State of the Climate
Global Analysis
September 2008

National Oceanic and Atmospheric Administration

National Climatic Data Center

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Based on preliminary data, the globally averaged combined land and sea surface temperature was the ninth warmest on record for September and for the January-September year-to-date period.
September 2008 temperatures were above average in Australia, India, Iceland, the Middle East region, northern Africa, western, north-central, and eastern continental U.S., most of Alaska, eastern Asia, and parts of South America. Meanwhile, cooler-than-average conditions were present across the south-central continental U.S., South Africa, Paraguay, most of Mexico, Europe, and parts of central Russia.
Precipitation during September 2008 was variable in many areas. In general, precipitation was above average in Iceland, the Caribbean, northeastern and parts of the central continental U.S., southeastern Europe, India, and Southeast Asia. Drier-than-average conditions were observed across the Hawaiian Islands, northern Europe, western Alaska, western and southeastern contiguous U.S., southern Australia, northern India, parts of eastern Asia, and most of South America.
El Niño-Southern Oscillation (ENSO) conditions remained in a neutral phase 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 2008 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.

September's Land Surface Temperature Anomalies in degree Celsius

September's Land Surface Temperature
Anomalies in degrees Celsius

September's Blended Land and Sea Surface
Temperature Anomalies in degrees Celsius

During September, above average temperatures were observed across Australia, India, Iceland, the Middle East region, northern Africa, western, north-central, and eastern continental U.S., most of Alaska, eastern Asia, and parts of South America. Meanwhile, cooler-than-average conditions were present across the south-central continental U.S., South Africa, Paraguay, most of Mexico, Europe, and parts of central Russia.

During the second and third week of September, Hungary saw a marked contrast in temperatures. The city of Szeged had a new maximum temperature record for September 7 when temperatures rose to 37.6°C (100°F), surpassing the previous record of 36.7°C (98°F) set in 1946. Meanwhile on September 15, a new national record was set when the city of Sopron, Hungary recorded its coldest temperature of 8.6°C (47°F), surpassing the previous record set in Zalaegerszeg in 1925 when temperatures fell to 10.5°C (51°F).

Sea surface temperatures (SSTs) during September 2008 were warmer than average in the Atlantic, Indian, northwestern Pacific and eastern equatorial Pacific oceans. Cooler-than-average SSTs were present in parts of the southern oceans and in the central equatorial and northeastern Pacific Ocean. SST anomalies slightly decreased in all Niño regions during September 2008. Please see the September 2008 ENSO discussion for additional information.

Anomalously warm temperatures covered much of the world's land surface for the first nine months of the year. The January-September 2008 map shows the presence of warmer-than-average temperatures across all land areas, with the exception of parts of the northern continental U.S. and eastern Australia. Warmer-than-average SST conditions were present in the Atlantic and Indian oceans, eastern equatorial Pacific and parts of the northwest Pacific oceans. Cooler-than-average conditions were observed in the central equatorial Pacific, parts of the northeastern Pacific and some areas in the southern oceans.

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 September map, respectively) are generally reflected by areas of positive and negative temperature anomalies at the surface, respectively. For other Global products, please 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 / 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 ranks found in the tables below are based on records that began in 1880.

The combined global land and ocean surface temperature for September 2008 tied with 2001 as the ninth warmest since records began in 1880. The September global land surface temperature tied with 2004 as the eleventh warmest on record, while the global ocean surface temperature tied with 2001 as the seventh warmest in the 129-year record. The January-September year-to-date land and ocean temperature was the ninth warmest on record.

September	Anomaly	Rank (out of 129 years)	Warmest (or Next Warmest) Year on Record
Global Land Ocean Land and Ocean	+0.50°C (+0.90°F) +0.42°C (+0.76°F) +0.44°C (+0.79°F)	11^th warmest 7^th warmest 9^th warmest	2005 (+1.05°C/1.89°F) 1997 (+0.54°C/0.97°F) 2005 (+0.64°C/1.15°F)
Northern Hemisphere Land Ocean Land and Ocean	+0.49°C (+0.88°F) +0.47°C (+0.85°F) +0.48°C (+0.86°F)	12^th warmest 6^th warmest 9^th warmest	2005 (+1.20°C/2.16°F) 2003 (+0.67°C/1.21°F) 2005 (+0.83°C/1.49°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.53°C (+0.95°F) +0.38°C (+0.68°F) +0.40°C (+0.72°F)	12^th warmest 9^th warmest 9^th warmest	1997 (+1.18°C/2.12°F) 1997 (+0.55°C/0.99°F) 1997 (+0.63°C/1.13°F)

September's Global Land and Ocean plot

September's Global Hemisphere plot

January-September	Anomaly	Rank (out of 129 years)	Warmest (or Next Warmest) Year on Record
Global Land Ocean Land and Ocean	+0.70°C (+1.26°F) +0.36°C (+0.65°F) +0.45°C (+0.81°F)	8^th warmest 10^th warmest 9^th warmest	2007 (+1.03°C/1.85°F) 1998 (+0.52°C/0.94°F) 1998 (+0.63°C/1.13°F)
Northern Hemisphere Land Ocean Land and Ocean	+0.78°C (+1.40°F) +0.38°C (+0.68°F) +0.53°C (+0.95°F)	8^th warmest 8^th warmest 9^th warmest	2007 (+1.20°C/2.16°F) 2005 (+0.55°C/0.99°F) 2007 (+0.73°C/1.31°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.44°C (+0.79°F) +0.34°C (+0.61°F) +0.35°C (+0.63°F)	10^th warmest 13^th warmest 13^th warmest	2005 (+0.85°C/1.53°F) 1998 (+0.54°C/0.97°F) 1998 (+0.58°C/1.04°F)

January-September Global Land and Ocean plot

January-September Global Hemisphere plot

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. Precipitation during September 2008 was above average over areas that include Iceland, the Caribbean, northeastern and parts of the central continental U.S., southeastern Europe, India, and Southeast Asia. Drier-than-average conditions were observed across the Hawaiian Islands, northern Europe, western Alaska, western and southeastern contiguous U.S., southern Australia, northern India, parts of eastern Asia, and most of South America.

September's Precipitation Anomalies in Millimeters

September Precipitation Percent Departures

September's Precipitation Percent Departures

According to the Australian Bureau of Meteorology (BoM), Melbourne experienced its driest September when just 12 mm (0.47 inch) of rain fell, surpassing the previous record of 13.4 mm (0.53 inch) set in 1907. The states of South Australia and Victoria had their eighth driest September on record, with Victoria having its driest September since 1971. Meanwhile, South Australia had its fifth driest year-to-date on record, but the driest since 1959. However, Australia as a whole received slightly above average precipitation. This was Australia's 33^rd wettest September in the 109-year record.

During September 2008, Hurricanes Gustav, Hanna, and Ike, and Tropical Storm Kyle brought torrential rain across the Caribbean and parts of the continental U.S., triggering fatal floods and causing havoc across the affected areas. Preliminary damage estimates of $31.5 billion U.S. dollars rank Ike as the third most destructive U.S. land falling hurricane after Katrina (2005) and Andrew (1992). Meanwhile in the northwestern Pacific Ocean, three typhoons (Sinlaku, Hagupit, and Jangmi) brought heavy rain and strong winds to parts of Southeast Asia.

Additional details on flooding and drought can also be found on the September Global Hazards page.

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ENSO SST Analysis

First week of September's ENSO condtions Map

Click here for animated loop

During September 2008, sea surface temperatures (SST) were slightly below average across the central equatorial Pacific Ocean, while slightly above average temperatures remained in the eastern equatorial Pacific Ocean. These conditions (shown in the adjacent animation of weekly sea surface temperature anomalies) are indicative of a neutral ENSO phase. A comprehensive summary of September 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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Sea Ice Extent

September's Northern Hemisphere
Sea Ice Extent plot

According to the National Snow and Ice Data Center, the September 2008 Northern Hemisphere sea ice extent, which is measured from passive microwave instruments onboard NOAA satellites, was the second least September sea ice extent on record, behind 2007. Average ice extent during September 2008 was 1.80 million square miles (4.67 million square kilometers), which is 34 percent below the 1979-2000 average. Sea ice extent for September has decreased at a rate of 11.7 percent per decade, since satellite records began in 1979. The lowest Northern Hemisphere sea ice extent occurs in September each year.

September's Southern Hemisphere
Sea Ice Extent plot

Meanwhile, the September 2008 Southern Hemisphere sea ice extent was slightly below the 1979-2000 mean. This was the eighth least sea ice extent in September (1.2 percent below the 1979-2000 mean) over the 30-year historical period. Sea ice extent for September has increased at a rate of 0.6 percent per 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). Global averages from radiosonde data are available from 1958 to present, while satellite measurements began in 1979.

Lower Troposphere

Current Month / 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.

September	Anomaly	Rank (out of 30 years)	Warmest (or Next Warmest) Year on Record	Trend
UAH low-trop	+0.16°C/+0.29°F	10^th warmest	1998 (+0.43°C/0.77°F)	+0.12°C/decade
*RSS low-trop	+0.21°C/+0.38°F	13^th warmest	1998 (+0.53°C/0.95°F)	+0.19°C/decade

*Version 03_0

January- September	Anomaly	Rank (out of 30 years)	Warmest [Coolest] (or Next Warmest [Coolest]) Year on Record	Trend
UAH low-trop	0.00°C/0.00°F	20^th warmest (11^th coolest)	1998 (+0.59°C/+1.06°F) [1984 (-0.23°C/-0.41°F)]	+0.12°C/decade
*RSS low-trop	+0.06°C/+0.11°F	16^th warmest	1998 (+0.66°C/+1.19°F)	+0.17°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 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.

RATPAC January-September plot

Radiosonde measurements indicate that for the January-September year-to-date period, temperatures in the mid-troposphere were 0.15°C (0.27°F) above average, resulting in the 20^th warmest January-September since global measurements began in 1958. However, as shown in the table below, satellite measurement of the January-September year-to-date period for the middle troposphere varied from fifth coolest (26^th warmest) to eleventh coolest (20^th warmest) on record.

The global mid-troposphere temperatures were slightly above average in September 2008. As shown in the table below, satellite measurement for September 2008 ranked from 13^th warmest to 20^th warmest on record.

September	Anomaly	Rank (out of 30 years)	Warmest [Coolest] (or Next Warmest [Coolest]) Year on Record	Trend
UAH mid-trop	+0.01°C/+0.02°F	17^th warmest	1998 (+0.43°C/+0.77°F)	+0.07°C/decade
*RSS mid-trop	+0.06°C/+0.11°F	17^th warmest	1998 (+0.49°C/+0.89°F)	+0.13°C/decade
**UW-UAH mid-trop	+0.15°C/+0.28°F	11^th warmest	1998 (+0.60°C/+1.08°F)	+0.15°C/decade
*UW-RSS mid-trop	+0.18°C/+0.33°F	13^th warmest	1998 (+0.65°C/+1.16°F)	+0.20°C/decade

*Version 03_0

January- September	Anomaly	Rank (out of 30 years)	Warmest [Coolest] (or Next Warmest [Coolest]) Year on Record	Trend
UAH mid-trop	-0.14°C/-0.25°F	26^th warmest (5^th coolest)	1998 (+0.54°C/+0.97°F) [1984 (-0.22°C/-0.40°F)]	+0.04°C/decade
*RSS mid-trop	-0.08°C/-0.14°F	22^nd warmest (9^th coolest)	1998 (+0.58°C/+1.04°F) [1985 (-0.22°C/-0.40°F)]	+0.09°C/decade
**UW-UAH mid-trop	-0.04°C/-0.07°F	22^nd warmest (9^th coolest)	1998 (+0.68°C/+1.22°F) [1984 (-0.25°C/-0.45°F)]	+0.11°C/decade
*UW-RSS mid-trop	+0.01°C/0.02°F	20^th warmest	1998 (+0.71°C/+1.28°F)	+0.16°C/decade
RATPAC	+0.15°C/+0.27°F	20^th warmest (out of 51 years)	1998 (+0.80°C/+1.44°F)	+0.14°C/decade

*Version 03_0

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Stratosphere

Current Month

The table below summarizes stratospheric conditions for September 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.

September	Anomaly	Rank (out of 30 years)	Coolest Year on Record
UAH stratosphere	-0.64°C (-1.15°F)	5^th coolest	1996 (-0.80°C/-1.44°F)
*RSS stratosphere	-0.59°C (-1.06°F)	5^th coolest	1996 (-0.73°C/-1.31°F)

*Version 03_0

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For additional details on precipitation and temperatures in September, 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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