Solar Influences on Climate
Lead Research Organisation:
Imperial College London
Department Name: Physics
Abstract
One of the greatest science policy issues today is to determine what actions should be taken in response to human-induced changes in the Earth's climate. In order to attribute observed effects to human activity, however, it is essential that we have confidence in our ability to distinguish human-induced changes from those due to natural causes. The fundamental source of energy for the climate system is the Sun but the contribution of solar variability to recent climate change is not well known due to uncertainties in both the magnitude of the Sun's variations and the mechanisms of the climate response. Satellite measurements of total solar irradiance over the past 26 years show that it varies by ~0.1% over the 11-year solar cycle. However, with no reliable direct measurements having been made before the satellite era, studies of the role of solar variability in determining historical climate rely on reconstructions based on proxy activity indicators such as sunspot numbers. There are large uncertainties in these reconstructions and the spectral composition of the irradiance, which is important in determining the impact on atmospheric temperature and composition, is even less well known. Better specification of the temporal variation of total and spectral irradiance is necessary to provide the input required for climate studies. Signals of solar activity throughout the atmosphere have been detected in meteorological data but details of the links remain uncertain. For example, the direct effect on the temperature of the upper atmosphere is fairly well-understood but cannot explain the observed signal of solar variability at lower altitudes. One possible mechanism, based on the observation that variability in solar ultraviolet radiation is much greater than overall, suggests that the direct effects of the UV variations on the stratosphere may indirectly influence the atmosphere below by dynamical coupling, although details of how this takes place are unclear. Furthermore, the stratospheric impact may be associated with solar-induced changes in ozone but this response is not well established, with estimates from satellite data showing different structures from those predicted by theoretical models. In this project we will address all the key issues of uncertainty outlined above. The work will be carried out through a coordinated programme involving the participation of a number of overseas scientists who perceive the benefits of being involved in such an interdisciplinary collaborative project. We will use advanced theoretical models of the solar atmosphere to determine the relationship between solar irradiance and surface magnetic features (such as sunspots) and use this model, with the sunspot record, to determine the total and spectral irradiance over the past 300 years. Atmospheric measurements will be analysed to identify robust signals of solar influence on winds, temperature and chemical composition from the surface to the thermosphere. The irradiance data will be used in a number of different global circulation models of the Earth's atmosphere to investigate the impact of the solar variability and the results compared with the observational analyses. Discrepancies will be used to define further model experiments and to identify the key dynamical and chemical mechanism(s) through which solar variability influences tropospheric climate. The advances in understanding gained through these analyses will be used to improve the representation of the relevant processes in climate models. Beneficiaries will include all interested in climate change including researchers, policymakers and the general public. The irradiance reconstructions will be made available to climate modelling centres. The meteorological data analyses will be submitted to international assessments of trends in temperature and ozone while our advances in understanding of the processes involved will help to advance medium and long-range forecasting.
Organisations
Publications
Matthes Katja
(2015)
Earth's climate response to a changing Sun
Maycock AC
(2015)
Possible impacts of a future grand solar minimum on climate: Stratospheric and global circulation changes.
in Journal of geophysical research. Atmospheres : JGR
National Research Council
(2013)
Review of NOAA Working Group Report on Maintaining the Continuation of Long-term Satellite Total Solar Irradiance Observation
National Research Council
(2013)
Review of NOAA Working Group Report on Maintaining the Continuation of Long-Term Satellite Total Irradiance Observations.
Oman L
(2010)
Multimodel assessment of the factors driving stratospheric ozone evolution over the 21st century
in Journal of Geophysical Research: Atmospheres
Polvani, L. M.; Sobel, A. H.; Waugh, D. W.
(2010)
The Stratosphere: Dynamics, Transport, and Chemistry
Roscoe H
(2007)
Influences of ozone depletion, the solar cycle and the QBO on the Southern Annular Mode
in Quarterly Journal of the Royal Meteorological Society
Roy I
(2010)
Solar cycle signals in sea level pressure and sea surface temperature
in Atmospheric Chemistry and Physics
Roy I
(2011)
The influence of solar variability and the quasi-biennial oscillation on lower atmospheric temperatures and sea level pressure
in Atmospheric Chemistry and Physics
Scaife A
(2013)
A mechanism for lagged North Atlantic climate response to solar variability
in Geophysical Research Letters
Shine K
(2009)
Stratospheric Temperature and Radiative Forcing Response to 11-Year Solar Cycle Changes in Irradiance and Ozone
in Journal of the Atmospheric Sciences
Shuckburgh E
(2007)
Transport and Mixing in Kinematic and Dynamically Consistent Flows
in Journal of the Atmospheric Sciences
Simpson I
(2012)
A Mechanism for the Effect of Tropospheric Jet Structure on the Annular Mode-Like Response to Stratospheric Forcing
in Journal of the Atmospheric Sciences
Simpson I
(2009)
The Role of Eddies in Driving the Tropospheric Response to Stratospheric Heating Perturbations
in Journal of the Atmospheric Sciences
Simpson I
(2010)
The Impact of the State of the Troposphere on the Response to Stratospheric Heating in a Simplified GCM
in Journal of Climate
Solanki S
(2013)
Solar Irradiance Variability and Climate
in Annual Review of Astronomy and Astrophysics
Sparrow S
(2009)
Annular Variability and Eddy-Zonal Flow Interactions in a Simplified Atmospheric GCM. Part I: Characterization of High- and Low-Frequency Behavior
in Journal of the Atmospheric Sciences
Sukhodolov T
(2016)
Evaluation of simulated photolysis rates and their response to solar irradiance variability
in Journal of Geophysical Research: Atmospheres
Tian W
(2010)
Effects of stratosphere-troposphere chemistry coupling on tropospheric ozone
in Journal of Geophysical Research: Atmospheres
Tian W
(2010)
Chemistry-Climate Model Simulations of Twenty-First Century Stratospheric Climate and Circulation Changes
in Journal of Climate
Tian W
(2009)
Impact of increasing stratospheric water vapor on ozone depletion and temperature change
in Advances in Atmospheric Sciences
Unruh Y
(2011)
Solar Irradiance Models and Measurements: A Comparison in the 220-240 nm wavelength band
in Surveys in Geophysics
Unruh Y
(2008)
Spectral irradiance variations: comparison between observations and the SATIRE model on solar rotation time scales
in Astronomy & Astrophysics
Wen G
(2013)
Reconciliation of modeled climate responses to spectral solar forcing
in Journal of Geophysical Research: Atmospheres
Woollings T
(2010)
Enhanced signature of solar variability in Eurasian winter climate
in Geophysical Research Letters
Zhong W
(2013)
The greenhouse effect and carbon dioxide
in Weather
Zhong W
(2008)
Influence of the prescribed solar spectrum on calculations of atmospheric temperature
in Geophysical Research Letters
Description | Role of variations in UV radiation on climate |
Exploitation Route | Research further developed by scientists across the world. Investigation by Met Office has found that seasonal forecasts may be improved by a knowledge of the state of the Sun. |
Sectors | Energy Environment |
Description | They have advanced understanding of how the Sun influences the climate. They have led to an understanding by Met agencies that the models used for climate forecasting need to include a good representation of the stratosphere, and external factors which influence it. They have informed debate on the role of the Sun in climate change useful for policymakers. |
First Year Of Impact | 2010 |
Sector | Environment |
Impact Types | Societal Policy & public services |
Description | Advice to DECC |
Geographic Reach | National |
Policy Influence Type | Contribution to a national consultation/review |
Impact | info to government on factors influencing climate change, specifically the Sun |
Description | House of Commons Environmental Audit Committee |
Geographic Reach | National |
Policy Influence Type | Participation in a guidance/advisory committee |
Impact | advice to government on factors influencing cliamte change |
Description | US Natioanl Academy of Sciences Panel on continuation of long-term satellite TSI observation |
Geographic Reach | North America |
Policy Influence Type | Participation in a guidance/advisory committee |
Impact | US government decision on new satellite instrumentation |
Description | about 75 schools talks, amateur meteorological societies, media interviews |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | I can provide details of all the activities if necessary continuing interest in solar influences on climate from all branches of society |
Year(s) Of Engagement Activity | 2006,2007,2008,2009,2010,2011,2012,2013,2014,2015,2016 |