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-year
average for February.
Northern Hemisphere: +0.72 C (about 1.3 degrees Fahrenheit) above 20-year
average for February.
Southern Hemisphere: +0.51 C (about 0.92 degrees Fahreneheit) above 20-year
average 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) for
the month reported.)
Notes on data released March 8, 2010:
The El Nino Pacific Ocean warming event continues to dominate the global
temperature keeping it quite warm, although not so in selected locations
where many in the U.S. and Europe experienced colder than usual conditions
through February, according to Dr. John Christy, professor of atmospheric
science and director of the Earth System Science Center (ESSC) at The
University of Alabama in Huntsville.
Globally, February 2010 was the second warmest February in the 32-year
temperature record behind February 1998 (+0.75 C). While January 2010 was
the warmest January, it was in 4th place overall behind February, April and
May 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 tropics
hit 1.29 C above average in February 1998,” Christy said. “Last month the
tropics were +0.79 above average, the largest departure for any month in the
tropics since 1998.”
UAHuntsville introduces satellite dataset v5.3
“We have updated our satellite temperature dataset to account for the
mismatch between the average seasonal cycle produced by the older microwave
sounding units (MSUs) and the newer advanced MSUs,” Christy said. “This
affects the value of the individual monthly departures, but does not affect
the 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 +0.132
since 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 seasonal
cycle is removed from the newer AMSU instruments (since 1998) versus the
older MSU instruments that were on satellites before 1998.
“It was brought to our attention that the UAH data tended to have some
systematic peculiarities with specific months,” Christy said. “February
tended to be relatively warmer while September was relatively cooler when
compared to other datasets.
“In v5.2 of our dataset we relied considerably on the older MSUs to
construct the average seasonal cycle that is used to calculate monthly
departures for the AMSU instruments. This created the peculiarities noted
above. In v5.3 we have limited this influence.
“The adjustments are minor in terms of climate, as they impact relative
departures 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 that
February is the appropriate month to introduce v5.3 where readers will see
the differences most clearly.
“There is no change in the long-term trend, as both v5.2 and v5.3 show
warming at the rate of +0.132 C per decade,” Christy said. “All that happens
is 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 and
February 2010 is the second warmest February behind February 1998 in the
32-year record.”
A more detailed discussion of this issue is available from Dr. Christy at:
christy@nsstc.uah.edu.
As part of an ongoing joint project between UAHuntsville, NOAA and NASA,
Christy and Spencer use data gathered by advanced microwave sounding units
on NOAA and NASA satellites to get accurate temperature readings for almost
all regions of the Earth. This includes remote desert, ocean and rain forest
areas where reliable climate data are not otherwise available.
The satellite-based instruments measure the temperature of the atmosphere
from the surface up to an altitude of about eight kilometers above sea
level. Once the monthly temperature data is collected and processed, it is
placed in a “public” computer file for immediate access by atmospheric
scientists in the U.S. and abroad.
Neither Christy nor Spencer receives any research support or funding from
oil, coal or industrial companies or organizations, or from any private or
special interest groups. All of their climate research funding comes from
federal and state grants or contracts.
For Additional Information:
Dr. John Christy, (256) 961-7763
john.christy@nsstc.uah.edu
Dr. Roy Spencer, (256) 961-7960
roy.spencer@nsstc.uah.edu