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Climate of 2008
February in Historical Perspective

Including Boreal Winter

National Climatic Data Center
13 March 2008

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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 December 2007 - February 2008 and February 2008 are shown on the dot maps below. The dot maps, below 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 dot maps, below right, are a product of a merged land surface and sea surface temperature anomaly analysis developed by Smith and Reynolds (2005). Temperature anomalies with respect to the 1961-1990 mean for land and ocean are analyzed separately and then merged to form the global analysis. Additional information on this product is available.

Unlike January-February 2007 when warm anomalies covered much of the globe, January-February 2008 had cooler-than-average temperatures across the Middle East region, Kazakhstan, Mongolia, Alaska, parts of the western and north-central contiguous U.S., northern Africa, and most of China. The map of temperature anomalies shows the presence of warmer-than-average temperatures across Europe, western and central Russia, central and western Australia, and the southern Plains to the eastern Great Lakes of the contiguous U.S. Warmer-than-average sea surface temperatures (SSTs) were present in the Atlantic and Indian oceans, the Niño 1+2 region, and parts of the northwest Pacific Ocean. Cooler-than-average conditions were observed in all Niño regions (with the exception of Niño 1+2 region), parts of the northeastern Pacific and some areas in the southern oceans.

During the boreal winter, temperatures were above average across Europe, western and central Russia, eastern Brazil, the eastern and south-central contiguous U.S., parts of eastern Asia, and southern parts of Chile and Argentina. Cooler-than-average conditions occurred from the Middle East region to parts of China, north-central and the southwestern states of the contiguous U.S., and eastern Australia.

As shown in the maps below, temperatures across Europe were 2-5°C (4-9°F) above average. These warm anomalous conditions resulted in the warmest winter in Finland since records began more than a century ago. During December 2007 - February 2008, Southern Finland experienced a total of 20-30 days of below zero mean temperatures, while Central Finland had only 45-55 days. This was 30-40 and 25-35 days less than typical for Southern and Central Finland, respectively. These conditions also led to a reduction of number of days that had at least 1 cm (0.4 inches) of snow on the ground, with Southern and Southwestern Finland experiencing a total of 20-30 days while Central Finland had 50-60 days. Typically, snow covers the ground more than 70 days during the winter. According to the Finnish Meteorology Institute (FMI), the second mildest winter occurred in 1924-1925.

According to reports (released on 26 February 2008), Sweden might have experienced its warmest winter since records began in 1756. The previous record was set during the winter of 1972-1973 when the mean temperature for winter was 1.9°C (3.4°F). Since the report was released, the data available at the time suggested the winter 2007-2008 mean temperature average would be near 2.0-2.2°C (3.6-4°F) (BBC News).

During February, above average temperatures were observed across Europe, most of Russia, northwestern and southern parts of Africa, southern Chile and Argentina, and the eastern and south-central states of the contiguous U.S. Meanwhile, cooler-than-average conditions were present across China, northern India, western Alaska, the northcentral states of the contiguous U.S., parts of central Africa, eastern and southern Australia, and parts of the Middle East Region.

According to the Bureau of Meteorology (BoM), New South Wales, Australia experienced anomalously cool conditions during February. The state anomaly of -2.67°C (4.81°F) was the second lowest on record, behind 1954.

February SSTs were warmer than average in the Atlantic and parts of the North Indian and northwestern Pacific oceans. Cooler-than-average conditions were present in parts of the southern oceans and in the Niño regions, with the exception of the Niño 1+2 region where the monthly temperature anomaly rose to +0.23°C (+0.41°F). Temperature anomalies across the Niño 3.4 and 4 regions remained more than 1°C (1.8°F) below average. Please see the latest ENSO discussion for additional information.

The mean position of the upper level ridges of high pressure and troughs of low pressure (depicted by positive and negative 500-millibar height anomalies on the December-February 2008 map and the February map) are generally reflected by areas of positive and negative temperature anomalies at the surface, respectively. For other Global products see the Climate Monitoring Global Products page.

Images of sea surface temperature conditions are available for all weeks during 2008 at the weekly SST page.

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Temperature Rankings and Graphics

Current Month / Seasonal / Year-to-date

Effective with the February 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).

The combined global land and ocean surface temperature was the fifteenth warmest on record in February and the sixteenth warmest on record for boreal winter (December-February). The presence of a strong La Niña contributed to a global average temperature that was the coolest since the La Niña episode of 2000-2001.

February	Anomaly	Rank	Warmest (or Next Warmest) Year on Record
Global Land Ocean Land and Ocean	+0.62°C (+1.12°F) +0.29°C (+0.52°F) +0.38°C (+0.68°F)	21st warmest 12th warmest 15th warmest	2002 (+1.65°C/2.97°F) 1998 (+0.55°C/0.99°F) 1998 (+0.82°C/1.48°F)
Northern Hemisphere Land Ocean Land and Ocean	+0.70°C (+1.26°F) +0.26°C (+0.47°F) +0.43°C (+0.77°F)	21st warmest 10th warmest 15th warmest	2002 (+2.14°C/3.85°F) 1998 (+0.53°C/0.95°F) 2002 (+1.04°C/1.87°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.34°C (+0.61°F) +0.33°C (+0.59°F) +0.33°C (+0.59°F)	20th warmest 20th warmest 17th warmest	1983 (+0.94°C/1.69°F) 1998 (+0.57°C/1.03°F) 1998 (+0.61°C/1.10°F)

December-February	Anomaly	Rank	Warmest (or Next Warmest) Year on Record
Global Land Ocean Land and Ocean	+0.48°C (+0.86°F) +0.26°C (+0.47°F) +0.32°C (+0.58°F)	23rd warmest 16th warmest 16th warmest	2007 (+1.38°C/2.48°F) 1998 (+0.55°C/0.99°F) 2007 (+0.72°C/1.30°F)
Northern Hemisphere Land Ocean Land and Ocean	+0.51°C (+0.92°F) +0.27°C (+0.49°F) +0.36°C (+0.65°F)	26th warmest 11th warmest 14th warmest	2007 (+1.61°C/2.90°F) 1998 (+0.52°C/0.94°F) 2007 (+0.92°C/1.66°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.36°C (+0.65°F) +0.26°C (+0.47°F) +0.28°C (+0.50°F)	15th warmest 26th warmest 23rd warmest	1998 (+0.80°C/1.44°F) 1998 (+0.57°C/1.03°F) 1998 (+0.61°C/1.10°F)

January-February	Anomaly	Rank	Warmest (or Next Warmest) Year on Record
Global Land Ocean Land and Ocean	+0.30°C (+0.54°F) +0.27°C (+0.49°F) +0.28°C (+0.50°F)	34th warmest 15th warmest 22nd warmest	2002 (+1.55°C/2.79°F) 1998 (+0.54°C/0.97°F) 2007 (+0.73°C/1.31°F)
Northern Hemisphere Land Ocean Land and Ocean	+0.27°C (+0.49°F) +0.26°C (+0.47°F) +0.26°C (+0.47°F)	45th warmest 11th warmest 28th warmest	2002 (+2.01°C/3.62°F) 1998 (+0.52°C/0.94°F) 2002 (+0.99°C/1.78°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.39°C (+0.70°F) +0.29°C (+0.52°F) +0.30°C (+0.54°F)	14th warmest 22nd warmest 18th warmest	1998 (+0.81°C/1.46°F) 1998 (+0.56°C/1.01°F) 1998 (+0.59°C/1.06°F)

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 boreal winter, above average precipitation fell over areas that include Great Britain, Scandinavia, the northeastern and central regions of the contiguous U.S., and parts of the Hawaiian Islands, Australia, and the northwestern countries of South America. Drier-than-average conditions were observed in western and south-central U.S., most of Europe, and parts of the southern countries of South America.

During February 2008, above average precipitation fell over areas that include the Philippines, northern and eastern Australia, the Hawaiian Islands, parts of the northwestern countries of South America, and the eastern and parts of the central contiguous U.S. Drier-than-average conditions were observed across most of Europe, the south-central and western parts of the contiguous U.S., parts of Brazil and eastern Asia.

Although much needed rain fell over the southeastern region of the contiguous U.S. during February, exceptional drought continued to affect the area. Spain suffered from the worst drought in more than a decade while Portugal had the worst winter drought since 1917. Meanwhile, in the Hawaiian and the Philippine islands, heavy rain fell prompting widespread floods. Additional details on flooding and drought can also be found on the February Global Hazards page.

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ENSO SST Analysis

Below average sea surface temperature (SST) anomalies continued in all the Niño regions with the exception of the Niño 1+2 region where SST anomalies were warmer than average. These conditions are indicative of a mature ENSO cold event (shown in the adjacent animation of weekly sea surface temperature anomalies). A comprehensive summary of February 2008 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 since 2003 at the weekly SST page.

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Northern Hemisphere Snow Cover Extent

As shown in the time series to the right, the mean Northern Hemisphere snow cover extent during winter 2007/2008 was above average. This can be primarily attributed to the multiple snow and ice storms that affected much of the Northern Hemisphere during the winter. This resulted in the 4th largest snow cover extent on record. The mean Northern Hemisphere winter snow cover extent for the 1967-2008 period of record was 136.4 million square kilometers.

Across North America, snow cover for winter 2007/2008 was above average, the 6th largest extent since satellite records began in 1967. A series of snow and ice storms struck the U.S. since the beginning of winter. The heavy snowfall during the winter prompted more than 4,700 new daily snowfall records and several new seasonal records across the contiguous U.S. The mean North America winter snow cover extent was 51.2 million square kilometers for the 1967-2008 period of record.

As depicted in the time series to the right, Eurasia's snow cover extent during winter 2007/2008 was above average. During January 2008, China suffered its worst severe winter weather in 5 decades. Although analysis of the causes of unusually severe winter storms in southern China continues, scientists at NOAA's Earth System Research Laboratory have early indications that the severe weather may have been due to the presence of unusually strong and persistent high pressure over Eastern Europe combined with low pressure over Southwest Asia. This pattern directed a series of storms across the region while northerly low level flow introduced cold air from Mongolia. Unusually warm water temperatures in the China Sea may have provided a favorable environment of available moisture that enhanced the severity of these storms. Also, parts of the Middle East region experienced their heaviest snowfall in more than a decade while other areas saw snow fall for the first time in living memory. In February 2008, severe winter weather continued to affect much of Eurasia, prompting the winter 2007/2008 to have the 4th largest snow cover extent over the 41-year historical period. On average, the Eurasian boreal winter snow cover extent was 85.2 million square kilometers for the 1967-2008 period of record.

Data were provided by the Global Snow Laboratory, Rutgers University.

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Sea Ice Extent

According to the National Snow and Ice Data Center, the February 2008 Northern Hemisphere sea ice extent, which is measured from passive microwave instruments onboard NOAA satellites, was below the 1979-2000 mean, but greater than the previous four years. This was the fifth least February sea ice extent on record. Including 2008, the past five years had the least February sea ice extent since records began in 1979. Sea ice extent for February has decreased at a rate of 2.8%/decade (since satellite records began in 1979) as temperatures in the high latitude Northern Hemisphere have risen at a rate of approximately 0.37°C/decade over the same period.

Meanwhile, the February 2008 Southern Hemisphere sea ice extent was much above the 1979-2000 mean. This was the second largest sea ice extent in February (27% above the 1979-2000 mean) over the 30-year historical period, behind 2003. Sea ice extent for February has increased at a rate of 3.4%/decade.

For further information on the Northern and Southern Hemisphere snow and ice conditions, please visit the NSIDC News page, provided by the NOAA's National Snow and Ice Data center (NSIDC).

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Troposphere

Temperatures above the Earth's surface are measured within the lower troposphere, middle troposphere, and stratosphere using in-situ balloon-borne instruments (radiosondes) and polar-orbiting satellites (NOAA's TIROS-N). The radiosonde and satellite records have been adjusted to remove time-dependent biases (artificialities caused by changes in radiosonde instruments and measurement practices as well as changes in satellite instruments and orbital features through time).

Lower Troposphere

Current Month / Seasonal / Year-to-date

These temperatures are for the lowest 8 km (5 miles) of the atmosphere. Information on the UAH and RSS sources of troposphere data is available.

February	Anomaly	Rank	Warmest (or Next Warmest) Year on Record	Trend
UAH low-trop	+0.02°C/0.04°F	18th warmest	1998 (+0.76°C/1.37°F)	+0.18°C/decade
*RSS low-trop	-0.01°C/-0.02°F	20th warmest	1998 (+0.73°C/1.31°F)	+0.17°C/decade

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December- February	Anomaly	Rank	Warmest (or Next Warmest) Year on Record	Trend
UAH low-trop	+0.03°C/0.05°F	17th warmest	1998 (+0.55°C/0.99°F)	+0.16°C/decade
*RSS low-trop	-0.004°C/-0.01°F	20th warmest	1998 (+0.56°C/1.01°F)	+0.16°C/decade

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January- February	Anomaly	Rank	Warmest (or Next Warmest) Year on Record	Trend
UAH low-trop	-0.01°C/-0.03°F	18th warmest	1998 (+0.67°C/1.21°F)	+0.17°C/decade
*RSS low-trop	-0.04°C/-0.08°F	21st warmest	1998 (+0.62°C/1.12°F)	+0.17°C/decade

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Mid-troposphere

Current Month / Seasonal / Year-to-date

These temperatures are for the atmospheric layer centered in the mid-troposphere (approximately 3-10 km (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 10 km (6 miles).) Because the stratosphere has cooled due to increasing greenhouse gases in the troposphere and losses of ozone in the stratosphere, the stratospheric contribution to the tropospheric average, as measured from satellites, may create an artificial component of cooling to the mid-troposphere temperatures. The University of Washington (UW) versions of the UAH and RSS analyses attempt to remove the stratospheric influence from the mid-troposphere measurements, and as a result the UW versions tend to have a larger warming trend than either the UAH or RSS versions. For additional information, please see NCDC's Microwave Sounding Unit page.

The radiosonde data used in this global analysis were developed using the Lanzante, Klein, Seidel (2003) ("LKS") bias-adjusted dataset and the First Difference Method (Free et al. 2004) (RATPAC). Additional details are available. Satellite data have been adjusted 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 University of Washington (UW) (Fu et al. 2004)** to remove the influence of the stratosphere on the mid-troposphere value. Global averages from radiosonde data are available from 1958 to present, while satellite measurements began in 1979.

Radiosonde measurements indicate that for the January-February year-to-date period, temperatures in the mid-troposphere were 0.16°C (0.29°F) above average, resulting in the nineteenth warmest January-February since global measurements began in 1958. However, as shown in the table below, satellite measurement of the January-February year-to-date period for the middle troposphere varied from eighteenth to twenty-third warmest on record.

Similar to January-February year-to-date, radiosonde measurements indicate that temperatures were 0.16°C (0.29°F) above average during the boreal winter, giving December-February a rank of nineteenth warmest on record. The table below shows that satellite measurements for the boreal winter varied from eighteenth to twenty-second warmest on record.

The global mid-troposphere temperatures were slightly cooler or slightly warmer than average in February 2008 depending on the analysis. As shown in the table below, satellite measurement for February 2008 ranked from seventeenth to twentieth warmest on record.

February	Anomaly	Rank	Warmest (or Next Warmest) Year on Record	Trend
UAH mid-trop	-0.05°C/-0.09°F	20th warmest	1998 (+0.67°C/1.21°F)	+0.08°C/decade
*RSS mid-trop	-0.02°C/-0.04°F	19th warmest	1998 (+0.71°C/1.27°F)	+0.12°C/decade
**UW-UAH mid-trop	+0.04°C/0.07°F	17th warmest	1998 (+0.80°C/1.45°F)	+0.15°C/decade
**UW-*RSS mid-trop	+0.06°C/0.10°F	17th warmest	1998 (+0.83°C/1.49°F)	+0.18°C/decade

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December- February	Anomaly	Rank	Warmest (or Next Warmest) Year on Record	Trend
UAH mid-trop	-0.10°C/-0.17°F	22nd warmest	1998 (+0.45°C/0.82°F)	+0.05°C/decade
*RSS mid-trop	-0.05°C/-0.10°F	22nd warmest	1998 (+0.49°C/0.89°F)	+0.10°C/decade
**UW-UAH mid-trop	-0.01°C/-0.02°F	19th warmest	1998 (+0.58°C/1.04°F)	+0.12°C/decade
**UW-*RSS mid-trop	+0.02°C/0.04°F	18th warmest	1998 (+0.60°C/1.08°F)	+0.16°C/decade
RATPAC	+0.16°C/0.29°F	19th warmest	1998 (+0.59°C/1.06°F)	+0.15°C/decade

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January- February	Anomaly	Rank	Warmest (or Next Warmest) Year on Record	Trend
UAH mid-trop	-0.12°C/-0.21°F	23rd warmest	1998 (+0.58°C/1.05°F)	+0.07°C/decade
*RSS mid-trop	-0.07°C/-0.12°F	21st warmest	1998 (+0.62°C/1.12°F)	+0.11°C/decade
**UW-UAH mid-trop	-0.03°C/-0.06°F	18th warmest	1998 (+0.72°C/1.30°F)	+0.14°C/decade
**UW-*RSS mid-trop	0.00°C/0.00°F	18th warmest	1998 (+0.75°C/1.34°F)	+0.17°C/decade
RATPAC	+0.16°C/0.29°F	19th warmest	2005 (+0.75°C/1.35°F)	+0.14°C/decade

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Stratosphere

Current Month / Seasonal

The table below summarizes stratospheric conditions for February 2008. On average, the stratosphere is located approximately between 16-23 km (10-14 miles) above the Earth's surface. Over the last decade, stratospheric temperatures have been below average in part due to the depletion of ozone. The large positive anomaly in 1982 was caused by the volcanic eruption of El Chichon in Mexico, and the sharp jump in temperature in 1991 was a result of the eruption of Mt. Pinatubo in the Philippines. In both cases the temperatures returned to pre-eruption levels within two years.

February	Anomaly	Rank	Coolest Year on Record
UAH stratosphere	-0.51°C (-0.92°F)	4th coolest	2006 (-0.70°C/-1.26°F)
*RSS stratosphere	-0.53°C (-0.96°F)	5th coolest	2006 (-0.75°C/-1.34°F)

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December- February	Anomaly	Rank	Coolest Year on Record
UAH stratosphere	-0.56°C (-1.00°F)	8th coolest	2006 (-0.74°C/-1.33°F)
*RSS stratosphere	-0.48°C (-0.87°F)	8th coolest	2006 (-0.69°C/-1.25°F)

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For additional details on precipitation and temperatures in February, 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.

Free, M., D.J. Seidel, J.K. Angell, J. Lanzante, I. Durre and T.C. Peterson (2005) Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC): A new dataset of large-area anomaly time series, J. Geophys. Res., 10.1029/2005JD006169.

Free, M., J.K. Angell, I. Durre, J. Lanzante, T.C. Peterson and D.J. Seidel(2004), Using first differences to reduce inhomogeneity in radiosonde temperature datasets, J. Climate, 21, 4171-4179.

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.

Lanzante, J.R., S.A. Klein, and D.J. Seidel (2003a), Temporal homogenization of monthly radiosonde temperature data. Part I: Methodology, J. Climate, 16, 224-240.

Lanzante, J.R., S.A. Klein, and D.J. Seidel (2003b), Temporal homogenization of monthly radiosonde temperature data. Part II: trends, sensitivities, and MSU comparison, J. Climate, 16, 241 262.

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.

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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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For questions about this report, please contact:

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David Easterling
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Asheville, NC 28801-5001
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email: David.Easterling@noaa.gov

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