Changes in Atmospheric Constituents and in Radiative Forcing

The development of this
review article has evolved from work carried out by an international
team of the International Space Science Institute (ISSI),
Bern, Switzerland, and from work carried out under the auspices
of Scientific Committee on Solar Terrestrial Physics (SCOSTEP)
Climate and Weather of the Sun‐Earth System (CAWSES‐1).
The support of ISSI in providing workshop and meeting facilities
is acknowledged, especially support from Y. Calisesi and V. Manno.
SCOSTEP is acknowledged for kindly providing financial assistance
to allow the paper to be published under an open access
policy. L.J.G. was supported by the UK Natural Environment
Research Council (NERC) through their National Centre for Atmospheric
Research (NCAS) Climate program. K.M. was supported
by a Marie Curie International Outgoing Fellowship within the
6th European Community Framework Programme. J.L. acknowledges
support by the EU/FP7 program Assessing Climate Impacts
on the Quantity and Quality of Water (ACQWA, 212250) and from
the DFG Project Precipitation in the Past Millennium in Europe
(PRIME) within the Priority Program INTERDYNAMIK. L.H.
acknowledges support from the U.S. NASA Living With a Star
program. G.M. acknowledges support from the Office of Science
(BER), U.S. Department of Energy, Cooperative Agreement
DE‐FC02‐97ER62402, and the National Science Foundation. We
also wish to thank Karin Labitzke and Markus Kunze for supplying
an updated Figure 13, Andrew Heaps for technical support, and
Paul Dickinson for editorial support. Part of the research was
carried out under the SPP CAWSES funded by GFG. J.B. was
financially supported by NCCR Climate–Swiss Climate Research.

/pdf/solar-influences-on-climate-48ynhy9kuz.pdf

Solar influences on climate

[1] The dynamical impact of the 11-year solar cycle is investigated with the focus on the stratopause region where solar ultraviolet heating is greatest. The most important variation in solar forcing longer than the diurnal cycle is the annual cycle. Thus the climatological features of the zonal wind variation associated with the annual cycle were first studied to characterize the basic features of the atmosphere's dynamical response to changes in solar radiative forcing. The 11-year solar cycle effect was then investigated. The results of the analysis suggest that in a climatological mean state the stratopause circulation evolves from a radiatively controlled state to one dynamically controlled during winter in both hemispheres. The transition period is characterized by a poleward shift of the westerly jet. The solar cycle effect appears as a change in the balance between the radiatively and dynamically controlled states. The radiatively controlled state lasts longer during the solar maximum phase, and the stratopause subtropical jet reaches a higher speed. The large dynamical response to relatively weak radiative forcing may be understood by the bimodal nature of the winter atmosphere due to interaction with meridionaly propagating planetary waves and zonal mean zonal winds. It is suggested that the solar influence produced in the upper stratosphere and stratopause region is transmitted to the lower stratosphere through (1) modulation of the internal mode of variation in the polar night jet and (2) a change in the Brewer-Dobson circulation. The first process is significant in the middle and high latitudes, whereas the latter is prominent in the equatorial region.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2002JD002224

Dynamical response to the solar cycle

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).

https://hal.archives-ouvertes.fr/hal-00355600/document

An update of observed stratospheric temperature trends

The absolute value of total solar irradiance is not known to better than ca.0.3% but measurements from satellite instruments over the past two solar cycles have shown that it varies by ca.0.1% on t...

/pdf/the-effects-of-solar-variability-on-the-earth-s-climate-1mtjqwseru.pdf

Vic Williams

Papers

The global signal of the 11-year solar cycle in the stratosphere: observations and models