Island Stations Research Articles

Phenology and social status of the endemic Sable Island Sweat Bee, Lasioglossum sablense

Lasioglossum (Dialictus) sablense Gibbs, 2010 (Hymenoptera: Halictidae) is endemic to Sable Island, an isolated sandbar located about 160 km east of Nova Scotia, Canada. Lasioglossum sablense is currently listed as Threatened due to its restricted geographic distribution, and promoting its conservation requires detailed information about nesting phenology, behaviour, and other life history details. We combined measurements of body size, wear, and ovarian status from adult females collected from flowers in 2016 and 2017 with measurements and behavioural observations of foragers collected at the Sable Island Station in 2019 and 2022, to compile a preliminary description of flight phenology and social behaviour. Like many members of its genus, L. sablense exhibited a diphasic life history. Phase 1 began when large, fertilized adult females emerged from hibernation, began nest and brood cell construction, and foraged to provision Brood 1, which comprised both daughters and sons. Most nests initiated during Phase 1 reactivated during Phase 2, with adult Brood 1 daughters foraging to provision Brood 2. Observations of bees at nest entrances demonstrated that some reactivated nests contained multiple adult females. Phase 1 foragers were larger, less worn, and had marginally higher levels of ovarian development than Phase 2 foragers. Five large females collected during Phase 2 had high levels of wear, suggesting they were long-lived Phase 1 foundresses that resumed foraging during Phase 2. Taken together, these observations suggest a mix of univoltine (single generation) and bivoltine (two generation) life histories, as well as a mix of solitary and social behaviour in L. sablense.

Field experiment and simulation of hot air curtain for cold protection in subway aisle in severe cold regions

Harbin Subway is the northernmost subway line in China. In winter, outdoor temperature can reach −37.7 °C. Cold protection has emerged as a critical priority for subway operations in the region. In this paper, taking the aisle of a typical island station in Harbin as the research object, long-term and short-term field experiment on the thermal environment of the aisle were carried out. The field test data of the station and the full-scale model were used to conduct numerical simulations on the effect of supply air temperature, speed, and angle on the aisle environment. The modified PET temperature scale and average power consumption during the operation of the hot air curtain were used to evaluated the cold protection solutions of the air curtain. The results revealed that the average temperature of the cross-sections in the aisle without cold protection measures dropped by 5.4 °C–6.3 °C from its initial level after the train left the station. Without increasing average power consumption, changing the supply air angle of hot air curtain can improve the thermal environment in the aisle. Considering the three aspects of cold protection effect, passenger thermal comfort and power consumption, this paper recommends that the cold protection solution for aisles with a length less than or equal to 76.7 m, L-shaped and similar layouts is 35 °C for the supply air temperature, 9 m/s for the wind speed, and the range of the difference between the supply air angle and the aisle inclination angle is 6° <θ-α < 11°.

Analisis kondisi padang lamun di Gili Balu, Sumbawa Barat

This research is conducted in seagrass meadow communities on Belang Island, Paserang Island, Kenawa Island, and Namo Island which are located in Gili Balu, West Sumbawa. Exploratory data collection was carried out in January 2022 and data processing was carried out from October to December 2022. The data collection procedure used was a training procedure for seagrass conditions using the line transect and square transect methods referring to the LIPI Seagrass Meadow Monitoring Guidebook. Data collection was carried out at each station by spreading the transect line 100 m long and placing the square transect to the right side of the line transect. Monitoring is carried out every 10 m and is carried out up to a point of 100 m. Data collection was repeated 3 times. Data processing was carried out to obtain categories and conditions of seagrass meadow compared to seagrass cover categories by the LIPI Seagrass Monitoring Guidebook and parameters of seagrass conditions by Decree of the Minister of Environment No. 200 of 2004. From the research conducted, it is found that there are 2 stations in the rare category, which are Namo and Kenawa Island, 4 stations with medium category closure of seagrass meadow, which are Paserang Island, Northwestern Belang Island, Southern Belang Island and Eastern Belang Island. The good closing category is obtained by the West Belang Island station. Seagrass meadow communities that are classified as damaged and poor are Namo Island, Kenawa Island, and Northwest Belang Island. Paserang Island and the southern and eastern parts of Belang Island are classified as damaged and unhealthy seagrass meadow. The western part of Belang Island is classified as in good and healthy seagrass condition status.

First PWV Retrieval Using MERSI‐LL Onboard FY‐3E and Cross Validation With Co‐Platform Occultation and Ground GNSS

AbstractFY‐3E plays a vital role in the meteorological global earth observing system. Precipitable water vapor (PWV) is an essential parameter for the water cycle and global climate change. Here, we carry out the PWV retrieval using the MERSI‐LL sensor onboard the FY‐3E satellite for the first time. The retrieval accuracy under different cloudage conditions is validated by the extra PWV from ground‐based GNSS and spaceborne occultation. For the results against ground‐based GNSS, the total accuracy shows an RMSE of 2.69–3.36 mm as the clouds increase, and correlation coefficients higher than 0.95. The spatial accuracy distribution indicates that inland stations have higher accuracy than the coast and island stations. As for the results against spaceborne occultation, the verification accuracy varies with the spatial pairing distance, showing poor accuracy in the low latitude area. This study can provide an essential reference for the community to understand the current water vapor inversion performance of MERSI‐LL.

Concentrations and loads of metals, nutrients and organic contaminants entering the St. Lawrence River at Wolfe Island, 2000 to 2019

Water quality trends and loads were analyzed at Wolfe Island for the years 2000 to 2019. This station captures the nutrient and contaminant concentrations leaving the Canadian Great Lakes system into the St. Lawrence River. In addition to tracking what is leaving the Great lakes system, this station provides an indication of contaminants flowing downstream where a number of sensitive areas exist such as the Thousand Island National Park as well as the St. Lawrence River Area of Concern at Cornwall. In terms of trends, trace metals and PAHs are generally decreasing at Wolfe Island while the nutrients and major ions are increasing. Organic compounds are more challenging to summarize since the number of non-detects prevented modeling of many or the frequency of analysis was too low to model. In a general sense, there is an overall decreasing trend in the organics and the large number of compounds whose concentrations are below detection levels does signify the very low concentration of these contaminants. A notable change in trend predominantly for the metals was noted around 2010 and is discussed herein. The amount of recent (5 years) exceedances of the most stringent water quality guidelines is lower than the previous study period (only PCBs and phosphorus, PFOS and most likely dieldrin). While there are many additional downstream sources of contaminants after the Wolfe Island station, the reductions observed from this study indicate a lower contribution from the Great Lakes in many cases.

The weakening effect of urbanization on tropical cyclone surface winds : An observational study for Shanghai

The observation-reanalysis difference method (OMR) and wind profile fitting method were used to analyze the influence urbanization has on the near-surface wind speed in Shanghai during tropical cyclone events. The data used include daily wind speed data from the Shanghai Meteorological Observatory Station collected from 1991 to 2020, hourly wind speed data from 100 m high wind towers from 2017 to 2019, and reanalysis data that covered the same period. The results indicated that during tropical cyclone occurrence, the wind speed of the OMR in the central urban region was significantly lower than that in the suburban area, and the OMR declined more obviously over the year, down to −8 m/s in 2020. Urbanization leads to the increase of average wind weakening rate to be higher than the maximum wind weakening rate, causing the maximum weakening rate of the central urban region to the average wind over 80%, while maximum wind speed was less than 80%. The weakening rate of both the average and maximum wind speeds during tropical cyclone impacts is greater than the rate that the annual average wind speed was reduced. A logarithmic variation was visible in the wind profile of the island station during tropical cyclone occurrence, with an average friction velocity U∗ of 0.9389 m/s and an average rough length Z0 of 0.4915 m. The wind speed during tropical cyclone events was higher than the three-year average wind speed within each layer. The suburban stations show a linear variation, and every hundred meters of height results in an increase of 5–6 m/s in the wind speed change rate. At 100 m of altitude, the wind speed in the suburban region is reduced by approximately 40%.

РУХ ПРОТИ ЯДЕРНОЇ ЕНЕРГЕТИКИ У США: ВІД АВАРІЇ НА ТРИ-МАЙЛ-АЙЛЕНД ДО ЧОРНОБИЛЬСЬКОЇ КАТАСТРОФИ

The purpose of the research is to highlight the formation and development of the movement against nuclear energy in the USA in the 1970s and 1980s. The research methodology is based on the principle of historicism and problem-chronological and complex approaches. We used the following methods: historical and systemic – in the process of considering the movement against nuclear energy in the USA as an integrated part of the social activity of the American public in the period of the 1970s – 1980s; historical-chronological – to identify features and changes in the dynamics of the movement against atomic energy; problem-genetic – in the study of the impact on the movement of key incidents in atomic energy; comparative – to establish common and different forms, character and activity of anti-nuclear power protest organizations in the USA. The scientific novelty of the article. For the first time in Ukrainian historiography, an attempt was made to investigate the origins of the movement against nuclear energy in the USA, its dynamics and key events as one of the largest social phenomena of the country in the 1970s and 1980s. In the example of the Three Mile Island station district, the development of protest organizations and the strategy of rallying American society in the conditions of a radiation incident is traced; the impact of the Chornobyl disaster on the activation of the movement against nuclear energy in the USA was revealed. The article also shows the impact of anti-nuclear public activism on the social and political sphere of the USA. Conclusions. An organized movement against nuclear energy emerged in the mid-1970s as opposition to the development of the U.S. civilian nuclear program. The Three Mile Island incident in March 1979 undermined social confidence in the industry, fueling anti-nuclear activism. The Chornobyl disaster in Ukraine on April 26, 1986, mobilized and consolidated the movement against nuclear energy in the United States, finally halting the development of the industry for more than 30 years.

Lower tropospheric states revealed in high vertical-resolution radiosonde data in Korea and synoptic patterns for instability based on a self-organizing map

Seasonal and spatial characterizations of wind and stability in the lower troposphere below 1500 m are investigated using 1 s high-resolution operational radiosonde data observed at five stations (Baengnyeongdo, Heuksando, National Typhoon Center (NTC), Bukgangneung, and Pohang) in South Korea for 4 years (July 2016–June 2020), concentrating on four variables: horizontal wind speed (HWS), vertical wind shear (VWS), squared Brunt–Väisälä frequency (N2), and Richardson number (Ri). Significant seasonal variations are identified in these variables due to the heterogeneity of the geographical locations as well as seasonal variations in the synoptic patterns. VWS is high in spring and summer at two island stations on the west of the Korean Peninsula, Baengnyeongdo, and Heuksando, whereas it is high in winter at NTC, Bukgangneung, and Pohang, leading to frequent Kelvin–Helmholtz (KH) instability (KHI; 0 ≤ Ri < 1/4). Below z = 1000 m, static stability is lower in winter than in summer at all stations, resulting in a higher convective instability (Ri < 0) in winter, which is attributed to the inflow of the marine boundary layer. The frequent convective instability observed in spring at Bukgangneung suggests a potential relationship with mountain wave breaking and downslope windstorms. The microstructures of the lower tropospheric instabilities revealed in the current radiosonde observations are not properly represented in the high-resolution local numerical weather prediction and analysis system, namely local Data Assimilation and Prediction System (LDAPS) of Korea Meteorological Administration. In particular, the observed convective and KH instabilities, which are approximately 45% for the whole period, are rarely (approximately 15%) represented in LDAPS. The synoptic patterns favorable for the convective and KH instabilities cases are identified based on a self-organizing map clustering algorithm: (1) west-high and east-low patterns with extended Siberian high in winter, (2) strong low-pressure systems susceptible to KHI from spring to fall, (3) weak high-pressure systems with potential convective instability, accompanying northerly or north-westerly flows with cold advection at 925 hPa.

Variability of biothermal conditions in the vicinity of the Polish Antarctic station in the South Shetlands, West Antarctica

There are nine year-round and 11 seasonal scientific stations in the South Shetland Islands, an area often visited by cruise ships and sailing yachts. Although this is the warmest part of Antarctica, the weather conditions may be demanding for humans. We analysed the variability of biothermal conditions near Henryk Arctowski Station Polish Antarctic Station, on King George Island, during the period 2013–2021, using the wind chill index (WCI), which combines air temperature and wind speed, to determine thermal sensation. WCI values were interpreted using two cold sensation categorisations. Hourly WCI values were assigned to thermal sensation classes that ranged from “comfortable” to “frosty.” The most favourable biothermal conditions occurred from December to February. The “cold” sensation was dominant in all months, its average occurrence frequency ranging from 56.4% (in January) to 84.4% (in July). From November to March, there was no risk of frostbite to uncovered body parts. Such conditions occurred only from April to October, with a frequency of 0.2–6.8%; biothermal conditions were also the most variable in this period. Maximal WCI hourly values show that dangerous weather conditions may occur throughout the day in June and for most of the day from July to September. An abrupt change in biothermal conditions was more often caused by wind speed change than by air temperature change. The most marked WCI changes occurred from April to September, on average five times per year. Our results indicate that biothermal conditions in the vicinity of Arctowski Station are predominantly favourable for outdoor work only if a person wears proper winter clothing.

Towards improved seasonal rainfall prediction in the tropical Pacific Islands

The El Niño Southern Oscillation (ENSO) is a major influence on interannual variability of rainfall in stations in the tropical southwest Pacific. Predictions of seasonal rainfall, especially a season or two ahead, are of great value to these countries. This paper therefore examines the correlations over ~ 60 years between seasonal rainfall and 8 ENSO indicators at 16 island stations, allowing for lead times. The results show the influence on rainfall of the position and movement of the South Pacific Convergence Zone (SPCZ) during ENSO events, and that the Southern Oscillation Index (SOI), the sea surface temperature anomaly in the central Pacific (Niño 3.4), and the warm water volume in the eastern Pacific (WWV1) have longer lead times compared to most other ENSO indicators. These indicators can therefore be used with confidence in SCOPIC, a widely used statistical tool for prediction of seasonal rainfall. (As global climate models generally have systematic errors in their depiction of the SPCZ, they cannot yet be used directly to reliably predict seasonal rainfall in this region.) For several sites near the SPCZ, we find that a moderately good forecast of rainfall in both spring and summer can be made from indicators measured in June–July (i.e., 3–6 months in advance.)

The Relationship Between Wind, Waves, Bathymetry, and Microseisms in Yellowstone Lake, Yellowstone National Park

AbstractWe conducted a multidisciplinary geophysical experiment to study the relationship between wind, waves, bathymetry, and microseisms in Yellowstone Lake—a small, isolated body of water in which wind‐driven gravity waves excite low‐amplitude seismic energy at periods ∼1.0 s with a regular daily pattern. During 25 June–4 August 2018, we deployed 40 short‐period seismometers, four meteorological stations, and two wave gauges in and around Yellowstone Lake. These instruments were complemented by seven permanent seismometers on the lake perimeter, and a contemporaneous deployment of 10 lake bottom seismometers (LBS) on the floor of the north‐central portion of the lake. The daily wind cycle, with southwesterly winds rising from ∼0 m/s in the early morning to maxima of 10–15 m/s in the late afternoon, generated lake waves with significant heights of ∼0.3–0.4 m and dominant periods of 1.5–2.5 s, which in turn generated microseisms with dominant periods of ∼0.8–1.2 s, in excellent agreement with the double‐frequency generation mechanism. Microseism energy was strongest on the lake floor stations, followed by the island stations and those along the northeastern coast of the lake, suggesting that these sites are closest to the source region where interference between incident and shoreline‐reflected waves is responsible for microseism generation. Smaller amplitude single‐frequency microseism energy was observed primarily along the northeastern lake shoreline. Both types of microseism energy are sensitive to shoreline morphology and lake wave dynamics, such that long‐term monitoring of lake microseisms may further our understanding of how these processes change over time.

The Study of Wind Field ERA-20C in Monsoon Domains for Rainfall Predictor in Indonesia (Java, Sumatra, and Borneo)

In recent years, various research institutions have developed diverse global data reanalysis projects. This provides an opportunity to gain long-term of meteorological data for local scale. This study aims to select the potential predictor of wind fields u and v of the ERA-20C dataset, a reanalysis dataset, at 850 mb from seven domains or windows of Asian, Maritime Continent, Australian, and Western North Pacific monsoon related physically to rainfall anomaly patterns in Indonesia. The vector wind velocity scalar was obtained by using a Helmholtz decomposition to separate the total circulation v = (u,v) into the divergent component/velocity potential (χ) or Phi and rotational component/stream function (ψ) or Psi for obtaining the scalar variable of vector wind velocity. The method applied Singular value decomposition (SVD) to identify pairs of spatial patterns (expansion coefficients) between the predictors of Phi and Psi in seven domains, with rainfall data from 48 stations in Java, Sumatra, and Borneo Islands from 1981 to 2010. The results revealed that spatial patterns correlations of Java Islands were the highest in the Maritime Continent monsoon domain (80o−150o E and 15oS−15o N), while Sumatra and Borneo Island were in the Western North Pacific monsoon domain (100o–130o E and 5o–15o N) with predictor Psi. The lowest correlation for Java, Sumatra, and Borneo was the Australian monsoon domain (110o E–130o E and 5o S–15o S) with predictor Phi. In general, spatial pattern correl-ations of Java Island were higher than others, agreeing with monsoonal rainfall type dominantly in the region.

Characteristics of the Oceanic Ambient Seismic Noise Around Tristan da Cunha in the South Atlantic From OBS Data

AbstractIt has long been recognized that specific ambient seismic noise is generated within the ocean. Therefore, ocean bottom seismometers have advantages to reveal the noise characteristics directly in the deep sea. We use the seismic recordings around Tristan da Cunha collected by 20 OBSs and two island stations to investigate the ambient noise sources in the middle of the South Atlantic. We analyzed the power spectral density, ambient noise cross‐correlations, and correlations with wave heights model. While primary microseisms (∼10–20 s) in this region are deficient, the secondary microseisms are strong and dominate the ambient noise at periods of ∼1–10 s, with the peak broadening to shorter periods (1–3 s). The secondary microseisms are strongly correlated with the local wave heights, especially at shorter periods (∼1–3 s), suggesting that the microseisms are affected mostly by local wave interactions. We observed clear Empirical Green's functions at periods of ∼3–10 s, indicating the existence of distant sources of secondary microseisms. Results of asymmetry analysis of cross‐correlations suggest the prominent direction of the distant source should be located to the Southwest and show barely seasonal variations. The correlations with wave heights indicate a possible source region in the southeast Pacific Ocean. Therefore, besides the dominating local wave‐wave interactions, the secondary microseisms around Tristan region are affected simultaneously by persistent distant sources from the deep basin in the Southeast Pacific Ocean, which might be related to the intense wave‐wave interactions caused by the blocking effect of the Drake Passage on ocean currents and waves.

Seismometer Orientation Correction via Teleseismic Receiver Function Measurements in West Africa and Adjacent Islands

AbstractTo establish a robust method of determining and correcting the misorientation of seismometers with radial and tangential components of the teleseismic receiver function (RF), we assess the measurement of the amplitude of P-wave phase arrivals at zero seconds (PRFamp method) and the energy of the width of the time window around the P-wave phase arrival (PRFenergy method) using varying Gaussian factors, ranging from 0.5 to 5.0 with equivalent cutoff frequencies. To understand the efficacy and discrepancies in these methods, and their results across different geological terrains, we conduct an assessment of their performance on 26 permanent seismic stations located in West Africa and adjacent islands. We conduct several tests to examine the effect of varying Gaussian factors on the estimates of misorientation. These effects are more noticeable in results from stations for which RFs are indicative of 3D or complex structures and islandic stations. Statistical analyses reveal good correlation between the results obtained from both the methods, although results from PRFamp method proves to be more stable due to their proximity to the statistical mean and standard deviation results. In comparison with the PRFenergy results, there is a smaller error difference and uncertainty, a higher correlation coefficient, a relatively lower standard deviation, and better convergence around the mean misorientation obtained using PRFamp. From both the methods, estimates from continental stations reveal similar trends, results from coastal stations tend to be consistent, whereas some island stations show a reverse trend in sensor misorientation classification. We propose that the PRFamp yields more consistent results and is less sensitive to subsurface heterogeneities. Gaussian filtering with an alpha value (α) of 1.5 is recommended as a trade-off between oversimplification and complications due to subsurface structures. However, we suggest that multiple approaches be adopted to provide robust bases for the estimation and comparison of sensor orientation correction calculations.

Климатические характеристики туманов восточного побережья Каспийского моря и их изменения с 1970 по 2020 г.

In the Caspian Sea, fogs of varying intensity are observed throughout the year. The research aimed to determine the number of days with fog and their duration (in hours) for each month from 1970 (1986) to 2020 at four meteorological stations: Kulaly Island, Fort Shevchenko, Tushchibek, and Aktau. The study included statistical analysis and assessment of climate change in the form of fog indicator longterm series approximation based on two non-stationary average models, including the evaluation of their efficiency and statistical significance. The assessment of climate change revealed the most significant reductions at the Tushchibek and Fort Shevchenko Stations, with decreased fog conditions observed in summer and autumn. At the Kulaly Island Station, the changes were detected in autumn; and were practically absent at the Aktau Station.

Bayesian regional moment tensor from ocean bottom seismograms recorded in the Lesser Antilles: implications for regional stress field

SUMMARY Seismic activity in the Lesser Antilles (LA) is characterized by strong regional variability along the arc reflecting the complex subduction setting and history. Although routine seismicity monitoring can rely on an increasing number of island stations, the island-arc setting means that high-resolution monitoring and detailed studies of fault structures require a network of ocean bottom seismometers (OBS). As part of the 2016–2017 Volatile recycling at the Lesser Antilles arc (VoiLA) project, we deployed 34 OBS stations in the forearc and backarc. During the deployment time, 381 events were recorded within the subduction zone. In this paper, we perform full-waveform regional moment tensor (RMT) inversions, to gain insight into the stress distribution along the arc and at depth. We developed a novel inversion approach, AmΦB—‘Amphibious Bayesian’, taking into account uncertainties associated with OBS deployments. Particularly, the orientation of horizontal components (alignment uncertainty) and the high noise level on them due to ocean microseisms are accounted for using AmΦB. The inversion is conducted using a direct, uniform importance sampling of the fault parameters within a multidimensional tree structure: the uniXtree-sampling algorithm. We show that the alignment of the horizontal OBS components, particularly in high noise level marine environments, influences the obtained source mechanism when using standard least-squares (L2) RMT inversion schemes, resulting in systematic errors in the recovered focal mechanisms including high artificial compensated linear vector dipole (CLVD) contributions. Our Bayesian formulation in AmΦB reduces these CLVD components by nearly 60 per cent and the aberration of the focal geometry as measured by the Kagan angle by around 40 per cent relative to a standard L2 inversion. Subsequently, we use AmΦB-RMT to obtain 45 (Mw &amp;gt; 3.8) regional MT solutions, out of which 39 are new to any existing database. Combining our new results with existing solutions, we subsequently analyse a total of 151 solutions in a focal mechanism classification (FMC) diagram and map them to the regional tectonic setting. We also use our newly compiled RMT database to perform stress tensor inversions along the LA subduction zone. On the plate interface, we observe the typical compressional stress regime of a subduction zone and find evidence for upper-plate strike slip and normal fault behaviour in the north that becomes a near arc-perpendicular extensional stress regime towards the south. A dominant slab perpendicular extensional stress regime is found in the slab at 100–200 km beneath the central part of the arc. We interpret this stress condition to be a result of slab pull varying along the arc due to partial slab detachment along previously hypothesized lateral slab tear near Grenada, at the southern end of the LA arc, leading to reactivation of pre-existing structures around the subducted Proto-Caribbean ridge.

Heat deficit mitigation strategies for elevated rail stations in cold regions of China based on thermal comfort assessment

The elevated station of rail transit is different from the conventional underground stations; such buildings are complex in space form. In the cold region in winter, the elevated station is greatly affected by the outdoor climate environment, and passengers feel cold, so it is urgent to improve its thermal environment. In this paper, taking the Xi'an rail transit elevated stations in China as the research objects, the internal environment investigation and thermal comfort assessment of the elevated station were carried out by using subjective survey questionnaire combined with field monitoring. The thermal design temperature in elevated stations in winter in cold areas was determined by calculating change process of passengers' heat deficit rate (HDR). And then the heat deficit mitigation strategy of elevated stations in winter in cold areas was put forward, and the rationality and reliability of the strategy were verified Through the corresponding simulation. The field measurement results show that the temperature of the investigated stations is lower than the threshold of cold sensation, and the air flow rate is significant. The temperature of side station is lower than that of island station. The questionnaire results show that passengers who want to reduce the wind speed generally vote for the temperature to increase simultaneously. By analysing the change of thermal deficit rate in the whole process of passengers entering the station, it is found that for two kinds of stations in the platform layer the heat deficit rate reaches a peak, which is −50.7 W/m2 and −53.2 W/m2, respectively. It is found that the appropriate temperature range to meet the requirements of thermal comfort should be 14.8 °C–20.8 °C. The simulation results indicated that the temperature in platform can be raised from the current 3.6 °C–6.8 °C–11.3 °C–13.6 °C by using the fully enclosed platform combined with thermal insulation system proposed. In order to reach to the minimum requirement of 14.8 °C in the station in winter, the station temperature can be further improved by optimizing the enclosure structure or installing additional air conditioning system to reach the comfort requirement. This study provides reliable basic data for the mitigation of heat deficit and developing a standard design for elevated stations.

Earth’s Upper Crust Seismically Excited by Infrasound from the 2022 Hunga Tonga–Hunga Ha’apai Eruption, Tonga

AbstractRecords of pressure variations on seismographs were historically considered unwanted noise; however, increased deployments of collocated seismic and acoustic instrumentation have driven recent efforts to use this effect induced by both wind and anthropogenic explosions to invert for near-surface Earth structure. These studies have been limited to shallow structure because the pressure signals have relatively short wavelengths (&amp;lt;∼300 m). However, the 2022 eruption of Hunga Tonga–Hunga Ha’apai (also called “Hunga”) volcano in Tonga generated rare, globally observed, high-amplitude infrasound signals with acoustic wavelengths of tens of kilometers. In this study, we examine the acoustic-to-seismic coupling generated by the Hunga eruption across 82 Global Seismographic Network (GSN) stations and show that ground motion amplitudes are related to upper (0 to ∼5 km) crust material properties. We find high (&amp;gt;0.8) correlations between pressure and vertical component ground motion at 83% of the stations, but only 30% of stations show this on the radial component, likely due to complex tilt effects. We use average elastic properties in the upper 5.2 km from the CRUST1.0 model to estimate vertical seismic/acoustic coupling coefficients (SV/A) across the GSN network and compare these to recorded observations. We exclude many island stations from these comparisons because the 1° resolution of the CRUST1.0 model places a water layer below these stations. Our simple modeling can predict observed SV/A within a factor of 2 for 94% of the 51 non-island GSN stations with high correlations between pressure and ground motion. These results indicate that analysis of acoustic-to-seismic coupling from the eruption could be used to place additional constraints on crustal structure models at stations with collocated seismic and pressure sensors. Ultimately, this could improve tomographic imaging models, which rely on methods that are sensitive to local structure.

Dynamic Response Analysis on Stress and Displacement of the Shield Tunnel Structure and Soil Layer under Train-Induced Vibration in Xiamen Metro Line 6

Tunnel engineering develops rapidly. To study the dynamic response of shield tunnel structure and its bottom soil layer caused by metro train operation, a three-dimensional finite-difference dynamic calculation method is used to establish a shield tunnel-soil layer coupling model based on the shield tunnel project of Maluan Central Station-Jimei Island Station of Xiamen Metro Line 6, and the dynamic response of tunnel structure and its bottom soil layer caused by metro train operation is calculated. The results show that: Under the action of train-induced vibration, the shield tunnel structure mainly bears compressive stress and generates compressive deformation. The dynamic response of tunnel structure represents a significant increasing trend with the enhancement of train-induced vibration load. Under the same load strength, dynamic response change amplitude of structure is not obvious with tunnel structural stiffness, stress is gradually increasing, and displacement is weakening. The deeper the soil depth at the bottom of the shield tunnel structure, the weaker the dynamic response of the soil layer. The stress response of the soil layer at the same depth is increasing with the train-induced vibration load improving, but the displacement response has a stage characteristic. The dynamic response of the soil layer at the same depth does not change obviously with the increase in shield tunnel structural stiffness, but the stress response gradually increases, and the displacement response becomes weak. In general, investigation of the dynamic response of the subway shield tunnel under train-induced vibration has important practical significance for maintaining the long-term safe operation of subway tunnels.

Abundance, Species Diversity, and Conservation Status of Reef Fishes in Dumanquillas Bay, Zamboanga, Philippines

Zamboanga is one of the significant fishing grounds in the Mindanao Region, but little is known about the conservation status of reef fishes, particularly in Dumanquillas Bay, Zamboanga. Thus, this study assessed the abundance, species diversity, and conservation status of reef fishes in the bay. The assessment was conducted within eight sampling stations from May 6 to May 16, 2014. Reef fishes were censused using a line-intercept method. Fourteen thousand fifty individuals and 140 fish species belonging to 30 families were recorded―dominated by the family Pomacentridae. The number of fish individuals was significantly more abundant in Triton Island Station than in other sampling stations, while Muyong Island has the most diverse reef fishes. Almost all species are classified as the least concern category, except for Plectropomus areolatus of Cabog Island, which is under the vulnerable (VU) category. The number of less-valued species was higher than the commercially high-valued species. Therefore, it may indicate the overharvest of the latter group of species. This comprehensive study on reef fishes in Dumangquillas Bay may serve as a reference for fisheries resource management planning or for drafting fisheries policies in the bay.