Long-term coastal-polynya dynamics in the southern Weddell Sea from MODIS thermal-infrared imagery

Based upon thermal-infrared satellite imagery in combination with ERA-Interim atmospheric reanalysis data, we derive long-term polynya characteristics such as polynya area, thin-ice thickness distribution, and ice-production rates for a 13-year investigation period (2002–2014) for the austral winter (1 April to 30 September) in the Antarctic southern Weddell Sea. All polynya parameters are derived from daily cloud-cover corrected thin-ice thickness composites. The focus lies on coastal polynyas which are important hot spots for new-ice formation, bottom-water formation, and heat/moisture release into the atmosphere. MODIS has the capability to resolve even very narrow coastal polynyas. Its major disadvantage is the sensor limitation due to cloud cover. We make use of a newly developed and adapted spatial feature reconstruction scheme to account for cloud-covered areas. We find the sea-ice areas in front of the Ronne and Brunt ice shelves to be the most active with an annual average polynya area of 3018 ± 1298 and 3516 ± 1420 km2 as well as an accumulated volume ice production of 31 ± 13 and 31 ± 12 km3, respectively. For the remaining four regions, estimates amount to 421 ± 294 km2 and 4 ± 3 km3 (Antarctic Peninsula), 1148 ± 432 km2 and 12 ± 5 km3 (iceberg A23A), 901 ± 703 km2 and 10 ± 8 km3 (Filchner Ice Shelf), as well as 499 ± 277 km2 and 5 ± 2 km3 (Coats Land). Our findings are discussed in comparison to recent studies based on coupled sea-ice/ocean models and passive-microwave satellite imagery, each investigating different parts of the southern Weddell Sea

Multi-Decadal Variability of Polynya Characteristics and Ice Production in the North Water Polynya by Means of Passive Microwave and Thermal Infrared Satellite Imagery

The North Water (NOW) Polynya is a regularly-forming area of open-water and thin-ice, located between northwestern Greenland and Ellesmere Island (Canada) at the northern tip of Baffin Bay. Due to its large spatial extent, it is of high importance for a variety of physical and biological processes, especially in wintertime. Here, we present a long-term remote sensing study for the winter seasons 1978/1979 to 2014/2015. Polynya characteristics are inferred from (1) sea ice concentrations and brightness temperatures from passive microwave satellite sensors (Advanced Microwave Scanning Radiometer (AMSR-E and AMSR2), Scanning Multichannel Microwave Radiometer (SMMR), Special Sensor Microwave Imager/Sounder (SSM/I-SSMIS)) and (2) thin-ice thickness distributions, which are calculated using MODIS ice-surface temperatures and European Center for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis data in a 1D thermodynamic energy-balance model. Daily ice production rates are retrieved for each winter season from 2002/2003 to 2014/2015, assuming that all heat loss at the ice surface is balanced by ice growth. Two different cloud-cover correction schemes are applied on daily polynya area and ice production values to account for cloud gaps in the MODIS composites. Our results indicate that the NOW polynya experienced significant seasonal changes over the last three decades considering the overall frequency of polynya occurrences, as well as their spatial extent. In the 1980s, there were prolonged periods of a more or less closed ice cover in northern Baffin Bay in winter. This changed towards an average opening on more than 85% of the days between November and March during the last decade. Noticeably, the sea ice cover in the NOW polynya region shows signs of a later-appearing fall freeze-up, starting in the late 1990s. Different methods to obtain daily polynya area using passive microwave AMSR-E/AMSR2 data and SSM/I-SSMIS data were applied. A comparison with MODIS data (thin-ice thickness ≤ 20 cm) shows that the wintertime polynya area estimates derived by MODIS are about 30 to 40% higher than those derived using the polynya signature simulation method (PSSM) with AMSR-E data. In turn, the difference in polynya area between PSSM and a sea ice concentration (SIC) threshold of 70% is fairly low (approximately 10%) when applied to AMSR-E data. For the coarse-resolution SSM/I-SSMIS data, this difference is much larger, particularly in November and December. Instead of a sea ice concentration threshold, the PSSM method should be used for SSM/I-SSMIS data. Depending on the type of cloud-cover correction, the calculated ice production based on MODIS data reaches an average value of 264.4 ± 65.1 km 3 to 275.7 ± 67.4 km 3 (2002/2003 to 2014/2015) and shows a high interannual variability. Our achieved long-term results underline the major importance of the NOW polynya considering its influence on Arctic ice production and associated atmosphere/ocean processes

Thin-ice dynamics and ice production in the Storfjorden polynya for winter-seasons 2002/2003–2013/2014 using MODIS thermal infrared imagery

Spatial and temporal characteristics of the Storfjorden polynya, which forms regularly in the proximity of the islands Spitsbergen, Barentsøya and Edgeøya in the Svalbard archipelago under the influence of strong north-easterly winds, have been investigated for the period 2002/2003 to 2013/2014 using thermal infrared satellite imagery. Thin-ice thicknesses were calculated from MODIS ice-surface temperatures, combined with ECMWF ERA-Interim atmospheric reanalysis data in an energy-balance model. Based on calculated thin-ice thicknesses, associated quantities like polynya area and total ice production were derived and compared to previous remote sensing and modeling studies. A basic coverage-correction scheme was applied to account for cloud-gaps in the daily composites. The sea ice in the Storfjorden area experiences a late fall freeze-up in several years over the 12 winter-period, with an increasing frequency of large polynya events until the end of December. During the regarded period, the mean polynya area is 4555.7 ± 1542.9 km2. The average ice production in the fjord is estimated with 28.3 ± 8.5 km3 per winter and therefore lower than in previous studies. Despite this comparatively short record of 12 winter-seasons, a significant positive trend of 20.2 km3 per decade could be detected, which contrasts earlier reports of a slightly negative trend in accumulated ice production prior to 2002. Derived estimates underline the importance of this relatively small coastal polynya system considering its contribution to the cold halocline layer through salt release during ice formation processes

Hendiadys in naturally occurring interactions : A cross-linguistic study of double verb constructions

Double verb constructions known as hendiadys have been studied primarily in literary texts and corpora of written language. Much less is known about their properties and usage in spoken language, where expressions such as 'come and see', 'go and tell', 'sit and talk' are particularly common, and where we can find an even richer diversity of other constructions. In this study, we investigate hendiadys in corpora of naturally occurring social interactions in four languages, Danish, English (US and UK), Finnish and Italian, with the objective of exploring whether hendiadys is used systematically in recurrent interactional and sequential circumstances, from which it is possible to identify the pragmatic function(s) that hendiadys may serve. Examining hendiadys in conversation also offers us a special window into its grammatical properties, for example when a speaker self-corrects from a non-hendiadic to a hendiadic expression, exposing the boundary between related grammatical forms and demonstrating the distinctiveness of hendiadys in context. More broadly, we demonstrate that hendiadys is systematically associated with talk about complainable matters, in environments characterised by a conflict, dissonance, or friction that is ongoing in the interaction or that is being reported by one participant to another. We also find that the utterance in which hendiadys is used is typically in a subsequent and possibly terminal position in the sequence, summarising or concluding it. Another key finding is that the complainable or conflictual element in these interactions is expressed primarily by the first conjunct of the hendiadic construction. Whilst the first conjunct is semantically subsidiary to the second, it is pragmatically the most important one. This analysis leads us to revisit a long-established asymmetry between the verbal components of hendiadys, and to bring to light the synergy of grammar and pragmatics in language usage.Peer reviewe

Unmanned aerial vehicle based tree canopy characteristics measurement for precision spray applications

The critical components for applying the correct amount of agrochemicals are fruit tree characteristics such as canopy height, canopy volume, and canopy coverage. An unmanned aerial vehicle (UAV)-based tree canopy characteristics measurement system was developed using image processing approaches. The UAV captured images using a high-resolution red-green-blue (RGB) camera. A digital surface model (DSM) and a digital terrain model (DTM) were generated from the captured images. A tree canopy height map was generated from the subtraction of DSM and DTM. A total of 24 apple trees were randomly targeted to measure the canopy characteristics. Region of interest (ROI) was generated across the boundary of each targeted tree. The height of all pixels within each ROI was computed separately. The pixel with maximum height was considered as the height of the respective tree. For computing canopy volume, the sum of all pixel heights from individual ROI was multiplied by the square of ground sample distance (GSD) of 5.69 mm·pixel−1. A segmentation method was employed to calculate the canopy coverage of the individual trees. The segmented canopy pixel area was divided by the total pixel area within the ROI. The results showed an average relative error of 0.2 m(6.64%) while comparing automatically measured tree height with ground measurements. For tree canopy volume, a mean absolute error of 0.25 m3 and a root mean square error of 0.33 m3 were achieved. The study estimated the possible agrochemical requirement for spraying the fruit trees, ranging from 0.1 to 0.32 l based on tree canopy volumes. The overall investigations suggest that the UAV-based tree canopy characteristics measurements could be a potential tool to calculate the pesticide requirement for precision spraying applications in tree fruit orchards

Nanostructural organization of naturally occurring composites - part II: silica-chitin-based biocomposites

Investigations of the micro- and nanostructures and chemical composition of the sponge skeletons as examples for natural structural biocomposites are of fundamental scientific relevance. Recently, we show that some demosponges (Verongula gigantea, Aplysina sp.) and glass sponges (Farrea occa, Euplectella aspergillum) possess chitin as a component of their skeletons. The main practical approach we used for chitin isolation was based on alkali treatment of corresponding external layers of spicules sponge material with the aim of obtaining alkali-resistant compounds for detailed analysis. Here, we present a detailed study of the structural and physicochemical properties of spicules of the glass sponge Rossella fibulata. The structural similarity of chitin derived from this sponge to invertebrate alpha chitin has been confirmed by us unambiguously using physicochemical and biochemical methods. This is the first report of a silica-chitin composite biomaterial found in Rossella species. Finally, the present work includes a discussion related to strategies for the practical application of silica-chitin-based composites as biomaterials

The surface energy balance of early summer land-fast sea ice in Atka Bay, Antarctica

In-situ measurements of the land-fast sea ice energy balance are scarce. We present a data set that comprises eddy-covariance measurements of sensible and latent heat as well as measurements of the sea-ice temperature gradient, long-wave and short-wave radiation measurements over land-fast sea ice in Atka Bay, Antarctica. With this setup we are able to monitor all components of the sea-ice energy budget. Additionally, we also measured the turbulent flux of CO2 over sea ice. This 37 day-long data set is evaluated for the transition period from austral winter to summer (November to December 2012) with regard to atmospheric stability and the general weather conditions. Results for the eddy-covariance measurements show an average sensible heat flux of 6.45+-10.72 W/m2 and a latent heat flux of 12.71+-9.48 W/m2 (with one standard deviation respectively) for low pressure/high wind-speed conditions. The average net radiation is 44.37+-41.54 W/m2 and for the CO2 flux an average of -3.35+-3.37μmol/m2 was measured. During high pressure/low wind-speed conditions an average of -3.03+-10.48 W/m2 and 10.76+-10.52 W/m2 was recorded for the sensible and latent heat flux, while the average net radiation and the CO2 flux are 35.63+-56.70 W/m2 and -1.95+-1.72μmol/m2 respectively. The fast ice is therefore found as a sink of CO2 for both situations

Phase-Specific Strain Hardening and Load Partitioning of Cold Rolled Duplex Stainless Steel X2CrNiN23-4

Multi-phase materials often times consist of constituents with high contrasts in phase-specific mechanical properties. Here, even after homogeneous plastic deformation phase-specific residual stresses develop that may affect the components behaviour in service. For numerical simulation of phase-specific residual stresses, knowledge of the particular phase-specific strain hardening behaviour is essential. In this study, the strain hardening of ferrite and austenite in cold rolled duplex stainless steel of type X2CrNiN23-4 is investigated. By means of X-ray diffraction, the phase-specific load partitioning and residual stress evolution are analysed for uniaxial load application in three directions within the sheets plane, taking into account the sheet metals phase specific anisotropy. In order to assess the necessity for experimental determination of anisotropic phase specific behaviour, the strain hardening parameters, derived from only one loading direction, are implemented in a mean-field approach for prediction of phase-specific stresses. A simplified simulation approach is applied that only considers macroscopic plastic anisotropy and results are compared to experimental findings. For all investigated loading directions, it was observed that austenite is the high-strength phase. This load partitioning behaviour was confirmed by the evolution of phase-specific residual stresses as a result of uniaxial elasto-plastic loading. With the simplified and fast numerical approach, satisfying results for prediction of anisotropic phase-specific (residual) stresses are obtained

Non-phenacetin analgesics and analgesic nephropathy: Clinical assessment of high users from a case-control study [1]*

Background. A recent large-scale case-control study on analgesic nephropathy (SAN) [1] found no increased risk of end-stage renal disease (ESRD) in users of combined or single formulations of phenacetin-free analgesics. In a subgroup of 22 high users, however, a dose-dependent increased risk was found, which raised the question if these patients presented or not with analgesic nephropathy (AN). Methods. The individual questionnaires of this subgroup of high users were reviewed, and the total lifetime intake of different types of analgesics was calculated. For evidence of AN, the following data were considered: (1) the amount and type of analgesics consumed, (2) the cause of ESRD, as diagnosed by the nephrologist in charge of the patient and (3) renal imaging and other relevant laboratory data. Results. This group of ESRD patients consumed on average 7.8 kg of antipyretic analgesics (range 30.8-2.7 kg) over an average of 21.5 years (range 35-6 years). Single analgesics were exclusively used by 12 patients (54.5%) and combined analgesics by 5 patients (22.7%), while 5 patients used both. None of the patients was diagnosed as having AN, and a review of the questionnaires did not disclose evidence suggestive of AN. The possibility that, irrespective of AN, the analgesic (ab)use contributed to the progression of existing renal diseases cannot be answered in the absence of well-defined criteria. The data supporting the existence of such an analgesic-associated nephropathy (AAN) are, however, not consistent and most likely due to confounding by indication. Conclusion. In a group of ESRD patients with high use of non-phenacetin analgesics, no evidence of AN was found. There is no evidence that (ab)use of analgesics or NSAIDs other than phenacetin leads to a pathologically or clinically defined renal disease that could be named AN or AA