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Title |
Detecting Regime Transitions of the Nocturnal and Polar Near-Surface Temperature Inversion |
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Journal |
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Year |
2020 |
Publication |
Journal of the atmospheric sciences |
Abbreviated Journal |
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Volume |
77 |
Issue |
8 |
Pages |
2921-2940 |
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Abstract |
Abstract Many natural systems undergo critical transitions, i.e., sudden shifts from one dynamical regime to another. In the climate system, the atmospheric boundary layer can experience sudden transitions between fully turbulent states and quiescent, quasi-laminar states. Such rapid transitions are observed in polar regions or at night when the atmospheric boundary layer is stably stratified, and they have important consequences in the strength of mixing with the higher levels of the atmosphere. To analyze the stable boundary layer, many approaches rely on the identification of regimes that are commonly denoted as weakly and very stable regimes. Detecting transitions between the regimes is crucial for modeling purposes. In this work a combination of methods from dynamical systems and statistical modeling is applied to study these regime transitions and to develop an early warning signal that can be applied to nonstationary field data. The presented metric aims to detect nearing transitions by statistically quantifying the deviation from the dynamics expected when the system is close to a stable equilibrium. An idealized stochastic model of near-surface inversions is used to evaluate the potential of the metric as an indicator of regime transitions. In this stochastic system, small-scale perturbations can be amplified due to the nonlinearity, resulting in transitions between two possible equilibria of the temperature inversion. The simulations show such noise-induced regime transitions, successfully identified by the indicator. The indicator is further applied to time series data from nocturnal and polar meteorological measurements. |
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1013 |
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0022-4928, 1520-0469 |
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yes |
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8151 |
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Title |
The Year of Polar Prediction in the Southern Hemisphere (YOPP-SH) |
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Journal |
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Year |
2020 |
Publication |
Bulletin of the american meteorological society |
Abbreviated Journal |
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Volume |
101 |
Issue |
10 |
Pages |
E1653-E1676 |
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1013 |
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0003-0007, 1520-0477 |
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yes |
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8150 |
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Title |
Oxygen isotope mass balance of atmospheric nitrate at Dome C, East Antarctica, during the OPALE campaign |
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Journal |
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Year |
2016 |
Publication |
Atmospheric Chemistry and Physics |
Abbreviated Journal |
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Volume |
16 |
Issue |
4 |
Pages |
2659-2673 |
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1011,1149 |
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Bachelor's thesis |
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1680-7316 |
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yes |
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Serial |
8149 |
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Author |
Q. Libois, G. Picard, J. L. France, L. Arnaud, M. Dumont, C. M. Carmagnola, M. D. King |
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Title |
Influence of grain shape on light penetration in snow |
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Journal |
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Year |
2013 |
Publication |
The Cryosphere |
Abbreviated Journal |
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Volume |
7 |
Issue |
6 |
Pages |
1803-1818 |
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1011,1013 |
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Bachelor's thesis |
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ISSN |
1994-0416 |
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Approved |
yes |
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Call Number |
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Serial |
8148 |
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Author |
E. Gautier, J. Savarino, J. Erbland, A. Lanciki, P. Possenti |
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Title |
Variability of sulfate signal in ice core records based on five replicate cores |
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Journal |
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Year |
2016 |
Publication |
Climate of the Past |
Abbreviated Journal |
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Volume |
12 |
Issue |
1 |
Pages |
103-113 |
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Abstract |
Abstract. Current Volcanic Reconstructions Based On Ice Core Analysis Have Significantly Improved Over The Past Few Decades By Incorporating Multiple-core Analyses With A High Temporal Resolution From Different Parts Of The Polar Regions Into A Composite Common Volcanic Eruption Record. Regional Patterns Of Volcanic Deposition Are Based On Composite Records, Built From Cores Taken At Both Poles. However, In Many Cases Only A Single Record At A Given Site Is Used For These Reconstructions. This Assumes That Transport And Regional Meteorological Patterns Are The Only Source Of The Dispersion Of The Volcanic Products. Here We Evaluate The Local-scale Variability Of A Sulfate Profile In A Low-accumulation Site (Dome C, Antarctica), In Order To Assess The Representativeness Of One Core For Such A Reconstruction. We Evaluate The Variability With Depth, Statistical Occurrence, And Sulfate Flux Deposition Variability Of Volcanic Eruptions Detected In Five Ice Cores, Drilled 1 M Apart From Each Other. Local-scale Variability, Essentially Attributed To Snow Drift And Surface Roughness At Dome C, Can Lead To A Non-exhaustive Record Of Volcanic Events When A Single Core Is Used As The Site Reference, With A Bulk Probability Of 30 % Of Missing Volcanic Events And Close To 65 % Uncertainty On One Volcanic Flux Measurement (Based On The Standard Deviation Obtained From A Five-core Comparison). Averaging N Records Reduces The Uncertainty Of The Deposited Flux Mean Significantly (By A Factor 1? ? N); In The Case Of Five Cores, The Uncertainty Of The Mean Flux Can Therefore Be Reduced To 29 %. |
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1011 |
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ISSN |
1814-9324 |
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yes |
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Call Number |
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Serial |
8147 |
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Author |
T. A. Berhanu, J. Savarino, J. Erbland, W. C. Vicars, S. Preunkert, J. F. Martins, M. S. Johnson |
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Title |
Isotopic effects of nitrate photochemistry in snow: a field study at Dome C, Antarctica |
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Journal |
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Year |
2015 |
Publication |
Atmospheric Chemistry and Physics |
Abbreviated Journal |
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Volume |
15 |
Issue |
19 |
Pages |
11243-11256 |
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Abstract |
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Programme |
1011 |
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ISSN |
1680-7316 |
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yes |
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Call Number |
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Serial |
8146 |
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Title |
Contribution of sea ice organic matter in the diet of Antarctic fishes: a diatom-specific highly branched isoprenoid approach |
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Journal |
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Year |
2014 |
Publication |
Polar Biology |
Abbreviated Journal |
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Volume |
37 |
Issue |
7 |
Pages |
903-910 |
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Keywords |
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Programme |
1010 |
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ISSN |
1432-2056 |
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yes |
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Serial |
8145 |
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Title |
Autoxidative and photooxidative reactivity of highly branched isoprenoid (HBI) alkenes |
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Journal |
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Year |
2014 |
Publication |
Lipids |
Abbreviated Journal |
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Volume |
49 |
Issue |
5 |
Pages |
481-494 |
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Abstract |
Autoxidation of several mono-, di-, tri- and tetra-unsaturated highly branched isoprenoid (HBI) alkenes was induced in organic solvents using a radical initiator and enhancer, and their degradation rates were compared to those of classical phytoplanktonic lipids (mono-unsaturated fatty acids, sterols and chlorophyll phytyl side-chain). Autoxidation of two HBI trienes was also investigated in senescent and highly photodegraded diatom cells, collected in the Antarctic, using Fe2+ ions as radical inducers. Autoxidation rates of HBI alkenes were found to increase with the number of tri-substituted double bonds, as expected. Further, HBI trienes possessing one bis-allylic position (where hydrogen abstraction is highly favoured) were found to be particularly reactive towards autoxidation and degraded at similar rates compared to polyunsaturated fatty acids in diatom cells. By comparison of the autoxidation products of the most reactive tri-unsaturated HBI with the corresponding photooxidation products, some specific tracers of these two types of abiotic degradation processes were identified. The lack of reactivity of the mono-unsaturated HBI IP25 and a structurally similar di-unsaturated HBI towards autoxidative degradation supports the good preservation of these biomarkers in marine sediments. |
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1010 |
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yes |
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8144 |
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Title |
Trace elements in Antarctic fish species and the influence of foraging habitats and dietary habits on mercury levels |
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Year |
2015 |
Publication |
Science of The Total Environment |
Abbreviated Journal |
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Volume |
538 |
Issue |
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Pages |
743-749 |
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Keywords |
Heavy metals Nototheniidae Southern Ocean Stable isotopes |
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Abstract |
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1010 |
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ISSN |
0048-9697 |
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yes |
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8143 |
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Title |
High turnover rates indicated by changes in the fixed N forms and their stable isotopes in Antarctic landfast sea ice |
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Year |
2015 |
Publication |
Journal of Geophysical Research: Oceans |
Abbreviated Journal |
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Volume |
120 |
Issue |
4 |
Pages |
3079-3097 |
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Keywords |
Antarctic isotopes nitrogen nutrients sea ice |
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Abstract |
We report concentration and nitrogen and oxygen isotopic measurements of nitrate, total dissolved nitrogen, and particulate nitrogen from Antarctic landfast sea ice, covering almost the complete seasonal cycle of sea ice growth and decay (from April to November). When sea ice forms in autumn, ice algae growth depletes nitrate and accumulates organic N within the ice. Subsequent low biological activity in winter imposes minor variations in the partitioning of fixed N. In early spring, the coupling between nitrate assimilation and brine convection at the sea ice bottom traps a large amount of fixed N within sea ice, up to 20 times higher than in the underlying seawater. At this time, remineralization and nitrification also accelerate, yielding nitrate concentrations up to 5 times higher than in seawater. Nitrate ?15N and ?18O are both elevated, indicating a near-balance between nitrification and nitrate assimilation. These findings require high microbially mediated turnover rates for the large fixed N pools, including nitrate. When sea ice warms in the spring, ice algae grow through the full thickness of the ice. The warming stratifies the brine network, which limits the exchange with seawater, causing the once-elevated nitrate pool to be nearly completely depleted. The nitrate isotope data point to light limitation at the base of landfast ice as a central characteristic of the environment, affecting its N cycling (e.g., allowing for nitrification) and impacting algal physiology (e.g., as reflected in the N and O isotope effects of nitrate assimilation). |
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1010 |
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ISSN |
2169-9291 |
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yes |
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Call Number |
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Serial |
8142 |
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