scholarly journals Vertical structure of Antarctic tropospheric ozone depletion events: characteristics and broader implications

2010 ◽  
Vol 10 (16) ◽  
pp. 7775-7794 ◽  
Author(s):  
A. E. Jones ◽  
P. S. Anderson ◽  
E. W. Wolff ◽  
H. K. Roscoe ◽  
G. J. Marshall ◽  
...  
Keyword(s):  
High Altitude ◽  
Ozone Depletion ◽  
Tropospheric Ozone ◽  
Large Scale ◽  
Field Experiments ◽  
Strong Association ◽  
Vertical Component ◽  
Low Pressure ◽  
The Arctic ◽  
Low Pressure Systems

Abstract. The majority of tropospheric ozone depletion event (ODE) studies have focussed on time-series measurements, with comparatively few studies of the vertical component. Those that exist have almost exclusively used free-flying balloon-borne ozonesondes and almost all have been conducted in the Arctic. Here we use measurements from two separate Antarctic field experiments to examine the vertical profile of ozone during Antarctic ODEs. We use tethersonde data to probe details in the lowest few hundred meters and find considerable structure in the profiles associated with complex atmospheric layering. The profiles were all measured at wind speeds less than 7 ms−1, and on each occasion the lowest inversion height lay between 10 m and 40 m. We also use data from a free-flying ozonesonde study to select events where ozone depletion was recorded at altitudes >1 km above ground level. Using ERA-40 meteorological charts, we find that on every occasion the high altitude depletion was preceded by an atmospheric low pressure system. An examination of limited published ozonesonde data from other Antarctic stations shows this to be a consistent feature. Given the link between BrO and ODEs, we also examine ground-based and satellite BrO measurements and find a strong association between atmospheric low pressure systems and enhanced BrO that must arise in the troposphere. The results suggest that, in Antarctica, such depressions are responsible for driving high altitude ODEs and for generating the large-scale BrO clouds observed from satellites. In the Arctic, the prevailing meteorology differs from that in Antarctica, but, while a less common effect, major low pressure systems in the Arctic can also generate BrO clouds. Such depressions thus appear to be fundamental when considering the broader influence of ODEs, certainly in Antarctica, such as halogen export and the radiative influence of ozone-depleted air masses.

scholarly journals Vertical structure of Antarctic tropospheric ozone depletion events: characteristics and broader implications

2010 ◽  
Vol 10 (3) ◽  
pp. 8189-8246 ◽  
Author(s):  
A. E. Jones ◽  
P. S. Anderson ◽  
E. W. Wolff ◽  
H. K. Roscoe ◽  
G. J. Marshall ◽  
...  
Keyword(s):  
High Altitude ◽  
Ozone Depletion ◽  
Tropospheric Ozone ◽  
Large Scale ◽  
Field Experiments ◽  
Strong Association ◽  
Vertical Component ◽  
Low Pressure ◽  
The Arctic ◽  
Low Pressure Systems

Abstract. The majority of tropospheric ozone depletion event (ODE) studies have focussed on time-series measurements, with comparatively few studies of the vertical component. Those that exist have almost exclusively used free-flying balloon-borne ozonesondes and almost all have been conducted in the Arctic. Here we use measurements from two separate Antarctic field experiments to examine the vertical profile of ozone during Antarctic ODEs. We use tethersonde data to probe details in the lowest few hundred meters and find considerable structure in the profiles associated with complex atmospheric layering. The profiles were all measured at wind speeds less than 7 ms−1, and on each occasion the lowest inversion height lay between 10 m and 40 m. We also use data from a free-flying ozonesonde study to select events where ozone depletion was recorded at altitudes >1 km above ground level. Using ERA-40 meteorological charts, we find that on every occasion the high altitude depletion was preceded by an atmospheric low pressure system. An examination of limited published ozonesonde data from other Antarctic stations shows this to be a consistent feature. Given the link between BrO and ODEs, we also examine ground-based and satellite BrO measurements, and find a strong association between enhanced BrO and atmospheric low pressure systems. The results suggest that, in Antarctica, such depressions are responsible for driving high altitude ODEs and for generating the large-scale BrO clouds observed from satellites. In the Arctic, the prevailing meteorology differs from that in Antarctica, but we show that major low pressure systems in the Arctic, when they occur, can also generate BrO clouds. Such depressions thus appear to be fundamental when considering the broader influence of ODEs, particularly in Antarctica, such as halogen export and the radiative influence of ozone-depleted air masses.

scholarly journals Whole-genome sequence data suggests environmental adaptation of Ethiopian sheep populations

2021 ◽  
Author(s):  
Pamela Wiener ◽  
Christelle Robert ◽  
Abulgasim Ahbara ◽  
Mazdak Salavati ◽  
Ayele Abebe ◽  
...  
Keyword(s):  
High Altitude ◽  
Environmental Variables ◽  
Large Scale ◽  
Sequence Data ◽  
Strong Association ◽  
Environmental Adaptation ◽  
Whole Genome Sequence ◽  
Single Nucleotide Variants ◽  
High Altitude Adaptation ◽  
Altitude Adaptation

Abstract Great progress has been made over recent years in the identification of selection signatures in the genomes of livestock species. This work has primarily been carried out in commercial breeds for which the dominant selection pressures, are associated with artificial selection. As agriculture and food security are likely to be strongly affected by climate change, a better understanding of environment-imposed selection on agricultural species is warranted. Ethiopia is an ideal setting to investigate environmental adaptation in livestock due to its wide variation in geo-climatic characteristics and the extensive genetic and phenotypic variation of its livestock. Here, we identified over three million single nucleotide variants across 12 Ethiopian sheep populations and applied landscape genomics approaches to investigate the association between these variants and environmental variables. Our results suggest that environmental adaptation for precipitation-related variables is stronger than that related to altitude or temperature, consistent with large-scale meta-analyses of selection pressure across species. The set of genes showing association with environmental variables was enriched for genes highly expressed in human blood and nerve tissues. There was also evidence of enrichment for genes associated with high-altitude adaptation although no strong association was identified with hypoxia-inducible-factor (HIF) genes. One of the strongest altitude-related signals was for a collagen gene, consistent with previous studies of high-altitude adaptation. Several altitude-associated genes also showed evidence of adaptation with temperature, suggesting a relationship between responses to these environmental factors. These results provide a foundation to investigate further the effects of climatic variables on small ruminant populations.

scholarly journals Springtime daily variations in lower-tropospheric ozone over east Asia: the role of cyclonic activity and pollution as observed from space with IASI

2015 ◽  
Vol 15 (18) ◽  
pp. 10839-10856 ◽  
Author(s):  
G. Dufour ◽  
M. Eremenko ◽  
J. Cuesta ◽  
C. Doche ◽  
G. Foret ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
East Asia ◽  
Tropospheric Ozone ◽  
North China Plain ◽  
North China ◽  
Low Pressure ◽  
The North ◽  
The North China Plain ◽  
Co Observations ◽  
Low Pressure Systems

Abstract. We use satellite observations from IASI (Infrared Atmospheric Sounding Interferometer) on board the MetOp-A satellite to evaluate the springtime daily variations in lower-tropospheric ozone over east Asia. The availability of semi-independent columns of ozone from the surface up to 12 km simultaneously with CO columns provides a powerful observational data set to diagnose the processes controlling tropospheric ozone enhancement on synoptic scales. By combining IASI observations with meteorological reanalyses from ERA-Interim, we develop an analysis method based only on IASI ozone and CO observations to identify the respective roles of the stratospheric source and the photochemical source in ozone distribution and variations over east Asia. The succession of low- and high-pressure systems drives the day-to-day variations in lower-tropospheric ozone. A case study analysis of one frontal system and one cut-off low system in May 2008 shows that reversible subsiding and ascending ozone transfers in the upper-troposphere–lower-stratosphere (UTLS) region, due to the tropopause perturbations occurring in the vicinity of low-pressure systems, impact free and lower-tropospheric ozone over large regions, especially north of 40° N, and largely explain the ozone enhancement observed with IASI for these latitudes. Irreversible stratosphere–troposphere exchanges of ozone-rich air masses occur more locally in the southern and southeastern flanks of the trough. The contribution to the lower-tropospheric ozone column is difficult to dissociate from the tropopause perturbations generated by weather systems. For regions south of 40° N, a significant correlation has been found between lower-tropospheric ozone and carbon monoxide (CO) observations from IASI, especially over the North China Plain (NCP). Considering carbon monoxide observations as a pollutant tracer, the O3–CO correlation indicates that the photochemical production of ozone from primary pollutants emitted over such large polluted regions significantly contributes to the ozone enhancements observed in the lower troposphere via IASI. When low-pressure systems circulate over the NCP, stratospheric and pollution sources play a concomitant role in the ozone enhancement. IASI's 3-D observational capability allows the areas in which each source dominates to be determined. Moreover, the studied cut-off low system has enough potential convective capacity to uplift pollutants (ozone and CO) and to transport them to Japan. The increase in the enhancement ratio of ozone to CO from 0.16 on 12 May over the North China Plain to 0.28 over the Sea of Japan on 14 May indicates photochemical processing during the plume transport.

Experimental study of large-scale fire behavior under low pressure at high altitude

2013 ◽  
Vol 31 (6) ◽  
pp. 481-494 ◽  
Author(s):  
Wei Yao ◽  
Xiaokang Hu ◽  
Jianzhong Rong ◽  
Jian Wang ◽  
Hui Zhang
Keyword(s):  
Experimental Study ◽  
High Altitude ◽  
Large Scale ◽  
Fire Behavior ◽  
Low Pressure

scholarly journals Projected Changes in South Asian Monsoon Low Pressure Systems

2020 ◽  
Vol 33 (17) ◽  
pp. 7275-7287 ◽  
Author(s):  
Wenhao Dong ◽  
Yi Ming ◽  
V. Ramaswamy
Keyword(s):  
South Asian ◽  
Large Scale ◽  
Climate Model ◽  
Asian Summer Monsoon ◽  
Central India ◽  
Low Pressure ◽  
Geophysical Fluid Dynamics Laboratory ◽  
South Asian Summer Monsoon ◽  
Projected Changes ◽  
Low Pressure Systems

AbstractMonsoon low pressure systems (MLPSs) are among the most important synoptic-scale disturbances of the South Asian summer monsoon. Potential changes in their characteristics in a warmer climate would have broad societal impacts. Yet, the findings from a few existing studies are inconclusive. We use the Geophysical Fluid Dynamics Laboratory (GFDL) coupled climate model CM4.0 to examine the projected changes in the simulated MLPS activity under a future emission scenario. It is shown that CM4.0 can skillfully simulate the number, genesis location, intensity, and lifetime of MLPSs. Global warming gives rise to a significant decrease in MLPS activity. An analysis of several large-scale environmental variables, both dynamic and thermodynamic, suggests that the decrease in MLPS activity can be attributed mainly to a reduction in low-level relative vorticity over the core genesis region. The decreased vorticity is consistent with weaker large-scale ascent, which leads to less vorticity production through the stretching term in the vorticity equation. Assuming a fixed radius of influence, the projected reduction in MLPSs would significantly lower the associated precipitation over north-central India, despite an overall increase in mean precipitation.

Tropospheric Ozone Depletion Events in the Arctic Spring of 2009: Modeling and Observations

2020 ◽  
Author(s):  
Maximilian Herrmann ◽  
Holger Sihler ◽  
Ulrich Platt ◽  
Eva Gutheil
Keyword(s):  
Chemical Reactions ◽  
Ozone Depletion ◽  
Tropospheric Ozone ◽  
Vertical Direction ◽  
Arctic Region ◽  
Sea Salt ◽  
The Arctic ◽  
Parameter Study ◽  
Atmospheric Pollutant ◽  
The Arctic Region

<p>Ozone is an important atmospheric pollutant in the troposphere due to its high oxidation potential. In the Arctic troposphere, ozone mainly originates from transport and photo-chemical reactions involving nitrogen oxides and volatile organic compounds, resulting in a background mixing ratio of 30 to 50 nmol/mol. During polar spring, so-called tropospheric ozone depletion events (ODEs) are regularly observed, in which ozone mixing ratios in the boundary layer drop to almost zero levels coinciding with a surge in reactive bromine levels on the time scale of hours to days. The source of the reactive bromine is sea salt, i.e. aerosol and deposits on the ice. However, it is not fully understood how the salt bromide is oxidized and reactive bromine is released into the air. The most widely accepted emission mechanism is autocatalytic and termed “bromine explosion”. ODEs strongly change the lifetime of ozone and organic gases, they cause the removal and deposition of mercury as well as the transport of reactive bromine into the free troposphere. In order to model ODEs, the software package WRF-Chem is employed to simulate the meteorology and the emission, the transport, mixing, chemical reactions of trace gases as well as aerosols. For this purpose, the MOZART chemical reaction mechanism coupled with the MOSAIC aerosol model is extended to include bromine and chlorine chemistry. A resolution of 20 km for a 5,000 km x 5,000 km region in horizontal directions is employed, enabling the comparison of the simulation results to satellite GOME-2 BrO with a larger resolution. In vertical direction, 64 non-linear grid cells are used with a finer resolution near the ground. The simulation domain is centered north of Barrow (Utqiaġvik), Alaska and covers most of the Arctic region. The time from February 1 to May 1, 2009 is simulated. Improvements and differences to existing models include more complex bromine chemistry, the inclusion of chlorine chemistry, MOSAIC aerosols, and nudging of meteorological fields to ERA-INTERIM data.The simulations reveal that the first bromine explosions occur in early February in the Bering Sea and then extend to the Beaufort Sea in the middle of February, with further bromine explosions in the Arctic region through the end of the simulation. Simulations results are compared with the GOME-2 BrO measurements and in-situ ozone observations at Barrow (Utqiaġvik), Alaska. The comparison shows good agreement with respect to occurrence and location of ODEs. The simulations indicate that the existence and replenishment of bromine in the sea ice is necessary for the ODEs to occur throughout the observation time. Inclusion of direct release of bromine by the deposition of ozone is essential for the proper prediction of the frequent recurrence of ODEs as found through observations. The largest uncertainty in the model is the strength of the bromine deposition and emission from the ice/snow surface as well as the amount of available bromine in the sea salt, which is varied in a parameter study.</p>

Tropospheric ozone depletion in polar regions A comparison of observations in the Arctic and Antarctic

Tellus B ◽  
1998 ◽  
Vol 50 (1) ◽  
pp. 34-50 ◽  
Author(s):  
S. WESSEL ◽  
S. AOKI ◽  
P. WINKLER ◽  
R. WELLER ◽  
A. HERBER ◽  
...  
Keyword(s):  
Ozone Depletion ◽  
Tropospheric Ozone ◽  
The Arctic ◽  
Polar Regions

scholarly journals Multiscale interactions between monsoon intra-seasonal oscillations and low pressure systems that produce heavy rainfall events of different spatial extents

2021 ◽  
pp. 1-36
Author(s):  
Akshaya C Nikumbh ◽  
Arindam Chakraborty ◽  
G.S. Bhat ◽  
Dargan M. W. Frierson
Keyword(s):  
Large Scale ◽  
Thermodynamic Characteristics ◽  
Central India ◽  
Low Pressure ◽  
Monsoon Trough ◽  
The Other ◽  
Rainfall Events ◽  
Other Hand ◽  
Seasonal Oscillations ◽  
Low Pressure Systems

AbstractThe sub-seasonal and synoptic-scale variability of the Indian summer monsoon rainfall are controlled primarily by monsoon intra-seasonal oscillations (MISO) and low pressure systems (LPS), respectively. The positive and negative phases of MISO lead to alternate epochs of above-normal (active) and below-normal (break) spells of rainfall. LPSs are embedded within the different phases of MISO and are known to produce heavy precipitation events over central India. Whether the interaction with the MISO phases modulates the precipitation response of LPSs, and thereby the characteristics of extreme rainfall events (EREs) remains unaddressed in the available literature. In this study, we analyze the LPSs that produce EREs of various spatial extents viz., Small, Medium, and Large over central India from 1979 to 2012. We also compare them with the LPSs that pass through central India and do not give any ERE (LPS-noex). We find that thermodynamic characteristics of LPSs that trigger different spatial extents of EREs are similar. However, they show differences in their dynamic characteristics. The ERE producing LPSs are slower, moister and more intense than LPS-noex. The LPSs that lead to Medium and Large EREs tend to occur during the positive phase of MISO when an active monsoon trough is present over central India. On the other hand, LPS-noex and the LPSs that trigger Small EREs occur mainly during the neutral or negative phases of the MISO. The large-scale dynamic forcing, intensification of LPSs, and diabatic generation of low-level potential vorticity due to the presence of active monsoon trough help in the organization of convection and lead to Medium and Large EREs. On the other hand, the LPSs that form during the negative or neutral phases of MISO do not intensify much during their lifetime and trigger scattered convection, leading to EREs of small size.

scholarly journals Short-term variations in the13C/12C ratio of CO as a measure of Cl activation during tropospheric ozone depletion events in the Arctic

1999 ◽  
Vol 104 (D1) ◽  
pp. 1691-1697 ◽  
Author(s):  
Thomas Röckmann ◽  
Carl A. M. Brenninkmeijer ◽  
Paul J. Crutzen ◽  
Ulrich Platt
Keyword(s):  
Ozone Depletion ◽  
Tropospheric Ozone ◽  
The Arctic ◽  
Short Term
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