scholarly journals Multiple input control strategies for robust and adaptive climate engineering in a low-order 3-box model

2018 ◽  
Vol 474 (2217) ◽  
pp. 20180447 ◽  
Author(s):  
F. Bonetti ◽  
C. McInnes
Keyword(s):  
Adaptive Control ◽  
Radiative Forcing ◽  
Climate Model ◽  
Control Strategies ◽  
Adaptive Controller ◽  
Multivariable Control ◽  
Balance Model ◽  
Solar Radiation Management ◽  
Climate Engineering ◽  
Low Order

A low-order 3-box energy balance model for the climate system is employed with a multivariable control scheme for the evaluation of new robust and adaptive climate engineering strategies using solar radiation management. The climate engineering measures are deployed in three boxes thus representing northern, southern and central bands. It is shown that, through heat transport between the boxes, it is possible to effect a degree of latitudinal control through the reduction of insolation. The approach employed consists of a closed-loop system with an adaptive controller, where the required control intervention is estimated under the RCP 4.5 radiative scenario. Through the online estimation of the controller parameters, adaptive control can overcome key issues related to uncertainties of the climate model, the external radiative forcing and the dynamics of the actuator used. In fact, the use of adaptive control offers a robust means of dealing with unforeseeable abrupt perturbations, as well as the parametrization of the model considered, to counteract the RCP 4.5 scenario, while still providing bounds on stability and control performance. Moreover, applying multivariable control theory also allows the formal controllability and observability of the system to be investigated in order to identify all feasible control strategies.

scholarly journals Radiative and climate impacts of a large volcanic eruption during stratospheric sulfur geoengineering

2016 ◽  
Vol 16 (1) ◽  
pp. 305-323 ◽  
Author(s):  
A. Laakso ◽  
H. Kokkola ◽  
A.-I. Partanen ◽  
U. Niemeier ◽  
C. Timmreck ◽  
...  
Keyword(s):  
Volcanic Eruption ◽  
Radiative Forcing ◽  
Climate Changes ◽  
Climate Model ◽  
Volcanic Eruptions ◽  
Climate Impacts ◽  
Solar Radiation Management ◽  
Atmospheric Conditions ◽  
Maximum Increase ◽  
Global Mean

Abstract. Both explosive volcanic eruptions, which emit sulfur dioxide into the stratosphere, and stratospheric geoengineering via sulfur injections can potentially cool the climate by increasing the amount of scattering particles in the atmosphere. Here we employ a global aerosol-climate model and an Earth system model to study the radiative and climate changes occurring after an erupting volcano during solar radiation management (SRM). According to our simulations the radiative impacts of the eruption and SRM are not additive and the radiative effects and climate changes occurring after the eruption depend strongly on whether SRM is continued or suspended after the eruption. In the former case, the peak burden of the additional stratospheric sulfate as well as changes in global mean precipitation are fairly similar regardless of whether the eruption takes place in a SRM or non-SRM world. However, the maximum increase in the global mean radiative forcing caused by the eruption is approximately 21 % lower compared to a case when the eruption occurs in an unperturbed atmosphere. In addition, the recovery of the stratospheric sulfur burden and radiative forcing is significantly faster after the eruption, because the eruption during the SRM leads to a smaller number and larger sulfate particles compared to the eruption in a non-SRM world. On the other hand, if SRM is suspended immediately after the eruption, the peak increase in global forcing caused by the eruption is about 32 % lower compared to a corresponding eruption into a clean background atmosphere. In this simulation, only about one-third of the global ensemble-mean cooling occurs after the eruption, compared to that occurring after an eruption under unperturbed atmospheric conditions. Furthermore, the global cooling signal is seen only for the 12 months after the eruption in the former scenario compared to over 40 months in the latter. In terms of global precipitation rate, we obtain a 36 % smaller decrease in the first year after the eruption and again a clearly faster recovery in the concurrent eruption and SRM scenario, which is suspended after the eruption. We also found that an explosive eruption could lead to significantly different regional climate responses depending on whether it takes place during geoengineering or into an unperturbed background atmosphere. Our results imply that observations from previous large eruptions, such as Mount Pinatubo in 1991, are not directly applicable when estimating the potential consequences of a volcanic eruption during stratospheric geoengineering.

scholarly journals Interactions between reducing CO 2 emissions, CO 2 removal and solar radiation management

2012 ◽  
Vol 370 (1974) ◽  
pp. 4343-4364 ◽  
Author(s):  
Naomi E. Vaughan ◽  
Timothy M. Lenton
Keyword(s):  
Carbon Dioxide ◽  
Solar Radiation ◽  
Carbon Dioxide Emissions ◽  
Radiative Forcing ◽  
Carbon Capture ◽  
Climate Model ◽  
Carbon Capture And Storage ◽  
Solar Radiation Management ◽  
Radiation Management ◽  
And Storage

We use a simple carbon cycle–climate model to investigate the interactions between a selection of idealized scenarios of mitigated carbon dioxide emissions, carbon dioxide removal (CDR) and solar radiation management (SRM). Two CO 2 emissions trajectories differ by a 15-year delay in the start of mitigation activity. SRM is modelled as a reduction in incoming solar radiation that fully compensates the radiative forcing due to changes in atmospheric CO 2 concentration. Two CDR scenarios remove 300 PgC by afforestation (added to vegetation and soil) or 1000 PgC by bioenergy with carbon capture and storage (removed from system). Our results show that delaying the start of mitigation activity could be very costly in terms of the CDR activity needed later to limit atmospheric CO 2 concentration (and corresponding global warming) to a given level. Avoiding a 15-year delay in the start of mitigation activity is more effective at reducing atmospheric CO 2 concentrations than all but the maximum type of CDR interventions. The effects of applying SRM and CDR together are additive, and this shows most clearly for atmospheric CO 2 concentration. SRM causes a significant reduction in atmospheric CO 2 concentration due to increased carbon storage by the terrestrial biosphere, especially soils. However, SRM has to be maintained for many centuries to avoid rapid increases in temperature and corresponding increases in atmospheric CO 2 concentration due to loss of carbon from the land.

scholarly journals Substantial Climate Response outside the Target Area in an Idealized Experiment of Regional Radiation Management

Climate ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 66
Author(s):  
Sudhakar Dipu ◽  
Johannes Quaas ◽  
Martin Quaas ◽  
Wilfried Rickels ◽  
Johannes Mülmenstädt ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Climate Model ◽  
Heat Waves ◽  
Climate Impacts ◽  
The Arctic ◽  
Solar Radiation Management ◽  
Target Area ◽  
Local Cooling ◽  
Target Region ◽  
Radiation Management

Radiation management (RM) has been proposed as a conceivable climate engineering (CE) intervention to mitigate global warming. In this study, we used a coupled climate model (MPI-ESM) with a very idealized setup to investigate the efficacy and risks of CE at a local scale in space and time (regional radiation management, RRM) assuming that cloud modification is technically possible. RM is implemented in the climate model by the brightening of low-level clouds (solar radiation management, SRM) and thinning of cirrus (terrestrial radiation management, TRM). The region chosen is North America, and we simulated a period of 30 years. The implemented sustained RM resulted in a net local radiative forcing of −9.8 Wm−2 and a local cooling of −0.8 K. Surface temperature (SAT) extremes (90th and 10th percentiles) show negative anomalies in the target region. However, substantial climate impacts were also simulated outside the target area, with warming in the Arctic and pronounced precipitation change in the eastern Pacific. As a variant of RRM, a targeted intervention to suppress heat waves (HW) was investigated in further simulations by implementing intermittent cloud modification locally, prior to the simulated HW situations. In most cases, the intermittent RRM results in a successful reduction of temperatures locally, with substantially smaller impacts outside the target area compared to the sustained RRM.

scholarly journals Estimating the Impact of Artificially Injected Stratospheric Aerosols on the Global Mean Surface Temperature in the 21th Century

Climate ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 85 ◽  
Author(s):  
Sergei Soldatenko
Keyword(s):  
Surface Temperature ◽  
Radiative Forcing ◽  
Global Temperature ◽  
Balance Model ◽  
Solar Radiation Management ◽  
Aerosol Layer ◽  
Aerosol Emission ◽  
Global Mean Surface Temperature ◽  
The Impact ◽  
Global Mean

In this paper, we apply the optimal control theory to obtain the analytic solutions of the two-component globally averaged energy balance model in order to estimate the influence of solar radiation management (SRM) operations on the global mean surface temperature in the 21st century. It is assumed that SRM is executed via injection of sulfur aerosols into the stratosphere to limit the global temperature increase in the year 2100 by 1.5 °C and keeping global temperature over the specified period (2020–2100) within 2 °C as required by the Paris climate agreement. The radiative forcing produced by the rise in the atmospheric concentrations of greenhouse gases is defined by the Representative Concentration Pathways and the 1pctCO2 (1% per year CO2 increase) scenario. The goal of SRM is formulated in terms of extremal problem, which entails finding a control function (the albedo of aerosol layer) that minimizes the amount of aerosols injected into the upper atmosphere to satisfy the Paris climate target. For each climate change scenario, the optimal albedo of the aerosol layer and the corresponding global mean surface temperature changes were obtained. In addition, the aerosol emission rates required to create an aerosol cloud with optimal optical properties were calculated.

scholarly journals Radiative and climate effects of stratospheric sulfur geoengineering using seasonally varying injection areas

2017 ◽  
Author(s):  
Anton Laakso ◽  
Hannele Korhonen ◽  
Sami Romakkaniemi ◽  
Harri Kokkola
Keyword(s):  
Temperature Gradient ◽  
Solar Radiation ◽  
Radiative Forcing ◽  
Climate Model ◽  
Cost Effective ◽  
Solar Radiation Management ◽  
Meridional Temperature Gradient ◽  
Management Scenarios ◽  
Zonal Distribution ◽  
Climate Effects

Abstract. Stratospheric sulfur injections have often been suggested as a cost effective geoengineering method to prevent or slow down global warming. In geoengineering studies these injections are commonly targeted to the equator, where the intensity of the solar radiation is highest. However, it may not be the most optimal aerosol injection strategy because the radiative forcing concentrating over the equator decreases the meridional temperature gradient. In this study we employ alternative aerosol injection scenarios to investigate if the resulting radiative forcing can be optimized to be zonally more uniform without decreasing the global efficacy. We used a global aerosol-climate model together with an Earth system model to study the radiative and climate effects of stratospheric sulfur injection scenarios with different injection areas. According to our simulations, varying the SO2 injection area seasonally would result in a similar global mean cooling effect as injecting SO2 to the equator, but with a more uniform zonal distribution of shortwave radiative forcing. Compared to the case of equatorial injections, in the optimized injection scenario where the maximum sulfur production from injected SO2 followed the maximum of solar radiation, the shortwave radiative forcing decreased by 27 % over the equator (between the latitudes between 20° N and 20° S) and increased by 15 % over higher latitudes. Compared to the continuous injections to equator, in summer months the radiative forcing was increased by 17 % and 14 % and winter months decreased by −14 % and −16 % at northern and southern hemispheres respectively. However, these forcings do not translate into very significant changes in temperatures. Based on ESM simulations, changes in forcing would lead only to 0.05 K warmer winters and 0.05 K cooler summers at the northern hemisphere which is roughly 3 % of the cooling resulted from solar radiation management scenarios studied here. At the same time the meridional temperature gradient was better maintained.

Fiberglass Reinforced Plastic Winding System Adaptive Controller Design

2012 ◽  
Vol 182-183 ◽  
pp. 1890-1894
Author(s):  
Zeng Tao Xue ◽  
Zheng Li
Keyword(s):  
Adaptive Control ◽  
Controller Design ◽  
Control Strategies ◽  
Adaptive Controller ◽  
System Control ◽  
Technology Study ◽  
Reinforced Plastic ◽  
Advanced Control ◽  
Control Principle ◽  
Model Reference Adaptive

This paper mainly introduces the components of fiberglass reinforced plastic winding automatic control system. According to the model reference adaptive control principle, an algorithm of adaptive control and its gain adjustable controller are presented, which is very suitable for the position servo system control. The control algorithm is relatively simple, and not only has achieved fine effects on the control of fiberglass reinforced plastic winding machines, but also has accomplished with small errors following any given speed as proved in simulations. It is expected that this research can be helpful to the fiberglass reinforced plastic winding technology study and improvements with advanced control strategies.

scholarly journals Radiative and climate effects of stratospheric sulfur geoengineering using seasonally varying injection areas

2017 ◽  
Vol 17 (11) ◽  
pp. 6957-6974 ◽  
Author(s):  
Anton Laakso ◽  
Hannele Korhonen ◽  
Sami Romakkaniemi ◽  
Harri Kokkola
Keyword(s):  
Solar Radiation ◽  
Radiative Forcing ◽  
Climate Model ◽  
Cost Effective ◽  
Solar Radiation Management ◽  
Management Scenarios ◽  
Zonal Distribution ◽  
Climate Effects ◽  
Low Latitudes ◽  
Radiation Management

Abstract. Stratospheric sulfur injections have often been suggested as a cost-effective geoengineering method to prevent or slow down global warming. In geoengineering studies, these injections are commonly targeted to the Equator, where the yearly mean intensity of the solar radiation is the highest and from where the aerosols disperse globally due to the Brewer–Dobson Circulation. However, compensating for greenhouse gas-induced zonal warming by reducing solar radiation would require a relatively larger radiative forcing to the mid- and high latitudes and a lower forcing to the low latitudes than what is achieved by continuous equatorial injections. In this study we employ alternative aerosol injection scenarios to investigate if the resulting radiative forcing can be targeted to be zonally more uniform without decreasing the global the mean radiative forcing of stratospheric sulfur geoengineering. We used a global aerosol–climate model together with an Earth system model to study the radiative and climate effects of stratospheric sulfur injection scenarios with different injection areas. According to our simulations, varying the SO2 injection area seasonally would result in a similar global mean cooling effect as injecting SO2 to the Equator, but with a more uniform zonal distribution of shortwave radiative forcing. Compared to the case of equatorial injections, in the seasonally varying injection scenario where the maximum sulfur production from injected SO2 followed the maximum of solar radiation, the shortwave radiative forcing decreased by 27 % over the Equator (the latitudes between 20° N and 20° S) and increased by 15 % over higher latitudes. Compared to the continuous injections to the Equator, in summer months the radiative forcing was increased by 17 and 14 % and in winter months decreased by 14 and 16 % in Northern and Southern hemispheres, respectively. However, these forcings do not translate into as large changes in temperatures. The changes in forcing would only lead to 0.05 K warmer winters and 0.05 K cooler summers in the Northern Hemisphere, which is roughly 3 % of the cooling resulting from solar radiation management scenarios studied here.

scholarly journals Incorrect Asian aerosols affecting the attribution and projection of regional climate change in CMIP6 models

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Zhili Wang ◽  
Lei Lin ◽  
Yangyang Xu ◽  
Huizheng Che ◽  
Xiaoye Zhang ◽  
...  
Keyword(s):  
Climate Change ◽  
Radiative Forcing ◽  
Impact Analysis ◽  
Climate Model ◽  
Regional Climate ◽  
Eastern China ◽  
Coupled Model ◽  
Regional Climate Change ◽  
Anthropogenic Aerosol ◽  
Wide Range

AbstractAnthropogenic aerosol (AA) forcing has been shown as a critical driver of climate change over Asia since the mid-20th century. Here we show that almost all Coupled Model Intercomparison Project Phase 6 (CMIP6) models fail to capture the observed dipole pattern of aerosol optical depth (AOD) trends over Asia during 2006–2014, last decade of CMIP6 historical simulation, due to an opposite trend over eastern China compared with observations. The incorrect AOD trend over China is attributed to problematic AA emissions adopted by CMIP6. There are obvious differences in simulated regional aerosol radiative forcing and temperature responses over Asia when using two different emissions inventories (one adopted by CMIP6; the other from Peking university, a more trustworthy inventory) to driving a global aerosol-climate model separately. We further show that some widely adopted CMIP6 pathways (after 2015) also significantly underestimate the more recent decline in AA emissions over China. These flaws may bring about errors to the CMIP6-based regional climate attribution over Asia for the last two decades and projection for the next few decades, previously anticipated to inform a wide range of impact analysis.

scholarly journals Anthropogenic forcing and response yield observed positive trend in Earth’s energy imbalance

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shiv Priyam Raghuraman ◽  
David Paynter ◽  
V. Ramaswamy
Keyword(s):  
Radiative Forcing ◽  
Climate Model ◽  
Solar Spectrum ◽  
Internal Variability ◽  
Satellite Observations ◽  
Positive Trend ◽  
Energy Imbalance ◽  
Model Simulations ◽  
Heat Uptake ◽  
Climate Model Simulations

AbstractThe observed trend in Earth’s energy imbalance (TEEI), a measure of the acceleration of heat uptake by the planet, is a fundamental indicator of perturbations to climate. Satellite observations (2001–2020) reveal a significant positive globally-averaged TEEI of 0.38 ± 0.24 Wm−2decade−1, but the contributing drivers have yet to be understood. Using climate model simulations, we show that it is exceptionally unlikely (<1% probability) that this trend can be explained by internal variability. Instead, TEEI is achieved only upon accounting for the increase in anthropogenic radiative forcing and the associated climate response. TEEI is driven by a large decrease in reflected solar radiation and a small increase in emitted infrared radiation. This is because recent changes in forcing and feedbacks are additive in the solar spectrum, while being nearly offset by each other in the infrared. We conclude that the satellite record provides clear evidence of a human-influenced climate system.

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