Ice-ocean interactions at Riiser-Larsen Ice Shelf assessed by unveiling of seabed beneath it

The Riiser-Larsen ice shelf is the fourth largest ice shelf on Earth. The detailed depth and shape of the seabed beneath the ice shelf is entirely unknown. Since bed topography beneath ice shelves generally poses the controlling factor of heat exchange between the open ocean and water cavities, this unknown factor inhibits proper assessment of ice-ocean interactions. In coastal Dronning Maud Land, the intrusion of Warm Deep Water – a warm intermediate water mass transported by the Weddell Gyre – into the ice shelf cavities is strongly dependent on seabed depth. We are addressing this shortcoming by generating a bathymetric model beneath the ice shelf based on the inversion of gravity data and complementary data sets of magnetic and ice penetrating radar data, all acquired during the joint AWI-BGR airborne campaign ‘RIISERBATHY’ in 2022/23. The resulting model will have a resolution of 5 to 10 km and is complemented offshore by shipborne hydroacoustic data. We present the first versions of the model here. Modelled depths can be compared to thermocline depths of available in-situ oceanographic data close to and at the calving fronts. In doing so, we will identify key regions of possible entry for Warm Deep Water into the cavity beneath the ice shelf

Recent and past processes at the ice-sheet base of Jutulstraumen drainage basin (Antarctica)

Future sea-level predictions require that the history and physical state of the Antarctic ice sheet is well understood and constrained by observations. Much of the ice sheets’ ice-dynamic properties are governed by processes at the ice-bed interface which can be imaged with radar sounding surveys. Moreover, certain processes at the ice-sheet base can have an effect all the way to the ice surface, which in turn can be observed with satellites. Here we use a combination of ultra-wideband radio-echo sounding data, satellite radar and laser altimetry data to characterize the evolution of the subglacial morphology of the Jutulstraumen drainage basin (western Dronning Maud Land, Antarctica). Based on the classification of the bed topography, we reconstruct the step-by-step modifications the subglacial landscape has experienced since the beginning of the glaciation of Antarctica, 34 million years ago. In addition, between 2017 and 2020, we find evidence of active episodic cascade-like subglacial water transport along the subglacial valley network. The combination of these observations will represent an important step towards a better understanding of large-scale ice-sheet dynamics in western Dronning Maud Land

Ice-flow history and observations from the ice base of Jutulstraumen drainage basin (Antarctica)

Future sea-level predictions require that the history of the Antarctic Ice Sheet is well understood and constrained by observations. Much of the ice sheets’ ice-dynamic properties are governed by processes at the ice-bed interface which can be imaged with radar sounding surveys. Here we use a combination of ultra-wideband radio-echo sounding data, satellite radar and laser altimetry data, as well as electromagnetic waveform modeling to characterize the properties of the ice base and the evolution of the subglacial morphology of the Jutulstraumen drainage basin (western Dronning Maud Land, Antarctica). Based on the classification of the bed topography, we reconstruct the step-by-step modifications the subglacial landscape has experienced since the beginning of the glaciation of Antarctica, 34 million years ago. Between 2017 and 2020, we find evidence of active episodic cascade-like subglacial water transport along the subglacial valley network. In addition, our high-resolution radio-echo sounding data reveal a cluster of anomalous basal ice units whose material properties we constrain by electromagnetic waveform modeling. Through this, we aim to derive the physical conditions at the ice base, and establish a link to the subglacial hydrology system. The combination of these observations will represent an important step towards a better understanding of large-scale ice-sheet dynamics in western Dronning Maud Land

Ripening and development of chilling injury in ‘monte carlo’ tomatoes treated with 1-methylcyclopropene

[PORT] O armazenamento de tomates do tipo não longa-vida sob baixas temperaturas tem sido utilizado para incrementar sua vida pós-colheita. No entanto, sob essas condições, ao invés de manter a qualidade, os frutos podem desenvolver sintomas de injúrias causadas pelas baixas temperaturas. Portanto, o objetivo deste trabalho foi avaliar o efeito da inibição da ação do etileno sobre o amadurecimento e o desenvolvimento de injúria pelo frio em tomates ‘Monte Carlo’ armazenados a 10°C e 5°C. O experimento foi conduzindo em esquema bifatorial (3x2), com diferentes temperaturas de armazenamento (20°C, 10°C e 5°C) e a aplicação ou não de 1μl l-1 de 1-metilciclopropeno (1-MCP), um composto que bloqueia a ação do etileno. Depois de 14 dias de armazenamento, a síntese de etileno e a respiração pós-armazenamento foi maior nos frutos armazenados a 5°C, sendo estimulada pela aplicação de 1-MCP. Nos demais frutos, a aplicação desse composto reduziu tanto a produção de etileno, quanto à respiração. A ocorrência de dano por frio foi estimulada pelo armazenamento a 5°C e levemente intensificada pela inibição da ação do etileno. O tratamento dos frutos a 10°C com 1-MCP prejudicou o desenvolvimento da coloração vermelha, demonstrando que essa temperatura reduz a capacidade dos frutos em superar a inibição promovida pelo 1-MCP. O tratamento com 1-MCP manteve a firmeza da polpa e a acidez titulável dos frutos mantidos a 20°C e 10°C mais elevada, não apresentando efeito sobre essas características a 5°C. Concluise que a qualidade de tomates não longa-vida pode ser mantida por até 14 dias com o armazenamento a 10°C ou com a aplicação de 1-MCP a 20°C. A aplicação desse composto combinado com o armazenamento a 10°C pode prejudicar o amadurecimento pósarmazenamento dos frutos, enquanto que a 5°C estimula levemente o desenvolvimento de sintomas de injúria pelo frio. [ENG] The cold storage has been a commom practice for extending the postharvest life of non-long-life tomatoes. However, instead of maintaining quality, low temperatures may lead tomato fruits to develop chilling injury symptoms. Thus, this work aimed to evaluate the effect of inhibiting the ethylene action on the ripening and development of chilling injury in ‘Monte Carlo’ tomato fruits stored at 10°C and 5°C. The experiment was a bifatorial (3x2), with different storage temperature (20°C, 10°C and 5°C) and the treatment or not of 1,0 μl l-1 of 1-methylcyclopropene (1-MCP), a compound that irreversible blocks the ethylene action. After 14 days of storage, 5°C-stored fruits showed higher ethylene synthesis and respiration. Whereas 1-MCP enhanced this effect at 5°C, it reduced the ethylene production and respiration at 20°C and 10°C. Chilling injury was sharply increased at 5°C and slightly stimulated by inhibiting ethylene action. 1-MCP-treated fruits stored at 10°C showed lower post-storage red color development, suggesting that at this temperature the ability of the fruits in overcomming the inihibition caused by 1-MCP is decreased. 1-MCP reduced flesh firmness and acidity loss in fruits stored at 20°C and 10°C but not at 5°C. Thus, we conclude that the quality of non-long-life tomato fruits can be maintained during 14 days either by storing at 10°C or by applying 1-MCP at 20°C. Whereas the application of 1-MCP associated with the storage at 10°C may damage the ripening of the fruits, at 5°C it increase slightly the development of chilling injury symptoms

Photonic and Optomechanical Thermometry

Temperature is one of the most relevant physical quantities that affects almost all processes in nature. However, the realization of accurate temperature standards using current temperature references, like the triple point of water, is difficult due to the requirements on material purity and stability of the environment. In addition, in harsh environments, current temperature sensors with electrical readout, like platinum resistors, are difficult to implement, urging the development of optical temperature sensors. In 2018, the European consortium Photoquant, consisting of metrological institutes and academic partners, started investigating new temperature standards for self-calibrated, embedded optomechanical sensor applications, as well as optimised high resolution and high re- liability photonic sensors, to measure temperature at the nano and meso-scales and as a possible replacement for the standard platinum resistant thermometers. This article presents an overview of the results obtained with sensor prototypes that exploit photonic and optomechanical techniques for sensing temperatures over a large temperature range (5 K to 300 K). Different concepts are demon- strated, including ring resonators, ladder-like resonators and suspended membrane optomechanical thermometers, highlighting initial performance and challenges, like self-heating that need to be overcome to realize photonic and optomechanical thermometry applications.This work was carried out under the 17FUN05 PhotOQuanT project, which has received funding from the EMPIR program, co-financed by the Participating States and the European Union’s Horizon 2020 research and innovation progra

Antarctic Bedmap data: Findable, Accessible, Interoperable, and Reusable (FAIR) sharing of 60 years of ice bed, surface, and thickness data

One of the key components of this research has been the mapping of Antarctic bed topography and ice thickness parameters that are crucial for modelling ice flow and hence for predicting future ice loss and the ensuing sea level rise. Supported by the Scientific Committee on Antarctic Research (SCAR), the Bedmap3 Action Group aims not only to produce new gridded maps of ice thickness and bed topography for the international scientific community, but also to standardize and make available all the geophysical survey data points used in producing the Bedmap gridded products. Here, we document the survey data used in the latest iteration, Bedmap3, incorporating and adding to all of the datasets previously used for Bedmap1 and Bedmap2, including ice bed, surface and thickness point data from all Antarctic geophysical campaigns since the 1950s. More specifically, we describe the processes used to standardize and make these and future surveys and gridded datasets accessible under the Findable, Accessible, Interoperable, and Reusable (FAIR) data principles. With the goals of making the gridding process reproducible and allowing scientists to re-use the data freely for their own analysis, we introduce the new SCAR Bedmap Data Portal (https://bedmap.scar.org, last access: 1 March 2023) created to provide unprecedented open access to these important datasets through a web-map interface. We believe that this data release will be a valuable asset to Antarctic research and will greatly extend the life cycle of the data held within it. Data are available from the UK Polar Data Centre: https://data.bas.ac.uk (last access: 5 May 2023​​​​​​​). See the Data availability section for the complete list of datasets.publishedVersio

Bedmap3 updated ice bed, surface and thickness gridded datasets for Antarctica

Abstract We present Bedmap3, the latest suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60 °S. Bedmap3 incorporates and adds to all post-1950s datasets previously used for Bedmap2, including 84 new aero-geophysical surveys by 15 data providers, an additional 52 million data points and 1.9 million line-kilometres of measurement. These efforts have filled notable gaps including in major mountain ranges and the deep interior of East Antarctica, along West Antarctic coastlines and on the Antarctic Peninsula. Our new Bedmap3/RINGS grounding line similarly consolidates multiple recent mappings into a single, spatially coherent feature. Combined with updated maps of surface topography, ice shelf thickness, rock outcrops and bathymetry, Bedmap3 reveals in much greater detail the subglacial landscape and distribution of Antarctica’s ice, providing new opportunities to interpret continental-scale landscape evolution and to model the past and future evolution of the Antarctic ice sheets.</jats:p

European Partnership in Metrology project: photonic and quantum sensors for practical integrated primary thermometry (PhoQuS-T)

Current temperature sensors require regular recalibration to maintain reliable temperature measurement. Photonic/quantum-based approaches have the potential to radically change the practice of thermometry through provision of in situ traceability, potentially through practical primary thermometry, without the need for sensor recalibration. This article gives an overview of the European Partnership in Metrology (EPM) project: Photonic and quantum sensors for practical integrated primary thermometry (PhoQuS-T), which aims to develop sensors based on photonic ring resonators and optomechanical resonators for robust, small-scale, integrated, and wide-range temperature measurement. The different phases of the project will be presented. The development of the integrated optical practical primary thermometer operating from 4 K to 500 K will be reached by a combination of different sensing techniques: with the optomechanical sensor, quantum thermometry below 10 K will provide a quantum reference for the optical noise thermometry (operating in the range 4 K to 300 K), whilst using the high-resolution photonic (ring resonator) sensor the temperature range to be extended from 80 K to 500 K. The important issues of robust fibre-to-chip coupling will be addressed, and application case studies of the developed sensors in ion-trap monitoring and quantum-based pressure standards will be discussed