Global Highlights:
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Contents of this Section: |
The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. The most current data may be accessed via the Global Surface Temperature Anomalies page. |
IntroductionTemperature anomalies for December are shown on the two maps* below. The dot map on the left uses anomalies that were calculated from the Global Historical Climatology Network (GHCN) data set of land surface stations using a 1961-1990 base period. The map on the right is a blended product which uses satellite and surface anomaly values of measured land and ocean temperatures as well as SSTs with the base period of 1988-2004. Both maps reflect conditions during December 2004, indicating above average temperatures in Alaska, parts of West Africa, Norway, western and southern Australia, Japan and the majority of eastern Europe, with cooler than average temperatures over most of Siberia, the Middle East, Mexico, parts of Southeast Asia and the eastern half of Canada.
Above average sea surface temperatures are also evident in the blended product, above right. Warmer than average conditions covered large parts of the central and eastern Pacific in association with weak El Niño conditions. Sea surface temperatures were also warmer than average in much of the northern Pacific. The mean position of upper level ridges of high pressure and troughs of low pressure (depicted by positive and negative 500 millibar height anomalies on the December 2004 map) are generally reflected by areas of positive and negative temperature anomalies at the surface, respectively. For other Global products see the Climate Monitoring Global Products page. |
Temperature Rankings and GraphicsCurrent Month / Year-to-date
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The most current data may be accessed via the Global Surface Temperature Anomalies page.
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The maps below were produced from SSM/I satellite data using a base period of 1988-2004. The map on the left reflects surface liquid wetness conditions, while the map on the right reflects snow cover conditions for the month. Snow covered areas that are normally snow-free during this month will appear drier than average on the wetness image since a wetness value cannot be determined for regions that are snow covered. This is due to the snow crystalline structure which produces a considerable amount of scatter and makes it difficult for the SSM/I to accurately detect the surface conditions. Data in these areas that are normally snow covered are displayed as missing. The SSM/I products are experimental and are under continuing review and development. |
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ENSO SST Analysisanimated loop |
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References: Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global
Historical Climatology Network Database. Bull. Amer. Meteorol.
Soc., 78, 2837-2849. |