GREAT-LAKES AIR-TEMPERATURE TRENDS FOR LAND STATIONS, 1901-1987

An examination of gridded data developed from quality controlled land station temperature data for the 1901-1987 period for the Great Lakes basin reveals temperature trends not previously reported On an annual basis, from early 1900 through the mid 1950s, a 5-year moving average shows that overall basin temperatures increased A cooler regime prevailed for the remainder of the period of record. Seasonal 5-year moving averages show that spring temperatures increased throughout the period. Summer temperatures were highly variable, but with an early upward trend through the mid 1940s and a recent downward trend for the remainder of the period Fall temperatures slowly warmed from the early 1900s until the mid 1960s, but have recently shown a cooling trend Winter temperatures show an upward trend with intermittent wide swings from the early 1900s through the mid 1950s after which a lower temperature regime has prevailed Temperature differences between a warm and a cool year and the long term mean show markedly varying patterns.