First record of the genus Beris Latreille (Diptera, Stratiomyidae) from Korea, with description of a new species

The subfamily Beridinae of the family Stratiomyidae contains about 280 known species globally, and distributed all over the biogeographical areas except polar region. In the Korean peninsula, the species diversity of this subfamily has been poorly known so far, in accordance with National species list of Korea by National Institue of Biological Resources. In this paper, the soldier fly genus Beris Latreille is reported for the first time from Korea based on following three species: B. fuscipes Meigen, B. hirotui Ôuchi, and B. tigris Lee and Suh, sp. nov. Among them, B. tigris Lee and Suh, sp. nov. was confirmed to be newly discovered. Consequently, three species within this genus have been identified from the Korean peninsula. The identification key, description, external photographs, and taxonomic notes of these Korean species are presented herein.

Stratospheric Final Warmings fall into two categories with different evolution over the course of the year

In early spring the stratospheric zonal circulation reverses from westerly to easterly. The transition, called Stratospheric Final Warming (SFW), may be smooth and late, mainly controlled by the solar radiative heating of the polar region, or early and abrupt with rapid increase of polar temperature and deceleration of the zonal wind, forced by the planetary wave activity. Here we present a study, based on 71 years meteorological reanalysis data. Two composites of radiative and dynamical SFWs have been built. There is a very significant difference in the evolution during the year of polar temperature and 60°N zonal wind between the two composites. The state of the polar vortex on given month is anticorrelated with its state 2 to 3 months earlier. Early winter is anticorrelated with mid-winter and mid-winter with late winter/early spring. The summer stratosphere keeps a memory of its state in April–May after the SFW until late June.

Stream Boundary Detection of a Hyper-Arid, Polar Region Using a U-Net Architecture: Taylor Valley, Antarctica

Convolutional neural networks (CNNs) are becoming an increasingly popular approach for classification mapping of large complex regions where manual data collection is too time consuming. Stream boundaries in hyper-arid polar regions such as the McMurdo Dry Valleys (MDVs) in Antarctica are difficult to locate because they have little hydraulic flow throughout the short summer months. This paper utilizes a U-Net CNN to map stream boundaries from lidar derived rasters in Taylor Valley located within the MDVs, covering ∼770 km2. The training dataset consists of 217 (300 × 300 m2) well-distributed tiles of manually classified stream boundaries with diverse geometries (straight, sinuous, meandering, and braided) throughout the valley. The U-Net CNN is trained on elevation, slope, lidar intensity returns, and flow accumulation rasters. These features were used for detection of stream boundaries by providing potential topographic cues such as inflection points at stream boundaries and reflective properties of streams such as linear patterns of wetted soil, water, or ice. Various combinations of these features were analyzed based on performance. The test set performance revealed that elevation and slope had the highest performance of the feature combinations. The test set performance analysis revealed that the CNN model trained with elevation independently received a precision, recall, and F1 score of 0.94±0.05, 0.95±0.04, and 0.94±0.04 respectively, while slope received 0.96±0.03, 0.93±0.04, and 0.94±0.04, respectively. The performance of the test set revealed higher stream boundary prediction accuracies along the coast, while inland performance varied. Meandering streams had the highest stream boundary prediction performance on the test set compared to the other stream geometries tested here because meandering streams are further evolved and have more distinguishable breaks in slope, indicating stream boundaries. These methods provide a novel approach for mapping stream boundaries semi-automatically in complex regions such as hyper-arid environments over larger scales than is possible for current methods.

Intercomparison of CO measurements from TROPOMI, ACE-FTS, and a high-Arctic ground-based Fourier transform spectrometer

The TROPOspheric Monitoring Instrument (TROPOMI) provides a daily, spatially resolved (initially 7×7 km2, upgraded to 7×5.6 km2 in August 2019) global dataset of CO columns; however, due to the relative sparseness of reliable ground-based data sources, it can be challenging to characterize the validity and accuracy of satellite data products in remote regions such as the high Arctic. In these regions, satellite intercomparisons can supplement model- and ground-based validation efforts and serve to verify previously observed differences. In this paper, we compare the CO products from TROPOMI, the Atmospheric Chemistry Experiment (ACE) Fourier transform spectrometer (FTS), and a high-Arctic ground-based FTS located at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Nunavut (80.05∘ N, 86.42∘ W). A global comparison of TROPOMI reference profiles scaled by the retrieved total column with ACE-FTS CO partial columns for the period from 28 November 2017 to 31 May 2020 displays excellent agreement between the two datasets (R=0.93) and a small relative bias of -0.83±0.26% (bias ± standard error of the mean). Additional comparisons were performed within five latitude bands: the north polar region (60 to 90∘ N), northern mid-latitudes (20 to 60∘ N), the equatorial region (20∘ S to 20∘ N), southern mid-latitudes (60 to 20∘ S), and the south polar region (90 to 60∘ S). Latitudinal comparisons of the TROPOMI and ACE-FTS CO datasets show strong correlations ranging from R=0.93 (southern mid-latitudes) to R=0.86 (equatorial region) between the CO products but display a dependence of the mean differences on latitude. Positive mean biases of 7.93±0.61 % and 7.21±0.52 % were found in the northern and southern polar regions, respectively, while a negative bias of -9.41±0.55% was observed in the equatorial region. To investigate whether these differences are introduced by cloud contamination, which is reflected in the TROPOMI averaging kernel shape, the latitudinal comparisons were repeated for cloud-covered pixels and clear-sky pixels only, as well as for the unsmoothed and smoothed cases. Clear-sky pixels were found to be biased higher with poorer correlations on average than clear+cloudy scenes and cloud-covered scenes only. Furthermore, the latitudinal dependence on the biases was observed in both the smoothed and unsmoothed cases. To provide additional context to the global comparisons of TROPOMI with ACE-FTS in the Arctic, both satellite datasets were compared against measurements from the ground-based PEARL-FTS. Comparisons of TROPOMI with smoothed PEARL-FTS total columns in the period of 3 March 2018 to 27 March 2020 display a strong correlation (R=0.88); however, a positive mean bias of 14.7±0.16 % was also found. A partial column comparison of ACE-FTS with the PEARL-FTS in the period from 25 February 2007 to 18 March 2020 shows good agreement (R=0.79) and a mean positive bias of 7.89±0.21 % in the ACE-FTS product relative to the ground-based FTS. The magnitude and sign of the mean relative differences are consistent across all intercomparisons in this work, as well as with recent ground-based validation efforts, suggesting that the current TROPOMI CO product exhibits a positive bias in the high-Arctic region. However, the observed bias is within the TROPOMI mission accuracy requirement of ±15 %, providing further confirmation that the data quality in these remote high-latitude regions meets this specification.

A Local-Global Analysis Method for Arctic Drilling Riser Suffering from Ice Load

As world energy consumption intensifies, the oil and gas exploitation technology in the polar region are drawing more and more attention. However, due to the harsh environment, the oil and gas exploitation operation in the polar region are faced with enormous challenges, such as low temperature and sea ice collision, etc. This paper mainly focuses on the structural strength and integrity study of the arctic drilling riser suffering from the floe collision loading. First, the discrete element software IceDEM is employed to develop a local drilling riser - sea ice interaction model subjected to the floe collision loading in the splash zone, and the corresponding dynamic collision response between the drilling riser and the floe ice could be calculated and acquired. Then, a global drilling riser model is built within the framework of general finite element analysis software ABAQUS to investigate the dynamic behavior of the arctic drilling riser in the polar environment, and the dynamic collision loading derived from IceDEM simulation is also introduced in this global model. Finally, the dynamic responses of the arctic drilling riser based on the finite element simulation are investigated to research the riser’s security and integrity, which can provide reference for the design and application of the drilling riser in the polar region.

FUNCTIONAL CONNECTIVITY WITHIN LANGUAGE REGIONS IN APHASIC PATIENTS DURING REAL-TIME fMRI-BASED NEUROFEEDBACK TRAINING

Stroke is known to disrupt connectivity in the brain in addition to forming scars. This study analyzed the connectivity changes within the language regions and the adjoining brain regions during real-time Functional Magnetic Resonance Imaging-based neurofeedback training for the rehabilitation of stroke-affected patients with expressive aphasia. The study hypothesizes that with repeated sessions of the training, a rise in functional connectivity within the language regions will be observed for the aphasic patients. The experiment was conducted on three groups of subjects: test patients, control patients, and normal participants. Only the test and the normal groups underwent the training. In the training, the subjects exercised language activity covertly to upregulate the Broca’s area. Neurofeedback of the Broca activity (amplified when it is correlated with the Wernicke activity) is visually presented to the subjects to motivate them to improve their performance and stimulate upregulation of functional connectivity of the Broca’s and Wernicke’s areas. The key observations are as follows: For all the groups, a rise in functional connectivity was noticed mostly among the left hemispheric Regions of Interest (ROIs). While comparing the normal group over the test group, ROIs in the frontal polar region were noticed to have good functional connectivity. While comparing the test group over the control group, ROIs in the supra parietal, and the right central opercular regions were found to have good functional connectivity. This study can contribute to the design of rehabilitative training systems that are tuned to activate the regions that have been observed to show increased functional connectivity.