Published data were used to analyse the long-term annual temperature trends at eight locations located in central America. Stations selected were located in Mexico and Belize.
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 25 years to 65 years of complete annual data. The earliest record, at Manzanillo and Zamora, both commenced in 1925.
The plots shown below are of the annual mean temperatures at each of the eight 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 eight 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 in 1960.
ANNUAL MEAN TEMPERATURE TRENDS FOR INDIVIDUAL STATIONS
La Paz (Mexico) 1934-2014
Manzanillo (Mexico) 1925-2015
Zamora (Mexico) 1904-2010
Guanajuato (Mexico) 1952-2015
Morelia (Mexico) 1951-2015
Tampico (Mexico) 1952-2014
Chetumal (Mexico) 1953-2015
Belize (Belize) 1941-2015
DISCUSSION AND COMMENTS
- The data analysed was limited to that which were available on the KNMI website.
- The annual mean temperature trend-lines for eight stations in Mexico and Belize all mshowed cyclical but variable patterns.
- Five of the stations had Lows or plateaus around 1970-1980.
- Seven of the stations showed increasing trend-lines since around 1970-1980.
- many of the records were badly broken but four stations had a High or plateau around 2000-2010.
- Zamora was an exception with Lows around 1940 and 2000 and a High around 1970.
- The increase in temperature from ~1960 to ~2010 was generally 0.5-1.5 deg C.
- The trend-lines for the eight stations were all cyclical but variable.
- Seven stations showed increasing trend-lines since 1970-1980 with four stations having a High or plateau around 2000-2010.
- Zamora was an exception having a cyclical trend-line but with Lows around 1940 and 2000 and a High around 1970.
- The temperature rise between around 1960 and around 2010 was generally 0.5-1.5 deg C.
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.