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Global Analysis - Annual 2002

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Global Analysis

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Global Analysis

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Note: GHCN-M Data Notice

An omission in processing a correction algorithm led to some small errors on the Global Historical Climatology Network-Monthly dataset (GHCN-M v3.2.0). This led to small errors in the reported land surface temperatures in the October, November, December and Annual U.S. and global climate reports. On February 14, 2013, NCDC fixed this error in its software, included an additional improvement (described below), and implemented both changes as GHCN-M version 3.2.1. With this update to GHCN-M, the Merged Land and Ocean Surface Temperature dataset also is subsequently revised as MLOST version 3.5.3.

The net result of this new version of GHCN-M reveals very small changes in temperature and ranks. The 2012 U.S. temperature is 0.01°F higher than reported in early January, but still remains approximately 1.0°F warmer than the next warmest year, and approximately 3.25°F warmer than the 20th century average. The U.S. annual time series from version 3.2.1 is almost identical to the series from version 3.2.0 and that the 1895-2012 annual temperature trend remains 0.13°F/decade. The trend for certain calendar months changed more than others (discussed below). For the globe, ranks of individual years changed in some instances by a few positions, but global land temperature trends changed no more than 0.01°C/century for any month since 1880.

NCDC uses two correction processes to remove inhomogeneities associated with factors unrelated to climate such as changes in observer practices, instrumentation, and changes in station location and environment that have occurred through time. The first correction for time of observation changes in the United States was inadvertently disabled during late 2012. That algorithm provides for a physically based correction for observing time changes based on station history information. NCDC also routinely runs a .pairwise correction. algorithm that addresses such issues, but in an indirect manner. It successfully corrected for many of the time of observation issues, which minimized the effect of this processing omission.

The version 3.2.1 release also includes the use of updated data to improve quality control and correction processes of other U.S. stations and neighboring stations in Canada and Mexico.

Compared to analyses released in January 2013, the trend for certain calendar months has changed more than others. This effect is related to the seasonal nature of the reintroduced time-of-observation correction. Trends in U.S. winter temperature are higher while trends in summer temperatures are lower. For the globe, ranks of individual years changed in some instances by a few positions, but global temperature trends changed no more than 0.01°C/century for any month since 1880.

More complete information about this issue is available at this supplemental page.

NCDC will not update the static reports from October through December 2012 and the 2012 U.S and Global annual reports, but will use the current dataset (GHCN-M v. 3.2.1 and MLOST v. 3.5.3) for the January 2013 report and other comparisons to previous months and years.

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PLEASE NOTE: The ranks and temperature anomalies in this report represent the values known at the time the report was issued. The actual ranks will change as subsequent years are added to the dataset. The anomalies themselves may change slightly as missing or erroneous data is resolved. Also, in 2009, NCDC switched to ERSST version 3b (from version 2) as a component of its global surface temperature dataset. Because the versions have slightly different methodologies, the calculated temperature anomalies will differ slightly. For more information about this switch please see the Global Surface Temperature Anomalies FAQ .

Global Temperatures

Global temperatures in 2002 were 0.56°C (1.01°F)* above the long-term (1880-2001) average**, which places 2002 as the second warmest year on record. The only warmer year was 1998 in which a strong El Niño contributed to higher global temperatures. Land temperatures were 0.87°C (1.57°F)* above average and ocean temperatures 0.42°C (0.76°F)* above the 1880-2001 mean. Both land and ocean temperature ranks as second warmest on record.

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The map of temperature anomalies (above right) contains data from an in-situ and satellite blended data set of land and ocean temperatures. The period of record for this data set is 1988 to the present, a relatively warm period compared to the base period used in the creation of the land only map of temperature anomalies below. Some minor differences result from the differences in base periods and data that are used to construct the two maps.

Neutral ENSO conditions at the beginning of 2002 gave way to a strengthening El Niño episode during late boreal summer and continuing into early winter. Moderate positive anomalies of equatorial Pacific sea surface temperatures (El Niño conditions) are expected to persist through the early part of 2003.

The Northern Hemisphere temperature averaged near record levels in 2002 at 0.63°C (1.13°F) above the long-term average. The Southern Hemisphere also reflected the globally warmer conditions, with a positive anomaly near 0.46°C (0.83°F).

Annual anomalies in excess of 1.0°C (1.8°F) were widespread across much of North America and Asia. Additional details on temperatures throughout the world are included below.

*Anomalies use most recent station data and NCEP OI Version 2.

**The 1880-2001 average combined land and ocean annual temperature is 13.9°C (56.9°F), the annually averaged land temperature for the same period is 8.5°C (47.3°F), and the long-term annually averaged sea surface temperature is 16.1°C (60.9°F).

Global Precipitation

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Global precipitation was below the 1961-1990 average in 2002. Much of Australia experienced severe drought, with the eastern part of the country the worst affected. India monsoon rainfall was 19 percent below normal, with the resulting drought characterized as the worst since 1987. Other drought-affected areas included the western United States and portions of the north coast of China.

After a dry beginning to 2002, several typhoons brought excessive rains to parts of southeast Asia and Japan, the southeast coast of China, Taiwan and the Philippines. In contrast to drought conditions during the first half of 2002, the onset of monsoon rains in southeast Asia promoted extensive flooding along the Mekong Delta. Seasonal flooding in much of south Asia (Nepal, Bangladesh and northeastern India) during June-August claimed more than 1,000 lives. In the eastern United States, long-term drought was ameliorated by a turn to wetter weather, due in part to moisture from tropical systems.

Additional information on other notable weather events can be found in the Significant Events section of this report.

References

IPCC, 2001: Climate Change 2001: The Scientific Basis, Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel of Climate Change. J.T. Houghton, Y. Ding, D.J. Griggs, M. Noguer, P.J. vander Linden, X.Dai, K. Maskell, and C.A. Johnson (Eds.), Cambridge University Press, 881 pp.

NOAA's National Climatic Data Center is the world's largest active archive of weather data. The preliminary temperature and precipitation rankings are available from the center by calling: 828-271-4800.

NOAA works closely with the academic and science communities on climate-related research projects to increase the understanding of El Niño and improve forecasting techniques. NOAA's Climate Prediction Center monitors, analyzes and predicts climate events ranging from weeks to seasons for the nation. NOAA also operates the network of data buoys and satellites that provide vital information about the ocean waters, and initiates research projects to improve future climate forecasts.

Citing This Report

NOAA National Climatic Data Center, State of the Climate: Global Analysis for Annual 2002, published online December 2002, retrieved on June 19, 2013 from http://www.ncdc.noaa.gov/sotc/global/2002/13.