Latitudinal Distance Research Articles

Inter‐decadal variability of the location of maximum intensity of category 4–5 typhoons and its implication on landfall intensity in East Asia

This study investigates the variations of the location of the lifetime‐maximum intensity (LMI) of the tropical cyclones (TCs) over the western North Pacific and the possible implications on the TC landfall intensity in different regions of East Asia. While the annual mean LMI latitude of TCs with at least tropical storm intensity shows a significant upwards trend during 1960–2016, that for intense typhoons (category 4–5) has no trend but a significant inter‐decadal variation, with distinct periods of higher latitude (1960–1969 and 1991–2011) and lower latitude (1970–1990, 2012–2016). A comparison of the spatial patterns of LMI during the periods 1970–1990 and 1991–2011 shows that the LMI location migrates from the southern to the northern part of East Asia from the first to the second period. This shift results from a higher percentage of recurving and north oriented TCs, a northwards shift of genesis locations and an increase in latitudinal distance between genesis position and LMI location in the second period. The frequency of intense typhoon landfalls and the average landfall intensities of the landfalling TCs therefore increase in Japan, the Korean Peninsula and east China but decrease in southern China. The higher frequency and average landfall intensity lead to higher annual maximum landfall intensity, which is more significant for Japan and the Korean Peninsula. However, the effect on landfall intensity in the southern part of East Asia is not obvious, with only a significant decrease in annual maximum landfall intensities in southern China.

Optimizing layout of wind farm turbines using genetic algorithms in Tehran province, Iran

Installation layout of wind turbines plays a prominent role in the design of every wind farm. Thus, the wind farm layout optimization problem is proposed to maximize the total power output with the minimum cost. In this research, Kahrizak region in Tehran province of Iran is selected as a windy region and its real wind speed data are gleaned. Three different scenarios are also considered, with various number of generations and populations for GA parameters, effective distances, and longitude and latitude distances of turbines from each other. Among these scenarios, the best result is obtained for the one in which the longitudinal distance between turbines is greater than the latitudinal distance. By observing the wind rose of Kahrizak region, it is observed that the dominant wind direction of the region is toward the east and south–east. Therefore, by increasing the longitudinal distance of the turbines from each other, the efficiency can be improved and the turbine layout becomes more realistic. In this case, the efficiency rate and normalized cost of turbines are 89.5% and 37.4, respectively, and also 56 turbines are needed. The amounts of efficiency and power output are very convenient for real wind speed data of a region.

Estimating winter wheat planting area in north China driven by the East Asia monsoon

Mapping and monitoring cropland areas and distributions from remote sensing data could provide early warning information of threats to the global and regional food security. Winter wheat is traditionally the most cultivated food crop in China, and the Huang-Huai-Hai (HHH) plain is an important winter wheat production base. Due to a long latitudinal distance, the same winter wheat growth stage delays from the north to the south of the plain. Influenced by the monsoon climate, isolines of the winter wheat phenology are oriented in a northeast–southwest direction, which is similar to that of the temperature distribution. In this paper, Moderate Resolution Imaging Spectroradiometer-enhanced vegetation index (EVI) was applied to estimate the winter wheat planting information on the HHH plain, using a model built according to seasonal change of the winter wheat EVI. The result shows that the average accuracy of the estimation was 75.4% with a standard deviation of 26.1%, when the impacts from the phenology delay and the monsoon climate were not considered. When winter wheat phenology delay was considered with and without the influences from the monsoon climate, the accuracy was 93.2% with a standard deviation of 6.1% and 84.7% with a standard deviation of 11.0%, respectively. The accuracy increased evidently. Therefore, both the phenology delay and monsoon climate impacts should be taken into consideration when estimating the winter wheat planting information in a large monsoon climate region.

What Has Controlled the Poleward Migration of Annual Averaged Location of Tropical Cyclone Lifetime Maximum Intensity Over the Western North Pacific Since 1961?

AbstractThe long‐term tendency of the average latitude at which tropical cyclones (TCs) reach their lifetime maximum intensity (LMI) over the western North Pacific (WNP) is investigated in this study. Despite the post‐1961 significant poleward shift in the annual mean LMI latitude, the migration rate is nonuniform on decadal timescales, having an insignificant trend and a significant increasing trend before and after 1980, respectively. Interdecadal fluctuations of TC genesis latitude (φG) as well as increases in latitudinal distance between genesis position and LMI location (Δφ) are both responsible for the observed LMI latitude trends. The former is linked to the Interdecadal Pacific Oscillation (IPO), which favors TCs forming in the northwestern (southeastern) quadrant of the WNP in negative (positive) IPO phases. The latter primarily results from the continuous warming of WNP sea surface temperature, which further increases the maximum potential intensity and extends the region favorable for TC development to higher latitudes.

Identification of Floral Relicts Based on Spatial Distance of Isolation

The identification of climatic relicts is seldom straightforward. These species are threatened owing to current climatic trends, which underlines the importance of carrying out ecological and biogeographic investigations of them. Here we introduce a novel approach to improve the identification of climatic relicts. We are focusing on thermophilic relict plants of the Pannonian biogeographic region from the Holocene Thermal Maximum (HTM). We argue that a minimal mean annual temperature difference (MATD) of the HTM compared to the recent climate allowed a continuous northward expansion for the taxa investigated. We measured latitudinal distances between the recent occurrences of relicts and those of the main distribution found further south. Regarding estimates for MATD (1.0–2.5 °C), we only consider species with a distribution which has a 150–350 km North-South gap, since a latitudinally directed distance can be translated into temperature, showing a poleward cooling trend. Of the 15 selected species, 12 were recorded with values of 1.0–1.7 °C MATD, and three with values of 1.8–2.5 °C, some of which are presumably interglacial species. Woody species are over-represented among them (four species), using the Hungarian flora as a reference. The proposed method allows the prediction of potential climate-related changes in the future distribution of species, constrained by the topographic features of their habitats.

Investigation of the causes of the longitudinal variation of the electron density in the Weddell Sea Anomaly

AbstractThis paper investigates and quantifies the causes of the Weddell Sea Anomaly (WSA), a region near the tip of South America extending from approximately 30° to 120°W geographic longitude and 50° to 75°S geographic latitude at solar minimum between 2007 and 2010. This region is unusual because the midnight peak electron density exceeds the midday peak electron density in summer. This study is far more quantitative than previous studies because, unlike other models, it assimilates selected data parameters to constrain a physical model in order to investigate other aspects of the data. It is shown that the commonly accepted explanation that the WSA is related to the magnetic field declination and inclination effects on the neutral wind does not explain the longitudinal variation of the electron density. Rather, longitudinal changes in the neutral winds and neutral densities are the most likely explanation for the WSA. These longitudinal wind and density changes are attributed to the varying latitudinal distance from the auroral zone energy input. No contributions from the plasmasphere or other sources are required. Furthermore, it is shown that a widely used empirical thermosphere density model overestimates the longitudinal changes in the WSA region.

Geographic variation and acclimation effects on thermoregulation behavior in the widespread lizard Liolaemus pictus

Populations at the warm range margins of the species distribution may be at the greatest risks of extinction from global warming unless they can tolerate extreme environmental conditions. Yet, some studies suggest that the thermal behavior of some lizard species is evolutionarily rigid. During two successive years, we compared the thermal biology of two populations of Liolaemus pictus living at the northern (warmer) and one population living at the southern (colder) range limits, thus spanning an 800km latitudinal distance. Populations at the two range margins belong to two deeply divergent evolutionary clades. We quantified field body temperatures (Tb), laboratory preferred body temperatures (PBT), and used operative temperature data (Te) to calculate the effectiveness of thermoregulation (E). During one year in all populations, we further exposed half of the lizards to a cold or a hot acclimation treatment to test for plasticity in the thermal behavior. The environment at the southern range limit was characterized by cooler weather and lower Te. Despite that, females had higher Tb and both males and females had higher PBT in the southernmost population (or clade) than in the northernmost populations. Acclimation to cold conditions led to higher PBT in all populations suggesting that plastic responses to thermal conditions, instead of evolutionary history, may contribute to geographic variation. Lizards regulated moderately well their body temperature (E≈0.7): they avoided warm microhabitats in the northern range but capitalized on warm microhabitats in the southern range. We review literature data to show that Liolaemus species increase their thermoregulation efficiency in thermally challenging environments. Altogether, this indicates that habitats of low thermal quality generally select against thermoconformity in these lizards.

Decoupling of latitudinal gradients in species and genus geographic range size: a signature of clade range expansion

AbstractAimClade range size is a function of species range sizes but also depends on the geographic deployment of species: clade range expansion should therefore depend partly on the tendency of a clade to produce new species. Previous work has shown empirically that species‐rich clades are more likely to expand outside their present distributions, i.e. to overcome niche conservatism, than species‐poor ones. This pattern can follow from a neutral probabilistic model of clade‐level range expansion arising from differences in net species diversification between clades. We show that predictions of this model discriminate between weaker and stronger climatic niche conservatism, and compare these predictions with range‐size patterns of marine bivalves at the species and clade (genus) level.LocationWestern Pacific, eastern Pacific and western Atlantic.MethodsWe decompose the latitudinal and thermal distribution of genera into within‐species and among‐species components. We use a neutral model in which species range expansion does not vary with latitude and descendants originate within the ranges of their ancestors (model with spatial dependency) or where descendants originate independently of ancestral ranges (model without spatial dependency).ResultIn accord with model predictions: (1) genus latitudinal range size is weakly related to the latitudinal range sizes of congeneric species, but strongly depends on per‐genus species richness; (2) among‐species latitudinal distances correlate positively with per‐genus species richness; and (3) genus latitudinal and thermal range sizes increase towards higher latitudes because genera that are species rich anywhere within their range increase in proportion towards higher latitudes.Main conclusionsApplication of the neutral probabilistic model to marine bivalves shows that tropical niche conservatism is only moderately strong, and that species diversification plays a significant role in range expansion of bivalve genera to new latitudes and climates, even when thermal range sizes and limits of congeneric species show significant correlations, and are thus conserved to some degree.

Changes and drivers of plant community in the natural broadleaved forests across geographic gradient

Geographic variation can lead to the changes of local plant species, which play crucial roles in primary production and ecosystem structure. Therefore, understanding multiple scale distribution patterns of plant species is important for us to effectively monitor ecosystem changes due to climate changes and other modifications. Here, we mainly investigated the distribution pattern of wood vascular plants and key environmental controlling forces in natural broadleaved forest along the latitudinal gradient across 24 geographic regions of China continental territory. The results showed that the richness and diversity of plant community significantly decreased with the increasing latitude. The similarity of plant community also decreased with increasing latitudinal distance. The mean annual precipitation and mean annual temperature played the most important roles in the distribution of plant community across latitudinal gradient, followed by soil pH and soil moisture.

Geometry of movement of the outer surface of the embryo during Xenopus gastrulation

The surface of Xenopus laevis embryos was marked with carbon particles, after which the location of mark groups was recorded by time-lapse video imaging and subsequent image analysis until their disappearance in the depth of gastric invagination. Measuring the distances between individually identifiable marks whose size is smaller than the size of a single cell makes it possible to quantitatively analyze the geometry of collective cell movement without any external coordinate system. During the dorsal blastopore lip (DBL) formation, the invagination of surface cells fundamentally differs from the preceding and subsequent lateromedial (LM) intercalation, being associated with a decrease in the meridional distance and an increase in the latitudinal distance between the marked surface sites. The sites that began to move towards the DBL later overtake the areas that started movement earlier, which leads to a “plug” in the movement of cells. Pushing the “plug” into the inner layers by changing the DBL shape becomes the rate-limiting stage of gastrulation; then, the directed cell movement is replaced by epiboly based on LM intercalation when the marks remaining on the outer surface of the marginal zone diverge along its meridians without directed migration towards the blastopore. As a result, directional movement of cells and LM intercalation become successive phases of collective cell movement, and the entire morphogenesis of DBL is the direct consequence of epiboly deceleration occurring upon gastric invagination.

Biogeography of aquatic hyphomycetes: Current knowledge and future perspectives

Abstract Since Ingold's (1942) initial description, mycologists have been interested in deciphering global distribution patterns of aquatic hyphomycetes, a group of fungi that play a key role in plant-litter decomposition in freshwaters. However, many questions remain largely unanswered. In this review, we used distribution data of morphospecies from studies throughout the world in an attempt to better understand the magnitude of global species richness, patterns of biodiversity and the extent of cosmopolitanism versus endemism. Sampling efforts have varied among geographic regions, and correlate significantly with species richness. Community similarity decreased with geographic or latitudinal distance. Species richness was highest at mid-latitudes (temperate streams), and high community similarities were found between geographically distant locations in similar climatic zones. Studies relying on morphotypes have undoubtedly provided relevant information on the geographic distribution of aquatic hyphomycetes. However, metagenomic approaches combining taxonomic, phylogenetic and functional diversity in coordinated surveys will be the best option to better decipher diversity patterns of these fungi and their functional roles at a global scale.

New climatic classification of Nepal

Although it is evident that Nepal has an extremely wide range of climates within a short latitudinal distance, there is a lack of comprehensive research in this field. The climatic zoning in a topographically complex country like Nepal has important implications for the selection of scientific station network design and climate model verification, as well as for studies examining the effects of climate change in terms of shifting climatic boundaries and vegetation in highly sensitive environments. This study presents a new high-resolution climate map of Nepal on the basis of long-term (1981–2010) monthly precipitation data for 240 stations and mean air temperature data for 74 stations, using original and modified Koppen–Geiger climate classification systems. Climatic variables used in Koppen–Geiger system were calculated (i) at each station and (ii) interpolated to 1-km spatial resolution using kriging which accounted for latitude, longitude, and elevation. The original Koppen–Geiger scheme could not identify all five types of climate (including tropical) observed in Nepal. Hence, the original scheme was slightly modified by changing the boundary of coldest month mean air temperature value from 18 °C to 14.5 °C in order to delineate the realistic climatic condition of Nepal. With this modification, all five types of climate (including tropical) were identified. The most common dominant type of climate for Nepal is temperate with dry winter and hot summer (Cwa).

Colonization of a host tree by herbivorous insects under a changing climate

Climate warming has been predicted to increase the abundance of herbivorous insects. Together with concurrent poleward shifts in many insect species this may increase herbivore pressure on plants. However, the manner in which plants at higher latitudes become colonized by herbivorous insects in the future is unknown. We established a translocation experiment using 26 micropropagated silver birch Betula pendula genotypes from six populations originating from 60°N to 67°N, to study the susceptibility of the translocated birches to local herbivores. The birches were planted at three different latitudes in Finland (60°N, 62°N and 67°N). We studied the effect of source population and latitudinal translocation on herbivore density, species richness, and community composition among the genotypes growing in the same environmental conditions in two years; 2011 and 2012. The source population explained the variation in the herbivore density only in 2012, whereas latitudinal translocation did not affect herbivore density. Variation in species richness was not explained by the source population or by the latitudinal translocation. At two of the study sites, the similarity of the herbivore communities among the populations decreased with increasing latitudinal distance of the source populations, possibly because birch populations that grow geographically closer to each other are genetically more similar, and therefore support a more similar composition of the arthropod community. All birch genotypes were colonized by local herbivores, suggesting that as herbivores shift their ranges polewards, they are able to colonize novel host‐plant genotypes. This enables compositional changes in insect communities on their host plants in the future, which in turn, might affect total herbivory and eventually, plant growth.

Geographical variation in echolocation vocalizations of the Himalayan leaf‐nosed bat: contribution of morphological variation and cultural drift

Ecologists and evolutionary biologists have a long‐standing interest in the patterns and causes of geographical variation in animals’ acoustic signals. Nonetheless, the processes driving acoustic divergence are still poorly understood. Here, we studied the geographical variation in echolocation vocalizations (commonly referred to as echolocation ‘pulses’ given their short duration and relatively stereotypic nature, and to contrast them from the communicative vocalizations or ‘calls’) of a widespread bat species Hipposideros armiger in south China, and assessed whether the acoustic divergence was driven by either ecological selection, or cultural or genetic drift. Our results revealed that the peak frequency of echolocation pulses varied significantly across populations sampled, with the maximum variation of about 6 kHz. The peak frequency clustered into three groups: eastern and western China, Hainan and southern Yunnan. The population differences in echolocation pulses were not significantly related to the variation in climatic (mean annual temperature, mean annual relative humidity, and mean annual precipitable water) or genetic (genetic distance) factors, but significantly related to morphological (forearm length) variation which was correlated with mean annual temperature. Moreover, the acoustic differences were significantly correlated with geographical and latitudinal distance after controlling for ‘morphological distance’. Thus, neither direct ecological selection nor genetic drift contributed to the acoustic divergence observed in H. armiger. Instead, we propose that the action of both indirect ecological selection (i.e. selection on body size) as well as cultural drift promote, in part, divergence in echolocation vocalizations of individuals within geographically distributed populations.

Bergmann’s rule for Neomys fodiens in the middle of the distribution range

Abstract The body size of Palearctic Sorex shrews decreases at higher latitudes, and as such the Bergmann’s rule does not work. However, no analysis has ever been done for water shrew (Neomys fodiens) in the middle of distribution range. Analysis of available literature data showed that some body and skull measurements of N. fodiens are negatively correlated to latitude. Measurements of 158 water shrews from Estonia and Lithuania were also analyzed with respect to the short scale latitudinal pattern. We found that populations are separated (Wilk’s lambda = 0.363, p<0.0001). Differences are related to PC1 (skull size), explaining 49.80% of the variance and PC2 (body size), explaining 10.06% of the variance. Estonian shrews are smaller in their body and skull (most differences significant) and their skulls are relatively shorter and wider in the area of the brain case. Thus, the negative correlation of body and skull size to latitude in N. fodiens is applicable even over quite short latitudinal distances. Further analysis of diagnostic characters between N. fodiens and N. anomalus is required.

The three-dimensional structure of the Eta Carinae Homunculus★

We investigate, using the modelling code shape, the three-dimensional structure of the bipolar Homunculus nebula surrounding Eta Carinae as mapped by new ESO Very Large Telescope/X-Shooter observations of the H2 λ = 2.121 25 μm emission line. Our results reveal for the first time important deviations from the axisymmetric bipolar morphology: (1) circumpolar trenches in each lobe positioned point symmetrically from the centre and (2) off-planar protrusions in the equatorial region from each lobe at longitudinal (∼55°) and latitudinal (10°-20°) distances from the projected apastron direction of the binary orbit. The angular distance between the protrusions (∼110°) is similar to the angular extent of each polar trench (∼130°) and nearly equal to the opening angle of the wind–wind collision cavity (∼110°). As in previous studies, we confirm a hole near the centre of each polar lobe and no detectable near-IR H2 emission from the thin optical skirt seen prominently in visible imagery. We conclude that the interaction between the outflows and/or radiation from the central binary stars and their orientation in space has had, and possibly still has, a strong influence on the Homunculus. This implies that prevailing theoretical models of the Homunculus are incomplete as most assume a single-star origin that produces an axisymmetric nebula. We discuss how the newly found features might be related to the Homunculus ejection, the central binary, and the interacting stellar winds.

Genetic population structure of spotted seatrout Cynoscion nebulosus along the south-eastern U.S.A.

Analyses of the genetic population structure of spotted seatrout Cynoscion nebulosus along the south-eastern U.S. coast using 13 microsatellites suggest significant population differentiation between fish in North Carolina (NC) compared with South Carolina (SC) and Georgia (GA), with New River, NC, serving as an area of integration between northern and southern C. nebulosus. Although there is a significant break in gene flow between these areas, the overall pattern throughout the sampling range represents a gradient in genetic diversification with the degree of geographic separation. Latitudinal distance and estuarine density appear to be main drivers in the genetic differentiation of C. nebulosus along the south-eastern U.S. coast. The isolation-by-distance gene-flow pattern creates fine-scale differences in the genetic composition of proximal estuaries and dictates that stocking must be confined to within 100 km of the location of broodstock collection in order to maintain the natural gradient of genetic variation along the south-eastern U.S. coast.

Zoning Northern Eurasia based on the fauna of terrestrial vertebrates and their classification by similarity of distribution

For the purpose of zoning on the basis of fauna of terrestrial vertebrates, Northern Eurasia was considered within the boundaries of the Soviet Union in 1991 and divided into 245 mapping units. Mapping units were marked on the World Vegetation Map at a scale of 1: 20000000 in such a way that each mapping unit occupied a territory within the limits of a natural subzone having a latitudinal distance of 10°. A list of the vertebrate species was generated for each unit. Jaccard similarity coefficients were calculated for the lists; the coefficients were used as the basis for performing the cluster analysis of fauna of the mapping units. Based on the results of calculations, a hierarchical classification has been created. This classification includes 5 faunistic regions (regional groups of subregions), 6 subregions, 18 provinces, and 14 districts. Environmental factors that correlate with faunistic heterogeneity in the studied territory were described. The proposed zoning takes into account 57% of the variance of the similarity coefficients of the faunas of specific regions (coefficient of multiple correlation is 0.75). It is 2–2.5 times more informative than the previously developed schemes on particular groups of animals, which reflected, as the researchers thought at that moment, the heterogeneity of fauna of terrestrial vertebrates in general. Association with environmental factors and natural conditions may explain 82% of the heterogeneity of the fauna (correlation coefficient is 0.91). Comparing the results of zoning that were carried out for different classes of terrestrial vertebrates (amphibians, reptilians, birds, and mammals), we found significant similarity between causes of fauna heterogeneity (zonal features, provinciality, heat availability, and their combined effect). Nevertheless, differences in tolerance to the environment among the studied animal classes resulted in the substantial discordance of the boundaries of the described taxa and their hierarchy. This discordance was found during zoning. A classification of 1243 species of terrestrial vertebrates inhabiting the territory under study is performed based on the similarity of their occurrence (the average in the lower taxon faunistic zoning) and covers three types of distribution: Northern, Middle and Southern. These in turn are divided into 7 subtypes and 13 classes. The informative presentation of the classification is equal to 53% of the variance (correlation coefficient is 0.73).

An Algorithm for Concurrent Location of Earthquake Epi- and Hypocentres Using P-Arrivals in an Interpolative Tabular Scan

This paper describes an algorithm which can be used to simultaneously locate the Epicentre and Hypocentre of a given Earthquake in a single pass. The data used is a set of P-wave arrival timings, emanating from the given Earthquake. The algorithm uses tables of arrival times formed from a variety of point-to-point (P2P) Ray Tracers, on which it performs a 2-space interpolative scan. The 2-space concerned is Depth and Latitudinal Distance. In this paper there is a full description of the algorithmic process and an example is given of its use. The algorithm appears to be rapid and can routinely locate Epi- and Hypocentre pairs in scanning, say, 1000 points from a specified depth, within 4 seconds on a 3.2 Giga Hertz machine. This is without invoking parallelism and is using data from 10 -12 stations. As such it would seem suitable for use within an Earthquake Early Warning (EEW) regime.

Continued expansion of the trans-Atlantic invasive marine angiosperm Halophila stipulacea in the Eastern Caribbean

Halophila stipulacea (Hydrocharitaceae) is reported for the first time from Aruba, Curaçao, Grenadines (Grenada), St. Eustatius, St. John (US Virgin Islands), St. Martin (France), and St. Vincent and the Grenadines, bringing the total number of known occurrences from eastern Caribbean islands to 19. Native to the Red Sea and western Indian Ocean, H. stipulacea spread to the Mediterranean Sea in the late 1800s and became established in the eastern Caribbean in 2002. The species has dispersed north and south of its first sighting in Grenada and now spans a latitudinal distance of 6° (>700km), most likely facilitated by a combination of commercial and recreational boat traffic. The continuing range expansion of H. stipulacea indicates the species has successfully acclimated to surviving in the Caribbean environment, warranting further investigation into its ecological interactions with the indigenous seagrasses.