Land-sea Boundary Research Articles

Estimation of IFOV Inter-Channel Deviation for Microwave Radiation Imager Onboard FY-3G Satellite

The Microwave Radiation Imager (MWRI) onboard the FengYun satellite plays a crucial role in global change monitoring and numerical weather prediction. Estimating and correcting geolocation errors are important to retrieving accurate geophysical variables. However, the instantaneous field of view (IFOV) inter-channel deviation, which is mainly caused by the structure mounting error and measurement error of feedhorns, is less studied. In this present study, we constructed a general theoretical model to automatically estimate the IFOV inter-channel deviations suitable for conical-scanning instruments. The model can automatically detect the along-track and across-track vectors that pass through the land–sea boundary points and are perpendicular to the actual coastlines. Regarding the midpoints of the vectors as the brightness temperature (Tb) inflection points, the IFOV inter-channel deviation is the pixel offset or distance of the maximum gradients of the Tb near the inflection points for each channel relative to the 89-GHz V-pol channel. We tested the model’s operational performance using the FY-3G/MWRI-Rainfall Mission (MWRI-RM) observations. Considering that parameter uploading adjusted the IFOV inter-channel deviations, the model’s validity was verified by comparing the adjustments calculated by the model with the theoretical changes caused by parameter uploading. The result shows that the differences between them for all window channels are less than 100 m, indicating the model’s effectiveness in evaluating the IFOV inter-channel deviation for the MWRI-RM. Furthermore, the estimated on-orbit IFOV inter-channel deviations for the MWRI-RM show that all channel deviations are less than 1 km, meeting the instrument’s design requirement of 2 km. We believe this study will provide a foundation for IFOV inter-channel registration of passive microwave payloads and spatial matching of multiple payloads.

The impact of high rainfall events on the submesoscale salinity field in a coastal sea: Greater Cook Strait, New Zealand

ABSTRACT River inflow into the coastal oceanic environment can result in low salinity submesoscale features (LSMFs). The enhanced water column stability sustained within these coherent structures affects local biological productivity. With-event and seasonal variability of LSMFs were investigated in a coastal sea -- Greater Cook Strait -- that is characterised by strong tidal and wind forcing as well as being forced at the land-sea boundary by several major rivers. A combination of ocean glider and satellite observations revealed the existence of seasonal variability in temperature, chlorophyll and stratification in LSMFs. High rainfall from ex-cyclone enhanced production of LSMFs in seasons when they would otherwise be less frequent. Stronger stratification was observed at the end of spring, in summer and at the beginning of autumn both in ambient shelf conditions and within LSMFs. Subsurface chlorophyll-a maxima were found associated with summer and spring LSMFs, when temperature had a stronger contribution to vertical stratification. In the available samples, LSMFs were advected seawards when river discharges exceeded 600 m 3 s − 1 . When river flows were lower than this threshold, other drivers such as wind or currents were required to advect the observed LSMFs offshore.

Cross-boundary effects of human impacts on animal assemblages in the coastal zone

Human impacts on ecosystems often transcend ecosystem boundaries and environmental realms, complicating ecosystem assessment, conservation, and management. Whether and how different impacts affect ecosystems in distinct but adjacent domains remains untested in many settings, and is rarely tested concurrently at the same spatial scales. In this study, we quantified the effects of coastal urbanisation on the structure of terrestrial coastal vertebrate assemblages (including birds, reptiles and mammals using baited trail cameras) and marine surf zone fish assemblages (using baited underwater videography) at 100 sites along 50 km of beach in eastern Australia. Sites occurred along a gradient of intensities of urban land conversion in the hind dunes. While the effects of urbanisation on the species sampled were pervasive across both ecosystems, the area of urbanised land mattered more for the coastal vertebrates observed, while proximity to urbanised land was more important for the surf zone fish observed. Here, fewer individuals and species of coastal vertebrates were found at sites with a greater extent of urbanised land within 5 km. Conversely, fish assemblages were more diverse in the surf zones abutting urban areas and more abundant at sites approximately 150 m from urbanised land. The spatial properties of these landscapes, including proximity to headlands for coastal vertebrates and reefs for fish, modified the effects of urbanisation. Our findings suggest that urbanisation can have ecologically nuanced effects that are detectable across the land-sea boundary, and stress the importance of landscape context when assessing and conserving animal assemblages in and around coastal cities.

SEVERE CYCLONIC STORM SITRANG: A METEOROLOGICAL ANALYSIS OF ITS FORMATION, INTENSITY, AND IMPACT ON BANGLADESH

Employing a non-central difference method of lines in tandem with the 4th order Runge-Kutta technique, this study adopts a sophisticated computational approach, ensuring precision and efficiency to resolve the shallow water equations and predict water levels caused by a cyclone in the coastal area of Bangladesh. To discretize spatial derivatives, a 4-point backward finite difference method utilized while keeping time derivatives continuous. The authors transformed the shallow water equations with boundary conditions into an initial value problem and used the Runge-Kutta(4,4) method for solving this transformed initial value problem. To effectively include the land-sea boundary and bottom structure at a reasonable charge, the authors used a high-resolution approach. To create a regular and stable tidal oscillation in the area, the authors applied the tidal component to the southern boundary of the primary model. Then ran the surge model to estimate water elevations caused by the nonlinear interaction between tide and surge. Using numerical experiments, the authors simulated water heights generated by tide, pure surge, and tide surge interaction caused by the intense cyclonic storm SITRANG. The study's simulated results demonstrate a commendable alignment with the reported data.

THE IMPACT SHORELINE MODIFICATIONS ON LEKANG TURTLE (Lepidochelys olivacea) CONSERVATION ALONG COASTAL OF KULONPROGRO, INDONESIA

Changes in oceanographic circumstances that continue to occur will generate challenges for coastal ecology, one of which is a change in the sea-land boundary. It is possible to have an impact on the olive ridley turtles that rise to lay their eggs by changing the region of this coastal area, particularly at Trisik Beach, Kulonprogo, and Yogyakarta Special Region. The goal of this study was to use a Geographic Information System to estimate the effect of changes in the coastline on the distribution of olive ridley turtles on Trisik Beach, Kulon Progo, and Yogyakarta Special Region in 2020-2022. Digitizing the shoreline reveals changes in the coastline, which is then analyzed using Landsat 8 satellite data retrieved with ArcGIS software. The Landsat 8 photos span the years 2020-2022. Using the Digital Shoreline Analysis System (DSAS) toolbox, each image will go through area cropping or image cutting, geometric and radiometric correction, demarcation or development of a land-sea boundary line, on-screen digitalization, and automatic calculation of coastal changes. Trisik Beach's coastline alterations from 2020 to 2022 tended to create abrasion due to the shrinking beach area. The greatest average distance to a coastline alteration was -29.61 m, the smallest was -15.03 m, and the average speed of the greatest abrasion is -8.26 m/year, the smallest is -4.19 m/year, resulting in a 111,967.03 m2 reduction in coastal area. The association between shoreline alterations and the distribution of olive ridley turtle nesting on Trisik Beach is quite significant, with the beach area affecting 91.3% of turtle nests and 88.5% of turtle eggs.

Devonian diamond reservoir of the Urals

Research subject. The Takata formation of the Emsian tier of the Lower Devonian (D1tk) in the Urals is a reservoir of Devonian diamonds. Aim. Confirmation and determination of the diamond-bearing conditions of the reservoir. Materials and Methods. Generalization of primary and interpreted geological information. Lithofacial analysis. Historical and geological reconstruction. Cartographic analysis and geological and cartographic modeling in the ArcMapESRY GIS environment using the ModelBuilder module. Results. The Takata formation is part of the Emsian tier of the Lower Devonian. Tectonically, the Takata formation is located in the West Ural Folded Zone. The diamond content in the Urals is spatially related to the outputs of the Takata formation. The industrial diamond-bearing capacity and the highest density of diamond placers are located in the Vishersky, Chykmansky and Chusovskoy diamond-bearing regions of the Northern and Middle Urals within the Perm Krai. In the early Devonian, the Takata Sea existed in the Vishera diamond-bearing area; a large river with a delta flowed in the direction from northwest to southeast. The sediments of the formation comprise the facies cycle: flood-plain - channel alluvium - delta sediments - underwater-delta - marine sediments. Diamonds are concentrated in the thickness of coarse-grained alluvium, small-pebble basal conglomerates that formed on the land-sea boundary of the paleocontinent of the Russian Plate. Three facies types of the Takata formation section are distinguished: continental, coastal-marine and marine. Its diamond-bearing capacity is associated with the continental and coastal-marine sediments of the formation within the Perm Region. To the north and south of the diamond-bearing areas of the Perm Krai, the Takata formation is represented by marine sediments. According to the geodynamic model based on the geological section of the Northern Urals, the alluvial and coastal-marine Takata diamond placers were formed in the early Devonian as a result of the demolition of material from the Russian Plate. The sources of destruction were rocks of the Precambrian, Ordovician and Silurian. The main spatial-geomorphological criterion for searching for diamond-bearing conglomerates of the Takata formation is the maximum distance of demolition from these conglomerations to placers, equal to 500 m.

High black carbon episodes over a polluted metropolis near the land-sea boundary and their impact on associated atmospheric dynamics.

The present investigation outlines the crucial factors that influence the black carbon (BC) concentrations over a polluted metropolis, Kolkata (22.57°N, 88.37°E), India. Located in the eastern part of the Indo Gangetic Plain (IGP) outflow region and close to the land-ocean boundary, Kolkata is subject to contrasting seasonal maritime airflow from the Bay of Bengal and continental air mass from the IGP and Tibetan plateau region, which modulates the local concentration of BC. The origin of aerosol transport and associated atmospheric dynamics with high and low BC activities over Kolkata are examined during 2012-2015 using data from multi-technique sources which include measurements of ground-based instruments of aethalometer and multi-frequency microwave radiometer, reanalysis data from ERA-5 and MEERA-2, and model outputs from HYPSLIT back trajectory model simulations. The study highlights the control of IGP wind inflow on the occurrence of anomalous enhancements in BC concentration during weekends and holidays when local emissions are low. High BC events are associated with enhanced atmospheric heating below the boundary layer (2000m) and significant negative surface radiative forcing. The response of the boundary layer to high and low BC episodes, shown in the diurnal variation in comparison with the seasonal mean, is investigated. Dominant suppression of morning and night-time boundary layer height is observed on high BC days. During the daytime in pre-monsoon, post-monsoon, and winter seasons, boundary layer height peaks are found to be strongly controlled by high BC episode occurrences as obtained from the hourly data of ERA-5.

Climatological characteristics of nocturnal eastward‐propagating diurnal precipitation peak over South India during summer monsoon: Role of monsoon low‐level circulation and gravity waves

AbstractThis study explores the climatological diurnal cycle of precipitation during the summer monsoon season over southeast India using the Tropical Rainfall Measuring Mission (TRMM) 3G68 precipitation product from 2000 to 2014. The primary area of focus is the leeward side of the Western Ghats. We found that the climatological diurnal cycle over this area exhibits a bimodal peak with an afternoon/evening peak near the eastern slopes of the Western Ghats and a nocturnal peak near the southeast coast. This nocturnal peak near the southeast coast propagated offshore in the eastward direction with a phase speed of 18–20 m s−1 and attained an offshore peak in the late night/early morning. The afternoon diurnal peak is associated with daytime convection and propagates eastward over southeast India. The nocturnal peak is due to the convergence of intensified monsoon low‐level westerly winds along the land–sea boundary over the leeward side and supports the nocturnal diurnal peak to cross the coast at late night. The eastward‐propagating gravity waves support further eastward offshore propagation of nocturnal diurnal precipitation patterns. Altogether, the leeward‐side climatological diurnal peaks and diurnal variability in southeast India are controlled by complex precipitation types and their formation mechanisms due to monsoon low‐level westerly winds and gravity waves.

How much city is too much city? Biodiversity and ecosystem functioning along an urban gradient at the interface of land and sea

A huge proportion of the world’s population resides in urban areas along the coast. As cities expand, the ability of coastal ecosystems to provide the benefits people derive from nature, ranging from food from fisheries to coastal defense to maritime transportation and beyond, is in question. While it is well understood that coastal development changes ecosystems, quantitative insights about how terrestrial urbanization fundamentally alters ecosystem structure and function in adjacent freshwater and downstream coastal marine habitats remain rare, though a general expectation is that impacts of terrestrial urbanization will attenuate from land to freshwater to coastal marine habitats. Empirical assessments of these phenomena are especially important for species that rely on freshwater and coastal marine habitats at multiple points in their life cycles, including endangered and threatened Pacific salmon (Oncorhynchus spp.). We investigated associations between landscape-scale urbanization and ecosystem structure (biodiversity of epibenthic invertebrate taxa) and function (benthic net primary productivity and decomposition) in freshwater and coastal marine habitats across six pairs of more and less urbanized, coastal watersheds in Puget Sound, WA, USA, using principal components analysis, analysis of covariance, and Mantel tests. Greater upland urbanization was associated with greater reductions in freshwater biodiversity, measured as the density and evenness of epibenthic invertebrate families. In contrast and surprisingly, however, coastal marine biodiversity (measured as the density and evenness of epibenthic invertebrate families) tended to be higher at more urbanized sites, suggesting the potential role of low to moderate levels of urbanization-related disturbance in determining coastal marine biodiversity patterns. We found no statistical association between urbanization and freshwater and coastal marine ecosystem functions, estimated from changes in accumulated algal biomass on tiles (benthic net primary productivity) and loss of biomass from litter bags (decomposition). In addition, there was no evidence that changes in ecosystem structure and function with urbanization were more severe in freshwater than coastal marine habitats, as might be expected if the land-sea boundary diminished effects of landscape-scale urbanization. Our results suggest that the effects of urbanization can be complex and that attention to terrestrial, freshwater, and coastal marine systems in concert will produce more effective, ecosystem-based management.

Example of Coastline Changes from the Last Glacier Maximum to the Present: Çanakkale Strait

Climate change emerges as an important problem for the earth today. Although the negative effects of this problem are not directly reflected in the time we live in, it is revealed by the scientists working on the subject that it will be observed in human life for decades-centuries and will be observed in detail on the earth for thousands of tens of thousands of years later. This predicted climate change can be considered a normal situation when considering the time that has passed from the formation of the earth to the present, approximately 4.5 billion years (except that the difference between the reasons for climate changes in the past geological times and the predicted climate change is the human effect). The effects of Quaternary climate change can be observed on the earth both on a global scale and on a regional scale. As an example of global climate change, the continuous change of sea level can be given, and the best indicators of this change are geological/geomorphological structures such as marine terraces or submarine canyons observed on the coasts on the regional scale. On the local scale, stalactites and stalagmites observed in caves, lake sediments, deep sea sediments, glacial cores are among the best examples of climate change. In this study, the land-sea boundary (coastal line) changes of the coasts of the Çanakkale Strait, which is the southern branch of the Turkish Straits System, have been investigated, considering the sea level changes that show the climate change best in the last 25 thousand years. In this context, the coastal changes of the Çanakkale Strait coasts from the Late Pleistocene to the present are modeled using geographic information systems programs, by using different global and regional sea level change charts showing climate changes. The most striking of these new maps is the one from 20 thousand years ago. At this time, it is known that the global sea level is 120 meters lower than today and the deepest point of the Çanakkale Strait is around -113 meters today. Therefore, it is not possible to mention a Mediterranean-Black Sea waterway connection through the Çanakkale Strait at these times.

Long-Term Impact of Continental and Maritime Airflow on Aerosol Environment and Rain Microstructure Near Land–Sea Boundary

The present study deals with the interplay of multiple atmospheric processes in changing the microphysical properties of precipitation during the pre-monsoon season (March–May) using the long-term experimental data of raindrop size distributions (DSDs) spanning over 15 years (2005–2019) obtained at an urban tropical location, Kolkata (22.57°N, 88.37°E), near the land–sea boundary. The changing pattern of air mass flows from the maritime and continental region, which contribute to the formation of precipitation processes, has been responsible for the varying characteristics of rain. Changes in raindrop sizes are related to aerosol properties, cloud features, temperature, and relative humidity that change mass-weighted mean drop diameter ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D_{m}$ </tex-math></inline-formula> ) differently in low and high rain rate regimes. <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D_{m}$ </tex-math></inline-formula> has shown an increasing trend over time for low rain rates (< 15 mm/h), but a decreasing trend for high rain rate regimes (≥15 mm/h). An increase (decrease) in mean temperature (relative humidity) below the atmospheric boundary layer (< 1.6 km) has enhanced the evaporation of small raindrops and altered rain microphysical features. Based on satellite observations, it has been found that the increasing aerosol optical depth (AOD) has been accompanied by an increase in cloud effective radius (CER), resulting in the anti-Twomey effect, which is due to the dominance of maritime influence over continental activities. Because of the predominant maritime activities, sea salt aerosols have a greater presence, causing an increase in CER, which consequently prevents raindrops from becoming large enough before they fall, thereby reducing <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D_{m}$ </tex-math></inline-formula> at high rainfall rates.

Rain drop size distribution analysis at a tropical location near land-sea boundary

Rain events can be characterized by rain drop size distribution (DSD) that denotes the number of drops as a function of diameter per unit size interval and per unit volume of space. DSD (at ground level) describes the microstructure of precipitation during different phases of rain varying both spatially and temporally. DSD can be influenced by the nature and origin of rain. The present study investigates the role of continental and maritime airflow in influencing the precipitation features near the land-sea boundary. The data of the rain DSD used in the present analysis are collected from a ground-based disdrometer located at Kolkata, India, near land-sea boundary during the year of 2011–2017. The dataset is divided into two categories, namely, maritime and continental rainfall, based on the airflow trajectories associated with rain events exclusively from Bay of Bengal or land region in the west of Kolkata as derived from TRAJSTAT software. The events with trajectories extending both over land and sea region are excluded for the present study. Variations of the DSD parameters using the gamma model are presented showing the abundance of smaller drops during maritime rain events whereas dominance of larger rain drops in the case of the continental rain events. The Z-R relations are also found to be significantly different for these two types of rain. The present study reveals the microstructures of rain at a location where the influences of both land and sea climatic features prevail.

Instabilities of low-latitude easterly jets in the presence of moist convection and topography and related cyclogenesis, in a simple atmospheric model

A simple two-layer model, the moist-convective rotating shallow water, which allows for low-cost high-resolution numerical simulations of the dynamics of the moist atmosphere in the presence of topography, is used to identify and understand dynamical processes governing the evolution of easterly waves propagating on the background of a low-latitude easterly jet crossing a land-sea boundary, a setup crudely representing the African Easterly Jet over the West-African plateau and the Atlantic ocean. We perform a thorough linear stability analysis and identify the unstable modes of the jet, which we use then for initialisation of fully nonlinear numerical simulations. In this way, we determine nonlinear evolution of unstable perturbations of the jet, both in the “dry” and moist-convective environments and highlight essential differences between the two cases. We identify a mechanism of formation of intense lower-layer cyclonic vortices at the northern flank of the jet and determine the influence of the land-sea contrast upon this process.

Simultaneous gravity measurements using two superconducting gravimeters to observe temporal gravity changes below the nm s−2 level: ocean tide loading differences at different distances from the coast

SUMMARY Gravity monitoring might require observation of temporal changes of gravity below the nanometre per second squared (nm s−2) level, which can be achieved by precise isolation of the signal of interest from all other disturbing effects. One method of signal isolation is elimination of disturbing effects by taking the difference between gravity changes measured simultaneously using two gravimeters installed close together. Herein, we describe differences in temporal gravity changes below the nm s−2 level in the tidal frequency bands as observed through simultaneous measurements taken with three superconducting gravimeters (SGs) located 80, 93 and 94 m from the coastline in Tomakomai, Hokkaido, northern Japan. Those changes are consistent with differences in ocean tide loading effects on gravity at the SG locations computed using the software package GOTIC2, which uses a highly accurate land–sea boundary and ocean tide model near our site. The observed ocean tide loading differences were found to result from Newtonian attraction of the ocean tide mass within an angular distance of 0.003° from the SG locations. This result suggests that coastal observations of differential tidal gravity variations at different distances from the coast help to validate ocean tide loading computation models in the immediate vicinity of the SG stations. This method enables observation of non-periodic gravity changes occurring below the nm s−2 level over a few hours. Its salient benefit is that rapid and simple observation can be achieved without long-term continuous measurements, which is necessary for observing that level of gravity change with only one SG.

Reduced Sea-Surface Roughness Length at a Coastal Site

Sea-surface roughness length is a key parameter for characterizing marine atmospheric boundary layer. Although aerodynamic roughness lengths for homogeneous land and open water surfaces have been examined extensively, the extension of relevant knowledge to the highly inhomogeneous coastal area is problematic due to the complex mechanisms controlling coastal meteorology. This study presented a lidar-based observational analysis of sea-surface roughness length at a coastal site in Hong Kong, in which the wind data recorded from March 2012 to November 2015 were considered and analyzed. The results indicated the turning of wind near the land-sea boundary, leading to a dominative wind direction parallel to the coastline and an acceleration in wind. Moreover, the roughness lengths corresponding to two representative azimuthal sectors were compared, in which the roughness lengths for the onshore wind sector (i.e., 120°–240°) appear to be larger than the constant value (z0 = 0.2 mm) recommended in much existing literature, whereas the values for the alongshore wind sector (i.e., 60°–90°) are significantly smaller, i.e., about two orders of magnitude less than that of a typical sea surface. However, it is to be noted that the effect of atmospheric stability, which is of crucial importance in governing the marine atmospheric boundary layer, is not taken into account in this study.

Shoreline Extraction in SAR Image Based on Advanced Geometric Active Contour Model

Rapid and accurate extraction of shoreline is of great significance for the use and management of sea area. Remote sensing has a strong ability to obtain data and has obvious advantages in shoreline survey. Compared with visible-light remote sensing, synthetic aperture radar (SAR) has the characteristics of all-weather and all-day working. It has been well-applied in shoreline extraction. However, due to the influence of natural conditions there is a problem of weak boundary in extracting shoreline from SAR images. In addition, the complex micro topography near the shoreline makes it difficult for traditional visual interpretation and image edge detection methods based on edge information to obtain a continuous and complete shoreline in SAR images. In order to solve these problems, this paper proposes a method to detect the land–sea boundary based on a geometric active contour model. In this method, a new symbolic pressure function is used to improve the geometric active-contour model, and the global regional smooth information is used as the convergence condition of curve evolution. Then, the influence of different initial contours on the number and time of iterations is studied. The experimental results show that this method has the advantages of fewer iteration times, good stability and high accuracy.

Analysis of properties of integral equations of the field in the aperture of an open coaxial probe

Acoustic sounding systems are an effective means of monitoring the lower troposphere. They find application in various fields of science and technology. The problem of developing acoustic methods and means for remote sensing of the lower atmosphere remains relevant given the importance of information on the state of the atmospheric boundary layer for the functioning of areas such as meteorology, ecology, transport, especially aviation, agriculture and others. This problem has both theoretical and technical aspects. These, for example, include solving inverse problems of sound propagation in a turbulent atmosphere, compensation for wind shear, and others. A number of companies and universities create acoustic locators – sodars and radio-acoustic sounding systems. The paper discusses their application for assessing the propagation conditions of radio waves on surface paths near the land-sea boundary. Despite the development of satellite systems for transmitting information and positioning, traditional means of communication and navigation are still in demand. They occupy their niche in the general nomenclature of radio equipment, while remaining indispensable in emergency warning systems, navigation in limited areas, in emergency situations. The effectiveness of these tools largely depends on operational information on the state of the propagation paths of radio waves. One of the most complex objects for assessing the propagation conditions of radio waves is the atmospheric boundary layer. Its condition is largely determined by the state of the underlying surface, which in turn depends on the time of day, season, rainfall and other factors. To date, only very limited theoretical models of dynamics have been created for some states of the atmospheric boundary layer despite the considerable efforts of meteorological specialists. Therefore, information is required on the spatial distribution of meteorological parameters. The most promising solution to this problem is the use of remote non-contact sensing methods based on one or another form of wave processes. Acoustic waves are significantly more sensitive to changes in air parameters than other types of radiation. The objectives of this work are to present a comprehensive methodology for using remote, non-contact sensing methods, theoretical representations of the dynamics of APS and modern software for solving problems of promptly determining the conditions of RRS on surface paths and assessing the most promising ways of developing methods and means for obtaining this information.An example of the experimental results of radio-acoustic sounding and sodar monitoring of the atmospheric boundary layer near the land-sea boundary is given. Based on these results, the spatial-temporal distribution of the index of refractive index is estimated. An analysis of the results is given. The choice of ways to develop means of acoustic sensing and processing the information received is substantiated, taking into account the progress of electronic devices and systems.

Size-segregated water-soluble N-bearing species in the land-sea boundary zone of East China

Size-segregated aerosol samples were collected in the land-sea boundary zone of East China, the offshore area of East China Sea (ECS), to determine the concentrations of water-soluble inorganic nitrogen (WSIN), water-soluble organic nitrogen (WSON), urea, and free amino acids (FAAs), to quantify their sources, and to estimate their dry deposition fluxes. The results indicated that the mean concentrations of WSIN, WSON, urea, and FAAs in total suspended particle (TSP) were 547.14 nmol/m3, 258.64 nmol/m3, 12.69 nmol/m3, and 2589.03 pmol/m3, respectively. The WSIN, WSON, and urea concentrations in TSP showed remarkably spatial variation with the higher one during the shipping line (SL) 1 and SL4, while they exhibited the lower ones during SL3 and SL5. The biomass burning and fertilizer application in the continent provided important precursors for WSIN, WSON, and urea in the offshore areas. Besides, O3-related photochemical process also promoted the secondary formation of these species. In contrast, these anthropogenic sources played the minor roles on the relatively remote marine region (SL5). It was interesting to note that the total FAAs during SL5 did not show the lowest concentration, which might be contributed by the bubble bursting on the sea surface and the release of bacteria. The Positive Matrix Factorization (PMF) method identified fertilizer application and secondary formation were important sources for WSIN (35.54% and 27.53%) and WSON (43.07% and 40.46%), respectively. However, fertilizer application and combustion sources played the crucial important roles on urea (65.93% and 19.13%) and FAAs (51.35% and 16.35%). The mean dry deposition fluxes of WSIN, WSON, urea, and FAAs in the ECS offshore area were 206763.57 nmol m−2 d−1, 103763.07 nmol m−2 d−1, 4746.20 nmol m−2 d−1, and 1047.08 nmol m−2 d−1, respectively. The present study revealed that the ambient N-bearing particles in the land-sea boundary zone suffered from the combined effects of continental transport and the release of marine organisms.

Coastline Extraction from SAR Images Using Robust Ridge Tracing

Although ridge tracing has the advantages of continuity and high positioning accuracy compared with other edge-based methods, it is difficult to use ridge tracing to extract coastlines from Synthetic Aperture Radar (SAR) images because of the speckle noise that occurs in SAR images. This paper presents a new coastline extraction method for SAR images based on a more robust ridge tracing method. First, according to the statistical properties of the pixel intensities in the land and sea regions in a SAR image, an edge magnitude map that characterizes the boundary between them is produced by the ratio of the variance to the mean such that the magnitude at the land-sea boundary is much higher than that at other locations. Second, the pixel with the maximum magnitude in the map is adopted as the starting point for tracing, and strip windows, which reduce tracing failures, are adopted to obtain different average magnitudes corresponding to the eight neighborhood pixels around the starting point. Then, the neighborhood pixel with the maximum magnitude is adopted as the next tracing point. The above procedure is repeated to determine the direction of the next point. This process achieves part of the tracing operation. The complete coastline is then extracted by performing the other part of the tracing operation. The experimental results show that the proposed method is more robust than traditional methods, and we demonstrate its effectiveness with RADARSAT-2 and Sentinel-1A data.

Bioerosion in a changing world: a conceptual framework.

Bioerosion, the breakdown of hard substrata by organisms, is a fundamental and widespread ecological process that can alter habitat structure, biodiversity and biogeochemical cycling. Bioerosion occurs in all biomes of the world from the ocean floor to arid deserts, and involves a wide diversity of taxa and mechanisms with varying ecological effects. Many abiotic and biotic factors affect bioerosion by acting on the bioeroder, substratum, or both. Bioerosion also has socio-economic impacts when objects of economic or cultural value such as coastal defences or monuments are damaged. We present a unifying definition and advance a conceptual framework for (a) examining the effects of bioerosion on natural systems and human infrastructure and (b) identifying and predicting the impacts of anthropogenic factors (e.g. climate change, eutrophication) on bioerosion. Bioerosion is responding to anthropogenic changes in multiple, complex ways with significant and wide-ranging effects across systems. Emerging data further underscore the importance of bioerosion, and need for mitigating its impacts, especially at the dynamic land-sea boundary. Generalised predictions remain challenging, due to context-dependent effects and nonlinear relationships that are poorly resolved. An integrative and interdisciplinary approach is needed to understand how future changes will alter bioerosion dynamics across biomes and taxa.