Note: The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. Effective September 2012, the GHCN-M version 3.2.0 dataset of monthly mean temperature replaced the GHCN-M version 3.1.0 monthly mean temperature dataset. Beginning with the August 2012 Global monthly State of the Climate Report, released on September 17, 2012, GHCN-M version 3.2.0 is used for NCDC climate monitoring activities, including calculation of global land surface temperature anomalies and trends. For more information about this newest version, please see the GHCN-M version 3.2.0 Technical Report.
*The GHCN-M version 3.1.0 Technical Report was revised on September 5, 2012 to accurately reflect the changes incorporated in that version. Previously that report incorrectly included discussion of changes to the Pairwise Homogeneity Algorithm (PHA). Changes to the PHA are included in version 3.2.0 and described in the version 3.2.0 Technical Report. Please see the Frequently Asked Questions to learn more about this update.
Global Highlights:
- *Global average land and ocean
temperature was tenth warmest for December
- Lower tropospheric temperatures were above average during
December
- Temperatures in the lower stratosphere were cooler than
average
- During December, above average precipitation was most notable
across the eastern Mediterranean region and parts of Brazil with
below average precipitation across the eastern U.S and most of
western and southern Europe
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Contents of this Section:
|
 Introduction
| Using a 1992-2001 base
period as shown in the adjacent blended temperature
product of satellite and in-situ data, anomalously cold
temperatures during December in the Northern Hemisphere were
closely correlated to the location of upper level troughs of low
pressure. Dominant troughs of low pressure (depicted by
negative 500 millibar height anomalies) were centered across
eastern Europe and southern Alaska. Temperature anomalies
calculated from in-situ station
data using a 1961-1990 base period also show the cooler than
average temperatures in these regions with warmer than average
temperatures observed over most of North America, the Middle East
and the African Sahel region. |
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Temperature
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- Based on data available at the time of this
report, land temperatures in the tropical regions
(20°N-20°S) were warmest on record for December, or
0.99°C (1.78°F) above the 1880-2000 mean
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Precipitation
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- Much of Europe was relatively dry, with only
southeastern Europe and the eastern Mediterranean region
experiencing wetter than average weather
- Dry conditions persisted in the eastern U.S.,
southeast Canada and northern Argentina
- Above average precipitation fell in parts of
Brazil and southeast China
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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.
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