Global Temperature Report -- February 2010

Article ID: 562544

Released: 23-Mar-2010 8:00 AM EDT

Source Newsroom: University of Alabama Huntsville

  • Broken lines outline areas that were cooler than seasonal norms; solid lines outline areas that were warmer than seasonal norms. Each contour represents one degree Celsius.

Newswise — Global Temperature Report: February 2010

2nd warmest February in 32 years is fifth 'warmest' month overall

New dataset corrects seasonal cycles

Global climate trend since Nov. 16, 1978: +0.13 C per decade

February temperatures (preliminary)

Global composite temp.: +0.61 C (about 1.1 degrees Fahrenheit) above 20-yearaverage for February.

Northern Hemisphere: +0.72 C (about 1.3 degrees Fahrenheit) above 20-yearaverage for February.

Southern Hemisphere: +0.51 C (about 0.92 degrees Fahreneheit) above 20-yearaverage for February.

January temperatures (revised):

Global Composite: +0.63 C above 20-year average

Northern Hemisphere: +0.81 C above 20-year average

Southern Hemisphere: +0.45 C above 20-year average

(All temperature anomalies are based on a 20-year average (1979-1998) forthe month reported.)

Notes on data released March 8, 2010:

The El Nino Pacific Ocean warming event continues to dominate the globaltemperature keeping it quite warm, although not so in selected locationswhere many in the U.S. and Europe experienced colder than usual conditionsthrough February, according to Dr. John Christy, professor of atmosphericscience and director of the Earth System Science Center (ESSC) at TheUniversity of Alabama in Huntsville.

Globally, February 2010 was the second warmest February in the 32-yeartemperature record behind February 1998 (+0.75 C). While January 2010 wasthe warmest January, it was in 4th place overall behind February, April andMay 1998. February 2010 was 5th warmest overall, compared to seasonal norms.

"This is the most intense El Nino since the 1997-98 event, when the tropicshit 1.29 C above average in February 1998," Christy said. "Last month thetropics were +0.79 above average, the largest departure for any month in thetropics since 1998."

UAHuntsville introduces satellite dataset v5.3

"We have updated our satellite temperature dataset to account for themismatch between the average seasonal cycle produced by the older microwavesounding units (MSUs) and the newer advanced MSUs," Christy said. "Thisaffects the value of the individual monthly departures, but does not affectthe year to year variations. The overall trend remains the same."

Comparison of v5.2 and v5.3

Year Mth v5.2 v5.3 2009 1 0.304 0.213 2009 2 0.347 0.220 2009 3 0.206 0.174 2009 4 0.090 0.135 2009 5 0.045 0.102 2009 6 0.003 0.022 2009 7 0.411 0.414 2009 8 0.229 0.245 2009 9 0.422 0.502 2009 10 0.286 0.353 2009 11 0.497 0.504 2009 12 0.288 0.262 2010 1 0.721 0.630 2010 2 0.740 0.613

Glb trend +0.132 +0.132since 11/78

Christy and Dr. Roy Spencer, a principal research scientist in the ESSC,have been looking at making an adjustment to the way the average seasonalcycle is removed from the newer AMSU instruments (since 1998) versus theolder MSU instruments that were on satellites before 1998.

"It was brought to our attention that the UAH data tended to have somesystematic peculiarities with specific months," Christy said. "Februarytended to be relatively warmer while September was relatively cooler whencompared to other datasets.

"In v5.2 of our dataset we relied considerably on the older MSUs toconstruct the average seasonal cycle that is used to calculate monthlydepartures for the AMSU instruments. This created the peculiarities notedabove. In v5.3 we have limited this influence.

"The adjustments are minor in terms of climate, as they impact relativedepartures within the year and not the year-to-year variations," he said."Since the errors are largest in February (almost 0.13 C), we believe thatFebruary is the appropriate month to introduce v5.3 where readers will seethe differences most clearly.

"There is no change in the long-term trend, as both v5.2 and v5.3 showwarming at the rate of +0.132 C per decade," Christy said. "All that happensis a redistribution of a fraction of the anomalies among the months. Indeed,with v5.3 as with v5.2, January 2010 is still the warmest January andFebruary 2010 is the second warmest February behind February 1998 in the32-year record."

As part of an ongoing joint project between UAHuntsville, NOAA and NASA,Christy and Spencer use data gathered by advanced microwave sounding unitson NOAA and NASA satellites to get accurate temperature readings for almostall regions of the Earth. This includes remote desert, ocean and rain forestareas where reliable climate data are not otherwise available.

The satellite-based instruments measure the temperature of the atmospherefrom the surface up to an altitude of about eight kilometers above sealevel. Once the monthly temperature data is collected and processed, it isplaced in a "public" computer file for immediate access by atmosphericscientists in the U.S. and abroad.

Neither Christy nor Spencer receives any research support or funding fromoil, coal or industrial companies or organizations, or from any private orspecial interest groups. All of their climate research funding comes fromfederal and state grants or contracts.


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