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Digital broad-band seismic recordings from station HLG on the small island of Heligoland in the German Bight in the North Sea are available since 2001. Since July 2017, an additional local network of six broad-band seismometers is operational on Heligoland with a focus on investigations of local microseism in the North Sea.In this study, we combine information gathered by passive seismic registration and gravity measurements from a superconducting gravimeter on Heligoland. We utilize 20 years of passive seismic data for long period spectral investigations spanning periods of tens of seconds up to several years. In the period band between 70 to 100 s, H/V ratios reveal strong noise on the horizontal components occurring contemporaneously with strong storms. In addition, distinct peaks in the spectral data are observed at periods of 6, 12 and 24 hours, which can be related to ocean tides and atmospheric pressure variations that are affecting the amplitude of local microseism. We compare the spectral seismic data with three years of gravity spectra from a collocated superconducting gravimeter. They are highly comparable with the seismic spectra and show distinct differences between local tides in the North Sea and solid Earth tides. At even longer periods up to several years, the spectral seismic data reveal a strong signal at one year, accompanied by peaks at 0.5, 2, 3 and 8 years. These variations seem to affect mostly the secondary microseism of the Northern Atlantic recorded at station HLG., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

An iGrav superconducting gravimeter has been installed on the small offshore island of Helgoland in the North Sea approximately at sea level with the overall aim of high-accuracy determination of regional ocean tide loading (OTL) and non-tidal ocean loading (NTOL) signals. For validation, a second gravimeter (gPhoneX) has been setup to observe temporal gravity variations in parallel on the upper land of Helgoland. The first part of this study covers the determination of regional OTL parameters after elimination of the height-dependent gravity component by empirical transfer functions between the local sea level from a nearby tide gauge and local attraction effects. After reduction of all gravity recordings to sea level, the regional OTL parameters from both gravimeters agree at the level of a few 0.1 nm/s². The second part of this study shows the gravity residuals that are largely dominated by regional NTOL signals. Driven by strong westerly and easterly winds, the water level fluctuates between 1.15 m above mean high water and 1.50 m below mean low water, inducing gravity increases of up to 30 nm/s² and decreases of down to -40 nm/s², respectively, during the analysed time period. These high-accuracy gravity observations will be used as “ground truth” for the calibration and validation of ocean tide models and satellite gravimetry from GRACE Follow-On as well as corresponding de-aliasing products. Finally, the SG network in Central Europe will strongly benefit from an improved knowledge of non-tidal ocean loading signals of the North Sea., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Speculations about the origin of SARS-CoV-2 have catapulted bats into the spotlight of scientific and societal attention, with unforeseen consequences for bat conservation. In two global surveys with bat experts before and during the COVID-19 pandemic, we assessed their (i) threat perceptions, emotions towards bats and social trust in decision makers and (ii) the predictive potential of emotions, social trust and socio-demographic variables on threat perceptions. We also discuss (iii) the potential influence of the pandemic on threat perception and antecedents (emotions and social trust). We received 495 responses from 65 countries in September 2019 and 320 responses in June 2020 from 77 countries. We identified three major threat categories (indirect, direct and prejudice). Comparing threat perception, emotions and social trust between both surveys, we found that indirect threats (e.g., habitat modification) were considered as crucial, yet less so during the pandemic. During the pandemic, experts rated indirect threats lower and the perceived threat through prejudice (e.g., myths) higher than before the pandemic. During the pandemic, bat experts also expressed more compassion and sadness related to bats and trust in researchers and NGOs, but less trust in laypeople than before the pandemic. Emotions were particularly important predictors for threats through prejudice besides social trust. Socio-demographic variables (e.g., cultural and professional background) had predictive potential predominantly for direct threats (e.g., hunting and trade, wind turbines) and threats through prejudice. Our study highlights the role of emotions and social trust on threat perception among bat experts who remained relatively invisible during the pandemic despite their key role for bat conservation. More importantly, we echo previous calls to be more attentive to ecological grief also within the scientific community; especially as discussions around zoonotic spillover with valued study animals intensify.

We show that complex semisimple quantum groups, that is, Drinfeld doubles of $ q $-deformations of compact semisimple Lie groups, satisfy a categorical version of the Baum-Connes conjecture with trivial coefficients. This approach, based on homological algebra in triangulated categories, is compatible with the previously studied deformation picture of the assembly map, and allows us to define an assembly map with arbitrary coefficients for these quantum groups., 20 pages. Revised version, to appear in IMRN