Upper Air - September 2011


Contents of this Section:


Note: Beginning in December 2010, all data are reported here with respect to the 1981–2010 base period. Prior to December 2010, radiosonde data were reported with respect to the 1961–1990 base period and satellite 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. This change provides a more consistent comparison between the various datasets.


Note: Effective with the January 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.



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

Current Month | Year-to-date

These temperatures are for the lowest eight kilometers (five miles) of the atmosphere. Information on the University of Alabama in Huntsville (UAH) and Remote Sensing Systems (RSS) sources of troposphere data is available.

September Lower Troposphere
September Anomaly Rank
(out of 33 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.29 +0.52 Coolest 29th 1984 -0.61 -1.10 +0.18 +0.33
Warmest 5th 2010 +0.48 +0.86
RSS +0.18 +0.32 Coolest 25th 1984 -0.57 -1.03 +0.18 +0.32
Warmest 8th 2010 +0.40 +0.72
Year-to-Date Lower Troposphere
January–
September
Anomaly Rank
(out of 33 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.16 +0.29 Coolest 26th 1984 -0.32 -0.58 +0.13 +0.24
Warmest 6th 1998 +0.51 +0.92
RSS +0.07 +0.13 Coolest 22nd 1985 -0.38 -0.68 +0.14 +0.26
Warmest 11th 1998 +0.52 +0.94

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 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, September 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–September year-to-date period, temperatures in the mid-troposphere were 0.17°C (0.31°F) above average, resulting in the ninth warmest January–September period (out of 54 years). Satellite analyses of the January–September year-to-date period for the middle troposphere was the 8th to 15th warmest in the 33-year satellite record, depending on the data source.

The global mid-troposphere temperatures were well above average during September 2011. As shown in the table below, satellite measurements for September 2011 ranked fifth to ninth warmest on record, depending on the data source.

September Mid-troposphere
September Anomaly Rank
(out of 33 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.17 +0.31 Coolest 27th 1984 -0.56 -1.01 +0.12 +0.21
Warmest 6th 2010 +0.42 +0.76
RSS +0.14 +0.25 Coolest 25th 1984 -0.56 -1.01 +0.14 +0.25
Warmest 9th 2010, 1998 +0.40 +0.72
UW-UAH +0.28 +0.50 Coolest 29th 1984 -0.67 -1.21 +0.19 +0.34
Warmest 5th 2010 +0.52 +0.94
UW-RSS +0.24 +0.43 Coolest 28th 1984 -0.63 -1.13 +0.19 +0.35
Warmest 5th 1998 +0.50 +0.90
Year-to-Date Mid-troposphere
January–
September
Anomaly Rank
(out of 33 years*)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.02 +0.04 Coolest 17th 1993, 1989, 1984 -0.25 -0.45 +0.05 +0.09
Warmest 15th 1998 +0.51 +0.92
RSS +0.02 +0.04 Coolest 18th 1985 -0.28 -0.50 +0.09 +0.16
Warmest 15th 1998 +0.52 +0.94
UW-UAH +0.10 +0.18 Coolest 26th 1984 -0.32 -0.58 +0.11 +0.20
Warmest 8th 1998 +0.61 +1.10
UW-RSS +0.09 +0.16 Coolest 23rd 1984 -0.33 -0.59 +0.14 +0.26
Warmest 11th 1998 +0.60 +1.08
RATPAC* +0.17 +0.31 Coolest 46th 1965 -0.85 -1.53 +0.15 +0.28
Warmest 9th 2010 +0.57 +1.03

*RATPAC rank is based on 54 years of data

[ top ]


Stratosphere

Current Month

The table below summarizes stratospheric conditions for September 2011. On average, the stratosphere is located approximately 16–23 kilometers (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 Stratosphere
September Anomaly Rank
(out of 33 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH -0.43 -0.77 Coolest 8th 1996 -0.61 -1.10 -0.42 -0.75
Warmest 26th 1991 +1.64 +2.95
RSS -0.35 -0.63 Coolest 7th 1996 -0.53 -0.95 -0.30 -0.54
Warmest 27th 1991 +1.51 +2.72
Year-to-Date Stratosphere
January–
September
Anomaly Rank
(out of 33 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH -0.40 -0.72 Coolest 3rd 1996 -0.47 -0.85 -0.36 -0.65
Warmest 31st 1992, 1983 +1.01 +1.82
RSS -0.35 -0.63 Coolest 3rd 1996 -0.40 -0.72 -0.29 -0.52
Warmest 31st 1992 +0.99 +1.78

[ top ]


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.

[ top ]

Citing This Report

NOAA National Climatic Data Center, State of the Climate: Upper Air for September 2011, published online October 2011, retrieved on July 31, 2014 from http://www.ncdc.noaa.gov/sotc/upper-air/2011/9.