Climate Monitoring / Climate of 2005 / September / Global / Help

Climate of 2005 - September in Historical Perspective

National Climatic Data Center
13 October 2005

Global Analysis / Global Hazards / United States / U.S. Drought / Extremes
Use these links to access detailed analyses of Global and U.S. data.

Global Highlights:

Based on preliminary data, global averaged combined land and sea surface temperature for September 2005 was warmest on record.
September temperatures were above average over Alaska, Asia, eastern Europe and the majority of the U.S. Colder-than-average conditions occurred in France, western Australia and the U.S. Pacific Northwest.
Precipitation during September was above average over India, Taiwan, Alaska and parts of Canada, with drier than average conditions over eastern Europe, Mexico and the U.S. East Coast.
Neutral ENSO conditions continued during September.

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 September 2005 are shown on the two maps below. The dot map on the 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 map on the right is a blended product of a merged land air and sea surface temperature anomaly analysis which is based on data from the Global Historical Climatology Network (GHCN) of land temperatures and the Comprehensive Ocean-Atmosphere Data Set (COADS) of SST data. Temperature anomalies with respect to 1961-1990 are analyzed separately and then merged to form the global analysis. Additional information on this product is available.

During September 2005, there were above average temperatures over eastern Europe, Asia, Japan, the majority of North America and parts of Brazil. Cooler than average temperatures were observed over France, Spain, western Australia, central South America and along the U.S. West Coast.

Much warmer than average SSTs occurred over the North Pacific and the North Atlantic. Cooler than average conditions were observed off the U.S. Californian coast and the South Atlantic.

Current months 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 September 2005 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 2005 at the weekly SST page

Temperature Rankings and Graphics

Current Month / Year-to-date

September	Anomaly	Rank	Warmest Year on Record
Global Land Ocean Land and Ocean	+0.98°C (+1.76°F) +0.48°C (+0.86°F) +0.63°C (+1.13°F)	warmest 3rd warmest warmest	2nd - 1998 (+0.74°C/1.33°F) 2003 (+0.52°C/0.94°F) 2nd - 2003 (+0.57°C/1.03°F)
Northern Hemisphere Land Ocean Land and Ocean	+1.08°C (+1.94°F) +0.60°C (+1.08°F) +0.79°C (+1.42°F)	warmest 2nd warmest warmest	1998 (+0.80°C/1.44°F) 2003 (+0.65°C/1.17°F) 2nd - 2003 (+0.65°C/1.17°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.66°C (+1.19°F) +0.43°C (+0.77°F) +0.47°C (+0.85°F)	5th warmest 7th warmest 5th warmest	2003 (+0.77°C/1.39°F) 1997 (+0.55°C/1.00°F) 1997 (+0.58°C/1.04°F)

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January-September	Anomaly	Rank	Warmest Year on Record
Global Land Ocean Land and Ocean	+0.94°C (+1.70°F) +0.44°C (+0.79°F) +0.59°C (+1.06°F)	3rd warmest 2nd warmest 2nd warmest	1998 (+1.04°C/1.87°F) 1998 (+0.50°C/0.90°F) 1998 (+0.66°C/1.19°F)
Northern Hemisphere Land Ocean Land and Ocean	+0.95°C (+1.71°F) +0.52°C (+0.94°F) +0.70°C (+1.26°F)	3rd warmest warmest 2nd warmest	2002 (+1.14°C/2.05°F) Tie - 1998 (+0.52°C/0.94°F) 1998 (+0.75°C/1.35°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.77°C (+1.39°F) +0.40°C (+0.72°F) +0.47°C (+0.85°F)	2nd warmest 4th warmest 3rd warmest	1998 (+0.82°C/1.48°F) 1998 (+0.50°C/0.90°F) 1998 (+0.56°C/1.01°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 September 2005, above average precipitation fell over Alaska, India, Burma, Thailand, Taiwan, the U.S. northeast and lower Mississippi Valley, and southern Brazil. Below average precipitation was observed in Mexico, the Caribbean, Nepal, eastern Europe, parts of southeast Asia, Bolivia and other areas of South America, and the U.S. East Coast and Great Plains.

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ENSO SST Analysis

Last week of the month's ENSO condtions Map

Click here for animated loop

SSTs remained near average to slightly below average in the equatorial tropical Pacific during September, indicative of ENSO neutral conditions (shown in the adjacent animation of weekly sea surface temperature anomalies). A comprehensive summary of September 2005 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 during 2005 at the weekly SST page

Northern Hemisphere Sea Ice Extent

Northern Hemisphere sea ice extent, as measured from passive microwave instruments onboard NOAA satellites, was lowest on record for the month of September at 5.32 million square kilometers, as shown in the image to the right. This is the fourth consecutive year September sea ice extent has been below the long-term (1978-2000) mean. The lowest sea ice extent occurs in September each year, so the record low measured this past month is also the all-time low sea ice extent in the historical record. Data courtesy of NOAA's National Snow and Ice Data Center.

Monthly sea ice extent for the Northern Hemisphere

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Troposphere

Current Month
The table below summarizes mid-tropospheric conditions for September 2005. 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).

Analysis of the satellite record that began in 1979 indicates that global temperatures are increasing in the mid-troposphere, but the magnitude of the trend differs based on the analysis methods used in adjusting for factors such as orbital decay and inter-satellite differences.

Scientists at the University of Washington {UW}, developed a method for quantifying the stratospheric contribution to the satellite record of tropospheric temperatures and applied an adjustment to the UAH and RSS temperature record that attempts to remove the satellite contribution (cooling influence) from the middle troposphere record. This method results in trends that are larger than the those from the respective source.

Both the RSS and UW-RSS data indicate that September 2005 was the 3rd warmest on record. The UAH data indicate 4th warmest, and UW-UAH data indicate 2nd warmest for September 2005.

September	Anomaly	Rank	Warmest Year on Record	Trend
UAH mid-trop	+0.23°C/0.41°F	4th warmest	1998 (+0.44°C/0.79°F)	+0.09°C/decade
*RSS mid-trop	+0.34°C/0.61°F	3rd warmest	1998 (+0.52°C/0.94°F)	+0.18°C/decade
**UW-UAH mid-trop	+0.35°C/0.63°F	2nd warmest	1998 (+0.59°C/1.06°F)	+0.16°C/decade
*UW-RSS mid-trop	+0.47°C/0.85°F	3rd warmest	1998 (+0.66°C/1.19°F)	+0.24°C/decade

*Version 02_1

Mid-tropospheric and lower stratospheric temperature data are collected by NOAA's TIROS-N polar-orbiting satellites and adjusted for time-dependent biases 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 the University of Washington.

**An adjustment on both the RSS and UAH datasets provided by Fu et al. (2004) (University of Washington) is accomplished by deriving separate weighting coefficients for the MSU T2 and T4 over the tropics (30N to 30S), northern and southern hemispheres, and for the global mean by fitting radiosonde troposphere anomalies to radiosonde-simulated T2 and T4 anomalies over the period from 1958-2004 as

T850-300 = a0 + a2*T2 + a4*T4

where T850-300 is the radiosonde 850-300 hPa layer; T2 and T4 are the radiosonde simulated MSU brightness temperature anomalies; and a0, a2, and a4 are the coefficients derived from this linear regression.

Stratosphere

Current Month
The table below summarizes stratospheric conditions for September 2005. The stratosphere is located between 10-14 miles above the Earth's surface. Over the last decade, stratospheric temperatures have been below average in large part due to the depletion of ozone. The large increase in temperature in 1982 was caused by the volcanic eruption of El Chichon in Mexico, and the increase in 1991 was a result of the eruption of Mt. Pinatubo in the Philippines. Therefore the base period used is 1984-1990 which was chosen to avoid contamination by these eruptions.

September	Anomaly	Rank	Coolest Year on Record
UAH stratosphere	-0.63°C (-1.13°F)	3rd coolest	1996 (-0.74°C/-1.33°F)
*RSS stratosphere	-0.67°C (-1.21°F)	2nd coolest	1996 (-0.74°C/-1.33°F)

*Version 02_1

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For additional details on precipitation and temperatures in September, see the Global Hazards 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.

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fax: 828-271-4876
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For questions about this report, please contact:

Jay Lawrimore
NOAA/National Climatic Data Center
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fax: 828-271-4328
email: Jay.Lawrimore@noaa.gov

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David Easterling
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fax: 828-271-4328
email: David.Easterling@noaa.gov

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