State of the Climate
Global Analysis
March 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 fifth warmest on record for March 2007 and second warmest for January-March year-to-date.
March 2007 temperatures were above average in Europe, the contiguous U.S., southeastern Brazil, and most of Asia. Cooler-than-average conditions occurred in Alaska, central Russia, and parts of Canada.
Precipitation during March 2007 was above average in central U.S., northeastern Australia, the western coast of Canada, and parts of Europe. Drier than average conditions were observed in the southeastern U.S., eastern Brazil, and eastern Australia.
ENSO conditions remained in a neutral phase during March.

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 March 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.

Anomalously warm temperatures have covered much of the globe throughout the first three months of the year. The January-March 2007 map of temperature anomalies shows the presence of warmer than average temperatures across all land areas with the exception of cooler than average temperatures in Alaska. Additional information on Alaska temperatures are available on the US National page. Warmer than average Sea Surface Temperatures (SST) occured in the equatorial Pacific, North and South Atlantic and the Indian Ocean. Cooler than average conditions were observed in the northeastern Pacific and some areas in the South Pacific.

During March, there were above average temperatures across Europe, the contiguous U.S., Mexico, southeastern Brazil, and most of Asia. Cooler than average temperatures were observed in Alaska, central Russia, and parts of Canada. Warmer than average SSTs occurred in the North Atlantic Ocean, North Indian Ocean, Northwestern Pacific Ocean, and the Niño 4 region. SSTs decreased in the Niño 1+2, 3 and 3.4 regions during the month of March, indicative of neutral ENSO conditions. Please see the latest ENSO discussion for additional information.

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 March 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 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).

March 2007 ranked fifth warmest March since global surface records began in 1880 for combined global land and ocean surface temperatures. March land surface temperatures were fourth warmest, while ocean surface temperatures were sixth warmest in the 127-year record. The January - March 2007 land and ocean combined temperature is second warmest on record behind 2002.

Current Month / Year-to-date

March	Anomaly	Rank	Warmest Year on Record
Global Land Ocean Land and Ocean	+1.16°C (+2.09°F) +0.41°C (+0.74°F) +0.61°C (+1.10°F)	4th warmest 6th warmest 5th warmest	1990 (+1.45°C/2.61°F) 1998 (+0.51°C/0.92°F) 2002 (+0.75°C/1.35°F)
Northern Hemisphere Land Ocean Land and Ocean	+1.31°C (+2.36°F) +0.45°C (+0.81°F) +0.77°C (+1.39°F)	6th warmest 3rd warmest 5th warmest	1990 (+1.99°C/3.58°F) 2004 (+0.49°C/0.88°F) 1990 (+0.90°C/1.62°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.71°C (+1.28°F) +0.39°C (+0.70°F) +0.43°C (+0.77°F)	6th warmest 11th warmest 10th warmest	1988 (+1.60°C/2.88°F) 2002 (+0.56°C/1.01°F) 1988 (+0.63°C/1.13°F)

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January-March	Anomaly	Rank	Warmest Year on Record
Global Land Ocean Land and Ocean	+1.30°C (+2.34°F) +0.45°C (+0.81°F) +0.68°C (+1.22°F)	2nd warmest 5th warmest 2nd warmest	2002 (+1.50°C/2.70°F) 1998 (+0.53°C/0.95°F) 2002 (+0.73°C/1.31°F)
Northern Hemisphere Land Ocean Land and Ocean	+1.53°C (+2.75°F) +0.47°C (+0.85°F) +0.87°C (+1.57°F)	2nd warmest 3rd warmest 2nd warmest	2002 (+1.87°C/3.37°F) 1998 (+0.50°C/0.90°F) 2002 (+0.95°C/1.71°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.62°C (+1.12°F) +0.44°C (+0.79°F) +0.47°C (+0.85°F)	5th warmest 7th warmest 7th warmest	1998 (+0.86°C/1.55°F) 1998 (+0.56°C/1.01°F) 1998 (+0.60°C/1.08°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 March 2007, above average precipitation fell over areas that include the central U.S., northeastern Australia, the western coast of Canada, and parts of Europe. Drier than average conditions were observed in the southeastern U.S., eastern Brazil, and eastern Australia. Additional details on flooding and drought can also be found on the March Global Hazards page.

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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 March with the exception of the far western equatorial Pacific where SST were warmer than average. These conditions reflect the neutral ENSO phase (shown in the adjacent animation of weekly sea surface temperature anomalies). A comprehensive summary of March 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 March 2007 was below average, consistent with anomalously warm conditions across Asia, Europe, and the contiguous U.S. March 2007 snow cover extent for the Northern Hemisphere was the 9th lowest extent on record, and it has been below average in 15 of the past 20 years. Mean Northern Hemisphere March snow cover extent for the 1967-2007 period of record is 41.0 million square kilometers.

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Current season's North America Snow Cover extent

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Snow cover for March 2007 across North America was below average, being the 13th lowest extent since records began in 1967. March's low snow cover extent can be attributed to the anomalous warm conditions experienced across the contiguous U.S. where monthly mean temperatures where more than 5°F (3°C) above average in many places. Mean North America March snow cover extent is 15.8 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 March was below average and was the 11th lowest extent over the 41-year historical period. Much of this was due to the anomalously warm conditions that covered much of Europe and Asia during the past cold season. Average Eurasian March snow cover extent is 25.2 million square kilometers for the 1967-2007 period of record.

Current season's Eurasia Snow Cover extent

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

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Troposphere

Temperatures above the Earth's surface are measured within the lower troposphere, middle troposhere, and stratosphere 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).

Lower Troposphere
Current Month / Year-to-date

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

March	Anomaly	Rank	Warmest Year on Record	Trend
UAH low-trop	+0.38°C/0.68°F	3rd warmest	1998 (+0.49°C/0.88°F)	+0.13°C/decade
*RSS low-trop	+0.32°C/0.58°F	7th warmest	1998 (+0.63°C/1.13°F)	+0.21°C/decade

*Version 03_0

January- March	Anomaly	Rank	Warmest Year on Record	Trend
UAH low-trop	+0.44°C/0.79°F	2nd warmest	1998 (+0.57°C/1.03°F)	+0.16°C/decade
*RSS low-trop	+0.38°C/0.68°F	7th warmest	1998 (+0.68°C/1.22°F)	+0.23°C/decade

*Version 03_0

Mid-Troposphere
Current Month / Year-to-date

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 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). 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 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.

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Radiosonde measurements indicate that for the January-March year-to-date period, temperatures in the mid-troposphere were +0.75°C (1.35°F) above average being the warmest January-March since global measurements began in 1958. However, as shown in the table below, satellite measurements of the January-March year-to-date period for the middle troposphere varied from 2nd to 5th warmest on record depending on the analysis method.

The global mid-troposphere temperatures were warmer than average in March 2007, as shown in the table below. Satellite measurements for March 2007 varied from 3rd to 5th warmest on record depending on the analysis method.

March	Anomaly	Rank	Warmest Year on Record	Trend
UAH mid-trop	+0.23°C/0.41°F	5th warmest	1998 (+0.47°C/0.85°F)	+0.05°C/decade
*RSS mid-trop	+0.29°C/0.52°F	5th warmest	1998 (+0.54°C/0.97°F)	+0.12°C/decade
**UW-UAH mid-trop	+0.35°C/0.63°F	4th warmest	1998 (+0.60°C/1.08°F)	+0.11°C/decade
*UW-RSS mid-trop	+0.40°C/0.72°F	3rd warmest	1998 (+0.64°C/1.15°F)	+0.18°C/decade

*Version 03_0

January- March	Anomaly	Rank	Warmest Year on Record	Trend
UAH mid-trop	+0.26°C/+0.47°F	3rd warmest	1998 (+0.53°C/0.95°F)	+0.06°C/decade
*RSS mid-trop	+0.33°C/0.59°F	5th warmest	1998 (+0.60°C/1.08°F)	+0.13°C/decade
**UW-UAH mid-trop	+0.37°C/+0.67°F	2nd warmest	1998 (+0.67°C/1.21°F)	+0.12°C/decade
*UW-RSS mid-trop	+0.43°C/+0.77°F	3rd warmest	1998 (+0.71°C/1.28°F)	+0.19°C/decade
RATPAC	+0.75°C/1.35°F	warmest	2007 (+0.75°C/1.35°F)	+0.15°C/decade

*Version 03_0

Stratosphere

Current Month

The table below summarizes stratospheric conditions for March 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.

March	Anomaly	Rank	Coolest Year on Record
UAH stratosphere	-0.48°C (-0.86°F)	3rd coolest	1999 (-0.73°C/-1.31°F)
*RSS stratosphere	-0.48°C (-0.86°F)	4th coolest	2006 (-0.73°C/-1.31°F)

*Version 03_0

For additional details on precipitation and temperatures in March, 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.