State of the Climate
Global Analysis
May 2006

National Oceanic and Atmospheric Administration

National Climatic Data Center

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Global Highlights:

Based on preliminary data, globally averaged combined land and sea surface temperature was 5th warmest for May and 6th warmest on record for boreal spring (March - May 2006).
March - May 2006 temperatures were above average in much of southern Asia, western Africa, and the majority of North America. Below average conditions occurred in northern Europe, southern Africa, a majority of Russia, and Alaska.
Precipitation during March - May 2006 was above average in the Hawaiian Islands, the Amazon Basin, northern Australia, southeastern Asia and much of the Philippines, with drier-than-average conditions in eastern Australia, the southeastern U.S., Central America, and eastern South America.
Neutral ENSO conditions were present in the equatorial Pacific.
The Southern Hemisphere average land surface temperature was the 25th coolest May on record.

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.

Introduction

Temperature anomalies for March - May 2006 and May 2006 are shown on the four maps below. The dot maps on the left provide a spatial representation of anomalies calculated from the Global Historical Climatology Network (GHCN) data set of land surface stations using a 1961-1990 base period. The maps on the right are a product of a merged land surface and sea surface temperature anomaly analysis which is based on data from the GHCN of land temperatures and the Comprehensive Ocean-Atmosphere Data Set (COADS) of Sea-Surface Temperature (SST) data. Temperature anomalies with respect to 1961-1990 for land and ocean are analyzed separately and then merged to form the global analysis. Additional information on this product is available.

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 March - May 2006 map and the May 2006 map) are generally reflected by areas of positive and negative temperature anomalies at the surface, respectively.

Current season's Land Surface Temperature Dot map

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Current season's blended Land and sea surface Temperature Dot map

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Temperatures were cooler than average across large parts of the Southern Hemisphere land areas during May 2006. Cooler than average conditions are also reflected in the Mar-May (austral fall) season. Slightly cooler than average temperatures were also present in Russia and Eastern Europe.

Conversely, during Mar-May in the Northern Hemisphere (boreal spring), temperatures were more than 3°C (5°F) above average throughout large parts of Canada, the southern U.S. and northern Mexico, western Africa, and parts of southern Asia. The warmer than average temperatures contributed to persistent or worsening drought conditions in some of these areas. For additional information on drought and other extreme climate conditions refer to the Global Hazards page.

Ocean surface temperatures were warmer than average throughout much of the world during May and Mar-May. Although cooler than average conditions were present in the Niño 1+2 region in the March-May season, warmer than average temperatures throughout the central and eastern equatorial Pacific by May marked the completion of the transition from La Niña to ENSO-neutral conditions. Please see the latest ENSO discussion for additional information.

As shown in the maps below, large positive temperature anomalies occurred throughout much of the North American continent during the year-to-date five-month period. Mean temperatures in excess of 4°C (7°F) were commonplace, and new monthly mean temperature records were established in the United States for January and April. Above average temperatures were also present throughout much of South America, Africa, southern Asia and Greenland. Cooler than average temperatures occurred in eastern Europe, Russia, and western Australia.

Current month's Land SurfaceTemperature Dot map

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Current month's blended Land and sea surface Temperature Dot map

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While warmer than average temperatures covered most ocean surfaces during January-May 2006, the presence of cooler than average temperatures in the Niño 3.4 region is evidence of the weak La Niña episode which ended by March . Please see the latest ENSO discussion for additional information on the state of conditions in the equatorial Pacific.

Images of sea surface temperature conditions are available for all weeks during 2006 at the weekly SST page.

For other Global products see the Climate Monitoring Global Products page.

Temperature Rankings and Graphics

Effective with the January 2006 report, NCDC transitioned from the use of the Operational Global Surface Temperature Index (Quayle et al. 1999) to the blended land and ocean dataset developed by Smith and Reynolds (2005). The differences between the two methods are discussed in Smith et al. 2005.

Current Month / Seasonal / Year-to-date

May	Anomaly	Rank	Warmest Year on Record
Global Land Ocean Land and Ocean	+0.59°C (+1.06°F) +0.47°C (+0.85°F) +0.50°C (+0.90°F)	7th warmest 3rd warmest 5th warmest	2000 (+1.31°C/2.36°F) 1998 (+0.53°C/0.95°F) 1998 (+0.70°C/1.26°F)
Northern Hemisphere Land Ocean Land and Ocean	+0.95°C (+1.71°F) +0.46°C (+0.83°F) +0.64°C (+1.15°F)	4th warmest 3rd warmest 3rd warmest	2000 (+1.66°C/2.99°F) 2004 (+0.53°C/0.95°F) 2005 (+0.83°C/1.49°F)
Southern Hemisphere Land Ocean Land and Ocean	-0.45°C (-0.81°F) +0.48°C (+0.86°F) +0.34°C (+0.61°F)	25th coolest 2nd warmest 11th warmest	1992 (+1.41°C/2.54°F) 1998 (+0.59°C/1.06°F) 1998 (+0.63°C/1.13°F)

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March-May	Anomaly	Rank	Warmest Year on Record
Global Land Ocean Land and Ocean	+0.74°C (+1.33°F) +0.42°C (+0.76°F) +0.51°C (+0.92°F)	8th warmest 6th warmest 6th warmest	2002 (+1.16°C/2.09°F) 1998 (+0.44°C/0.79°F) 2004 (+0.56°C/1.01°F)
Northern Hemisphere Land Ocean Land and Ocean	+0.97°C (+1.75°F) +0.40°C (+0.72°F) +0.61°C (+1.10°F)	5th warmest 6th warmest 6th warmest	2002 (+1.53°C/2.75°F) 1998 (+0.49°C/0.88°F) 2002 (+0.78°C/1.40°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.08°C (+0.14°F) +0.45°C (+0.81°F) +0.40°C (+0.72°F)	49th warmest 5th warmest 8th warmest	1998 (+0.73°C/1.31°F) 1998 (+0.41°C/0.74°F) 1998 (+0.45°C/0.81°F)

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January-May	Anomaly	Rank	Warmest Year on Record
Global Land Ocean Land and Ocean	+0.69°C (+1.24°F) +0.40°C (+0.72°F) +0.48°C (+0.86°F)	11th warmest 6th warmest 6th warmest	2002 (+1.29°C/2.32°F) 1998 (+0.53°C/0.95°F) 2002 (+0.66°C/1.19°F)
Northern Hemisphere Land Ocean Land and Ocean	+0.82°C (+1.48°F) +0.36°C (+0.65°F) +0.53°C (+0.95°F)	11th warmest 6th warmest 7th warmest	2002 (+1.54°C/2.77°F) 2004 (+0.50°C/0.90°F) 2002 (+0.83°C/1.49°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.32°C (+0.58°F) +0.44°C (+0.79°F) +0.43°C (+0.77°F)	18th warmest 6th warmest 7th warmest	2005 (+0.89°C/1.60°F) 1998 (+0.56°C/1.01°F) 1998 (+0.61°C/1.10°F)

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The most current data may be accessed via the Global Surface Temperature Anomalies page.

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Precipitation

The maps below represent anomaly values based on the GHCN data set of land surface stations using a base period of 1961-1990. During March-May 2006, above average precipitation fell over areas that include India, Brazil, northern Australia, the Philippines, and Hawaii. Below average precipitation was observed in southern Brazil, Argentina, Pakistan, eastern Australia, and the southeastern U.S. Additional details on drought and heavy precipitation can also be found on the May Hazards page.

During May 2006, above average precipitation fell over areas that include southeast Asia, portions of southern India, Japan, South Africa, Hawaii, and the United Kingdom. Below average precipitation was observed across the majority of Australia, central South America, parts of southern Europe, and much of the U.S.

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recipitation Dot map in Millimeters for May

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ENSO SST Analysis

Last week of the month's ENSO condtions Map

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Sea Surface Temperatures were near average across the central tropical Pacific. La Niña conditions dissipated, indicating a more neutral state of ENSO (shown in the adjacent animation of weekly sea surface temperature anomalies). A comprehensive summary of May 2006 ENSO conditions can be found on the ENSO monitoring page. For the latest advisory on ENSO conditions go to NOAA's Climate Prediction Center (CPC) and the CPC ENSO Diagnostic Discussion
Images of sea surface temperature conditions are available for all weeks during 2006 at the weekly SST page

Troposphere

Current Month / Seasonal
Mid-tropospheric and lower stratospheric temperature data are collected by NOAA's TIROS-N polar-orbiting satellites and adjusted for time-dependent biases by the Global Hydrology and Climate Center at the University of Alabama in Huntsville (UAH). An independent analysis is also performed by Remote Sensing Systems (RSS) and a third analysis has been performed by Dr. Qiang Fu of the the University of Washington (UW) (Fu et al. 2004)** to remove the influence of the stratosphere on the mid-troposphere value.

The tables below summarize mid-tropospheric conditions for May 2006. These temperatures are for the atmospheric layer centered in the mid-troposphere (approximately 2-6 miles above the Earth's surface) which also includes a portion of the lower stratosphere. (The MSU channel used to measure mid-tropospheric temperatures receives about 25 percent of its signal above 6 miles). For additional information on MSU data used in this report, please see the Microwave Sounding Unit page.

All datasets indicate boreal spring temperatures and May temperatures were above average. Records began in 1979.

May	Anomaly	Rank	Warmest Year on Record	Trend
UAH mid-trop	+0.05°C/0.09°F	12th warmest	1998 (+0.60°C/1.08°F)	+0.04°C/decade
*RSS mid-trop	+0.005°C/0.010°F	14th warmest	1998 (+0.64°C/1.15°F)	+0.11°C/decade
**UW-UAH mid-trop	+0.15°C/0.27°F	10th warmest	1998 (+0.75°C/1.35°F)	+0.10°C/decade
*UW-RSS mid-trop	+0.06°C/0.11°F	14th warmest	1998 (+0.75°C/1.35°F)	+0.16°C/decade

*Version 02_1

March-May	Anomaly	Rank	Warmest Year on Record	Trend
UAH mid-trop	+0.10°C/0.18°F	10th warmest	1998 (+0.60°C/1.08°F)	+0.05°C/decade
*RSS mid-trop	+0.14°C/0.25°F	8th warmest	1998 (+0.65°C/1.17°F)	+0.12°C/decade
**UW-UAH mid-trop	+0.21°C/0.38°F	7th warmest	1998 (+0.73°C/1.31°F)	+0.11°C/decade
*UW-RSS mid-trop	+0.24°C/0.43°F	7th warmest	1998 (+0.78°C/1.40°F)	+0.18°C/decade

*Version 02_1

Stratosphere

Current Month / Seasonal
The tables below summarize stratospheric conditions for May 2006. On average, the stratosphere is located approximately between 10-14 miles above the Earth's surface. Over the last decade, stratospheric temperatures have been below average in large part due to the depletion of ozone. The large increase in temperature in 1982 was caused by the volcanic eruption of El Chichon in Mexico, and the increase in 1991 was a result of the eruption of Mt. Pinatubo in the Philippines. Therefore the base period used is 1984-1990 which was chosen to avoid contamination by these eruptions.

May	Anomaly	Rank	Coolest Year on Record
UAH stratosphere	-0.47°C (-0.85°F)	5th coolest	1996 (-0.63°C/-1.13°F)
*RSS stratosphere	-0.32°C (-0.58°F)	6th coolest	1996 (-0.53°C/-0.95°F)

*Version 02_1

March-May	Anomaly	Rank	Coolest Year on Record
UAH stratosphere	-0.55°C (-1.00°F)	3rd coolest	1998 (-0.62°C/-1.12°F)
*RSS stratosphere	-0.51°C (-0.92°F)	3rd coolest	1999 (-0.57°C/-1.03°F)

*Version 02_1

For additional details on precipitation and temperatures in May, see the Global Hazards page.

References

Christy, John R., R.W. Spencer, and W.D. Braswell, 2000: MSU Tropospheric Temperatures: Dataset Construction and Radiosonde Comparisons. J. of Atmos. and Oceanic Technology 17 1153-1170.

Fu, Q., C.M. Johanson, S.G. Warren, and D.J. Seidel, 2004: Contribution of stratospheric cooling to satellite-inferred tropospheric temperature trends. Nature, 429, 55-58.

Mears, Carl A., M.C. Schabel, F.J. Wentz, 2003: A Reanalysis of the MSU Channel 2 Tropospheric Temperature Record. J. Clim 16, 3650-3664.

Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global Historical Climatology Network Database. Bull. Amer. Meteorol. Soc., 78, 2837-2849.

Quayle, R. G., T. C. Peterson, A. N. Basist, and C. S. Godfrey, 1999: An operational near-real-time global temperature index. Geophys. Res. Lett., 26, 333-335.

Smith, T. M., and R. W. Reynolds (2005), A global merged land air and sea surface temperature reconstruction based on historical observations (1880-1997), J. Clim., 18, 2021-2036.