Climate of 2002
May in Historical Perspective

National Climatic Data Center, 17 June 2002

Global Highlights:

• Global average combined land and sea surface temperature was the third warmest on record for May and second warmest for March-May
• June 2001-May 2002 global temperature was the second warmest such 12-month period on record
• March-May temperatures were 3-5°C (5.4-9°F) warmer than average over much of Europe and eastern Asia
• Above average precipitation during March-May was noted across much of Argentina and Uruguay with drier than average conditions throughout most of Australia

Contents of this Section:

• Introduction
• Global Temperatures
  
  • June-May
  • March-May
  • May
• Global Precipitation
• Microwave Sounding Unit Data

Introduction

The March-May 2002 mean temperature was above the 1988-2002 average across much of Europe, Australia and eastern Asia as shown in the adjacent map of blended satellite and in-situ data. Much cooler than average temperatures occurred across most of Canada and parts central Russia. The mean position of upper level ridges and troughs of low pressure (depicted by positive and negative 500 millibar height anomalies), correspond to areas of positive and negative temperature anomalies, respectively. Similar distributions of temperature were noted during May 2002. Warmer-than-average sea surface temperatures were observed throughout the tropical Pacific during March-May, as a slow evolution toward mature El Niño conditions continued.

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March-May temperature anomalies calculated from the Global Historical Climatology Network data set of land surface stations using a 1961-1990 base period also show the warmer than average temperatures across Europe, eastern Asia, much of Australia and western Alaska. Cooler than average temperatures were observed over much of Canada as well as southern Chile and Argentina. Much of Canada also experienced colder than average temperatures during the month of May 2002.

Temperature

For the period June 2001-May 2002, the global average land and ocean temperature was 0.58°C (1.04°F) above average, the second warmest June-May on record The warmest June through May occurred 4 years ago during the last El Niño episode The June-May land surface temperature average was warmest on record, 0.92°C (1.66°F) above average Globally averaged ocean tempeatures for the same 12-month period were 0.43°C (0.77°F) above the 1880-2001 mean, or second warmest

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The global land and ocean seasonal temperature average (March-May 2002) was the second warmest boreal spring average in the 1880-2002 record, 0.63°C (1.13°F) above the long-term mean and 0.06°C (0.11°F) cooler than the El Niño spring of 1998 Temperatures averaged across ocean areas were second warmest on record globally, or 0.43°C (0.77°F) above the long-term March-May mean Land areas were warmest on record for the 5-month period from January-May 2002, or 1.24°C (2.23°F) above the 1880-2001 average

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The global average land and ocean temperature during May 2002 was 0.51°C (0.92°F) above the 1880-2001 monthly mean, ranking third warmest in the period of record Temperatures averaged across land areas also ranked as third warmest on record in May 2002, or 0.74°C (1.33°F) above average Sea surface temperatures averaged second warmest for May, or 0.41°C (0.74°F) above the long-term mean Global temperatures have increased at an average rate of approximately 0.6°C (1°F) per century since 1900, but the rate of warming during the past 25 years is almost three times higher

Serial monthly global surface temperature departures with respect to a 1971-2000 mean are shown in the figure to the right The recent return to record or near record temperature departures is evident, and monthly global temperatures (land and ocean) have been warmer than the 1971-2000 average for the last 73 consecutive months

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Precipitation

During boreal spring (March-May), much above average precipitation fell across parts of Argentina and Uruguay, interior China and the U.S. Ohio Valley Drier than average weather prevailed across much of Australia, coastal provinces of China and Taiwan, as well as the U.S. Gulf Coast and western states In May, heavier-than-average precipitation fell over much of Argentina, southern Brazil and Paraguay, with excessive rainfall observed across Madagascar. Additional regional analysis can be found on the Global Hazards page

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Microwave Sounding Unit Data

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Temperatures in the lowest 8km (5 miles) of the troposphere were 0.21°C (0.38°F) above average during March-May, or the fourth warmest such period in the satellite period of record (1979 to present) May temperatures in the lower troposphere were 0.20°C (0.36°F) above average

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March-May temperatures were below average in the lower stratosphere, with a departure of -0.21°C (-0.38°F) March-May temperatures in the lower stratosphere have been below average each year since 1993. The overall cooling trend is consistent with the response to losses in stratospheric ozone while the warm anomalies in 1992-1993 are due to the warming influence of the Mount Pinatubo eruption which occurred in the Philippines in June 1991. Lower stratospheric temperatures were 0.24°C (0.43°F) below average in May 2002, the tenth consecutive May with below average stratospheric temperatures.

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

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.

For all climate questions other than questions concerning this report, please contact the National Climatic Data Center's Climate Services Division:

Climate Services Division
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Asheville, NC 28801-5001
fax: 828-271-4876
phone: 828-271-4800
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For questions about this report, please contact:

David Easterling
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
fax: 828-271-4328
email: David.Easterling@noaa.gov

Jay Lawrimore
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
fax: 828-271-4328
email: Jay.Lawrimore@noaa.gov

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