF TRENDLINES
Annual Mean Temperature Trends
[ The basis of these trendlines can be seen from the analyses for the six individual stations – see next section. ]
Annual Mean Temperature Residual Trends
[ The individual trend-lines have been adjusted by constant amounts to be approximately zero at the trend-lines around 1970.
ANNUAL MEAN TEMPERATURE TRENDS FOR INDIVIDUAL STATIONS
Dar el Beida (Algeria ) 1856-2015
Tombouctou (Mali) 1898-2003
Kayes (Mali) 1896-1990
Wadi Halfa (Sudan) 1904-2010
Kandi (Benin) 1941-2009
Tambacounda (Senegal) 1941-2014
DISCUSSION AND COMMENTS
- The data analysed was limited to that which were available on the KNMI website.
- The annual mean temperature trend-lines for six stations located in Algeria, Benin, Mali and Senegal showed cyclical patterns, but with very different characteristics.
- The increase in temperature from ~1970 to ~2000 was generally 0.5-1.0 deg C.
- The trend-lines of the six stations varied considerably and no regional trend could be identified.
This article was written by Brian Gunter of Narooma, NSW. In his previous life Brian was an engineering hydrologist involved over many years in the analysis of rainfall and river flow data for the planning of water resources projects in Australia, Asia and Africa. In recent years he has been one of the Marine Rescue NSW (previously Royal Volunteer Coastal Patrol) volunteer weather observers who operate the Narooma station for the Bureau of Meteorology.