4-9 September 2022, Bonn, Germany
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UP2.5

The interconnection between the Sun, space weather and the atmosphere

The Sun is the main energy source for the Earth's atmosphere. The main manifestations of external forcing from space to the atmosphere are in variations in solar parameters such as the solar irradiance (including solar UV) and solar particle fluxes. These parameters can induce changes in the atmosphere both at local and global scales, and can influence over a large range of altitudes up to the thermosphere. Some of these changes have the potential to affect the troposphere through atmospheric coupling processes, particularly through the stratosphere-troposphere connection, and thus have the potential to influence weather and climate.
The field of space weather, that is the change in the environment between the Sun and the Earth, has seen a rapid increase in research activity in recent years and in associated large scientific advances. The weather and climate community can benefit from this via better representation of space weather effects and their associated impacts on the atmosphere.

The overarching goal of this session is to connect communities within the Sun-to-Earth system and in so doing promote Sun-to-Earth system science, products and services. The aim is to review the state-of-the-art and to identify possible interrelationships between Earth and the Sun and space weather by assessing the level of coupling in the relevant physical systems and processes.

Contributions from the following topics (but not exclusively) are welcome:
• Upper atmospheric dynamical variability and coupling between atmospheric layers e.g. thermosphere-ionosphere coupling
• Solar irradiance and energetic particle impacts on the atmosphere
• Solar variations and stratosphere-troposphere coupling
• Solar influence on climate variability
• Solar irradiance (spectral and total irradiance) variations
• Sun-Earth and Sun-planet interrelationships (of relevance to e.g. spacecraft for planetary exploration which require planet meteorology forecasts)
• Space weather observation, forecasting products and services

Convener: Mauro Messerotti | Co-conveners: Suzy Bingham, Jürgen Kusche
Orals
| Tue, 06 Sep, 09:00–10:30 (CEST)|Room HS 5-6
Posters
| Attendance Tue, 06 Sep, 11:00–13:00 (CEST) | Display Tue, 06 Sep, 08:00–18:00|b-IT poster area

Tue, 6 Sep, 09:00–10:30

Chairpersons: Suzy Bingham, George Pankiewicz

09:00–09:30
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EMS2022-704
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solicited
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Online presentation
Katya Georgieva

Sun, our home star, is a variable star. The variations in the appearance and energy output from the Sun are denoted as “solar activity”.  These variations range from milliseconds to decades, centuries, millennia, and beyond. The variations with time scales of up to a few solar rotation periods (~27 days) are referred to as “space weather”, and have significant impacts on the space-borne and ground-based technological systems. Longer-term solar activity variations are defined as “space climate”, and are supposed to be related to the terrestrial (and maybe other planets’) global climate variations.

A number of solar activity manifestations can affect the Earth’s atmosphere. The total solar irradiance (TSI) is the main energy source for the terrestrial system. TSI is dominated by visible light whose relative variations are only a fraction of a percent, but with the greatest absolute magnitude of change. With decreasing wavelength, the relative variations increase. Radiation in different spectral ranges affects different parts of the Earth’s atmosphere.

The Earth is also constantly exposed to the Sun’s corpuscular radiation as it together with the whole Solar System is inside the ever expanding solar atmosphere known as the “solar wind” – a flow of charged particles with embedded magnetic fields from the solar corona. On top of it, transient structures like Coronal Mass Ejections (CMEs) and High Speed Solar Wind Streams (HSSs) ride whose interactions with the terrestrial magnetic field lead to geomagnetic storms.

High energy particles from CME or HSS associated shocks, or (mostly) from their interactions with the Earth’s magnetosphere, precipitate in the high latitude atmosphere leading to increased ionization, enhanced production of compounds which affect the ozone balance, radiative heating and cooling, and finally changes in atmospheric dynamics and large-scale circulation modes like the North Atlantic Oscillation governing the weather over most of the Northern hemisphere.

The solar wind magnetic field modulates the flux of galactic cosmic rays, high energy particles coming from outside the Solar system. Due to their high energy, they penetrate deep into the atmosphere. Their variations are found to be strongly correlated with the atmospheric global electric circuit, cloud cover, albedo, and infrared opacity, determining the Earth’s energy balance.

In this review, after a short introduction to solar activity, I will describe its above mentioned agents, and explain the suggested mechanisms by which they influence the atmosphere and climate. I will present observational evidences of such influences, highlight the recent advances, and the still unsolved questions and uncertainties.  

How to cite: Georgieva, K.: Solar influences on the atmosphere and climate, EMS Annual Meeting 2022, Bonn, Germany, 5–9 Sep 2022, EMS2022-704, https://doi.org/10.5194/ems2022-704, 2022.

09:30–09:45
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EMS2022-403
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Onsite presentation
Shreya Bhattacharya et al.

Visual sunspot observations form the longest scientific record of solar activity, spanning over four centuries. Long term solar studies  are crucial to predict the future evolution of the solar cycles and at improving our understanding of the solar influence on Earth climate change.

As an important step for the ongoing sunspot number recalibration throughout the entire solar physics community, (Lefevre et al., 2018), SN Version 2 was released in July, 2015 (Clette et al., 2016), which helped in shedding new light to long-term solar variations and instabilities of the 11-year solar cycle. However, uncertainties remain and errors in past historical data need to be further revised using the data at our disposal  for a robust long-term series.

In 1843, Professor Rudolf Wolf  who coined the term “Sunspot Number”, founded a journal called the "Mittheilungen der Naturforschenden Gesellschaft in Berne" where he published yearbooks with all of his findings, including sunspot observations as far back as Galileo (Wolf, 1861). The journal was maintained from 1848 (Wolf, 1848) until his death (Wolf and Wolfer, 1894). The Sunspot records collected by him from his European colleagues and his auxiliary observers are all tabulated in this journal. The Royal Observatory of Belgium (https://www.astro.oma.be/en/), particularly the WDC-SILSO, conducted a mission between 2017 and 2019 to digitize all the data contained in the published Mittheilungen.

In this study we exploit this database along with other available recounts of various observers to identify scale discrepancies or inhomogeneities that happened along the Sunspot number series over time. We also introduce statistical techniques to implement confidence bands or errors on daily Sunspot Numbers, an information that existing versions lack. The long-term aim is a complete reconstruction of the Sunspot Number series from the available raw data instead of a recalibration.

How to cite: Bhattacharya, S., Lefevre, L., Clette, F., and Jansen, M.: Diagnosing and calibrating the multi-century Sunspot Number Series, EMS Annual Meeting 2022, Bonn, Germany, 5–9 Sep 2022, EMS2022-403, https://doi.org/10.5194/ems2022-403, 2022.

09:45–10:00
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EMS2022-461
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Online presentation
Ingrid Cnossen et al.

Not only the climate in the troposphere is changing, also at higher altitudes long-term trends have been observed. The global mean middle and upper atmosphere have been cooling, resulting in atmospheric contraction and a decline in thermosphere density at fixed height, mainly driven by the increase in atmospheric CO2 concentration. The secular variation of the Earth’s magnetic field is an additional driver of long-term change in the upper atmosphere, causing trends that are strongly location-dependent. While magnetic field changes are most important for the ionosphere, they also affect the temperature and wind structure throughout the thermosphere, mainly via changes in the strength and geographic distribution of Joule heating. Simulations with the Whole Atmosphere Community Climate Model eXtension (WACCM-X) suggest that perturbations induced by magnetic field changes in the lower thermosphere climate can further propagate downward via vertical dynamical coupling. Our results show a significant response in the zonal mean temperature and zonal wind in the Southern Hemisphere (SH) middle- to high-latitude troposphere, stratosphere, and mesosphere of up to ±2 K and ±2 m/s, as well as regionally significant changes in Northern Hemisphere (NH) polar surface temperatures of up to ±1.3 K, in December-January-February. In the SH, changes in gravity wave filtering in the thermosphere induce a change in the residual circulation that extends down into the upper mesosphere, where further changes in the zonal mean wind climatology are generated, together with changes in local planetary wave generation and/or amplification and gravity wave filtering. This induces an anomalous residual circulation that extends down into the troposphere. The NH middle atmosphere response is zonally asymmetric, consisting of a significant change in the positioning and shape of the upper stratospheric polar vortex, which is dynamically consistent with the surface temperature response. While the details of the lower and middle atmosphere responses may not be entirely accurate due to model limitations, the results from our simulations do indicate that dynamical coupling within the atmosphere can conceivably result in upper atmosphere processes having a significant effect on surface climate.

How to cite: Cnossen, I., Lu, H., and Liu, H.: Long-term change in the upper atmosphere and a possible effect on surface climate, EMS Annual Meeting 2022, Bonn, Germany, 5–9 Sep 2022, EMS2022-461, https://doi.org/10.5194/ems2022-461, 2022.

10:00–10:15
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EMS2022-394
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Online presentation
Matyas Herein et al.

Using an intermediate complexity climate model we investigate the so-called snowball Earth transition. For certain values (including its current value) of the solar constant, the climate system allows two different stable states: one of them is the snowball Earth, covered by ice and snow, and the other one is today's climate. In our setup, we consider the case when the climate system starts from its warm attractor (the stable climate we experience today), and the solar constant is changed according to the following scenario: it is decreased continuously and abruptly, over one year, to a state, where only the Snowball Earth's attractor remains stable. This induces an inevitable transition, or climate tipping from the warm climate. The reverse transition is also discussed. Increasing the solar constant back to its original value in a similar way, in individual simulations, depending on the rate of the solar constant reduction we find that either the system stays stuck in the snowball state or returns to a warm climate. However, using ensemble methods i.e., using an ensemble of climate realizations differing only slightly in their initial conditions we show that the transition from the snowball Earth to the warm climate is also possible with a certain probability which depends on the specific scenario used. From the point of view of dynamical systems theory, we can say that the system's snapshot attractor splits between the warm climate's and the snowball Earth's attractor. Despite the limitations of an intermediate complexity climate model, all this reveals that incautious geoengineering (e.g. overdone solar radiation shielding) could even result in a snowball-like climate.

How to cite: Herein, M., Haszpra, T., and Kaszas, B.: When the Earth goes white: the Snowball Earth attractor, EMS Annual Meeting 2022, Bonn, Germany, 5–9 Sep 2022, EMS2022-394, https://doi.org/10.5194/ems2022-394, 2022.

10:15–10:30
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EMS2022-99
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Online presentation
Paul Prikryl and Vojto Rušin

Extreme weather events caused by intensification of tropical and extratropical cyclones can have destructive impacts on infrastructure, society, and environment. Forecasting extreme weather continues to present challenges. In this study, we consider possible external factors that can lead to severe weather. It has been shown that significant weather events, including explosive extratropical cyclones [1,2], rapid intensification of tropical cyclones [3], and heavy rainfall causing floods and flash floods [4,5] tend to follow arrivals of solar wind high-speed streams from coronal holes. To further support these results, we use the NOAA Storm Prediction Center database of tornadoes in the superposed epoch analysis to study the occurrence of tornado outbreaks relative to arrival time of solar wind disturbances caused by solar activity. This includes solar flares that can launch coronal mass ejections [6], coronal holes that are sources of high-speed streams, and high-density plasma adjacent to the heliospheric current sheet where the interplanetary magnetic field reverses its polarity [7]. Solar wind coupling to the magnetosphere-ionosphere-atmosphere system generates globally propagating atmospheric gravity waves [8,9] that can reach the troposphere with attenuated amplitudes but are subject to amplification upon over-reflection in the troposphere. These atmospheric gravity waves can trigger/release moist instabilities leading to convection and latent heat release, which is the energy driving the storms [10]. 

[1] Prikryl P., et al., J. Atmos. Sol.-Terr. Phys. 149, 219–231, 2016. doi:10.1016/j.jastp.2016.04.002
[2] Prikryl P., et al., J. Atmos. Sol.-Terr. Phys. 171, 94–10, 2018. doi:10.1016/j.jastp.2017.07.023
[3] Prikryl P., et al., J. Atmos. Sol.-Terr. Phys. 183, 36-60, 2019. doi:10.1016/j.jastp.2018.12.009
[4] Prikryl P., et al., Ann. Geophys. 39 (4), 769–93, 2021. doi:10.5194/angeo-39-769-2021
[5] Prikryl P., et al., Atmosphere 12 (9), 2021. https://doi.org/10.3390/atmos12091186.
[6] Gopalswamy N., Geosci. Lett. 3(8), 2016. doi: 10.1186/s40562-016-0039-2
[7] Tsurutani B.T., et al., J. Geophys. Res. 121. 10130–10156, 2016. doi:10.1002/2016JA022499
[8] Mayr H.G., et al., Space Sci. Rev. 54, 297–375, 1990. doi:10.1007/BF00177800
[9] Mayr H.G., et al., J. Atmos. Sol.-Terr. Phys. 104, 7–17, 2013. doi:10.1016/j.jastp.2013.08.001
[10] Prikryl P., et al., Ann. Geophys. 27, 31–57, 2009. doi:10.5194/angeo-27-31-2009

How to cite: Prikryl, P. and Rušin, V.: Tropospheric weather influenced by solar wind coupling to the magnetosphere-ionosphere-atmosphere system, EMS Annual Meeting 2022, Bonn, Germany, 5–9 Sep 2022, EMS2022-99, https://doi.org/10.5194/ems2022-99, 2022.

Posters

P25
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EMS2022-43
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Onsite presentation
Daniel Verscharen

The Vigil mission is ESA's flagship operational space-weather mission, planned to be launched in 2027/28. It will combine remote-sensing and in-situ measurements to enable accurate space-weather predictions from its unique vantage point at the fifth Sun-Earth Lagrange point. This location will allow Vigil to observe remotely space-weather events that propagate along the Sun-Earth line. In addition, Vigil will observe the source regions of the solar wind and of other space-weather events about 4.5 days before these source regions will point at Earth. Likewise, in-situ measurements of the solar-wind plasma at the fifth Sun-Earth Lagrange point will sample solar-wind streams that point at Earth about 4.5 days later.

The Plasma Analyser (PLA) instrument onboard Vigil will measure the solar wind at the location of the spacecraft over a wide dynamic range of plasma parameters. The data from PLA will predict high-speed solar wind streams headed towards Earth. These high-speed streams can drive relativistic (>MeV) electron flux enhancements in the Earth's radiation belts. Although these events are less spectacular than coronal mass ejections and the associated geomagnetic storms, they are potentially more damaging to our infrastructure due to their longer duration. The associated flux enhancements especially pose a threat to spacecraft in Medium Earth Orbits and Geostationary Equatorial Orbits. PLA measurements will also support work to improve and validate models for solar-terrestrial relations in the inner heliosphere. These models can be used, for example, to provide better predictions of the background plasma conditions through which Earth-directed coronal mass ejections propagate.

PLA is currently designed and built at the University College London's Mullard Space Science Laboratory (UCL/MSSL). The instrument is an electrostatic plasma analyser that relies largely on the flight heritage of previous scientific instruments designed by UCL/MSSL. I will give a status update of the PLA development and an outlook into the space-weather prediction capabilities enabled by PLA and the other Vigil payload.

How to cite: Verscharen, D.: Measuring the solar wind with Vigil: solar-terrestrial relations and space-weather forecasting, EMS Annual Meeting 2022, Bonn, Germany, 5–9 Sep 2022, EMS2022-43, https://doi.org/10.5194/ems2022-43, 2022.

P26
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EMS2022-607
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CC
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Onsite presentation
Laure Lefevre et al.

We will present the international effort that led to the first-ever revision of the Sunspot and Group Numbers (let us call them "the Sunspot Series"), a well-known series that had never been put into question since its creation by Rudolf Wolf in 1849. We will review the process and its challenges (ISSI review paper, https://www.issibern.ch/teams/sunspotnoser/). 

At this point in time, the number of Group Number series available is still based on different techniques that enable the stitching of datasets of various quality over wildly different periods, and although they present an undeniable improvement over the original Group Number from Hayt & Schatten (1998), the resulting series remain to be extensively tested in order to be clearly validated by the scientific community.

Since this first revision in 2015 (Solar Physics Topical Issue, 2016), the Sunspot Series have become living datasets that require constant monitoring since more source data are being recovered regularly (Arlt & Vaquero, 2020). With the team from ISSI, we are currently driving a large effort to gather raw data from all around the world. At the Royal Observatory of Belgium, within the WDC-SILSO (https://wwwbis.sidc.be/silso/) where the original Mittheilungen have been digitized (2017-2019) we also have 2 PhD students working on stitching historical and modern sunspot numbers and evaluating the quality of the reconstructed series through advanced statistical techniques.

After this review of previous efforts, we will focus more specifically on the reconstruction of the International Sunspot Number from raw sunspot data (Bhattacharya et al., 2021, 2022, FARSUN belgian project) end present the potential impact of these revisions on end users (e.g. F10.7, Clette, 2021). 

How to cite: Lefevre, L., Bhattacharya, S., and Clette, F.: Reconstructing the Sunspot Number : challenges and impact, EMS Annual Meeting 2022, Bonn, Germany, 5–9 Sep 2022, EMS2022-607, https://doi.org/10.5194/ems2022-607, 2022.

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