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Upper Air ReportJuly 2008
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 began in 1979.
Lower Troposphere
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.
| July | Anomaly | Rank (out of 30 years) |
Warmest (or Next Warmest) Year on Record | Trend |
|---|---|---|---|---|
| UAH low-trop | +0.06°C/+0.11°F | 15th warmest | 1998 (+0.52°C/0.94°F) | +0.10°C/decade |
| *RSS low-trop | +0.15°C/0.27°F | 11th warmest | 1998 (+0.62°C/1.12°F) | +0.17°C/decade |
*Version 03_0
| January- July |
Anomaly | Rank (out of 30 years) |
Warmest [Coolest] (or Next Warmest [Coolest]) Year on Record | Trend |
|---|---|---|---|---|
| UAH low-trop | -0.02°C/-0.04°F | 19th warmest (12th coolest) |
1998 (+0.62°C/+1.12°F) [1985 (-0.22°C/-0.40°F)] |
+0.12°C/decade |
| *RSS low-trop | +0.03°C/+0.05°F | 20th warmest | 1998 (+0.68°C/+1.22°F) | +0.17°C/decade |
*Version 03_0
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 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.
Radiosonde measurements indicate that for the January-July year-to-date period, temperatures in the mid-troposphere were 0.13°C (0.23°F) above average, resulting in the 20th warmest January-July since global measurements began in 1958. However, as shown in the table below, satellite measurement of the January-July year-to-date period for the middle troposphere varied from fourth coolest (27th warmest) to tenth coolest (21st warmest) on record.
The global mid-troposphere temperatures were near average in July 2008. As shown in the table below, satellite measurement for July 2008 ranked from 13th warmest to 20th warmest on record.
| July | Anomaly | Rank (out of 30 years) |
Warmest [Coolest] (or Next Warmest [Coolest]) Year on Record | Trend |
|---|---|---|---|---|
| UAH mid-trop | -0.07°C/-0.13°F | 20th warmest (11th coolest) |
1998 (+0.47°C/+0.85°F) [1985 (-0.35°C/-0.63°F)] |
+0.05°C/decade |
| *RSS mid-trop | +0.02°C/+0.04°F | 17th warmest | 1998 (+0.51°C/+0.92°F) | +0.11°C/decade |
| **UW-UAH mid-trop | +0.03°C/+0.05°F | 17th warmest | 1998 (+0.59°C/+1.06°F) | +0.11°C/decade |
| **UW-*RSS mid-trop | +0.12°C/0.22°F | 13th warmest | 1998 (+0.63°C/+1.13°F) | +0.17°C/decade |
*Version 03_0
| January- July |
Anomaly | Rank (out of 30 years) |
Warmest [Coolest] (or Next Warmest [Coolest]) Year on Record | Trend |
|---|---|---|---|---|
| UAH mid-trop | -0.16°C/-0.29°F | 27th warmest (4th coolest) |
1998 (+0.57°C/+1.03°F) [1989 (-0.25°C/-0.45°F)] |
+0.04°C/decade |
| *RSS mid-trop | -0.10°C/-0.18°F | 24th warmest (7th coolest) |
1998 (+0.60°C/+1.08°F) [1989 (-0.23°C/-0.41°F)] |
+0.09°C/decade |
| **UW-UAH mid-trop | -0.07°C/-0.13°F | 22nd warmest (9th coolest) |
1998 (+0.70°C/+1.26°F) [1989 (-0.27°C/-0.49°F)] |
+0.10°C/decade |
| **UW-*RSS mid-trop | -0.01°C/-0.02°F | 21st warmest (10th coolest) |
1998 (+0.72°C/+1.30°F) [1989 (-0.24°C/-0.43°F)] |
+0.15°C/decade |
| RATPAC | +0.13°C/+0.23°F | 20th warmest (out of 51 years) |
1998 (+0.81°C/+1.46°F) | +0.14°C/decade |
*Version 03_0
Stratosphere
The table below summarizes stratospheric conditions for July 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.
| July | Anomaly | Rank (out of 30 years) |
Coolest Year on Record |
|---|---|---|---|
| UAH stratosphere | -0.59°C (-1.06°F) | 5th coolest | 1996 (-0.73°C/-1.31°F) |
| *RSS stratosphere | -0.49°C (-0.88°F) | 5th coolest | 1996 (-0.65°C/-1.17°F) |
*Version 03_0
For additional details on precipitation and temperatures in July, 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.
