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

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

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

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

Severe Multiorgan Failure Following Yellow Fever Vaccination

Background: The yellow fever (YF) vaccination is recommended by the WHO for peopletraveling or living in endemic areas at risk for yellow fever infections in Africa and South America.Although the live attenuated yellow fever vaccine is a safe and efficient vaccine, rare serious adverseevents after vaccination have been reported. Case presentation: We present the case of a 74-year-oldmale with multiorgan failure after yellow fever vaccination for a trip to Brazil. The patient requiredadmission to the intensive care unit with a prolonged stay due to severe organ dysfunction. Five daysafter the YF vaccination, the patient experienced nausea, vomiting, diarrhea, and general illness. Threedays later he sought medical attention and was transferred to the University Hospital Heidelberg withbeginning multiorgan failure and severe septic shock, including hypotonia, tachypnea, thrombopenia,and acute renal failure the same day. Within one week after vaccination, antibodies against YF viruswere already detectable and progressively increased over the next two weeks. Viral RNA was detectedin serum on the day of admission, with a viral load of 1.0×105copies/mL. The YF virus (YFV) RNAwas also present in tracheal secretions for several weeks and could be detected in urine samples upto 20 weeks after vaccination, with a peak viral load of 1.3×106copies/mL. After 20 weeks in theICU with nine weeks of mechanical ventilation, the patient was transferred to another hospital forfurther recovery. Conclusions: The risk for severe adverse events due to the YF vaccination should bebalanced against the risk of acquiring a severe YF infection, especially in elderly travelersPeer Reviewe

AWI's UWB radar: Advanced insights into and beneath the polar ice sheets

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

Preserved landscapes underneath the Antarctic Ice Sheet reveal the geomorphological history of Jutulstraumen Basin

The landscape of Antarctica, hidden beneath kilometre‐thick ice in most places, has been shaped by the interactions between tectonic and erosional processes. The flow dynamics of the thick ice cover deepened pre‐formed topographic depressions by glacial erosion, but also preserved the subglacial landscapes in regions with moderate to slow ice flow. Mapping the spatial variability of these structures provides the basis for reconstruction of the evolution of subglacial morphology. This study focuses on the Jutulstraumen Glacier drainage system in Dronning Maud Land, East Antarctica. The Jutulstraumen Glacier reaches the ocean via the Jutulstraumen Graben, which is the only significant passage for draining the East Antarctic Ice Sheet through the western part of the Dronning Maud Land mountain chain. We acquired new bed topography data during an airborne radar campaign in the region upstream of the Jutulstraumen Graben to characterise the source area of the glacier. The new data show a deep relief to be generally under‐represented in available bed topography compilations. Our analysis of the bed topography, valley characteristics and bed roughness leads to the conclusion that much more of the alpine landscape that would have formed prior to the Antarctic Ice Sheet is preserved than previously anticipated. We identify an active and deeply eroded U‐shaped valley network next to largely preserved passive fluvial and glacial modified landscapes. Based on the landscape classification, we reconstruct the temporal sequence by which ice flow modified the topography since the beginning of the glaciation of Antarctica.Airborne ice‐penetrating radar data reveal the evolution of the subglacial morphology of the Jutulstraumen Glacier drainage system in western Dronning Maud Land. We identify various geomorphological patterns that are related to different stages of subglacial erosion and allow us to reconstruct the temporal sequence by which ice flow modified the topography since the beginning of glaciation of Antarctica

Metrological Characterization of a High-Temperature Hybrid Sensor Using Thermal Radiation and Calibrated Sapphire Fiber Bragg Grating for Process Monitoring in Harsh Environments

Fiber Bragg gratings inscribed in single crystalline multimode sapphire fibers (S-FBG) are suitable for monitoring applications in harsh environments up to 1900 °C. Despite many approaches to optimize the S-FBG sensor, a metrological investigation of the achievable temperature uncertainties is still missing. In this paper, we developed a hybrid optical temperature sensor using S-FBG and thermal radiation signals. In addition, the sensor also includes a thermocouple for reference and process control during a field test. We analyzed the influence of the thermal gradient and hotspot position along the sensor for all three detection methods using an industrial draw tower and fixed point cells. Moreover, the signal processing of the reflected S-FBG spectrum was investigated and enhanced to determine the reachable measurement repeatability and uncertainty. For that purpose, we developed an analytical expression for the long-wavelength edge of the peak. Our findings show a higher stability against mechanical-caused mode variations for this method to measure the wavelength shift compared to established methods. Additionally, our approach offers a high robustness against aging effects caused by high-temperature processes (above 1700 °C) or harsh environments. Using temperature-fixed points, directly traceable to the International System of Units, we calibrated the S-FBG and thermocouple of the hybrid sensor, including the corresponding uncertainty budgets. Within the scope of an over 3-weeks-long field trial, 25 production cycles of an industrial silicon manufacturing process with temperatures up to 1600 °C were monitored with over 100,000 single measurements. The absolute calibrated thermocouple (Uk=2≈1K…4K) and S-FBG (Uk=2≈10K…14K) measurements agreed within their combined uncertainty. We also discuss possible strategies to significantly reduce the uncertainty of the S-FBG calibration. A follow-up measurement of the sensor after the long-term operation at high temperatures and the transport of the measuring system together with the sensor resulted in a change of less than 0.5 K. Thus, both the presented hybrid sensor and the measuring principle are very robust for applications in harsh environments