State of the Climate
Global Analysis
January 2007

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 the warmest on record for January 2007.
January temperatures were above average in Europe, Asia, western Africa, parts of South America, and the northeast half of the United States. Cooler-than-average conditions occurred in eastern Russia, eastern Alaska, and the southwestern contiguous U.S.
Precipitation during January was above average in Scandinavia, England, Indonesia, northern Europe, southern Brazil, and the southern Plains to the eastern Great Lakes of the contiguous U.S. Drier than average conditions were observed in India, Japan, western U.S., southern Europe, and the eastern coast of Australia.
ENSO conditions weakened but persisted in a warm phase (El Niño) during January.

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 January 2007 are shown on the dot maps below. The dot map, below left, provides 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 map, below right, is 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.

During January, there were above average temperatures across Europe, Asia, western Africa, parts of South America, and the northeast half of the United States. The anomalously warm conditions over Europe and Russia led to the 2nd lowest January snow cover extent on record for the Eurasian continent. Cooler than average temperatures were observed in eastern Russia, eastern Alaska, and the southwestern contiguous U.S. Warmer than average Sea Surface Temperatures (SSTs) occurred in the North Atlantic and the Niño regions. SSTs decreased in the Niño regions during the month of January, but were between 0.5°C and 1.0°C above average. Please see the latest ENSO discussion for additional information on the 2006/2007 El Niño event.

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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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 January 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 2007 at the weekly SST 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).

Based on preliminary data, the global land and ocean surface temperature for the month of January was 0.85°C (1.53°F) warmer than the 20th century average of 12.0°C (53.6°F), surpassing the previous record set in 2002, which was 0.71°C (1.28°F). The global land surface temperatures for the month were warmest on record as well, with a departure of 1.89°C (3.40°F) warmer than average. The global ocean surface temperatures were 4th warmest in the 128-year record, approximately 0.05°C (0.09°F) cooler than the record established in 1998.

Current Month

January	Anomaly	Rank	Warmest Year on Record
Global Land Ocean Land and Ocean	+1.89°C (+3.40°F) +0.47°C (+0.85°F) +0.85°C (+1.53°F)	warmest 4th warmest warmest	2002 (+1.44°C/2.59°F) 1998 (+0.52°C/0.94°F) 2002 (+0.71°C/1.28°F)
Northern Hemisphere Land Ocean Land and Ocean	+2.28°C (+4.10°F) +0.49°C (+0.88°F) +1.16°C (+2.09°F)	warmest 2nd warmest warmest	2002 (+1.87°C/3.37°F) 1998 (+0.51°C/0.92°F) 2002 (+0.93°C/1.67°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.71°C (+1.28°F) +0.46°C (+0.83°F) +0.50°C (+0.90°F)	4th warmest 6th warmest 4th warmest	2006 (+0.79°C/1.42°F) 1998 (+0.55°C/0.99°F) 1998 (+0.58°C/1.04°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 January 2007, above average precipitation fell over areas that include Scandinavia, England, Indonesia, southern Brazil, and the southern Plains to the eastern Great Lakes of the contiguous U.S. Below average precipitation was observed in India, Japan, western U.S., southern Europe, and the eastern coast of Australia. Additional details on flooding and drought can also be found on the January Global Hazards page.

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Precipitation Dot map in Percent for January

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ENSO SST Analysis

Last week of the month's ENSO condtions Map

Click here for animated loop

Sea Surface Temperatures decreased across the equatorial Pacific Ocean during January, as the El Niño episode weakened but persisted (shown in the adjacent animation of weekly sea surface temperature anomalies). A comprehensive summary of January 2007 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.

Northern Hemisphere Snow Cover Extent

As shown in the time series to the right, mean Northern Hemisphere snow cover extent during January 2007 was below average. Much of this was due to anomalously warm conditions across Asia, Europe, Canada, and the northeast half of the U.S. January 2007 snow cover extent on the Northern Hemisphere was the 4th lowest extent on record. Mean Northern Hemisphere January snow cover extent for the 1967-2007 period of record is 46.9 million square kilometers.

Northern Hemisphere January Snow Cover extent

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Snow cover for January 2007 across North America was above average. This was in part due to a series of snow and ice storms that struck the U.S. during the month of January. Mean North America January snow cover extent is 17.5 million square kilometers for the 1967-2007 period of record.

As depicted in the time series to the right, Eurasia's snow cover extent in January was the 2nd lowest on record behind 1981. Monthly mean temperatures above 5.0°C covered much of Europe and Russia. Average Eurasian January snow cover extent is 29.4 million square kilometers for the 1967-2007 period of record.

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(Data were provided by Global Snow Laboratory, Rutgers University).

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Troposphere

Current Month

Temperatures above the Earth's surface are measured using in-situ balloon-borne instruments (radiosondes) and polar-orbiting satellites (NOAA's TIROS-N). The radiosonde and the 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). Note: January's report contains troposphere data from satellites only. The in-situ measurements will return in the February 2007 report.

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 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.

Note: 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). 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 global mid-troposphere temperatures were warmer than average in January 2007, as shown in the table below. Satellite measurements indicate that January 2007 was the second warmest on record behind 1998 for all three analysis.

January	Anomaly	Rank	Warmest Year on Record	Trend
UAH mid-trop	+0.34°C/+0.61°F	2nd warmest	1998 (+0.48°C/0.86°F)	+0.06°C/decade
*RSS mid-trop	+0.44°C/0.79°F	2nd warmest	1998 (+0.54°C/0.97°F)	+0.13°C/decade
**UW-UAH mid-trop	+0.45°C/+0.81°F	2nd warmest	1998 (+0.62°C/1.12°F)	+0.12°C/decade
*UW-RSS mid-trop	+0.55°C/+0.99°F	2nd warmest	1998 (+0.66°C/1.19°F)	+0.19°C/decade

*Version 02_1

Stratosphere

Current Month

The table below summarizes stratospheric conditions for January 2007. 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 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.

January	Anomaly	Rank	Coolest Year on Record
UAH stratosphere	-0.53°C (-0.95°F)	7th coolest	2006 (-0.84°C/-1.51°F)
*RSS stratosphere	-0.43°C (-0.77°F)	8th coolest	2006 (-0.82°C/-1.48°F)

*Version 02_1

For additional details on precipitation and temperatures in January, 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.