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Global Analysis - April 2007

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Note: The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. Effective September 2012, the GHCN-M version 3.2.0 dataset of monthly mean temperature replaced the GHCN-M version 3.1.0 monthly mean temperature dataset. Beginning with the August 2012 Global monthly State of the Climate Report, released on September 17, 2012, GHCN-M version 3.2.0 is used for NCDC climate monitoring activities, including calculation of global land surface temperature anomalies and trends. For more information about this newest version, please see the GHCN-M version 3.2.0 Technical Report.

*The GHCN-M version 3.1.0 Technical Report was revised on September 5, 2012 to accurately reflect the changes incorporated in that version. Previously that report incorrectly included discussion of changes to the Pairwise Homogeneity Algorithm (PHA). Changes to the PHA are included in version 3.2.0 and described in the version 3.2.0 Technical Report. Please see the Frequently Asked Questions to learn more about this update.

Global Highlights:

Based on preliminary data, globally averaged combined land and sea surface temperature was the warmest on record for January-April year-to-date period and third warmest for April.
Global land surface temperature was warmest on record in April. Temperatures were above average in Europe, Alaska, western U.S., eastern Brazil, northwestern Africa, and most of Asia. Cooler-than-average conditions occurred in the Middle East Region and the eastern half of the contiguous U.S.
Precipitation during April 2007 was above average in the Northeast region of the contiguous U.S. and most of South America. Drier than average conditions were observed in Japan, southeastern U.S., southeastern China and most of Europe.
ENSO conditions remained in a neutral phase during April.

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 April 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 year. The January-April 2007 map of temperature anomalies shows the presence of warmer than average temperatures across all land areas, with the exception of Alaska. Additional information on Alaska temperatures are available on the U.S. 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 April, there were above average temperatures across Europe, Alaska, western U.S., eastern Brazil, northwestern Africa, and most of Asia. Cooler-than-average conditions occurred in the Middle East Region and the eastern half of the contiguous U.S. Warmer than average SSTs occurred in the Atlantic Ocean, North Indian Ocean, and the Northwestern Pacific Ocean. In the Niño regions, SST anomalies were in the range of average or slightly below average with the exception of the Niño 4 region where SST anomalies were slightly above average. These conditions are indicative of a persisting neutral ENSO phase. 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 April 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).

April 2007 ranked as the third warmest April since records began in 1880 for combined global land and ocean surface temperatures. The April land surface temperature ranked warmest on record, while ocean surface temperature ranked seventh warmest in the 127-year record. For the January-April year-to-date period, the global surface temperature ranked warmest on record.

Current Month / Year-to-date

April	Anomaly	Rank	Warmest (or Next Warmest) Year on Record	Ties
Global Land Ocean Land and Ocean	+1.37°C (+2.47°F) +0.41°C (+0.74°F) +0.67°C (+1.21°F)	warmest 7th warmest 3rd warmest	2000 (+1.30°C/2.34°F) 1998 (+0.53°C/0.95°F) 1998 (+0.70°C/1.26°F)	2001
Northern Hemisphere Land Ocean Land and Ocean	+1.57°C (+2.83°F) +0.43°C (+0.77°F) +0.86°C (+1.55°F)	2nd warmest 4th warmest warmest	2000 (+1.66°C/2.99°F) 2004 (+0.53°C/0.95°F) 2005 (+0.81°C/1.46°F)	2002
Southern Hemisphere Land Ocean Land and Ocean	+0.79°C (+1.42°F) +0.40°C (+0.72°F) +0.45°C (+0.81°F)	9th warmest 9th warmest 8th warmest	1992 (+1.41°C/2.54°F) 1998 (+0.59°C/1.06°F) 1988 (+0.63°C/1.13°F)	1983

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January-April	Anomaly	Rank	Warmest (or Next Warmest) Year on Record	Ties
Global Land Ocean Land and Ocean	+1.35°C (+2.43°F) +0.44°C (+0.79°F) +0.69°C (+1.24°F)	warmest 6th warmest warmest	2002 (+1.29°C/2.32°F) 1998 (+0.53°C/0.95°F) 2002 (+0.68°C/1.22°F)
Northern Hemisphere Land Ocean Land and Ocean	+1.56°C (+2.81°F) +0.46°C (+0.83°F) +0.88°C (+1.58°F)	warmest 3rd warmest warmest	2002 (+1.54°C/2.77°F) 2004 (+0.50°C/0.90°F) 2002 (+0.83°C/1.49°F)	2005
Southern Hemisphere Land Ocean Land and Ocean	+0.72°C (+1.30°F) +0.43°C (+0.77°F) +0.47°C (+0.85°F)	4th warmest 7th warmest 6th warmest	2005 (+0.89°C/1.60°F) 1998 (+0.56°C/1.01°F) 1998 (+0.61°C/1.10°F)	2001

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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 April 2007, above average precipitation fell over areas that include the Northeast region of the contiguous U.S. and most of South America. Drier than average conditions were observed in Japan, southeastern U.S., southeastern China and most of Europe. Additional details on flooding and drought can also be found on the April Global Hazards page.

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ENSO SST Analysis

Last week of the month's ENSO condtions Map

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Sea Surface Temperature anomalies were near average or slightly cooler than average across the central and eastern equatorial Pacific, indicative of a neutral ENSO phase (shown in the adjacent animation of weekly sea surface temperature anomalies). A comprehensive summary of April 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.

References

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.

Citing This Report

NOAA National Climatic Data Center, State of the Climate: Global Analysis for April 2007, published online May 2007, retrieved on May 24, 2013 from http://www.ncdc.noaa.gov/sotc/global/2007/4.