过去近50年全球变暖纬向平均模

Zonal Mean Mode of Global Warming over the Past 50 Years

Zonal mean annual temperature trends were estimated using four reanalysis and three analysis grid datasets. The trends over land and for the entire globe were estimated from 1958-2001 and 1979-2007, respectively. Estimates of temperature trends over land from Climate Research Unit (CRU) analysis data indicate more intense warming moving northward, at a rate of about 3.5ºC per century at 65ºN, then declining further to the north. CRU estimates indicated dramatic warming over the latitudes of the Antarctic Peninsula, with a localized cooling trend at 45ºS. A global estimate was conducted by comparing estimates of the reanalysis datasets. Temperature distribution trends of the reanalysis data were similar to those generated by land observations but with large bias in the Polar Regions. The bias could be reduced by comparing these estimates with those from the analysis data at high latitudes. Extreme warming trends were estimated at rates of 2.9ºC-3.5ºC per century in the Arctic and 3.2ºC-4.7ºC per century in the Antarctic for 1958-2001. Surface warming was even more intense in the Northern Hemisphere for 1979-2007, with extreme arctic warming rates ranging from 8.5ºC-8.9ºC per century, as estimated by the analysis and reanalysis datasets. Trends over Antarctica for this period were contradictory, as Japan Meteorological Agency (JMA) reanalysis (JRA-25) indicated a cooling trend at about -7ºC per century, while other reanalysis datasets showed sharp warming over the continent.