Modeling of the atmospheric response to a strong decrease of the solar activity

We estimate the consequences of a potential strong decrease of the solar activity using the model simulations of the future driven by pure anthropogenic forcing as well as its combination with different solar activity related factors: total solar irradiance, spectral solar irradiance, energetic electron precipitation, solar protons and galactic cosmic rays. The comparison of the model simulations shows that introduced strong decrease of solar activity can lead to some delay of the ozone recovery and partially compensate greenhouse warming acting in the direction opposite to anthropogenic effects. The model results also show that all considered solar forcings are important in different atmospheric layers and geographical regions. However, in the global scale the solar irradiance variability can be considered as the most important solar forcing. The obtained results constitute probably the upper limit of the possible solar influence. Development of the better constrained set of future solar forcings is necessary to address the problem of future climate and ozone layer with more confidenc

Analysis of the global atmospheric background sulfur budget in a multi-model framework

Sulfate aerosol in the stratosphere is an important climate driver, causing solar dimming in the years after major volcanic eruptions. Hence, a growing number of general circulation models are adapting interactive sulfur and aerosol schemes to improve the representation of relevant chemical processes and associated feedbacks. However, uncertainties of these schemes are not well constrained. Stratospheric sulfate is modulated by natural emissions of sulfur-containing species, including volcanic eruptive, and anthropogenic emissions. Model intercomparisons have examined the effects of volcanic eruptions, whereas the background conditions of the sulfur cycle have not been addressed in a global model intercomparison project. Assessing background conditions in global models allows us to identify model discrepancies as they are masked by large perturbations such as volcanic eruptions, yet may still matter in the aftermath of such a disturbance. Here, we analyze the atmospheric burden, seasonal cycle, and vertical and meridional distribution of the main sulfur species among nine global atmospheric aerosol models that are widely used in the stratospheric aerosol research community. We use observational and reanalysis data to evaluate model results. Overall, models agree that the three dominant sulfur species in terms of burdens (sulfate aerosol, OCS, and SO2) make up about 98 % of stratospheric sulfur and 95 % of tropospheric sulfur. However, models vary considerably in the partitioning between these species. Models agree that anthropogenic emission of SO2 strongly affects the sulfate aerosol burden in the Northern Hemispheric troposphere, while its importance is very uncertain in other regions. The total deposition of sulfur varies among models, deviating by a factor of two, but models agree that sulfate aerosol is the main form in which sulfur is deposited. Additionally, the partitioning between wet and dry deposition fluxes is highly model dependent. We investigate the areas of greatest variability in the sulfur species burdens and find that inter-model variability is low in the tropics and increases towards the poles. Seasonality in the southern hemisphere is depicted very similar among models. Differences are largest in the dynamically active northern hemispheric extratropical region, hence some of the differences could be attributed to the differences in the representation of the stratospheric circulation among underlying general circulation models. This study highlights that the differences in the atmospheric sulfur budget among the models arise from the representation of both chemical and dynamical processes, whose interplay complicates the bias attribution. Several problematic points identified for individual models are related to the specifics of the chemistry schemes, model resolution, and representation of cross-tropopause transport in the extratropics. Further model intercomparison research is needed focusing on the clarification of the reasons for biases, given also the importance of this topic for the stratospheric aerosol injection studies.</p

HEPPA-II model-measurement intercomparison project : EPP indirect effects during the dynamically perturbed NH winter 2008-2009

We compare simulations from three high-top (with upper lid above 120 km) and five medium-top (with upper lid around 80 km) atmospheric models with observations of odd nitrogen (NOx D NO+NO2), temperature, and carbon monoxide from seven satellite instruments (ACE-FTS on SciSat, GOMOS, MIPAS, and SCIAMACHY on Envisat, MLS on Aura, SABER on TIMED, and SMR on Odin) during the Northern Hemisphere (NH) polar winter 2008/2009. The models included in the comparison are the 3-D chemistry transport model 3dCTM, the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model, FinROSE, the Hamburg Model of the Neutral and Ionized Atmosphere (HAMMO-NIA), the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA), the modelling tools for SOlar Climate Ozone Links studies (SOCOL and CAO-SOCOL), and the Whole Atmosphere Community Climate Model (WACCM4). The comparison focuses on the energetic particle precipitation (EPP) indirect effect, that is, the polar winter descent of NOx largely produced by EPP in the mesosphere and lower thermosphere. A particular emphasis is given to the impact of the sudden stratospheric warming (SSW) in January 2009 and the subsequent elevated stratopause (ES) event associated with enhanced descent of mesospheric air. The chemistry climate model simulations have been nudged toward reanalysis data in the troposphere and stratosphere while being unconstrained above. An odd nitrogen upper boundary condition obtained from MIPAS observations has further been applied to medium-top models. Most models provide a good representation of the mesospheric tracer descent in general, and the EPP indirect effect in particular, during the unperturbed (pre-SSW) period of the NH winter 2008/2009. The observed NOx descent into the lower mesosphere and stratosphere is generally reproduced within 20 %. Larger discrepancies of a few model simulations could be traced back either to the impact of the models' gravity wave drag scheme on the polar wintertime meridional circulation or to a combination of prescribed NOx mixing ratio at the uppermost model layer and low vertical resolution. In March-April, after the ES event, however, modelled mesospheric and stratospheric NOx distributions deviate significantly from the observations. The too-fast and early downward propagation of the NO x tongue, encountered in most simulations, coincides with a temperature high bias in the lower mesosphere (0.2-0.05 hPa), likely caused by an overestimation of descent velocities. In contrast, upper-mesospheric temperatures (at 0.05-0.001 hPa) are generally underestimated by the high-top models after the onset of the ES event, being indicative for too-slow descent and hence too-low NOx fluxes. As a consequence, the magnitude of the simulated NOx tongue is generally underestimated by these models. Descending NOx amounts simulated with mediumtop models are on average closer to the observations but show a large spread of up to several hundred percent. This is primarily attributed to the different vertical model domains in which the NOx upper boundary condition is applied. In general, the intercomparison demonstrates the ability of state-of- the-art atmospheric models to reproduce the EPP indirect effect in dynamically and geomagnetically quiescent NH winter conditions. The encountered differences between observed and simulated NOx, CO, and temperature distributions during the perturbed phase of the 2009 NH winter, however, emphasize the need for model improvements in the dynamical representation of elevated stratopause events in order to allow for a better description of the EPP indirect effect under these particular conditions.Peer reviewe

HEPPA-II model–measurement intercomparison project: EPP indirect effects during the dynamically perturbed NH winter 2008-2009

We compare simulations from three high-top (with upper lid above 120 km) and five medium-top (with upper lid around 80 km) atmospheric models with observations of odd nitrogen (NOx  =  NO + NO2), temperature, and carbon monoxide from seven satellite instruments (ACE-FTS on SciSat, GOMOS, MIPAS, and SCIAMACHY on Envisat, MLS on Aura, SABER on TIMED, and SMR on Odin) during the Northern Hemisphere (NH) polar winter 2008/2009. The models included in the comparison are the 3-D chemistry transport model 3dCTM, the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model, FinROSE, the Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA), the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA), the modelling tools for SOlar Climate Ozone Links studies (SOCOL and CAO-SOCOL), and the Whole Atmosphere Community Climate Model (WACCM4). The comparison focuses on the energetic particle precipitation (EPP) indirect effect, that is, the polar winter descent of NOx largely produced by EPP in the mesosphere and lower thermosphere. A particular emphasis is given to the impact of the sudden stratospheric warming (SSW) in January 2009 and the subsequent elevated stratopause (ES) event associated with enhanced descent of mesospheric air. The chemistry climate model simulations have been nudged toward reanalysis data in the troposphere and stratosphere while being unconstrained above. An odd nitrogen upper boundary condition obtained from MIPAS observations has further been applied to medium-top models. Most models provide a good representation of the mesospheric tracer descent in general, and the EPP indirect effect in particular, during the unperturbed (pre-SSW) period of the NH winter 2008/2009. The observed NOx descent into the lower mesosphere and stratosphere is generally reproduced within 20 %. Larger discrepancies of a few model simulations could be traced back either to the impact of the models\u27 gravity wave drag scheme on the polar wintertime meridional circulation or to a combination of prescribed NOx mixing ratio at the uppermost model layer and low vertical resolution. In March–April, after the ES event, however, modelled mesospheric and stratospheric NOx distributions deviate significantly from the observations. The too-fast and early downward propagation of the NOx tongue, encountered in most simulations, coincides with a temperature high bias in the lower mesosphere (0.2–0.05 hPa), likely caused by an overestimation of descent velocities. In contrast, upper-mesospheric temperatures (at 0.05–0.001 hPa) are generally underestimated by the high-top models after the onset of the ES event, being indicative for too-slow descent and hence too-low NOx fluxes. As a consequence, the magnitude of the simulated NOx tongue is generally underestimated by these models. Descending NOx amounts simulated with medium-top models are on average closer to the observations but show a large spread of up to several hundred percent. This is primarily attributed to the different vertical model domains in which the NOx upper boundary condition is applied. In general, the intercomparison demonstrates the ability of state-of-the-art atmospheric models to reproduce the EPP indirect effect in dynamically and geomagnetically quiescent NH winter conditions. The encountered differences between observed and simulated NOx, CO, and temperature distributions during the perturbed phase of the 2009 NH winter, however, emphasize the need for model improvements in the dynamical representation of elevated stratopause events in order to allow for a better description of the EPP indirect effect under these particular conditions

Energetic particle influence on the Earth's atmosphere

This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth’s atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere

Role of external factors in the evolution of the ozone layer and stratospheric circulation in 21st century

The chemistry-climate model (CCM) SOCOL has been used to evaluate the contribu-tion of the main anthropogenic factors to the simulated changes of ozone and strato-spheric dynamics during the 21st century. As the main anthropogenic factors we con-sider atmospheric concentration of the greenhouse gases (GHG), ozone depleting substances (ODS) and sea surface temperature and sea ice (SST/SI) distribution. The lastone is considered here as an independent factor because the majority of the CCMsprescribe its evolution. We have performed three sets of “time-slice” numerical exper-iments with CCM SOCOL for the years 2000, 2050, and 2100 taking into account allfactors separately and all together. It was established that the total column ozone increase during the first half of the 21st century is caused by the ODS, especially in themiddle and high latitudes of both hemispheres. In the tropics and the extra tropical re-gion of the Northern Hemisphere (NH) the SST/SI forcing plays very important role inthe evolution of ozone atmospheric content during the second half of the 21st century.The GHG affect the temperature and ozone mainly in the upper stratosphere and in thelower stratosphere of the high latitudes of the Southern Hemisphere (SH). In the lowertropical stratosphere of the NH the long-term changes of the temperature, zonal windvelocity and the meridional circulation intensity are controlled mainly by the SST/SI.The strong contribution of the SST/SI to the ozone and circulation changes in the fu-ture implies that some differences between the simulated results could be caused by the applied SST/SI rather than by the CCM’s deficiencies. We suggest taking this issueinto account for the planning of the future model evaluation campaigns.ISSN:1680-7375ISSN:1680-736

Role of external factors in the evolution of the ozone layer and stratospheric circulation in 21st century

The chemistry-climate model (CCM) SOCOL has been used to evaluate the contributions of the main anthropogenic factors to the simulated changes of ozone and stratospheric dynamics during the 21st century. As the main anthropogenic factors we consider the atmospheric concentration of the greenhouse gases (GHG), ozone depleting substances (ODS) and sea surface temperature and sea ice (SST/SI). The latter is considered here as an independent factor because the majority of the CCMs prescribe its evolution. We have performed three sets of "time slice" numerical experiments for the years 2000, 2050, and 2100 taking into account all factors separately and all together. The total column ozone increase during the first half of the 21st century is caused by the ODS, especially in the middle and high latitudes of both hemispheres. In the tropics and the extra tropical region of the Northern Hemisphere (NH) the SST/SI forcing plays a very important role in the evolution of atmospheric ozone during the second half of the 21st century. The GHG affect the temperature and ozone mainly in the upper stratosphere and in the lower stratosphere of the high latitudes of the Southern Hemisphere (SH). In the lower tropical stratosphere of the NH, the long-term changes of the temperature, zonal wind and the meridional circulation are controlled mainly by the SST/SI. The strong contribution of the SST/SI to the ozone and circulation changes in the future implies that some differences between the results by different CCMs could be caused by the applied SST/SI rather than by the CCM's deficiencies. We suggest taking this issue into account for the planning of the future model evaluation campaigns.ISSN:1680-7375ISSN:1680-736

Transition of the Sun to a Regime of High Activity: Implications for the Earth Climate and Role of Atmospheric Chemistry

Abstract It was recently suggested that the Sun could switch to a high‐activity regime which would lead to a rise of ultraviolet radiation with an amplitude of about four times larger than the amplitude of an average solar activity cycle and a simultaneous drop in total solar irradiance. Here, we applied the SOCOLv3‐MPIOM model with an interacting ocean to simulate the response of chemistry, dynamics, and temperature of Earth's atmosphere to such a change in solar irradiance. We studied the effect of high activity regime on the atmosphere investigating the influence of the chemical and radiative processes on the climate, and chemistry of NO x, HO x, and O 3 . We find a climate cooling by up to 1K and a substantial increase in stratospheric ozone (up to 14%) and total ozone (up to 8%). To understand the role of the different processes we performed simulations with two sets of forcing accounting separately for the influence on chemical processes and for direct radiation energy balance. Our calculations show that the stratospheric O 3 response is almost fully driven by the chemical processes. We also found that the direct radiation processes lead to near‐surface cooling that results in the suppression of the Brewer‐Dobson circulation. This, in turn, leads to the reduction of H 2 O influx from the low layers of the troposphere and to less intensive transport of ozone from the tropics to the middle latitudes. The surface climate response is dominated by direct radiation influence with only a small contribution from chemical processes.Plain Language Summary It was recently suggested that activity of the Sun could significantly rise which would lead to a rise of ultraviolet radiation and a simultaneous drop in total solar irradiance. In this study, we modeled the response of chemistry, dynamics, and temperature of Earth's atmosphere to such a change in solar irradiance. We studied the effect of high activity regime on the atmosphere investigating the influence of the chemical and radiative processes on the climate, and chemistry. We find a climate cooling by up to 1K and a substantial increase in stratospheric ozone (up to 14%) and total ozone (up to 8%). Our calculations show that the stratospheric ozone response is almost fully driven by the chemical processes. We also found that the direct radiation processes lead to near‐surface cooling that results in the suppression of the Brewer‐Dobson circulation. This, in turn, leads to the reduction of water vapor influx from the low layers of the troposphere and to less intensive transport of ozone from the tropics to the middle latitudes. The surface climate response is dominated by direct radiation influence with only a small contribution from chemical processes.Key Points A switch of the Sun to a high activity regime would lead to a simultaneous increase of the UV irradiance and a drop of the longwave irradiance Solar UV changes control stratospheric ozone and temperature with only a small contribution from solar longwave Tropospheric climate is driven by direct changes in the surface radiation balance with no substantial contribution from the chemical processesAbstract It was recently suggested that the Sun could switch to a high‐activity regime which would lead to a rise of ultraviolet radiation with an amplitude of about four times larger than the amplitude of an average solar activity cycle and a simultaneous drop in total solar irradiance. Here, we applied the SOCOLv3‐MPIOM model with an interacting ocean to simulate the response of chemistry, dynamics, and temperature of Earth's atmosphere to such a change in solar irradiance. We studied the effect of high activity regime on the atmosphere investigating the influence of the chemical and radiative processes on the climate, and chemistry of NO x, HO x, and O 3 . We find a climate cooling by up to 1K and a substantial increase in stratospheric ozone (up to 14%) and total ozone (up to 8%). To understand the role of the different processes we performed simulations with two sets of forcing accounting separately for the influence on chemical processes and for direct radiation energy balance. Our calculations show that the stratospheric O 3 response is almost fully driven by the chemical processes. We also found that the direct radiation processes lead to near‐surface cooling that results in the suppression of the Brewer‐Dobson circulation. This, in turn, leads to the reduction of H 2 O influx from the low layers of the troposphere and to less intensive transport of ozone from the tropics to the middle latitudes. The surface climate response is dominated by direct radiation influence with only a small contribution from chemical processes.Plain Language Summary It was recently suggested that activity of the Sun could significantly rise which would lead to a rise of ultraviolet radiation and a simultaneous drop in total solar irradiance. In this study, we modeled the response of chemistry, dynamics, and temperature of Earth's atmosphere to such a change in solar irradiance. We studied the effect of high activity regime on the atmosphere investigating the influence of the chemical and radiative processes on the climate, and chemistry. We find a climate cooling by up to 1K and a substantial increase in stratospheric ozone (up to 14%) and total ozone (up to 8%). Our calculations show that the stratospheric ozone response is almost fully driven by the chemical processes. We also found that the direct radiation processes lead to near‐surface cooling that results in the suppression of the Brewer‐Dobson circulation. This, in turn, leads to the reduction of water vapor influx from the low layers of the troposphere and to less intensive transport of ozone from the tropics to the middle latitudes. The surface climate response is dominated by direct radiation influence with only a small contribution from chemical processes.Key Points A switch of the Sun to a high activity regime would lead to a simultaneous increase of the UV irradiance and a drop of the longwave irradiance Solar UV changes control stratospheric ozone and temperature with only a small contribution from solar longwave Tropospheric climate is driven by direct changes in the surface radiation balance with no substantial contribution from the chemical processesAbstract It was recently suggested that the Sun could switch to a high‐activity regime which would lead to a rise of ultraviolet radiation with an amplitude of about four times larger than the amplitude of an average solar activity cycle and a simultaneous drop in total solar irradiance. Here, we applied the SOCOLv3‐MPIOM model with an interacting ocean to simulate the response of chemistry, dynamics, and temperature of Earth's atmosphere to such a change in solar irradiance. We studied the effect of high activity regime on the atmosphere investigating the influence of the chemical and radiative processes on the climate, and chemistry of NO x, HO x, and O 3 . We find a climate cooling by up to 1K and a substantial increase in stratospheric ozone (up to 14%) and total ozone (up to 8%). To understand the role of the different processes we performed simulations with two sets of forcing accounting separately for the influence on chemical processes and for direct radiation energy balance. Our calculations show that the stratospheric O 3 response is almost fully driven by the chemical processes. We also found that the direct radiation processes lead to near‐surface cooling that results in the suppression of the Brewer‐Dobson circulation. This, in turn, leads to the reduction of H 2 O influx from the low layers of the troposphere and to less intensive transport of ozone from the tropics to the middle latitudes. The surface climate response is dominated by direct radiation influence with only a small contribution from chemical processes.Plain Language Summary It was recently suggested that activity of the Sun could significantly rise which would lead to a rise of ultraviolet radiation and a simultaneous drop in total solar irradiance. In this study, we modeled the response of chemistry, dynamics, and temperature of Earth's atmosphere to such a change in solar irradiance. We studied the effect of high activity regime on the atmosphere investigating the influence of the chemical and radiative processes on the climate, and chemistry. We find a climate cooling by up to 1K and a substantial increase in stratospheric ozone (up to 14%) and total ozone (up to 8%). Our calculations show that the stratospheric ozone response is almost fully driven by the chemical processes. We also found that the direct radiation processes lead to near‐surface cooling that results in the suppression of the Brewer‐Dobson circulation. This, in turn, leads to the reduction of water vapor influx from the low layers of the troposphere and to less intensive transport of ozone from the tropics to the middle latitudes. The surface climate response is dominated by direct radiation influence with only a small contribution from chemical processes.Key Points A switch of the Sun to a high activity regime would lead to a simultaneous increase of the UV irradiance and a drop of the longwave irradiance Solar UV changes control stratospheric ozone and temperature with only a small contribution from solar longwave Tropospheric climate is driven by direct changes in the surface radiation balance with no substantial contribution from the chemical processe

Modeling of the atmospheric response to a strong decrease of the solar activity

ISSN:1743-9213ISSN:1743-922