Global, Hemispheric, and Zonal Temperature Deviations Derived From a 54-Station Radiosonde Network

Graphics    Digital Data

Investigator

J. K. Angell
National Oceanic and Atmospheric Administration, Air Resources Laboratory (R/E/AR),
SSMC3, Station 3459,
1315 East West Highway,
Silver Spring, Maryland 20910, U.S.A.

About Jim Angell: From the Bulletin of the American Meteorological Society (2005) - Jim Angell's Contributions to Meteorology

Period of Record

1958-2010 (relative to a 1961-1990 average)

Methods

Surface temperatures and thickness-derived temperatures from a 54-station, globally distributed radiosonde network have been used to estimate global, hemispheric, and zonal annual and seasonal temperature deviations. Most of the temperature values used were column-mean temperatures, obtained from the differences in height (thickness) between constant-pressure surfaces at individual radiosonde stations. The pressure-height data before 1980 were obtained from published values in Monthly Climatic Data for the World. Between 1980 and 1990, Angell used data from both the Climatic Data for the World and the Global Telecommunications System (GTS) Network received at the National Meteorological Center. Between 1990 and 1995, the data were obtained only from GTS, and since 1995 the data have been obtained from National Center for Atmospheric Research files. The data are evaluated as deviations from the mean based on the interval 1961-1990. Time series for the earth's surface, and the 850-300mb, 300-100mb and 100-50mb layers are presented for north polar (60-90N), north temperate (30-60N), tropical (30S-30N), south temperate (30-60S) and south polar (60-90S) climate zones, as well as for the Northern and Southern hemispheres and the globe. The data presentation is more compact than in the case of Angell's 63-station network, with two fewer layers and three fewer climate zones, for a total eight time series.

It is important to point out that this 54-station analysis (Angell 2003) was conducted after Angell determined that nine tropical radiosonde stations in his 63-station network analysis were anomalous based on unrepresentatively large standard-error-of-regression values for 300–100-mb trends for the period 1958–2000. The effects of this discovery on the analysis are briefly described below in the section on temperature trends.

The data used in this analysis begin in 1958 except for the south temperate zone and Southern Hemisphere where the 100- 50mb data begin in 1964. The temperature deviations for the tropics, both hemispheres and the globe are obtained by a simple averaging of all the radiosonde-station temperature deviations within each of these four regions. Because of the relatively few stations in the Southern Hemisphere, the Southern Hemisphere is not weighted as heavily in the global average as is the Northern Hemisphere. The seasonal calculations are for the standard meteorological seasons (i.e., winter is defined as December, January, and February; spring is March, April, and May, etc.) and the annual calculations are for December through the following November (i.e., for the four meteorological seasons). For greater details, see Angell and Korshover (1983) and Angell (1988, 1991).

Trends

As stated in Angell (2003), "In the Tropics, the exclusion of the nine anomalous stations from the 63-station network for 1958–2000 results in a warming of the 300–100-mb layer rather than a cooling, a doubling of the warming of the 850–300-mb layer to a value of 0.13K per decade, and a greater warming at 850–300-mb than at the surface. The global changes in trend are smaller, but include a change to the same warming of the surface and the 850–300-mb layer during 1958–2000." In examining Angell's time seires through 2010, we see the warming trend in the 850-300-mb global series and that 1998 remains the warmest year in that series. Globally, at the surface, strong long-term warming is evident and 2007 is the warmest year in the series.

References

• Angell, J.K. 1988. Variations and trends in tropospheric and stratospheric global temperatures, 1958-87. Journal of Climate 1:1296-1313.
• Angell, J.K. 1991. Changes in tropospheric and stratospheric global temperatures, 1958-88. pp. 231-47. In M.E. Schlesinger (ed.), Greenhouse-Gas-Induced Climatic Change: A Critical Appraisal of Simulations and Observations. Elsevier Science Publishers, Amsterdam, Netherlands.
• Angell, J.K. 2003. Effect of exclusion of anomalous tropical stations on temperature trends from a 63-Station radiosonde network, and comparison with other analyses. Journal of Climate 16:2288-2295, doi: 10.1175/2763.1.
ANGELL
• Angell, J.K., and J. Korshover. 1983. Global temperature variations in the troposphere and stratosphere, 1958-82. Monthly Weather Review 111:901-21.

08/2011