scholarly journals On the relationship between total ozone and atmospheric dynamics and chemistry at mid-latitudes – Part 1: Statistical models and spatial fingerprints of atmospheric dynamics and chemistry

2013 ◽  
Vol 13 (1) ◽  
pp. 147-164 ◽  
Author(s):  
L. Frossard ◽  
H. E. Rieder ◽  
M. Ribatet ◽  
J. Staehelin ◽  
J. A. Maeder ◽  
...  
Keyword(s):  
North Atlantic ◽  
Statistical Models ◽  
Grid Cell ◽  
Atmospheric Dynamics ◽  
Total Column Ozone ◽  
The North ◽  
The North Atlantic ◽  
Column Ozone ◽  
The Antarctic ◽  
Total Column

Abstract. We use statistical models for mean and extreme values of total column ozone to analyze "fingerprints" of atmospheric dynamics and chemistry on long-term ozone changes at northern and southern mid-latitudes on grid cell basis. At each grid cell, the r-largest order statistics method is used for the analysis of extreme events in low and high total ozone (termed ELOs and EHOs, respectively), and an autoregressive moving average (ARMA) model is used for the corresponding mean value analysis. In order to describe the dynamical and chemical state of the atmosphere, the statistical models include important atmospheric covariates: the solar cycle, the Quasi-Biennial Oscillation (QBO), ozone depleting substances (ODS) in terms of equivalent effective stratospheric chlorine (EESC), the North Atlantic Oscillation (NAO), the Antarctic Oscillation (AAO), the El Niño/Southern Oscillation (ENSO), and aerosol load after the volcanic eruptions of El Chichón and Mt. Pinatubo. The influence of the individual covariates on mean and extreme levels in total column ozone is derived on a grid cell basis. The results show that "fingerprints", i.e., significant influence, of dynamical and chemical features are captured in both the "bulk" and the tails of the statistical distribution of ozone, respectively described by mean values and EHOs/ELOs. While results for the solar cycle, QBO, and EESC are in good agreement with findings of earlier studies, unprecedented spatial fingerprints are retrieved for the dynamical covariates. Column ozone is enhanced over Labrador/Greenland, the North Atlantic sector and over the Norwegian Sea, but is reduced over Europe, Russia and the Eastern United States during the positive NAO phase, and vice-versa during the negative phase. The NAO's southern counterpart, the AAO, strongly influences column ozone at lower southern mid-latitudes, including the southern parts of South America and the Antarctic Peninsula, and the central southern mid-latitudes. Results for both NAO and AAO confirm the importance of atmospheric dynamics for ozone variability and changes from local/regional to global scales.

scholarly journals The Wave Geometry of Final Stratospheric Warming Events

2021 ◽  
Author(s):  
Amy H. Butler ◽  
Daniela I. V. Domeisen
Keyword(s):  
North Atlantic ◽  
Polar Vortex ◽  
Stratospheric Warming ◽  
Stratospheric Polar Vortex ◽  
Total Column Ozone ◽  
Planetary Scale ◽  
The North ◽  
Downward Influence ◽  
Column Ozone ◽  
Total Column

Abstract. Every spring, the stratospheric polar vortex transitions from its westerly wintertime state to its easterly summertime state due to seasonal changes in incoming solar radiation, an event known as the final stratospheric warming (FSW). While FSWs tend to be less abrupt than reversals of the boreal polar vortex in midwinter, known as sudden stratospheric warming (SSW) events, their timing and characteristics can be significantly modulated by atmospheric planetary-scale waves. Just like SSWs, FSWs have been found to have predictable surface impacts. While SSWs are commonly classified according to their wave geometry, either by how the vortex evolves (whether the vortex displaces off the pole or splits into two vortices) or by the dominant wavenumber of the vortex just prior to the SSW (wave-1 versus wave-2), little is known about the wave geometry of FSW events. We here show that FSW events for both hemispheres in most cases exhibit a clear wave geometry. Most FSWs can be classified into wave-1 or wave-2 events, but wave-3 also plays a significant role in both hemispheres. Additionally, we find that in the Northern Hemisphere, wave-2 events are more likely to occur later in the spring, while in the Southern Hemisphere, wave-1 or wave-2 events show no clear preference in timing. The FSW enhances total column ozone over the pole of both hemispheres during spring, but the spatial distribution of ozone anomalies can be influenced by the wave geometry and the timing of the event. We also describe the stratosphere's downward influence on surface weather following wave-1 and wave-2 FSW events. Significant differences between the tropospheric response to wave-1 and wave-2 FSW events occur over North America and over the Southern Ocean, while no significant differences are found over the North Atlantic region, Europe, and Antarctica.

scholarly journals On the relationship between total ozone and atmospheric dynamics and chemistry at mid-latitudes – Part 1: Statistical models and spatial fingerprints of atmospheric dynamics and chemistry

2012 ◽  
Vol 12 (5) ◽  
pp. 13161-13199 ◽  
Author(s):  
L. Frossard ◽  
H. E. Rieder ◽  
M. Ribatet ◽  
J. Staehelin ◽  
J. A. Maeder ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Statistical Models ◽  
Total Ozone ◽  
Volcanic Eruptions ◽  
Atmospheric Dynamics ◽  
Quasi Biennial Oscillation ◽  
Total Column Ozone ◽  
Value Analysis ◽  
Column Ozone ◽  
Total Column

Abstract. We use models for mean and extreme values of total column ozone on spatial scales to analyze "fingerprints" of atmospheric dynamics and chemistry on long-term ozone changes at northern and southern mid-latitudes. The r-largest order statistics method is used for pointwise analysis of extreme events in low and high total ozone (termed ELOs and EHOs, respectively). For the corresponding mean value analysis a pointwise autoregressive moving average model (ARMA) is used. The statistical models include important atmospheric covariates to describe the dynamical and chemical state of the atmosphere: the solar cycle, the Quasi-Biennial Oscillation (QBO), ozone depleting substances (ODS) in terms of equivalent effective stratospheric chlorine (EESC), the North Atlantic Oscillation (NAO), the Antarctic Oscillation (AAO), the El~Niño/Southern Oscillation (ENSO), and aerosol load after the volcanic eruptions of El Chichón and Mt. Pinatubo. The influence of the individual covariates on mean and extreme levels in total column ozone is derived on a grid cell basis. The results show that "fingerprints", i.e., significant influence, of dynamical and chemical features are captured in both the "bulk" and the tails of the ozone distribution, respectively described by means and EHOs/ELOs. While results for the solar cycle, QBO and EESC are in good agreement with findings of earlier studies, unprecedented spatial fingerprints are retrieved for the dynamical covariates.

The wave geometry of final stratospheric warming events

2021 ◽  
Author(s):  
Amy H. Butler ◽  
Daniela I.V. Domeisen
Keyword(s):  
North Atlantic ◽  
Polar Vortex ◽  
Stratospheric Warming ◽  
Stratospheric Polar Vortex ◽  
Total Column Ozone ◽  
Planetary Scale ◽  
The North ◽  
Downward Influence ◽  
Column Ozone ◽  
Total Column

<p>Every spring, the stratospheric polar vortex transitions from its westerly wintertime state to its easterly summertime state due to seasonal changes in incoming solar radiation, an event known as the "final stratospheric warming" (FSW). While FSWs tend to be less abrupt than reversals of the boreal polar vortex in midwinter, known as sudden stratospheric warming (SSW) events, their timing and characteristics can be significantly modulated by atmospheric planetary-scale waves. Just like SSWs, FSWs have been found to have predictable surface impacts. While SSWs are commonly classified according to their wave geometry, either by how the vortex evolves (whether the vortex displaces off the pole or splits into two vortices) or by the dominant wavenumber of the vortex just prior to the SSW (wave-1 versus wave-2), little is known about the wave geometry of FSW events. We here show that FSW events for both hemispheres in most cases exhibit a clear wave geometry. Most FSWs can be classified into wave-1 or wave-2 events, but wave-3 also plays a significant role in both hemispheres. Additionally, we find that in the Northern Hemisphere, wave-2 events are more likely to occur later in the spring, while in the Southern Hemisphere, wave-1 or wave-2 events show no clear preference in timing. The FSW enhances total column ozone over the pole of both hemispheres during spring, but the spatial distribution of ozone anomalies can be influenced by the wave geometry and the timing of the event. We also describe the stratosphere's downward influence on surface weather following wave-1 and wave-2 FSW events. Significant differences between the tropospheric response to wave-1 and wave-2 FSW events occur over North America and over the Southern Ocean, while no significant differences are found over the North Atlantic region, Europe, and Antarctica. </p>

The Role of Oscillating Southern Hemisphere Westerly Winds: Global Ocean Circulation

2020 ◽  
Vol 33 (6) ◽  
pp. 2111-2130
Author(s):  
Woo Geun Cheon ◽  
Jong-Seong Kug
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
North Pacific ◽  
Global Ocean ◽  
The North ◽  
Westerly Winds ◽  
The North Atlantic ◽  
Global Ocean Circulation ◽  
The Antarctic ◽  
The North Pacific

AbstractIn the framework of a sea ice–ocean general circulation model coupled to an energy balance atmospheric model, an intensity oscillation of Southern Hemisphere (SH) westerly winds affects the global ocean circulation via not only the buoyancy-driven teleconnection (BDT) mode but also the Ekman-driven teleconnection (EDT) mode. The BDT mode is activated by the SH air–sea ice–ocean interactions such as polynyas and oceanic convection. The ensuing variation in the Antarctic meridional overturning circulation (MOC) that is indicative of the Antarctic Bottom Water (AABW) formation exerts a significant influence on the abyssal circulation of the globe, particularly the Pacific. This controls the bipolar seesaw balance between deep and bottom waters at the equator. The EDT mode controlled by northward Ekman transport under the oscillating SH westerly winds generates a signal that propagates northward along the upper ocean and passes through the equator. The variation in the western boundary current (WBC) is much stronger in the North Atlantic than in the North Pacific, which appears to be associated with the relatively strong and persistent Mindanao Current (i.e., the southward flowing WBC of the North Pacific tropical gyre). The North Atlantic Deep Water (NADW) formation is controlled by salt advected northward by the North Atlantic WBC.

Climate Response to External Sources of Freshwater: North Atlantic versus the Southern Ocean

2007 ◽  
Vol 20 (3) ◽  
pp. 436-448 ◽  
Author(s):  
Ronald J. Stouffer ◽  
Dan Seidov ◽  
Bernd J. Haupt
Keyword(s):  
Southern Ocean ◽  
Southern Hemisphere ◽  
North Atlantic ◽  
Surface Waters ◽  
Real World ◽  
The Other ◽  
Sea Surface ◽  
The North ◽  
The North Atlantic ◽  
The Antarctic

Abstract The response of an atmosphere–ocean general circulation model (AOGCM) to perturbations of freshwater fluxes across the sea surface in the North Atlantic and Southern Ocean is investigated. The purpose of this study is to investigate aspects of the so-called bipolar seesaw where one hemisphere warms and the other cools and vice versa due to changes in the ocean meridional overturning. The experimental design is idealized where 1 Sv (1 Sv ≡ 106 m3 s−1) of freshwater is added to the ocean surface for 100 model years and then removed. In one case, the freshwater perturbation is located in the Atlantic Ocean from 50° to 70°N. In the second case, it is located south of 60°S in the Southern Ocean. In the case where the North Atlantic surface waters are freshened, the Atlantic thermohaline circulation (THC) and associated northward oceanic heat transport weaken. In the Antarctic surface freshening case, the Atlantic THC is mainly unchanged with a slight weakening toward the end of the integration. This weakening is associated with the spreading of the fresh sea surface anomaly from the Southern Ocean into the rest of the World Ocean. There are two mechanisms that may be responsible for such weakening of the Atlantic THC. First is that the sea surface salinity (SSS) contrast between the North Atlantic and North Pacific is reduced. And, second, when freshwater from the Southern Ocean reaches the high latitudes of the North Atlantic Ocean, it hinders the sinking of the surface waters, leading to the weakening of the THC. The spreading of the fresh SSS anomaly from the Southern Ocean into the surface waters worldwide was not seen in earlier experiments. Given the geography and climatology of the Southern Hemisphere where the climatological surface winds push the surface waters northward away from the Antarctic continent, it seems likely that the spreading of the fresh surface water anomaly could occur in the real world. A remarkable symmetry between the two freshwater perturbation experiments in the surface air temperature (SAT) response can be seen. In both cases, the hemisphere with the freshwater perturbation cools, while the opposite hemisphere warms slightly. In the zonally averaged SAT figures, both the magnitude and the pattern of the anomalies look similar between the two cases. The oceanic response, on the other hand, is very different for the two freshwater cases, as noted above for the spreading of the SSS anomaly and the associated THC response. If the differences between the atmospheric and oceanic responses apply to the real world, then the interpretation of paleodata may need to be revisited. To arrive at a correct interpretation, it matters whether or not the evidence is mainly of atmospheric or oceanic origin. Also, given the sensitivity of the results to the exact details of the freshwater perturbation locations, especially in the Southern Hemisphere, a more realistic scenario must be constructed to explore these questions.

Remarks on the deep-sea genus Pseudolamprops (Cumacea: Lampropidae)

Zootaxa ◽  
2012 ◽  
Vol 3542 (1) ◽  
pp. 69 ◽  
Author(s):  
DANIEL ROCCATAGLIATA ◽  
UTE MÜHLENHARDT-SIEGEL
Keyword(s):  
Adult Female ◽  
North Atlantic ◽  
Deep Sea ◽  
New Records ◽  
New Combination ◽  
The North ◽  
New Material ◽  
The North Atlantic ◽  
The Antarctic ◽  
First Time

Based on two specimens collected in the Antarctic deep-sea (4928 m) the adult female and male of the genusPseudolamprops Gamô, 1989 are described for the first time. A new combination is proposed, Pseudolamprops profundus(Reyss, 1978) comb. nov., and several new records from the North Atlantic and Antarctica are provided. The diagnosis of Pseudolamprops is revised on the account of the new material available.

scholarly journals Antarctic ozone depletion between 1960 and 1980 in observations and chemistry–climate model simulations

2016 ◽  
Vol 16 (24) ◽  
pp. 15619-15627 ◽  
Author(s):  
Ulrike Langematz ◽  
Franziska Schmidt ◽  
Markus Kunze ◽  
Gregory E. Bodeker ◽  
Peter Braesicke
Keyword(s):  
Ozone Depletion ◽  
Climate Model ◽  
Total Column Ozone ◽  
Antarctic Ozone ◽  
Climate Model Simulations ◽  
Ozone Depleting Substances ◽  
Column Ozone ◽  
The Antarctic ◽  
Total Column

Abstract. The year 1980 has often been used as a benchmark for the return of Antarctic ozone to conditions assumed to be unaffected by emissions of ozone-depleting substances (ODSs), implying that anthropogenic ozone depletion in Antarctica started around 1980. Here, the extent of anthropogenically driven Antarctic ozone depletion prior to 1980 is examined using output from transient chemistry–climate model (CCM) simulations from 1960 to 2000 with prescribed changes of ozone-depleting substance concentrations in conjunction with observations. A regression model is used to attribute CCM modelled and observed changes in Antarctic total column ozone to halogen-driven chemistry prior to 1980. Wintertime Antarctic ozone is strongly affected by dynamical processes that vary in amplitude from year to year and from model to model. However, when the dynamical and chemical impacts on ozone are separated, all models consistently show a long-term, halogen-induced negative trend in Antarctic ozone from 1960 to 1980. The anthropogenically driven ozone loss from 1960 to 1980 ranges between 26.4 ± 3.4 and 49.8 ± 6.2 % of the total anthropogenic ozone depletion from 1960 to 2000. An even stronger ozone decline of 56.4 ± 6.8 % was estimated from ozone observations. This analysis of the observations and simulations from 17 CCMs clarifies that while the return of Antarctic ozone to 1980 values remains a valid milestone, achieving that milestone is not indicative of full recovery of the Antarctic ozone layer from the effects of ODSs.

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