On the detection of the solar signal in the tropical stratosphere

Abstract. We investigate the relative role of volcanic eruptions, El-Niño Southern-Oscillation (ENSO) and the Quasi-Biennal-Oscillation (QBO) in the quasi-decadal signal in the tropical stratosphere in temperature and ozone commonly attributed to the 11 yr solar cycle. For this purpose, we perform transient simulations with the Whole Atmosphere Community Climate Model forced from 1960 to 2004 with an 11 yr solar cycle in irradiance and different combinations of other forcings. An improved multiple regression technique is used to diagnose the 11 yr solar signal in the simulations. One set of simulations includes all observed forcings, and is thereby aimed at closely reproducing observations. Three idealized sets exclude ENSO variability, volcanic aerosol forcing, and QBO in tropical stratospheric winds, respectively. Differences in the derived solar response in the tropical stratosphere in the four sets quantify the impact of ENSO, volcanic events and the QBO in attributing quasi-decadal changes to the solar cycle in the model simulations. It is shown that most of the apparent solar-induced lower stratospheric temperature and ozone increase diagnosed in the simulations with all observed forcings is due to two major volcanic eruptions (i.e., El Chichón in 1982 and Mt. Pinatubo in 1991), that are concurrent with periods of high solar activity. While in the middle and upper tropical stratosphere, it is feasible to detect a robust solar signal, this is not the case in the tropical lower stratosphere, at least in a 45 yr record. The present results suggest that in the tropical lower stratosphere, the portion of decadal variability that can be unambigously linked to the solar cycle may be smaller than previously thought.

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On the detection of the solar signal in the tropical stratosphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-5251-2014 ◽

2014 ◽

Vol 14 (11) ◽

pp. 5251-5269 ◽

Cited By ~ 39

Author(s):

G. Chiodo ◽

D. R. Marsh ◽

R. Garcia-Herrera ◽

N. Calvo ◽

J. A. García

Keyword(s):

Solar Cycle ◽

Lower Stratosphere ◽

Decadal Variability ◽

Southern Oscillation ◽

Volcanic Eruptions ◽

High Solar Activity ◽

Relative Role ◽

Quasi Biennial Oscillation ◽

Solar Signal ◽

The Impact

Abstract. We investigate the relative role of volcanic eruptions, El Niño–Southern Oscillation (ENSO), and the quasi-biennial oscillation (QBO) in the quasi-decadal signal in the tropical stratosphere with regard to temperature and ozone commonly attributed to the 11 yr solar cycle. For this purpose, we perform transient simulations with the Whole Atmosphere Community Climate Model forced from 1960 to 2004 with an 11 yr solar cycle in irradiance and different combinations of other forcings. An improved multiple linear regression technique is used to diagnose the 11 yr solar signal in the simulations. One set of simulations includes all observed forcings, and is thereby aimed at closely reproducing observations. Three idealized sets exclude ENSO variability, volcanic aerosol forcing, and QBO in tropical stratospheric winds, respectively. Differences in the derived solar response in the tropical stratosphere in the four sets quantify the impact of ENSO, volcanic events and the QBO in attributing quasi-decadal changes to the solar cycle in the model simulations. The novel regression approach shows that most of the apparent solar-induced lower-stratospheric temperature and ozone increase diagnosed in the simulations with all observed forcings is due to two major volcanic eruptions (i.e., El Chichón in 1982 and Mt. Pinatubo in 1991). This is caused by the alignment of these eruptions with periods of high solar activity. While it is feasible to detect a robust solar signal in the middle and upper tropical stratosphere, this is not the case in the tropical lower stratosphere, at least in a 45 yr simulation. The present results suggest that in the tropical lower stratosphere, the portion of decadal variability that can be unambiguously linked to the solar cycle may be smaller than previously thought.

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Impact of November 2010 volcanic activity on the UTLS temperatures

10.5194/egusphere-egu2020-458 ◽

2020 ◽

Author(s):

Elżbieta Lasota ◽

Riccardo Biondi ◽

Florian Ladstädter ◽

Andrea K. Steiner

Keyword(s):

Lower Stratosphere ◽

Southern Oscillation ◽

Linear Trend ◽

Volcanic Eruptions ◽

Global Scale ◽

Stratospheric Aerosol ◽

Atmospheric Variability ◽

Maximum Warming ◽

The Impact ◽

Temperature Time

Recent studies have shown an increase of stratospheric aerosol optical depth in the last 20 years despite the absence of large volcanic eruptions in the same period, contributing to supporting the hypothesis that several minor eruptions could impact the atmospheric variability as a large one. November 2010 was a relatively active volcanic period in the tropical belt, three eruptions with Volcanic Explosivity Index higher than 3 occurred in a time span of about 3 weeks: Merapi, Tengger Caldera and Tungurahua. Merapi was the largest eruption of the three, directly overshooting the stratosphere and injecting a large amount of sulfur dioxide. In this study, we analyse the impact of this series of eruptions on the temperature derived from radio occultation observations in upper troposphere lower stratosphere at the local, regional and global scale. The impact of the Quasi&#226;&#128;&#144;Biennial Oscillation, El Ni&#241;o&#8211;Southern Oscillation, and linear trend on temperature is estimated and removed from temperature time series using multiple linear regression. Signatures of volcanic eruptions in temperature are analysed using post fit residuals. The results show significant warming in the lower stratosphere between 10&#176;S and 0&#176; for a period of 7 months after the eruptions with a maximum anomaly amplitude of about 1.4 K at 18 km altitude. Whilst the maximum warming in Merapi&#8217;s vicinity occurred 4 months after the eruption and reached the magnitude of almost 4 K.

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How can we understand the global distribution of the solar cycle signal on the Earth's surface?

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-12925-2016 ◽

2016 ◽

Vol 16 (20) ◽

pp. 12925-12944 ◽

Cited By ~ 17

Author(s):

Kunihiko Kodera ◽

Rémi Thiéblemont ◽

Seiji Yukimoto ◽

Katja Matthes

Keyword(s):

Solar Cycle ◽

Surface Temperature ◽

Zonal Wind ◽

High Solar Activity ◽

Mean Flow ◽

Central Pacific ◽

Solar Signal ◽

The Tropics ◽

Solar Influence ◽

The Impact

Abstract. To understand solar cycle signals on the Earth's surface and identify the physical mechanisms responsible, surface temperature variations from observations as well as climate model data are analysed to characterize their spatial structure. The solar signal in the annual mean surface temperature is characterized by (i) mid-latitude warming and (ii) no overall tropical warming. The mid-latitude warming during solar maxima in both hemispheres is associated with a downward penetration of zonal mean zonal wind anomalies from the upper stratosphere during late winter. During the Northern Hemisphere winter this is manifested by a modulation of the polar-night jet, whereas in the Southern Hemisphere, the upper stratospheric subtropical jet plays the major role. Warming signals are particularly apparent over the Eurasian continent and ocean frontal zones, including a previously reported lagged response over the North Atlantic. In the tropics, local warming occurs over the Indian and central Pacific oceans during high solar activity. However, this warming is counterbalanced by cooling over the cold tongue sectors in the southeastern Pacific and the South Atlantic, and results in a very weak zonally averaged tropical mean signal. The cooling in the ocean basins is associated with stronger cross-equatorial winds resulting from a northward shift of the ascending branch of the Hadley circulation during solar maxima. To understand the complex processes involved in the solar signal transfer, results of an idealized middle atmosphere–ocean coupled model experiment on the impact of stratospheric zonal wind changes are compared with solar signals in observations. Model integration of 100 years of strong or weak stratospheric westerly jet condition in winter may exaggerate long-term ocean feedback. However, the role of ocean in the solar influence on the Earth's surface can be better seen. Although the momentum forcing differs from that of solar radiative forcing, the model results suggest that stratospheric changes can influence the troposphere, not only in the extratropics but also in the tropics through (i) a downward migration of wave–zonal mean flow interactions and (ii) changes in the stratospheric mean meridional circulation. These experiments support earlier evidence of an indirect solar influence from the stratosphere.

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How can we understand the solar cycle signal on the Earth's surface?

10.5194/acp-2016-138 ◽

2016 ◽

Cited By ~ 1

Author(s):

Kunihiko Kodera ◽

Rémi Thiéblemont ◽

Seiji Yukimoto ◽

Katja Matthes

Keyword(s):

Solar Cycle ◽

Surface Temperature ◽

Zonal Wind ◽

High Solar Activity ◽

Late Winter ◽

Mean Flow ◽

Central Pacific ◽

Solar Signal ◽

The Tropics ◽

The Impact

Abstract. To understand solar cycle signals on the Earth's surface and identify the physical mechanisms responsible, surface temperature variations from observations as well as climate model data are analyzed to characterize their spatial structure. The solar signal in the annual mean surface temperature is characterized by (i) mid-latitude warming and (ii) no warming in the tropics. The mid-latitude warming during solar maxima in both hemispheres is associated with a downward penetration of zonal mean zonal wind anomalies from the upper stratosphere during late winter. During Northern Hemisphere winter this is manifested in a modulation of the polar-night jet whereas in the Southern Hemisphere the subtropical jet plays the major role. Warming signals are particularly apparent over the Eurasian continent and ocean frontal zones, including a previously reported lagged response over the North Atlantic. In the tropics, local warming occurs over the Indian and central Pacific oceans during high solar activity. However, this warming is counter balanced by cooling over the cold tongue sectors in the southeastern Pacific and the South Atlantic, and results in a very weak zonally averaged tropical mean signal. The cooling in the ocean basins is associated with stronger cross-equatorial winds resulting from a northward shift of the ascending branch of the Hadley circulation during solar maxima. To understand the complex processes involved in the solar signal transfer, results of an idealized middle atmosphere–ocean coupled model experiment on the impact of stratospheric zonal wind changes are compared with solar signals in observations. The model results suggest that both tropical and extra-tropical solar surface signals can result from circulation changes in the upper stratosphere through (i) a downward migration of wave–zonal mean flow interactions and (ii) changes in the stratospheric mean meridional circulation. These experiments support earlier evidence of an indirect solar influence from the stratosphere.

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Interannual Variability and Trends in Sea Surface Temperature, Lower and Middle Atmosphere Temperature at Different Latitudes for 1980–2019

Atmosphere ◽

10.3390/atmos12040454 ◽

2021 ◽

Vol 12 (4) ◽

pp. 454

Author(s):

Andrew R. Jakovlev ◽

Sergei P. Smyshlyaev ◽

Vener Y. Galin

Keyword(s):

Surface Temperature ◽

Sea Surface Temperature ◽

Lower Stratosphere ◽

Middle Atmosphere ◽

Southern Oscillation ◽

Lower Troposphere ◽

Reanalysis Data ◽

Sea Surface ◽

The Arctic ◽

The Impact

The influence of sea-surface temperature (SST) on the lower troposphere and lower stratosphere temperature in the tropical, middle, and polar latitudes is studied for 1980–2019 based on the MERRA2, ERA5, and Met Office reanalysis data, and numerical modeling with a chemistry-climate model (CCM) of the lower and middle atmosphere. The variability of SST is analyzed according to Met Office and ERA5 data, while the variability of atmospheric temperature is investigated according to MERRA2 and ERA5 data. Analysis of sea surface temperature trends based on reanalysis data revealed that a significant positive SST trend of about 0.1 degrees per decade is observed over the globe. In the middle latitudes of the Northern Hemisphere, the trend (about 0.2 degrees per decade) is 2 times higher than the global average, and 5 times higher than in the Southern Hemisphere (about 0.04 degrees per decade). At polar latitudes, opposite SST trends are observed in the Arctic (positive) and Antarctic (negative). The impact of the El Niño Southern Oscillation phenomenon on the temperature of the lower and middle atmosphere in the middle and polar latitudes of the Northern and Southern Hemispheres is discussed. To assess the relative influence of SST, CO2, and other greenhouse gases’ variability on the temperature of the lower troposphere and lower stratosphere, numerical calculations with a CCM were performed for several scenarios of accounting for the SST and carbon dioxide variability. The results of numerical experiments with a CCM demonstrated that the influence of SST prevails in the troposphere, while for the stratosphere, an increase in the CO2 content plays the most important role.

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Middle atmosphere response to the solar cycle in irradiance and ionizing particle precipitation

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-5045-2011 ◽

2011 ◽

Vol 11 (10) ◽

pp. 5045-5077 ◽

Cited By ~ 60

Author(s):

K. Semeniuk ◽

V. I. Fomichev ◽

J. C. McConnell ◽

C. Fu ◽

S. M. L. Melo ◽

...

Keyword(s):

Solar Cycle ◽

Radiative Forcing ◽

Climate Model ◽

Middle Atmosphere ◽

High Energy ◽

Galactic Cosmic Rays ◽

Particle Precipitation ◽

Solar Cycle Variation ◽

Cycle Variation ◽

The Impact

Abstract. The impact of NOx and HOx production by three types of energetic particle precipitation (EPP), auroral zone medium and high energy electrons, solar proton events and galactic cosmic rays on the middle atmosphere is examined using a chemistry climate model. This process study uses ensemble simulations forced by transient EPP derived from observations with one-year repeating sea surface temperatures and fixed chemical boundary conditions for cases with and without solar cycle in irradiance. Our model results show a wintertime polar stratosphere ozone reduction of between 3 and 10 % in agreement with previous studies. EPP is found to modulate the radiative solar cycle effect in the middle atmosphere in a significant way, bringing temperature and ozone variations closer to observed patterns. The Southern Hemisphere polar vortex undergoes an intensification from solar minimum to solar maximum instead of a weakening. This changes the solar cycle variation of the Brewer-Dobson circulation, with a weakening during solar maxima compared to solar minima. In response, the tropical tropopause temperature manifests a statistically significant solar cycle variation resulting in about 4 % more water vapour transported into the lower tropical stratosphere during solar maxima compared to solar minima. This has implications for surface temperature variation due to the associated change in radiative forcing.

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Revisiting the Krakatau 1883 Volcanic Aerosol Dispersal

10.5194/egusphere-egu21-10489 ◽

2021 ◽

Author(s):

Rafael Castro ◽

Tushar Mittal ◽

Stephen Self

Keyword(s):

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Volcanic Eruptions ◽

Climate Impact ◽

Volcanic Plume ◽

Quasi Biennial Oscillation ◽

Aerosol Cloud ◽

Pinatubo Eruption ◽

The Impact

The 1883 Krakatau eruption is one of the most well-known historical volcanic eruptions due to its significant global climate impact as well as first recorded observations of various aerosol associated optical and physical phenomena. Although much work has been done on the former by comparison of global climate model predictions/ simulations with instrumental and proxy climate records, the latter has surprisingly not been studied in similar detail. In particular, there is a wealth of observations of vivid red sunsets, blue suns, and other similar features, that can be used to analyze the spatio-temporal dispersal of volcanic aerosols in summer to winter 1883. Thus, aerosol cloud dispersal after the Krakatau eruption can be estimated, bolstered by aerosol cloud behavior as monitored by satellite-based instrument observations after the 1991 Pinatubo eruption. This is one of a handful of large historic eruptions where this analysis can be done (using non-climate proxy methods). In this study, we model particle trajectories of the Krakatau eruption cloud using the Hysplit trajectory model and compare our results with our compiled observational dataset (principally using Verbeek 1884, the Royal Society report, and Kiessling 1884).In particular, we explore the effect of different atmospheric states - the quasi-biennial oscillation (QBO) which impacts zonal movement of the stratospheric volcanic plume - to estimate the phase of the QBO in 1883 required for a fast-moving westward cloud. Since this alone is unable to match the observed latitudinal spread of the aerosols, we then explore the impact of an&#160; umbrella cloud (2000 km diameter) that almost certainly formed during such a large eruption. A large umbrella cloud, spreading over ~18 degrees within the duration of the climax of the eruption (6-8 hours), can lead to much quicker latitudinal spread than a point source (vent). We will discuss the results of the combined model (umbrella cloud and correct QBO phase) with historical accounts and observations, as well as previous work on the 1991 Pinatubo eruption. We also consider the likely impacts of water on aerosol concentrations and the relevance of this process for eruptions with possible significant seawater interactions, like Krakatau. We posit that the role of umbrella clouds is an under-appreciated, but significant, process for beginning to model the climatic impacts of large volcanic eruptions.

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The representation of solar cycle signals in stratospheric ozone. Part II: Analysis of global models

10.5194/acp-2017-477 ◽

2017 ◽

Cited By ~ 3

Author(s):

Amanda C. Maycock ◽

Katja Matthes ◽

Susann Tegtmeier ◽

Hauke Schmidt ◽

Rémi Thiéblemont ◽

...

Keyword(s):

Solar Cycle ◽

Solar Irradiance ◽

Climate Models ◽

Climate Model ◽

Stratospheric Ozone ◽

Temperature Response ◽

Solar Variability ◽

High Latitudes ◽

Stratospheric Temperature ◽

The Impact

Abstract. The impact of changes in incoming solar irradiance on stratospheric ozone abundances should be included in climate model simulations to fully capture the atmospheric response to solar variability. This study presents the first systematic comparison of the solar-ozone response (SOR) during the 11 year solar cycle amongst different chemistry-climate models (CCMs) and ozone databases specified in climate models that do not include chemistry. We analyse the SOR in eight CCMs from the WCRP/SPARC Chemistry-Climate Model Initiative (CCMI-1) and compare these with three ozone databases: the Bodeker Scientific database, the SPARC/AC&C database for CMIP5, and the SPARC/CCMI database for CMIP6. The results reveal substantial differences in the representation of the SOR between the CMIP5 and CMIP6 ozone databases. The peak amplitude of theSOR in the upper stratosphere (1–5 hPa) decreases from 5 % to 2 % between the CMIP5 and CMIP6 databases. This difference is because the CMIP5 database was constructed from a regression model fit to satellite observations, whereas the CMIP6 database is constructed from CCM simulations, which use a spectral solar irradiance (SSI) dataset with relatively weak UV forcing. The SOR in the CMIP6 ozone database is therefore implicitly more similar to the SOR in the CCMI-1 models than to the CMIP5 ozone database, which shows a greater resemblance in amplitude and structure to the SOR in the Bodeker database. The latitudinal structure of the annual mean SOR in the CMIP6 ozone database and CCMI-1 models is considerably smoother than in the CMIP5 database, which shows strong gradients in the SOR across the midlatitudes owing to the paucity of observations at high latitudes. The SORs in the CMIP6 ozone database and in the CCMI-1 models show a strong seasonal dependence, including large meridional gradients at mid to high latitudes during winter; such seasonal variations in the SOR are not included in the CMIP5 ozone database. Sensitivity experiments with a global atmospheric model without chemistry (ECHAM6.3) are performed to assess the impact of changes in the representation of the SOR and SSI forcing between CMIP5 and CMIP6. The experiments show that the smaller amplitude of the SOR in the CMIP6 ozone database compared to CMIP5 causes a decrease in the modelled tropical stratospheric temperature response over the solar cycle of up to 0.6 K, or around 50 % of the total amplitude. The changes in the SOR explain most of the difference in the amplitude of the tropical stratospheric temperature response in the case with combined changes in SOR and SSI between CMIP5 and CMIP6. The results emphasise the importance of adequately representing the SOR in climate models to capture the impact of solar variability on the atmosphere. Since a number of limitations in the representation of the SOR in the CMIP5 ozone database have been identified, CMIP6 models without chemistry are encouraged to use the CMIP6 ozone database to capture the climate impacts of solar variability.

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Influence of Arctic Stratospheric Ozone on Surface Climate in CCMI models

10.5194/acp-2018-1031 ◽

2018 ◽

Author(s):

Ohad Harari ◽

Chaim I. Garfinkel ◽

Olaf Morgenstern ◽

Guang Zeng ◽

Simone Tilmes ◽

...

Keyword(s):

Lower Stratosphere ◽

Climate Model ◽

Southern Oscillation ◽

Stratospheric Ozone ◽

Internal Variability ◽

Tropical Circulation ◽

Polar Cap ◽

Sea Level Pressure ◽

Surface Climate ◽

Stratospheric Variability

Abstract. The Northern Hemisphere and tropical circulation response to interannual variability in Arctic stratospheric ozone is analyzed in a set of the latest model simulations archived for the Chemistry-Climate Model Initiative (CCMI) project. All models simulate a connection between ozone variability and temperature/geopotential height in the lower stratosphere similar to that observed. A connection between Arctic ozone variability and polar cap sea-level pressure is also found, but additional analysis suggests that it is mediated by the dynamical variability that typically drives the anomalous ozone concentrations. The CCMI models also show a connection between Arctic stratospheric ozone and the El Nino Southern Oscillation (ENSO): the CCMI models show a tendency of Arctic stratospheric ozone variability to lead ENSO variability one to two years later. While this effect is much weaker than that observed, it is still statistically significant. Overall, Arctic stratospheric ozone is related to lower stratospheric variability and may also influence the surface in both polar and tropical latitudes, though these impacts can be masked by internal variability if data is only available for ~ 40 years.

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A global decadal mode in a high-end climate model and in observations: Any connection to the solar cycle?

10.5194/egusphere-egu21-4961 ◽

2021 ◽

Author(s):

Michael Ghil ◽

Yizhak Feliks ◽

Justin Small

Keyword(s):

Solar Cycle ◽

Sea Level ◽

North Atlantic ◽

Climate Model ◽

Decadal Variability ◽

Singular Spectrum Analysis ◽

Coupled System ◽

The North ◽

Spatio Temporal ◽

Decadal Mode

The present work addresses two persistent quandaries of the climate sciences: (i) the existence of global oscillatory modes in the coupled ocean&#8211;atmosphere system; and (ii) solar effects on this coupled system. Interannual oscillatory modes, atmospheric and oceanic, are present in several large regions of the globe. We examine here interannual-to-decadal variability over the entire globe in the Community Earth System Model (CESM) and in the NCEP-NCAR reanalysis, and apply multichannel singular spectrum analysis (MSSA) to these two datasets.In the fully coupled CESM1.1 model, with its resolution of 0.1 &#215; 0.1 degrees in the ocean and 0.25 &#215; 0.25 degrees in the atmosphere, the &#64257;elds analyzed are surface temperatures, sea level pressures and&#160; the 200-hPa geopotential. The simulation is 100-yr long and the last 66 yr are used in the analysis. The two statistically signi&#64257;cant periodicities in this IPCC-class model are 11 and 3.4 yr.In the reanalysis, the &#64257;elds of sea level pressure and of 200-hPa geopotential are analyzed at its resolution of 2.5 &#215; 2.5 degrees over the 68-yr interval 1949&#8211;2016. Oscillations with periods of 12 and 3.6 yr are found to be statistically signi&#64257;cant in this dataset. The spatio-temporal patterns&#160; of the oscillations in the two datasets are quite similar. The spatial pattern of these&#160; global oscillations over the North Paci&#64257;c and North Atlantic resemble the Paci&#64257;c Decadal Oscillation and the interannual variability found in the western North Atlantic, respectively.The two global modes, with their 11&#8211;12-yr and 3.4&#8211;3.6-yr periodicities, are quite robust, suggesting potential contributions of both to predictability at 1&#8211;3-yr horizons. On the other hand, the CESM run has no year-to-year changes in the prescribed insolation, excluding any role of the solar cycle in the model&#8217;s 11-yr mode. The solar cycle is present, however, in the reanalysis, since it is present in nature and hence it does affect the observations. We speculate, therefore, that regional oscillations &#8212; with their distinct near-periodicities and spatial patterns &#8212; are synchronized&#160; over the globe, thus yielding both the global oscillatory modes found in CESM. In nature, the decadal mode could be further synchronized with the solar cycle, but that does not seem to be the case, given the slight difference in period &#8212; 12 yr for the reanalysis and 11 yr for the solar cycle, which makes them drift in and out of phase.The work&#8217;s tentative conclusion is, therefore: (i) yes, there are global oscillatory modes in the climate system, especially a decadal mode; but (ii) no, this mode has little or nothing to do with the solar cycle.

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