Latitude Direction Research Articles

Calibration method of multi-projector display system with extra-large FOV and quantitative registration accuracy analysis.

The calibration of multi-projector display with extra-large field of view (FOV) and quantitative registration analysis for realizing perfect visual splicing is crucial and difficult. In this paper, we present a novel calibration method to realize the seamless splicing for a multi-projector display system with extra-large FOV. The display consists of 24 projectors, covering the range of 360 degrees in the longitude direction and 210 degrees in the latitude direction. A wide-angle camera fixed on a rotating optical system is used to scan the entire display scene and establish point-to-point correspondence between projector pixels and spatial points using the longitude and latitude information. Local longitude table and latitude table are established on the target of the wide-angle camera. A deterministic method is proposed to locate the North Pole of the display. The local tables corresponding to different camera views can be unified based on the image of the North Pole to form global longitude and latitude tables of arbitrary free-form surface. The mapping between the projector pixels and the camera pixels is established by inverse projection technique, and then each pixel of each projector can be appointed a pair of unique longitude and latitude values. A quantitative registration accuracy analysis method is proposed for multi-projector display system, in which, three-frequency temporal unwrapping method based on coded longitude and latitude values is applied to calculate the registration accuracy. Experiments prove that the registration error of the multi-projector system is less than 0.4 pixels.

Comprehensive Insights into Spatial-Temporal Evolution Patterns, Dominant Factors of NDVI from Pixel Scale, as a Case of Shaanxi Province, China.

Based on long term NDVI (1982–2015), climate, topographic factors, and land use type data information in Shaanxi Province, multiple methods (linear regression, partial and multiple correlation analysis, redundancy analysis and boosted regression trees method) were conducted to evaluate the spatial-temporal change footprints and driving mechanisms in the pixel scale. The results demonstrated that (1) the overall annual average and seasonal NDVI in this region showed a fluctuating upward trend, especially in spring. The difference between the end of season (eos) and start of season (sos) gradually increased, indicating the occurrence of temporal “greening” across most Shaanxi Province. (2) The overall spatial distribution of annual mean NDVI in Shaanxi Province was prominent in the south and low in the north, and 98.83% of the areas had a stable and increasing trend. Pixel scale analysis reflected the spatial continuity and heterogeneity of NDVI evolution. (3) Trend and breakpoint evaluation results showed that evolutionary trends were not homogeneous. There were obvious breakpoints in the latitude direction of NDVI evolution in Shaanxi Province, especially between 32–33 °N and in the north of 37 °N. (4) Compared with precipitation, the annual average temperature was significantly correlated with the vegetation indices (annual NDVI, max NDVI, time integrated NDVI) and phenology metrics (sos, eos). (5) Considering the interaction between environmental variables, the NDVI evolution was dominated by the combined influence of climate and geographic location factors in most areas.

Hypersonic Vehicle Trajectory Prediction Algorithm Based on Hough Transform

Trajectory prediction is a prerequisite for missile and high-speed vehicle guidance interception. To address the trajectory problem for the near space hypersonic unpowered gliding vehicle. Firstly, the trajectory prediction mechanism is analyzed. Based on the existing NSHV trajectory prediction method, the key techniques of trajectory prediction are discussed from the perspectives of prediction parameter selection and prediction parameter description. Then, a trajectory prediction method based on Hough transform is proposed. The core of the method is to select the longitude latitude, and high direction positions as prediction parameters, and use the Hough transform to fit the prior basis functions. In the latitude and longitude direction, the rationality of predicting parameters is discussed from two aspects: position extreme point and lateral maneuverability. In the height direction, for the NSHV oscillation drop characteristic, two Hough transforms are used to separate the periodic term from the linear term. In addition, we give the approximate interval of the parameter values of the method, and design a parameter adaptive scheme. Finally, trajectory prediction is performed on two different control patterns. The error of the prediction time of 100s is within 25km, and the results show the effectiveness of the proposed method.

Spatial and Temporal Variation Characteristics of the Intensity of Landfall Tropical Cyclones in China

Based on the tropical cyclone data of the United States Joint Typhoon Center, this paper analyses the characteristics of the temporal and spatial changes of tropical cyclones that landed in China from 1951 to 2015. The conclusions are as follows: (1) The frequency of landings showed a slow upward trend from 1951 to the early 1990s, and showed a slow downward trend from the late 1990s to 2015. In 1988, it changed from a low period to a high period. (2) Tropical cyclones are mainly distributed in the range of 130-140°E, 10-15°N east of the Philippine Islands, and the northeastern part of the South China Sea. The spatial distribution of the first eigenvector of the source frequency EOF is basically the same as the multi-year spatial distribution. From the time coefficient of the first mode, the change trend of the concentrated distribution has undergone a process of strengthening-weakening. From the perspective of the spatial distribution of the second mode, the source frequencies in the Northwest Pacific and the South China Sea have opposite spatial distribution characteristics in the latitude direction. (3) One of the main tracks of landfall tropical cyclones is westward from the tropical Pacific to the Philippine Sea and South China Sea, and the other from the tropical Pacific to the northwest to South Korea and Japan, affecting the area near the coast of East Asia. The spatial distribution of the first eigenvector of the track frequency EOF is basically the same as that of the multi-year spatial distribution, and the spatial distribution of the second mode has a positive-negative opposite spatial distribution characteristic in the meridian direction.

太行山南段连翘群落结构及其影响因子研究

连翘（Forsythia suspensa）不仅是一种常用大宗木本药用植物类型，而且也是重要的绿化植物类型。以太行山南段陵川境内广泛生长的连翘为研究对象，通过样方调查方法，解析连翘群落结构及影响因子，探讨海拔、坡向主要地形因子和土壤因子对群落格局的影响，以期有助于连翘的规模化种植。结果表明：（1）该区连翘群落可分为5类群丛：Ⅰ连翘（Forsythia suspensa）＋三裂绣线菊（Spiraea trilobata）-披针叶苔草（Carex lanceolata）群丛；Ⅱ连翘（Forsythia suspensa）＋白刺花（Sophora davidii）-披针叶苔草（Carex lanceolata）＋铁杆蒿（Tripolium vulgare）群丛；Ⅲ辽东栎（Quercus wutaishanica）-连翘（Forsythia suspensa）＋三裂绣线菊（Spiraea trilobata）-披针叶苔草（Carex lanceolata）+白头翁（Pulsatilla chinensis）群丛；Ⅳ油松（Pinus tabuliformis）-连翘（Forsythia suspensa）-披针叶苔草（Carex lanceolata）群丛；Ⅴ连翘（Forsythia suspensa）＋黄刺玫（Rosa xanthina）-披针叶苔草（Carex lanceolata）群丛。（2）海拔高度（H）、全钾（TK）和坡向（TRP）是影响该区连翘分布状况的3个主要环境因子。3个因子在4个层级水平上构成群落分型的主导因子。第一级主导因子是海拔高度（H=1330 m）；第二级是土壤总钾量（TK=19.07 mg/kg）和海拔（H>1330 m）；第三级是坡向（TRP=0.2775）、海拔（H>1330 m）和总钾量（TK<19.07 mg/kg）；第四级是总钾（TK=18.47 mg/kg）、海拔（H>1330 m）、和坡向（TRP>0.2775）。海拔高度和土壤肥力是影响太行山南段生境内连翘群落结构和规模化种植的要重环境因子。;Forsythia suspensa is one of the commonly used heavy bulk commodities Chinese medicinal plants and have essential for guarding human health. It is not only an important species of medicinal plants but also a vital for forest vegetation, in the same time also is a potential plant sources that used to improve ecology and beautify of the environment within many specific areas in China. Taihang Mountain is usually considered as one of the vital areas for biodiversity conservation in China.The study area located in Lingchuan, the southern of Taihang Mountains, Shanxi, is dominated by rocky hills and earthen hills, and belongs to a typical continental climate. There was high diversity of forest communities in the nature circumstance, among which, the distribution of the Forsythia suspensa mostly showed a typical shrub clusters community. It is a famous area of medical Forsythia suspensa mainly products all over our country. To research the community composition of Forsythia suspensa and reveal the effects of Forsythia suspensa community traits changes, resulted from the soil factors and the major topographic characteristics, an investigation was conducted in sixty typical sample poles (5 m×5 m) in the region. In the study, the impacts of the variety environment factors on the Forsythia suspensa community were analyzed by the sampling survey method.The major topographic factors included the Height above sea level (H), East longitude (E), Northern latitude (N) and slope direction (Transformation of aspect, TRP). Meanwhile the main soil factors were considered such as the soil Pondus Hydrogenii (pH)、Soil organic matter(TOC) soil total nitrogen (TN), soil total phosphorus (TP), soil total potassium (TK), soil available nitrogen (AN), soil available phosphorus (AP) and soil available potassium (AK). The results showed that (1) Forsythia communities in this area could be divided into five types of clusters, including Cluster I:Forsythia suspensa+Spiraea trilobata-Carex lanceolata; Cluster II:Forsythia suspensa+Sophora davidii-Carex lanceolata+Tripolium vulgare; Cluster III:Quercus wutaishanica-Forsythia suspensa+Spiraea trilobata-Carex lanceolata cluster; Cluster IV: Pinus tabuliformis -Forsythia suspensa-Carex lanceolata; and Cluster V:Forsythia suspensa+Rosa xanthine-Carex lanceolata. (2) H, TK, and TRP are three main environmental factors that affected the distribution of forsythia in this area. The three factors constitute the dominant factors for community typing at four levels. The first level of dominant factor is altitude (H=1330 m); the second level is total soil potassium (TK=19.07 mg/kg) and altitude (H>1330 m); the third level is slope direction (TRP=0.2775), altitude (H>1330 m), and total potassium (TK<19.07 mg/kg); the fourth level is total potassium (TK=18.47 mg/kg), altitude (H > 1330 m), and slope direction (TRP>0.2775). The study concluded that the development of forest medicinal herb forsythia on a large scale in the southern section of Taihang Mountains should not only pay attention to spatial distribution, but also implementation of necessary management measures to improve soil fertility to maintain the stability of forsythia community structure and enhance the Forsythia suspensa yield.

Characterizing Ionospheric Effect on GNSS Radio Occultation Atmospheric Bending Angle

AbstractGlobal Navigation Satellite System (GNSS) atmospheric radio occultation (RO) has been an active remote sensing method to explore the Earth's atmosphere recently. The RO products especially atmospheric bending angles have been widely used for climate study. However, the residual ionospheric error (RIE) still exists to a certain extent after the widely used linear combination in bending angle calculation. In this study, we analyzed both CHAMP and COSMIC data and did full 3‐D ray tracing to characterize RIE. It is found that the order of RIE is around ±0.1 μrad and has an obvious dependency on a variety of factors including altitude, latitude, local time, season, and solar activity level. The amplitude and complexity of RIE generally increase with altitude. It is closely related to the strength of the E layer and the asymmetry between LEO side and GNSS side. Along magnetic latitude direction, the RIE shows a pronounced feature of two peaks and three troughs. From both the simulated and observed RIE, we can identify clearly the ionospheric seasonal variation features, such as the semiannual variation, the equinox asymmetry and the annual anomaly. A spherical asymmetry factor was also defined to quantify the correlation between ionospheric spherical asymmetry degree and RIE. The study provides a comprehensive understanding of RIE, which could contribute to the correction of RIE in the future.

English

This study assessed the ecological fate of heavy metals within the vicinity of an area formally used as dump site in Igbogene, Bayelsa state. Soil auger was used to collect samples at 0 - 20 cm depth at 50, 100 and 150 m distances from the four cardinal points viz: North east and west and south east and west. The soil samples were sieved, ashed, digested and analyzed using atomic adsorption spectrometry. The heavy metals results ranged from 646.73 to 715.33 mg/kg (iron), 59.30 to 73.05 mg/kg (manganese), 83.20 to 114.18 mg/kg (zinc), 10.67 to 15.95 mg/kg (copper), 7.70 to 9.64 mg/kg (chromium), 11.56 to 14.48 mg/kg (cadmium), 10.09 to 13.86 mg/kg (lead), 4.57 to 6.33 mg/kg (nickel) and 3.52 to 4.92 mg/kg (vanadium). Statistically there was no significant variation (p&gt;0.05) across the various distances for each of the metals studied, but apparent decline in values exist as the distance away from the landfill increased. In addition, each of the metals showed positive significant correlation with each other at p&lt;0.01. Cluster analysis revealed two main clusters. These are samples from each of the latitude directions, southern direction (east and west) and northern direction (east and west).&nbsp; Pollution indices were higher in sample obtained from the southern direction (west and east) compared to northern area (west and east) but generally it ranged from no pollution to moderate pollution. Positive quantification of contamination indicates that pollution due to anthropogenic activities occurred in few instances. The ecological risk index showed low risk/fate of the heavy metals studied area. Key words: Environmental risk, heavy metals, dumps site, pollution indices, wastes. &nbsp

Pollen spectra of Polar Ural glaciers

The subject of this article is the pollen spectra of the samples from the surface of Romantic's Glacier, located in the Polar Urals in the Rai-Iz mountain range, as well as generalization of the results of published studies dedicated to glaciers of the Urals. The author also examines the pollen spectra of massive ice, which can be attributed to ice of atmospheric origin on the basis of similarity with the pollen spectra obtained from the surface of the glacier. The article reviews climatic peculiarities of the Polar Urals due to the existence of glaciers below the snow line, namely the landscapes of the Polar Urals, including vegetation as a source of pollen and spores falling onto the surface of glaciers of the Polar Urals, as well as possibility of distant pollen drift to the surface of Romantic&amp;rsquo;s Glacier. The main result consists in the conclusion that the composition pollen spectra of the Romantic&amp;rsquo;s Glacier in the Rai-Iz mountainous area is mainly determined by the long-range transport of pollen and spores from the western and south-western regions in a latitude direction. The pollen spectra obtained from the surface of the Romantic&amp;rsquo;s Glacier are characterized by significant presence of various pollen from broad-leaved rocks of lip, maple, oak, and hazel. Pine pollen and high forest birch are prevalent. Local vegetation is very poor. However, the pollen spectra indicates pollen of heath and crowfoot family, and grasses.

A Nonlinear Version of the Reynolds Equation for Flow in Rock Fractures With Complex Void Geometries

AbstractThis study presents a nonlinear Reynolds equation (NRE) for single‐phase flow through rock fractures. The fracture void geometry is formed by connected wedge‐shaped cells at pore scale, based on the measured aperture field. An approximate analytical solution to two‐dimensional Navier‐Stokes equations is derived using the perturbation method to account for flow nonlinearity for wedge‐shaped geometries. The derived perturbation solution shows that the main contributors to the determination of general flow behaviors in local wedges are the degree of aperture variation relative to mean aperture, the ratio of aperture variation to wedge length, the Reynolds number, and the degree of wedge asymmetry. The transmissivity of the entire fracture is then solved with a field of local cell transmissivity that varies along both longitude and latitude directions on the fracture plane. The performance of the proposed NRE is tested against flow experiments and flow simulations by solving numerically the three‐dimensional Navier‐Stokes equations for three cases of rock fractures with different void geometries. Results from the proposed model are in close agreement with those obtained from simulations and experiments. As the Reynolds number increases, the pressure difference obtained from the NRE demonstrates the same nonlinear behavior as that obtained from the simulations. Overall, the mean discrepancy between the proposed model and flow simulations is 5.7% for Reynolds number ranging from 0.1 to 20, indicating that the proposed NRE can capture the flow nonlinearity in rock fractures.

Micro-interface temperature field of catalytic particle under self-rotation regulation

The micro-interface formed inside and on the surface of the catalytic particle is the place where the catalytic reaction proceeds. The micro-interface temperature is one of the important factors determining the reaction efficiency. Numerical simulation was used to investigate the fluid-solid coupled heat transfer law of micro-interface under the regulation of spherical particles’ self-rotation. The results show it takes up to 4.78 s that the average surface temperature of non-rotating particle with a diameter of 3 mm decreases from 300 ℃ to 150 ℃, which is the lowest temperature required for high-efficiency selective catalytic reduction reaction of NOx with NH3, while self-rotation can reduce the cooling rate of particles. When the direction of particle self-rotation is perpendicular to gas velocity, as the self-rotation speed increases, the high-temperature area of the particle surface diffuses more fully to the latitude direction. Significant effect can be made as the self-rotation speed reaches 5 rad/s, the uniformity of the surface temperature can be increased by 27.1 % ~ 37.7 % compared with non-rotating particle, and the uniformity can be increased by a maximum of 49.5 % at a self-rotation speed of 500 rad/s.

Suitable gravity interpolation technique for large data gaps in Africa

The gravity database for the IAG African Geoid Project contains significantly large data gaps. These large data gaps affect the interpolation precision of the reduced gravity anomalies needed for the determination of the gravimetric geoid for Africa. Our aim is to develop a suitable interpolation technique that can be used for a proper gravity interpolation within large data gaps. A gap of 10° × 5° in the latitude and longitude directions, respectively, located at the high lands of Ethiopia has been artificially created within the gravity data set for Africa. The rest of the data set has been used to interpolate the gravity values at the gap points; then a comparison between the interpolated and the actual data values at the artificial data gap has been carried-out to determine the accuracy of the used interpolation technique. The unequal weight least-squares prediction (with the optimum curvature parameter at the origin) with an underlying grid at the gap areas computed by the satellite-only GO CONS GCF 2 DIR R5 model till degree and order 300, has been proposed as the developed interpolation approach. For comparison purpose, the Kriging interpolation technique has also been tested. Both the classical residual terrain modeling reduction and the window technique, suggested earlier by the authors to get rid of the double consideration of the topographic-isostatic masses within the data window in the framework of the remove-restore technique, have been used for the reduction process. A comparison between the data and interpolated values of the gravity at the gap points has been carried out. The results show that the developed interpolation technique gives better interpolation accuracy at the artificial data gap.

Earthquake Prediction in Physical Effects

In the paper author describes an opinion which is based on: the crustal plate latitude direction force created by the variety of earth rotation angular velocity and the crustal plate longitude direction force created by earth rotation are main forces which are able to cause earthquake. At same time, author gives estimated value of these forces on main crustal plates around earth, and describes that five physical effects which can be used in earthquake prediction.

Research on arc-shaped wheel wear and error compensation in arc envelope grinding

Arc envelope grinding method (AEGM) is commonly used for grinding large-aperture mirrors and greatly increases the wheel life and the machining accuracy. As the grinding point shifts on the arc-shaped wheel, a three-axis machine tool is qualified to manufacture aspherical or off-axis surfaces. However, compared with traditional aspherical grinding with a rotary table, grinding process on T3-configuration machine tools is more complicated. The grinding point varies in both latitude and longitude directions on the wheel. In this paper, a new algorithm for wear simulation based on 3D wheel-workpiece contact area is proposed to better understand the wear process in grinding aspherical surface. The resin-bonded diamond wheel was trued by GC (green silicon carbon) wheel. In order to get the grinding ratio, the wear of the wheel profile was measured after grinding a flat SiC-ceramic surface several times. Then, the wheel profile error was compensated first by analyzing the wheel-workpiece contact status. Gaussian process (GP) regression method was used to fit the form error and eliminate both noise and high-frequency waves in the measured data. The residual error was further compensated, and the compensation value was calculated by GP model. The proposed error compensation methods were verified on a three-axis grinder, and RMS value was successfully reduced by 37%.

High order isoparametric elements in boundary element method—Smooth spheroidal element

The smooth spheroidal element, a high order isoparametric element, is constructed and applied in the boundary element method (BEM) for modeling closed surface of spheroid as well as the field variables using a single element. The smoothness of the element is realized by repeated use of real nodes as auxiliary nodes of interpolation along both the latitude and meridian directions to remove the end node/line effects existing in the conventional closure element. The special techniques of shape function manipulations are suggested and presented to deal with the integrals with hyper- or near hyper-singularities in a uniform and simple way encountered in the BEM. A combined technique, the distance transformation with possible subdivision is proposed to improve the evaluation of near singular integrals. Through a number of numerical examples, the accuracy and efficiency of using high order smooth elements are demonstrated by checking the fitting accuracy of geometrical parameters, the computation costs and some bench mark tests in elasticity.

A New Geosynchronous SAR Constellation and its Signal Characteristics

The Geosynchronous Synthetic Aperture Radar (GEO SAR) has a long synthetic aperture time. The temporal decoherence and azimuth variance characteristics of echo are significant, that brings great challenges to signal to process. In order to reduce the synthetic aperture time and thus improve the observation flexibility and efficiency, this paper proposes a SAR system mounted on a special satellite in reverse equatorial geosynchronous orbit, so-called the reverse equatorial GEO SAR. The orbit is nearly circular and the orbital plane coincides with the equatorial plane. The satellite flies against the direction of the Earth's rotation. The relative velocity is accelerated twice and the synthetic aperture time is shorter. The satellite does not drift in latitude direction and drifts uniformly in longitude direction. The echo has azimuth invariance property. Meanwhile, the 24-hour continuous observation can be achieved for areas with a certain range of latitude by means of large squint technique and constellation design. As the GEO SAR has high orbit, large delay, large squint angle, and wide pulse width, the complex modulation effects are generated by continuous motion between the satellite and target during the imaging period. In this paper, the uniform acceleration curve motion is used to describe the motion of both satellite and target, and the linear approximation is used to describe the slant range change in the process of transmitting and receiving one pulse. Accordingly, an accurate signal model for the reverse equatorial GEO SAR is established, which provides a theoretical model for signal characteristics analysis and imaging algorithms development.

Are unintentionally produced polychlorinated biphenyls the main source of polychlorinated biphenyl occurrence in soils?

The production of polychlorinated biphenyls (PCBs) has been banned globally for decades, but PCB concentrations in environmental media remain relatively high, especially in urban areas. Emissions estimates, studies of soil gradients between urban and rural areas, and quantitative identification of regional sources of PCBs in soils are necessary for understanding the environmental behavior of PCBs. In this study, regional PCB emissions were estimated at a resolution of 10 km × 10 km, and the spatial distribution of soil PCBs from urban to rural areas was studied along the Bohai and Yellow Sea regions. Compared with rural areas, mean PCB concentrations in urban soils (20.7 ng/g) were found to be higher, and concentrations decreased with distance from the city. Across both latitude and longitude directions, high PCB emissions in urban areas matched the distribution of total PCB concentrations in soils. The concentrations of the pollutants PCB28, PCB52, PCB101, PCB118, PCB138, PCB153, and PCB180 in soils originated from 5-year emissions, and accounted for 97%, 95%, 84%, 81%, 58%, 57%, and 27% of the total emissions, respectively. Unintentionally produced PCB (UP-PCB) emissions, which are mainly derived from cement (42%), pig iron (37%), crude steel (18%), and rolled steel (3%) industries, are the major contributors to PCBs in soils. Further identification of the sources and fates of PCBs requires a combination of field, laboratory, and modeling efforts.

Spatiotemporal Change of Aeolian Desertification Land Distribution in Northern China from 2001 to 2015

Land desertification is one of the world’s most important global ecological environment problems and sensitive to global climate change. In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) and Gaofen-1 (GF-1) data were used to obtain aeolian desertification land distribution in Northern China. Aeolian desertification land distribution from 2001 to 2015 was used to analyze the spatiotemporal change in this area. Results show that aeolian desertification situation of 70 counties is expanded with low slope values and 250 counties is reversed. Aeolian desertification situation in most areas is improved in recent 15 years. Gravity center of the aeolian desertification has a trend to move towards the direction of the high latitude and low longitude. It moves towards north about 0.06° and west about 2.2° from 2001 to 2015. The main distribution area is between 90–100°E, 30– 40°N and altitude which less than 2000 m in desert and steppe climate zone. Aeolian desertification is worsening in recent 5 years around rivers and lakes. In recent years, the government has made great efforts to strengthen ecological construction with positive effect, but we still need to pay more attention to environment deterioration of rivers, lakes and the nearby areas in the future.

Wave dynamics on toroidal surface.

Wave dynamics on curved surfaces has attracted growing attention due to its close resemblance to the warped space time governed by general relativity. It also opens up opportunities for designing functional optical devices such as geodesic lenses. In this work we study the wave dynamics on the surface of a torus, a shape of considerable interest due to its nontrivial topology. Governed by the conservation of angular momentum, light propagates on the torus in two different types of modes: one is able to twist around and sweep through the whole surface of the torus; the other is confined within a certain angular range along the torus latitude direction. The confined mode exhibits an interesting self focusing or imaging behavior, which, similar to a geometric lens, shows no dependence of wavelength and thus suffers no chromatic aberration. By changing the geometric parameters of the torus, both the focusing point and the focusing distance can be controlled. Our work provides a new approach to manipulation of light propagation on a curved surface under the conservation of angular momentum.

Where Swedish polar research began: the Linnaean apostle Anton Rolandson Martin's voyage to Spitsbergen in 1758

ABSTRACTIn 1758 the renowned Swedish botanist Carl Linnaeus sent his student Anton Rolandson Martin to the Arctic on-board a whaler to collect scientific specimens. He became the first Swedish scientist to sail these northern waters and to set foot on Spitsbergen. But what route did the ship take and where exactly did he land? By using a combination of geographical information in Martin's diary together with latitude and wind directions from his meteorological records the ship's voyage has been reconstructed. The whaler set course directly to the west coast of Spitsbergen and then patrolled waters from there to the eastern flank of the ice fields off Greenland. The ship then returned to Spitsbergen as the whaling season drew to an end. Martin got the chance to set foot on land only once and for just two hours. After recent field work at the presumed locality 258 years after Martin's visit, his descriptions of the islets were checked and a first-hand comparison was made between the rock sample Martin brought home and the local bedrock. The author is now confident that the landing took place on Forlandsøyane islands, situated off the southwestern coast of Prins Karls Forland.

A Ulysses Detection of Secondary Helium Neutrals

Abstract The Interstellar Boundary EXplorer (IBEX) mission has recently studied the flow of interstellar neutral He atoms through the solar system and discovered the existence of a secondary He flow that likely originates in the outer heliosheath. We find evidence for this secondary component in Ulysses data. By coadding hundreds of Ulysses He beam maps together to maximize signal-to-noise ratio, we identify a weak signal that is credibly associated with the secondary component. Assuming a laminar flow from infinity, we infer the following He flow parameters: km s−1, , , and K; where λ and β are the ecliptic longitude and latitude direction in J2000 coordinates. The secondary component has a density that is 4.9 ± 0.9% that of the primary component. These measurements are reasonably consistent with measurements from IBEX, with the exception of temperature, where our temperature is much lower than IBEX’s T = 9500 K. Even the higher IBEX temperature is suspiciously low compared to expectactions for the outer heliosheath source region. The implausibly low temperatures are due to the incorrect assumption of a laminar flow instead of a diverging one, given that the flow in the outer heliosheath source region will be deflecting around the heliopause. As for why the IBEX and Ulysses T values are different, difficulties with background subtraction in the Ulysses data are a potential source of concern, but the discrepancy may also be another effect of the improper laminar flow assumption, which could affect the IBEX and Ulysses analyses differently.