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Contents of this Section:
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 date back to 1979.
Lower Troposphere
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.
| January | Anomaly | Rank (out of 32 years) |
Second Warmest Year on Record | Trend |
|---|---|---|---|---|
| UAH low-trop | +0.72°C/+1.30°F | warmest | 2007 (+0.59°C/+1.06°F)* | +0.18°C/decade |
| RSS low-trop | +0.64°C/+1.15°F | warmest | 2007 (+0.59°C/+1.06°F)* | +0.18°C/decade |
Mid-troposphere
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 2010, temperatures were above average, resulting in the second warmest—behind 1998—January since satellite records began in 1979.
| January | Anomaly | Rank (out of 32 years) |
Warmest Year on Record | Trend |
|---|---|---|---|---|
| UAH mid-trop | +0.48°C/+0.86°F | 2nd warmest | 1998 (+0.50°C/+0.90°F) | +0.07°C/decade |
| RSS mid-trop | +0.49°C/+0.88°F | 2nd warmest | 1998 (+0.53°C/+0.95°F) | +0.11°C/decade |
| UW-UAH mid-trop | +0.62°C/+1.12°F | 2nd warmest | 1998 (+0.64°C/+1.15°F) | +0.14°C/decade |
| UW-RSS mid-trop | +0.63°C/+1.14°F | 2nd warmest | 1998 (+0.65°C/+1.18°F) | +0.17°C/decade |
Stratosphere
The table below summarizes stratospheric conditions for January 2010. 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.
| January | Anomaly | Rank (out of 32 years) |
Coolest Year on Record |
|---|---|---|---|
| UAH stratosphere | -0.61°C (-1.10°F) | 9th coolest | 2006 (-0.80°C/-1.44°F) |
| RSS stratosphere | -0.63°C (-1.14°F) | 7th coolest | 2006 (-0.84°C/-1.50°F) |
For additional details on precipitation and temperatures in January, 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, CA, FJ Wentz, 2009, Construction of the RSS V3.2 lower tropospheric dataset from the MSU and AMSU microwave sounders. Journal of Atmospheric and Oceanic Technology, 26, 1493-1509.
Mears, CA, FJ Wentz, 2009, Construction of the Remote Sensing Systems V3.2 atmopsheric temperature records from the MSU and AMSU microwave sounders. Journal of Atmospheric and Oceanic Technology, 26, 1040-1056.
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.