scholarly journals Is there a direct solar proton impact on lower stratospheric ozone?

2020 ◽  
Author(s):  
Jia Jia ◽  
Antti Kero ◽  
Niilo Kalakoski ◽  
Monika E. Szeląg ◽  
Pekka T. Verronen
Keyword(s):  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Individual Case ◽  
Solar Proton ◽  
Special Focus ◽  
Ozone Level ◽  
Superposed Epoch Analysis ◽  
Potential Case ◽  
Epoch Analysis ◽  
The Individual

Abstract. We investigate Arctic polar atmospheric ozone responses to Solar Proton Events (SPEs) using MLS satellite measurements (2004–now) and WACCM-D simulations (1989–2012). Special focus is on lower stratospheric ozone depletion that has been proposed earlier based on superposed epoch analysis of ozonesonde anomalies (up to 10 % ozone decrease). Superposed Epoch Analysis (SEA) of the satellite dataset provides no evidence of any average SPE impact on the lower stratospheric ozone, although at the mesospheric altitudes a statistically significant ozone depletion is present. In the individual case studies, we find only one potential case (January 2005) in which the lower stratospheric ozone level was significantly decreased after the SPE onset. However, similar decreases could not be identified in other SPEs of similar or larger magnitude. We find a very good overall consistency between SPE-driven ozone anomalies derived from the WACCM-D model simulations and the Aura MLS data. The simulation results before the Aura MLS era indicate no significant effect on the lower stratospheric ozone either. As a conclusion, the SPE has a zero direct impact on the lower stratospheric ozone.

scholarly journals Is there a direct solar proton impact on lower-stratospheric ozone?

2020 ◽  
Vol 20 (23) ◽  
pp. 14969-14982
Author(s):  
Jia Jia ◽  
Antti Kero ◽  
Niilo Kalakoski ◽  
Monika E. Szeląg ◽  
Pekka T. Verronen
Keyword(s):  
Ozone Depletion ◽  
Climate Model ◽  
Model Simulation ◽  
Stratospheric Ozone ◽  
Solar Proton ◽  
Special Focus ◽  
Observation Data ◽  
Ozone Level ◽  
Superposed Epoch Analysis ◽  
The Individual

Abstract. We investigate Arctic polar atmospheric ozone responses to solar proton events (SPEs) using MLS (Microwave Limb Sounder) satellite measurements (2004–now) and WACCM-D (Whole Atmosphere Community Climate Model) simulations (1989–2012). Special focus is on lower-stratospheric (10–30 km) ozone depletion that has been proposed earlier based on superposed epoch analysis (SEA) of ozonesonde anomalies (up to 10 % ozone decrease at ∼ 20 km). SEA of the satellite dataset provides no solid evidence of any average SPE impact on the lower-stratospheric ozone, although at the mesospheric altitudes a statistically significant ozone depletion is present. In the individual case studies, we find only one potential case (January 2005) in which the lower-stratospheric ozone level was significantly decreased after the SPE onset (in both model simulation and MLS observation data). However, similar decreases could not be identified in other SPEs of similar or larger magnitude. Due to the input proton energy threshold of > 300 MeV, the WACCM-D model can only detect direct proton effects above 25 km, and simulation results before the Aura MLS era indicate no significant effect on the lower-stratospheric ozone. However, we find a very good overall consistency between WACCM-D simulations and MLS observations of SPE-driven ozone anomalies both on average and for the individual cases including January 2005.

Investigation of direct solar proton impact on Arctic stratospheric ozone

2021 ◽  
Author(s):  
Jia Jia ◽  
Antti Kero ◽  
Niilo Kalakoski ◽  
Monika E. Szeląg ◽  
Pekka T. Verronen
Keyword(s):  
Climate Model ◽  
Model Simulation ◽  
Stratospheric Ozone ◽  
Individual Case ◽  
Solar Proton ◽  
Observation Data ◽  
Ozone Level ◽  
Superposed Epoch Analysis ◽  
Average Decrease ◽  
The Individual

<p>Recent studies reported up to a 10 % average decrease of lower stratospheric ozone at ∼ 20 km altitude following solar proton events (SPEs), based on superposed epoch analysis (SEA) of ozonesonde anomalies. Our study uses 49 SPEs that occurred after the launch of Aura MLS (2004–now) and 177 SPEs that occurred in the WACCM-D (Whole Atmosphere Community Climate Model with D-region ion chemistry) simulation period (1989–2012) to evaluate Arctic polar atmospheric ozone changes following SPEs. At the mesospheric altitudes a statistically significant ozone depletion is present. At the lower stratosphere (<25 km), SEA of the satellite dataset provides no solid evidence of any average direct SPE impact on ozone. In the individual case studies, we find only one potential case (January 2005) in which the lower-stratospheric ozone level was significantly decreased after the SPE onset (in both model simulation and MLS observation data). However, similar decreases could not be identified in other SPEs of similar or larger magnitude. We find a very good overall consistency between WACCM-D simulations and MLS observations of SPE-driven ozone anomalies both on average and for the individual cases, including case in January 2005.</p>

scholarly journals Northern Hemisphere Stratospheric Ozone Depletion Caused by Solar Proton Events: The Role of the Polar Vortex

2018 ◽  
Vol 45 (4) ◽  
pp. 2115-2124 ◽  
Author(s):  
M. H. Denton ◽  
R. Kivi ◽  
T. Ulich ◽  
M. A. Clilverd ◽  
C. J. Rodger ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
Solar Proton ◽  
Stratospheric Ozone Depletion ◽  
Solar Proton Events

Superposed epoch analysis of coupling mechanisms captured by meteor radars during sudden stratospheric warmings

2021 ◽  
Author(s):  
Benedikt Gast ◽  
Ales Kuchar ◽  
Gunter Stober ◽  
Christoph Jacobi ◽  
Dimitry Pokhotelov ◽  
...  
Keyword(s):  
Zonal Wind ◽  
Lower Thermosphere ◽  
Rio Grande ◽  
Meridional Wind ◽  
Meteorological Conditions ◽  
Special Focus ◽  
Wind Component ◽  
Superposed Epoch Analysis ◽  
Epoch Analysis ◽  
Coupling Mechanisms

<p class="western" align="justify"><span lang="en-GB">Previous studies that analysed the mesosphere and lower thermosphere (MLT) dynamics during sudden stratospheric warmings (SSWs) were limited only to particular SSWs or focused on a particular station representative only for some regions. Here we describe a comprehensive study of the average meteorological conditions during SSWs with a special focus on the general contribution of planetary (PW) and gravity (GW) waves as primary coupling mechanisms between lower and upper atmosphere. The average meteorological conditions in the MLT during SSWs were analyzed using a superposed epoch analysis (Denton et al., 2019) of meteor radar measurements for stations in the northern (NH: Collm, Kiruna, Sodankyla, CMOR) and the southern hemisphere (SH: Rio Grande, Davis, Rothera) for the altitude range of 80–100 km Using the adaptive spectral filtering method (Stober et al., 2021), we study in detail PW and GW characteristics in addition to measured zonal and meridional wind components in a time period from 2000 to 2020.</span></p> <p class="western" align="justify"><span lang="en-GB">In the NH the zonal wind is typically decreasing from around two weeks before the SSW onset, corresponding to an increased PW activity. Around the SSW onset, latitudinal differences in the zonal wind component as well as the PW activity can be seen. In the weeks before the SSW onset, the stations in the NH also show an increased level of GW kinetic energy. The meridional wind at the NH stations fluctuates with a periodicity of about 10 days before and around the onset. In contrast to previous studies (e.g. Yasui et al., 2016), the measurements in the SH are consistent with the inter-hemispheric coupling hypothesis. The expected downward shift of GW drag (Körnich and Becker, 2010) was reproduced by a downward travelling layer of enhanced GW activity at Davis and Rio Grande. Finally, the role of the terdiurnal tide in the GW energy composite is considered.</span></p>

scholarly journals Solar proton events and stratospheric ozone depletion over northern Finland

2018 ◽  
Vol 177 ◽  
pp. 218-227 ◽  
Author(s):  
M.H. Denton ◽  
R. Kivi ◽  
T. Ulich ◽  
C.J. Rodger ◽  
M.A. Clilverd ◽  
...  
Keyword(s):  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Solar Proton ◽  
Stratospheric Ozone Depletion ◽  
Solar Proton Events

Shoulder Pain at Work: Causation Analysis

2017 ◽  
Vol 22 (1) ◽  
pp. 11-16
Author(s):  
Joel Weddington ◽  
Charles N. Brooks ◽  
Mark Melhorn ◽  
Christopher R. Brigham
Keyword(s):  
Epidemiological Data ◽  
Case Law ◽  
Individual Case ◽  
Shoulder Injury ◽  
Work Related ◽  
Clear Cut ◽  
The Individual ◽  
Causation Analysis ◽  
Injury Causation ◽  
Relevant Factors

Abstract In most cases of shoulder injury at work, causation analysis is not clear-cut and requires detailed, thoughtful, and time-consuming causation analysis; traditionally, physicians have approached this in a cursory manner, often presenting their findings as an opinion. An established method of causation analysis using six steps is outlined in the American College of Occupational and Environmental Medicine Guidelines and in the AMA Guides to the Evaluation of Disease and Injury Causation, Second Edition, as follows: 1) collect evidence of disease; 2) collect epidemiological data; 3) collect evidence of exposure; 4) collect other relevant factors; 5) evaluate the validity of the evidence; and 6) write a report with evaluation and conclusions. Evaluators also should recognize that thresholds for causation vary by state and are based on specific statutes or case law. Three cases illustrate evidence-based causation analysis using the six steps and illustrate how examiners can form well-founded opinions about whether a given condition is work related, nonoccupational, or some combination of these. An evaluator's causal conclusions should be rational, should be consistent with the facts of the individual case and medical literature, and should cite pertinent references. The opinion should be stated “to a reasonable degree of medical probability,” on a “more-probable-than-not” basis, or using a suitable phrase that meets the legal threshold in the applicable jurisdiction.

scholarly journals Solar Irradiance Variability Due to Solar Flares Observed in Lyman-Alpha Emission

Solar Physics ◽  
2021 ◽  
Vol 296 (3) ◽  
Author(s):  
Ryan O. Milligan
Keyword(s):  
Solar Flares ◽  
Solar Spectrum ◽  
Neutral Hydrogen ◽  
Solar Limb ◽  
High Background ◽  
Superposed Epoch Analysis ◽  
Lyman Alpha ◽  
Alpha Emission ◽  
Epoch Analysis ◽  
Very High

AbstractAs the Lyman-alpha (Ly$\upalpha $ α ) line of neutral hydrogen is the brightest emission line in the solar spectrum, detecting increases in irradiance due to solar flares at this wavelength can be challenging due to the very high background. Previous studies that have focused on the largest flares have shown that even these extreme cases generate enhancements in Ly$\upalpha $ α of only a few percent above the background. In this study, a superposed-epoch analysis was performed on ≈8500 flares greater than B1 class to determine the contribution that they make to changes in the solar EUV irradiance. Using the peak of the 1 – 8 Å X-ray emission as a fiducial time, the corresponding time series of 3123 B- and 4972 C-class flares observed in Ly$\upalpha $ α emission by the EUV Sensor on the Geostationary Operational Environmental Satellite 15 (GOES-15) were averaged to reduce background fluctuations and improve the flare signal. The summation of these weaker events showed that they produced a 0.1 – 0.3% enhancement to the solar Ly$\upalpha $ α irradiance on average. For comparison, the same technique was applied to 453 M- and 31 X-class flares, which resulted in a 1 – 4% increase in Ly$\upalpha $ α emission. Flares were also averaged with respect to their heliographic angle to investigate any potential center-to-limb variation. For each GOES class, the relative enhancement in Ly$\upalpha $ α at the flare peak was found to diminish for flares that occurred closer to the solar limb due to the opacity of the line and/or foreshortening of the footpoints. One modest event included in the study, a C6.6 flare, exhibited an unusually high increase in Ly$\upalpha $ α of 7% that may have been attributed to a failed filament eruption. Increases of this magnitude have hitherto only been associated with a small number of X-class flares.

scholarly journals The Toba supervolcano eruption caused severe tropical stratospheric ozone depletion

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Sergey Osipov ◽  
Georgiy Stenchikov ◽  
Kostas Tsigaridis ◽  
Allegra N. LeGrande ◽  
Susanne E. Bauer ◽  
...  
Keyword(s):  
Ozone Depletion ◽  
Water Cycle ◽  
Stratospheric Ozone ◽  
System Model ◽  
Earth System ◽  
Sulfate Aerosols ◽  
Winter Conditions ◽  
Attenuation Mechanism ◽  
The Tropics ◽  
Sulfur Emissions

AbstractSupervolcano eruptions have occurred throughout Earth’s history and have major environmental impacts. These impacts are mostly associated with the attenuation of visible sunlight by stratospheric sulfate aerosols, which causes cooling and deceleration of the water cycle. Supereruptions have been assumed to cause so-called volcanic winters that act as primary evolutionary factors through ecosystem disruption and famine, however, winter conditions alone may not be sufficient to cause such disruption. Here we use Earth system model simulations to show that stratospheric sulfur emissions from the Toba supereruption 74,000 years ago caused severe stratospheric ozone loss through a radiation attenuation mechanism that only moderately depends on the emission magnitude. The Toba plume strongly inhibited oxygen photolysis, suppressing ozone formation in the tropics, where exceptionally depleted ozone conditions persisted for over a year. This effect, when combined with volcanic winter in the extra-tropics, can account for the impacts of supereruptions on ecosystems and humanity.

Judicial Lawmaking, Discourse Theory, and the ICTY on Belligerent Reprisals

2011 ◽  
Vol 12 (5) ◽  
pp. 1261-1278 ◽  
Author(s):  
Milan Kuhli ◽  
Klaus Günther
Keyword(s):  
International Criminal Court ◽  
International Criminal ◽  
International Criminal Tribunal ◽  
Individual Case ◽  
Criminal Court ◽  
Discourse Theory ◽  
Criminal Courts ◽  
Normative Expectations ◽  
Judicial Lawmaking ◽  
The Individual

Without presenting a full definition, it can be said that the notion of judicial lawmaking implies the idea that courts create normative expectations beyond the individual case. That is, our question is whether courts' normative declarations have an effect which is abstract and general. Our purpose here is to ask about judicial lawmaking in this sense with respect to international criminal courts and tribunals. In particular, we will focus on the International Criminal Tribunal for the Former Yugoslavia (ICTY). No other international criminal court or tribunal has issued so many judgments as the ICTY, so it seems a particularly useful focus for examining the creation of normative expectations.

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