An update of observed stratospheric temperature trends

Abstract

An updated analysis of observed stratospheric temperature variability and trends is presented on the basis of satellite, radiosonde, and lidar observations. Satellite data include measurements from the series of NOAA operational instruments, including the Microwave Sounding Unit covering 1979-2007 and the Stratospheric Sounding Unit (SSU) covering 1979-2005. Radiosonde results are compared for six different data sets, incorporating a variety of homogeneity adjustments to account for changes in instrumentation and observational practices. Temperature changes in the lower stratosphere show cooling of ~0.5 K/decade over much of the globe for 1979-2007, with some differences in detail among the different radiosonde and satellite data sets. Substantially larger cooling trends are observed in the Antarctic lower stratosphere during spring and summer, in association with development of the Antarctic ozone hole. Trends in the lower stratosphere derived from radiosonde data are also analyzed, for a longer record (back to 1958); trends for the presatellite era (1958-1978) have a large range among the different homogenized data sets, implying large trend uncertainties. Trends in the middle and upper stratosphere have been derived from updated SSU data, taking into account changes in the SSU weighting functions due to observed atmospheric CO2 increases. The results show mean cooling of 0.5-1.5 K/decade during 1979-2005, with the greatest cooling in the upper stratosphere near 40-50 km. Temperature anomalies throughout the stratosphere were relatively constant during the decade 1995-2005. Long records of lidar temperature measurements at a few locations show reasonable agreement with SSU trends, although sampling uncertainties are large in the localized lidar measurements. Updated estimates of the solar cycle influence on stratospheric temperatures show a statistically significant signal in the tropics (~30°N-S), with an amplitude (solar maximum minus solar minimum) of ~0.5 K (lower stratosphere) to ~1.0 K (upper stratosphere)

Quantifying contributions to the recent temperature variability in the tropical tropopause layer

“…tropical tropopause temperatures dominate the amount of water vapour entering the stratosphere (Dessler et al, 2013(Dessler et al, , 2014Gettelman et al, 2009;Randel and Jensen, 2013). So far a long-term cooling in the lower stratosphere has been reported from the 1970s to 2000, although there are large differences between different data sets (Randel et al, 2009;Wang et al, 2012;Fueglistaler et al, 2013). The exact reason for the recent warming is therefore of great interest.…”

Signature of the 27-day solar rotation cycle in mesospheric OH and H<sub>2</sub>O observed by the Aura Microwave Limb Sounder

“…During the last decade the atmospheric response to the decadal solar variability has been studied based on observations (e.g. Soukharev and Hood, 2006;Fioletov, 2009;Randel et al, 2009) and the state-of-the-art transient chemistry-climate models (e.g. Egorova et al, 2004;Rozanov et al, 2004Rozanov et al, , 2008Schmidt et al, 2006;Marsh et al, 2007;Austin et al, 2008).…”

Temperature trends in the midlatitude summer mesosphere

“…[36] In Figure 16 we show a comparison of LIMA temperatures with observations from the Stratospheric Sounding Units (SSU) (see ftp://ftp.cpc.ncep.noaa.gov/wd53rl/ssu/) [Randel et al, 2009]. The uppermost altitude ("channel 47X") from SSU provides data for the lower mesosphere ( 52 km) with a maximum weight at pressures near 0.6 hPa.…”