Upper Air - January 2011
Contents of this Section:
Note: Beginning in December 2010, all lower troposphere, middle troposphere, and lower stratosphere satellite data are reported here with respect to the 1981–2010 base period. Prior to December 2010, data were reported with respect to the 1979–1998 base period. Remote Sensing Systems continues to provide data to NCDC with respect to the 1979–1998 base period; however, NCDC readjusts the data to the 1981–2010 base period so that the satellite measurements are comparable.
Note: Effective with the Janaury 2011 report, Remote Sensing Systems (RSS) transitioned to a new version (3.3) of the RSS MSU/AMSU atmospheric temperature datasets. Information about the differences between version 3.2 and 3.3 is available.
Upper Air Highlights
University of Alabama Huntsville satellite analyses report a lower troposphere January 2011 temperature equal to the 1981–2010 average, the 17th coolest (17th warmest) since satellite records began in 1979.
Remote Sensing Systems satellite analyses report a lower troposphere January temperature anomaly of 0.03°C (-0.06°F) below average, the 16th coolest (18th warmest) on record.
University of Alabama Huntsville satellite analyses report a January 2011 mid troposphere temperature anomaly of 0.14°C (0.25°F) below average, the eighth coolest (26th warmest) such period on record. When these analyses are adjusted to remove stratospheric influence, the anomaly decreases to 0.10°C (0.18°F) below average, the 13th coolest (21st warmest) on record.
Remote Sensing Systems satellite analyses report a January 2011 mid troposphere temperature anomaly of 0.09°C (0.16°F) below average, the 13th coolest (21st warmest) such period on record. When these analyses are adjusted to remove stratospheric influence, the anomaly decreases to 0.05°C (0.09°F) below average, the 17th coolest (17th warmest) on record.
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 date back to 1979.
These temperatures are for the lowest 8 km (5 miles) of the atmosphere. Information on the University of Alabama in Huntsville (UAH) and Remote Sensing Systems (RSS) sources of troposphere data is available.
(out of 33 years)
|Warmest Year on Record||Trend|
|UAH low-trop||+0.00°C/+0.00°F||17th warmest||2010 (+0.55°C/+0.99°F)*||+0.13°C/decade|
|RSS low-trop||-0.03°C/-0.06°F||18th warmest||2010 (+0.48°C/+0.86°F)*||+0.14°C/decade|
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 Microwave Sounding Unit [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.
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.
Satellite measurements indicate that for January 2011, temperatures were above average, resulting in the second warmest—behind 1998—January since satellite records began in 1979.
(out of 33 years)
|Warmest Year on Record||Trend|
|UAH mid-trop||-0.14°C/-0.25°F||26th warmest||1998 (+0.48°C/+0.86°F)||+0.02°C/decade|
|RSS mid-trop||-0.09°C/-0.16°F||21st warmest||1998 (+0.45°C/+0.81°F)||+0.08°C/decade|
|UW-UAH mid-trop||-0.10°C/-0.18°F||21st warmest||1998 (+0.57°C/+1.03°F)||+0.08°C/decade|
|UW-RSS mid-trop||-0.05°C/-0.09°F||17th warmest||1998 (+0.53°C/+0.95°F)||+0.14°C/decade|
The table below summarizes stratospheric conditions for January 2011. On average, the stratosphere is located approximately 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.
(out of 33 years)
|Coolest Year on Record|
|UAH stratosphere||-0.17°C (-0.31°F)||16th coolest||2006 (-0.57°C/-1.03°F)|
|RSS stratosphere||-0.14°C (-0.26°F)||16th coolest||2006 (-0.58°C/-1.05°F)|
For additional details on precipitation and temperatures in January, see the Global Analysis page.
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