Spectral discrimination of papyrus vegetation (Cyperus papyrus L.) in swamp wetlands using field spectrometry

Techniques for mapping and monitoring wetland species are critical for their sustainable management. Papyrus (Cyperus papyrus L.) is one of the most important species-rich habitats that characterize the Greater St. Lucia Wetlands Park (GSWP) in South Africa. This paper investigates whether papyrus could be discriminated from its co-existing species using ASD field spectrometer data ranging from 300 nm to 2500 nm, yielding a total of 2151 bands. Canopy spectral measurements from papyrus and three other species were collected in situ in the Greater St. Lucia Wetlands Park, South Africa. A new hierarchical method based on three integrated analysis levels was proposed and implemented to spectrally discriminate papyrus from other species as well as to reduce and subsequently select optimal bands for the potential discrimination of papyrus. In the first level of the analysis using ANOVA, we found that there were statistically significant differences in spectral reflectance between papyrus and other species on 412 wavelengths located in different portions of the electromagnetic spectrum. Using the selected 412 bands, we further investigated the use of classification and regression trees (CART) in the second level of analysis to identify the most sensitive bands for spectral discrimination. This analysis yielded eight bands which are considered to be practical for upscaling to airborne or space borne sensors for mapping papyrus vegetation. The final sensitivity analysis level involved the application of Jeffries-Matusita (JM) distance to assess the relative importance of the selected eight bands in discriminating papyrus from other species. The results indicate that the best discrimination of papyrus from its co-existing species is possible with six bands located in the red-edge and near-infrared regions of the electromagnetic spectrum. Overall, the study concluded that spectral reflectance of papyrus and its co-existing species is statistically different, a promising result for the use of airborne and satellite sensors for mapping papyrus. The three-step hierarchical approach employed in this study could systematically reduce the dimensionality of bands to manageable levels, a move towards operational implementation with band specific sensors.     

Review of Image Quality Measures for Solar Imaging

Observations of the solar photosphere from the ground encounter significant problems caused by Earth’s turbulent atmosphere. Before image reconstruction techniques can be applied, the frames obtained in the most favorable atmospheric conditions (the so-called lucky frames) have to be carefully selected. However, estimating the quality of images containing complex photospheric structures is not a trivial task, and the standard routines applied in nighttime lucky imaging observations are not applicable. In this paper we evaluate 36 methods dedicated to the assessment of image quality, which were presented in the literature over the past 40 years. We compare their effectiveness on simulated solar observations of both active regions and granulation patches, using reference data obtained by the Solar Optical Telescope on the Hinode satellite. To create images that are affected by a known degree of atmospheric degradation, we employed the random wave vector method, which faithfully models all the seeing characteristics. The results provide useful information about the method performances, depending on the average seeing conditions expressed by the ratio of the telescope’s aperture to the Fried parameter, \(D/r_{0}\). The comparison identifies three methods for consideration by observers: Helmli and Scherer’s mean, the median filter gradient similarity, and the discrete cosine transform energy ratio. While the first method requires less computational effort and can be used effectively in virtually any atmospheric conditions, the second method shows its superiority at good seeing (\(D/r_{0}<4\)). The third method should mainly be considered for the post-processing of strongly blurred images.     

Anisotropic Kepler and anisotropic two fixed centres problems

In this paper we show that the anisotropic Kepler problem is dynamically equivalent to a system of two point masses which move in perpendicular lines (or planes) and interact according to Newton’s law of universal gravitation. Moreover, we prove that generalised version of anisotropic Kepler problem as well as anisotropic two centres problem are non-integrable. This was achieved thanks to investigation of differential Galois groups of variational equations along certain particular solutions. Properties of these groups yield very strong necessary integrability conditions.     

Contribution of early impact events to metal‐silicate separation,thermal annealing,and volatile redistribution: Evidence in the Pułtusk H chondrite

Three‐dimensional X‐ray tomographic reconstructions and petrologic studies reveal voluminous accumulations of metal in Pu?tusk H chondrite. At the contact of these accumulations, the chondritic rock is enriched in troilite. The rock contains plagioclase‐rich bands, with textures suggesting crystallization from melt. Unusually large phosphates are associated with the plagioclase and consist of assemblages of merrillite, and fluorapatite and chlorapatite. The metal accumulations were formed by impact melting, rapid segregation of metal‐sulfide melt and the incorporation of this melt into the fractured crater basement. The impact most likely occurred in the early evolution of the H chondrite parent body, when post‐impact heat overlapped with radiogenic heat. This enabled slow cooling and separation of the metallic melt into metal‐rich and sulfide‐rich fractions. This led to recrystallization of chondritic rock in contact with the metal accumulations and the crystallization of shock melts. Phosphorus was liberated from the metal and subsumed by the silicate shock melt, owing to oxidative conditions upon slow cooling. The melt was also a host for volatiles. Upon further cooling, phosphorus reacted with silicates leading to the formation of merrillite, while volatiles partitioned into the residual halogen‐rich, dry fluid. In the late stages, the fluid altered merrillite to patchy Cl/F‐apatite. The above sequence of alterations demonstrates that impact during the early evolution of chondritic parent bodies might have contributed to local metal segregation and silicate melting. In addition, postshock conditions supported secondary processes: compositional/textural equilibration, redistribution of volatiles, and fluid alterations.     

Predicting site-specific storm wave run-up

Natural Hazards - Storm wave run-up causes beach erosion, wave overtopping, and street flooding. Extreme runup estimates may be improved, relative to predictions from general empirical formulae...     

First insights on spatial and temporal distribution patterns of humpback whales in the breeding ground at Sainte Marie Channel,Madagascar

The Sainte Marie Channel on the northeast coast of Madagascar is an important breeding ground for humpback whales; the first observation of birth was documented there, yet it has never been investigated for phenology and habitat use of humpback whales. The present study was aimed at examining temporal and spatial distribution patterns and the encounter rate of different social groups of humpback whales during the breeding season. We used a large set of opportunistic sightings data collected from whale-watching boats. A total of 3 247 sightings were collected during 897 whale-watching trips conducted between June and September from 2009 to 2013. Our study complements previous information on the seasonal presence of humpback whale social groups by demonstrating a persistent and well-structured temporal pattern in the succession of the different groups. Over the different years of the study period, groups without calves consistently dominated the first 30 days of the breeding season, followed by an increase in groups with calves. Interannual differences were observed in the encounter rates, with significantly higher global encounter rates in 2009, 2011 and 2013 (2.2, 2.3 and 2.3 sightings h^–1, respectively), and likewise for the mean encounter rates for groups with calves. In contrast, the encounter rate of groups without calves was similar over the study period. Although our study area exhibits a narrow configuration and poorly contrasting physiographic features due to its restricted spatial extent, we report a spatially segregated pattern of humpback whale social groups in the Sainte Marie Channel. A general linear model showed that groups with calves were influenced by water depth and distance from shore, being observed mostly in shallow waters (to 20 m depth) and close to the coastline (6 km). Our findings will be useful for the development of strategic sustained management plans by providing baseline information on humpback whale distribution at an important but poorly documented breeding site.     

Long-term evolution of Baltic Sea wave climate near a coastal segment in Poland; its drivers and impacts

The paper analyses long-term variability of wave climate near Poland for the 1958–2002 period. With spectral and cross-spectral analysis, linear regression and singular spectrum analysis the modes of long-term variability were quantified for the most energetic months (November–February). For monthly indices of North Atlantic Oscillation from 1950 until 2006, it was established that the long-term trends of NAO and significant wave height demonstrate a gentle coupling. For Januaries this relationship is strongest and dates back to 1960, for Februaries a certain consistency appears since 1975. For Novembers and Decembers no statistically discernible coupling was found. Thus, the Baltic Sea appears to be the easternmost NAO-affected region, despite its separation from the Atlantic. The hydrodynamic variability also includes a non-trivial oscillation in the January wave energy records with T=8 years. The same periodicity was identified with the multi-channel SSA technique in the long-term shoreline data of a neighboring beach. The study shows that even almost entirely isolated water bodies are becoming exposed to global climatic phenomena and accelerated erosion of sandy beaches, typical for the South Baltic region. On the other hand, the 8-year hydrodynamic cycle can be viewed as the driver of long-term shoreline evolution.     

Early onset of a microcystin-producing cyanobacterial bloom in an agriculturally-influenced Great Lakes tributary

In late May 2016, a cyanobacterial harmful algal bloom(cHAB) was detected in the Maumee River, the largest tributary to Lake Erie, the southernmost lake of the Laurentian Great Lakes system. Testing on 31 May identified Planktothrix agardhii as the dominant cyanobacterium with cell abundance exceeding 1.7×10~9 cells/L and total microcystins(MC) reaching 19 μg/L MC-LR equivalents, a level over 10-fold higher than the 2015 revised U.S. Environmental Protection Agency(EPA) national health advisory levels for drinking water exposure to adults. Low river discharge coincident with negligible precipitation through the latter half of May coincided with an 80% decline in river turbidity that likely favored bloom formation by a low-light adapted P. agardhii population. Also contributing to the c HAB were high initial nutrient loads and an increase of the river temperature from 13℃ to 26℃ over this same period. The bloom persisted through 5 June with microcystins exceeding 22 μg/L MC-LR equivalents at the bloom peak. By 6 June, the river had returned to its muddy character following a rain event and sampling on 7 June detected only low levels of toxin(0.6 μg/L) at public water systems located near the bloom origin. The elevated toxin production associated with this early onset bloom was without precedent for the Maumee River and an unique attribute of the c HAB was the high proportion of potentially-toxic genotypes. Whereas Planktothrix spp. is common in lotic environments, and has been previously detected in the Maumee, blooms are not commonly reported. This early onset, microcystin-producing c HAB provided a rare opportunity to glean insights into environmental factors that promote bloom development and dominance by Planktothrix in lotic environments.     

Health risk assessment related to an effect of sample size fractions: methodological remarks

Contents of As, Cd, Co, Cr, Cu, Ni, Pb and Zn were determined in the material collected in sandboxes of seven spa resorts located in S Poland (CCE) and their results used to establish a health risk of children. After sieving out grains > 2 mm, the bulk samples were quantitatively separated into four grain fractions: 2000–1000, 1000–200, 200–63 and < 63 µm. In each of them were determined: the mineral composition, the total contents of the elements, and the distribution of the elements among the fractions distribution factor. In the bulk material < 2 mm, the totals of the elements are 5–64 times lower than in the finest fractions (< 63 µm). Considering that the finest fractions are enriched in clay minerals such as clinochlore, illite and kaolinite, which can adsorb and desorb metals, this material is most dangerous for children, staying both permanently and temporarily in the spas. The total health risks HI resulting from non-carcinogenic elements present in the fractions < 63 µm are 1.26 and 0.94, for the children-residents 3 and 6 years old, respectively. The figures are disturbing as one of them exceeds and the other is close to a permissible limit of 1. The highest contribution (93.4%) into the total HI is caused by inadvertent swallowing the soil “dirt”: the ingestion path HQ _ing for the 3 years old residents is 1.17, and for the 6-year olds 0.88. With respect to the elements, the highest is the risk resulting from Pb: HQ _in values of the residents are 4.71E−01 and 3.54E−01 for the 3-year olds and the 6-year olds. Slightly lower are the HQ _ing values calculated for both age groups: in the case of Cr—3.12E−01 and 2.34E−01 and As—2.92E−01 and 2.19E−01). The dermal path (HQ _dermal ) contributes to the total HI much less as it equals 6.5%, while the contribution of the inhalation path (HQ _inhal ) is considerably the lowest and equals only 0.1%. The Risk indexes determined in the case of cancerogenic components for both age groups of the spa residents are lower than the permissible limit 10E−5 and equal 6.48E−06 and 9.72E−06, respectively. Considering the children that only visit the spas, all the calculated indexes, i.e., HI and Risk, are significantly lower than those determined for the children-residents.

     

Breaking waves in deep water: measurements and modeling of energy dissipation

Ocean Dynamics - In the presence of strong winds, ocean surface waves dissipate significant amounts of energy by breaking. Here, breaking rates and wave-following turbulent dissipation rate...