| 1. |
- Sallee, J. B., et al.
(author)
-
Southern ocean carbon and heat impact on climate
- 2023
-
In: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. - 1364-503X .- 1471-2962. ; 381:2249
-
Journal article (peer-reviewed)abstract
- The Southern Ocean greatly contributes to the regulation of the global climate by controlling important heat and carbon exchanges between the atmosphere and the ocean. Rates of climate change on decadal timescales are therefore impacted by oceanic processes taking place in the Southern Ocean, yet too little is known about these processes. Limitations come both from the lack of observations in this extreme environment and its inherent sensitivity to intermittent processes at scales that are not well captured in current Earth system models. The Southern Ocean Carbon and Heat Impact on Climate programme was launched to address this knowledge gap, with the overall objective to understand and quantify variability of heat and carbon budgets in the Southern Ocean through an investigation of the key physical processes controlling exchanges between the atmosphere, ocean and sea ice using a combination of observational and modelling approaches. Here, we provide a brief overview of the programme, as well as a summary of some of the scientific progress achieved during its first half. Advances range from new evidence of the importance of specific processes in Southern Ocean ventilation rate (e.g. storm-induced turbulence, sea-ice meltwater fronts, wind-induced gyre circulation, dense shelf water formation and abyssal mixing) to refined descriptions of the physical changes currently ongoing in the Southern Ocean and of their link with global climate.This article is part of a discussion meeting issue 'Heat and carbon uptake in the Southern Ocean: the state of the art and future priorities'.
|
|
| 2. |
|
|
| 3. |
- Smith, Madison M., et al.
(author)
-
Thin and transient meltwater layers and false bottoms in the Arctic sea ice pack—Recent insights on these historically overlooked features
- 2023
-
In: Elementa: Science of the Anthropocene. - 2325-1026. ; 11:1
-
Research review (peer-reviewed)abstract
- The rapid melt of snow and sea ice during the Arctic summer provides a significant source of low-salinity meltwater to the surface ocean on the local scale. The accumulation of this meltwater on, under, and around sea ice floes can result in relatively thin meltwater layers in the upper ocean. Due to the small-scale nature of these upper-ocean features, typically on the order of 1 m thick or less, they are rarely detected by standard methods, but are nevertheless pervasive and critically important in Arctic summer. Observations during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in summer 2020 focused on the evolution of such layers and made significant advancements in understanding their role in the coupled Arctic system. Here we provide a review of thin meltwater layers in the Arctic, with emphasis on the new findings from MOSAiC. Both prior and recent observational datasets indicate an intermittent yet longlasting (weeks to months) meltwater layer in the upper ocean on the order of 0.1 m to 1.0 m in thickness, with a large spatial range. The presence of meltwater layers impacts the physical system by reducing bottom ice melt and allowing new ice formation via false bottom growth. Collectively, the meltwater layer and false bottoms reduce atmosphere-ocean exchanges of momentum, energy, and material.The impacts on the coupled Arctic system are far-reaching, including acting as a barrier for nutrient and gas exchange and impacting ecosystem diversity and productivity.
|
|
| 4. |
- Droste, E. S., et al.
(author)
-
The influence of tides on the marine carbonate chemistry of a coastal polynya in the south-eastern Weddell Sea
- 2022
-
In: Ocean Science. - : Copernicus GmbH. - 1812-0784 .- 1812-0792. ; 18:5, s. 1293-1320
-
Journal article (peer-reviewed)abstract
- Tides significantly affect polar coastlines by modulating ice shelf melt and modifying shelf water properties through transport and mixing. However, the effect of tides on the marine carbonate chemistry in such regions, especially around Antarctica, remains largely unexplored. We address this topic with two case studies in a coastal polynya in the south-eastern Weddell Sea, neighbouring the Ekstrom Ice Shelf. The case studies were conducted in January 2015 (PS89) and January 2019 (PS117), capturing semi-diurnal oscillations in the water column. These are pronounced in both physical and biogeochemical variables for PS89. During rising tide, advection of sea ice meltwater from the north-east created a fresher, warmer, and more deeply mixed water column with lower dissolved inorganic carbon (DIC) and total alkalinity (TA) content. During ebbing tide, water from underneath the ice shelf decreased the polynya's temperature, increased the DIC and TA content, and created a more stratified water column. The variability during the PS117 case study was much smaller, as it had less sea ice meltwater input during rising tide and was better mixed with sub-ice shelf water. The contrasts in the variability between the two case studies could be wind and sea ice driven, and they underline the complexity and highly dynamic nature of the system. The variability in the polynya induced by the tides results in an air-sea CO2 flux that can range between a strong sink (-24 mmol m(-2) d(-1)) and a small source (3 mmol m(-2) d(-1)) on a semi-diurnal timescale. If the variability induced by tides is not taken into account, there is a potential risk of overestimating the polynya's CO2 uptake by 67 % or underestimating it by 73 %, compared to the average flux determined over several days. Depending on the timing of limited sampling, the polynya may appear to be a source or a sink of CO2. Given the disproportionate influence of polynyas on heat and carbon exchange in polar oceans, we recommend future studies around the Antarctic and Arctic coastlines to consider the timing of tidal currents in their sampling strategies and analyses. This will help constrain variability in oceanographic measurements and avoid potential biases in our understanding of these highly complex systems.
|
|
| 5. |
- Kadykalo, A. N., et al.
(author)
-
Disentangling ‘ecosystem services’ and ‘nature’s contributions to people’
- 2019
-
In: Ecosystems and People. - : Informa UK Limited. - 2639-5908 .- 2639-5916. ; 15:1, s. 269-287
-
Journal article (peer-reviewed)abstract
- People depend on functioning ecosystems, which provide benefits that support human existence and wellbeing. The relationship between people and nature has been experienced and conceptualized in multiple ways. Recently, ecosystem services (ES) concepts have permeated science, government policies, multi-national environmental agreements, and science–policy interfaces. In 2017, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) introduced a new and closely related concept–Nature’s Contributions to People (NCP). The introduction of NCP has sparked some lively discussion and confusion about the distinguishing characteristics between ES and NCP. In order to clarify their conceptual relation, we identify eleven specific claims about novel elements from the latest NCP literature and analyze how far ES research has already contributed to these corresponding conceptual claims in the existing ES literature. We find a mixed-picture, where on six specific conceptual claims (culture, social sciences and humanities, indigenous and local knowledge, negative contributions of nature, generalizing perspective, non-instrumental values and valuation) NCP does not differ greatly from past ES research, but we also find five conceptual claims (diverse worldviews, context-specific perspective, relational values, fuzzy and fluid reporting categories and groups, inclusive language and framing) where NCP provides novel conceptualizations of people and nature relations.
|
|
| 6. |
- Lieder, E O, et al.
(author)
-
Investigation of lifetimes in quadrupole bands of Gd-142
- 2008
-
In: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 35:2, s. 135-158
-
Journal article (peer-reviewed)abstract
- For a level scheme investigation of Gd-142 an experiment with the gamma -spectrometer EUROBALLIII has been carried out and lifetimes have been measured with EUROBALL IV using the Doppler-shift attenuation method. The high-spin states have been populated in these experiments by means of the(99)Ru(Ti-48, 2p3n) reaction at a beam energy of 240MeV and the Sn-114(S-32, 2p2n) reaction at 160MeV, respectively. Reduced E2 transition probabilities B(E2) were determined for 15 members of four quadrupole bands. For the interpretation of the positive-parity even-spin quadrupole bands, calculations in the cranked Nilsson-Strutinsky as well as interacting boson models have been performed. From the former calculations it was concluded that the high-spin states of the (+ , 0)(1) band in Gd-142 represent a triaxial nucleus rotating around the longest principal axis.
|
|
| 7. |
- Krause, M. S., et al.
(author)
-
Survey data on voluntary nature conservation commitments of German businesses and their perceptions towards conservation credits
- 2020
-
In: Data in Brief. - : Elsevier BV. - 2352-3409. ; 33
-
Journal article (peer-reviewed)abstract
- To preserve biodiversity and ecosystem services, company engagement is crucial. However, available data on manager views and perceptions regarding nature conservation in particular is rare. The presented survey data gives insights into current levels and forms of business commitments for nature conservation. The data contributes to understanding business attitudes towards voluntary conservation action and includes information about factors that influence their engagement. Moreover, the data informs about manager perceptions towards the concept of nature conservation credits and, as such, allows for an evaluation of a certified biodiversity and ecosystem services market. Importantly, the dataset contains essential company characteristics to put responses into greater context. The scope of the survey is limited to German companies from secondary and tertiary sectors. Companies were sampled through proportional stratified random sampling based on size and location. The data was collected through a self-administered online-survey, conducted in 2019. The database comprises responses of 747 companies that logged into the online system. The survey data were in part analysed through structural equation modelling for an investigation of factors that drive voluntary conservation commitments [1]. Related to this analysis, a subset of 618 companies is available that provided sufficiently completed questionnaires. Both datasets, i.e. the raw data as well as the first subset used for analysis, are hosted in the public repository Open Research Data of the Leibniz Centre for Agricultural Landscape Research (ZALF), Germany. The repository also stores all coding information as well as the questionnaire: https://www.doi.org/10.4228/ZALF.DK.149. The dataset can be used, for example, by researchers from the field of environmental business management and strategy.
|
|
| 8. |
- Droste, S., et al.
(author)
-
Finite-frequency noise in a quantum dot with normal and superconducting leads
- 2015
-
In: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 91:12, s. Art. no. 125401-
-
Journal article (peer-reviewed)abstract
- We consider a single-level quantum dot tunnel-coupled to one normal and one superconducting lead. We employ a diagrammatic real-time approach to calculate the finite-frequency current noise for subgap transport. The noise spectrum gives direct access to the internal dynamics of the dot. In particular, the noise spectrum shows sharp dips at the frequency of the coherent oscillations of Cooper pairs between the dot and the superconductor. This feature is most pronounced when the superconducting correlation is maximal. Furthermore, in the quantum-noise regime, omega > k(B)T, mu(N), the noise spectrum exhibits steps at frequencies equal to the Andreev addition energies. The height of these steps is related to the effective coupling strength of the excitations. The finite-frequency noise spectrum hence provides a full spectroscopy of the system.
|
|
