Eastern Longitude Research Articles

Polychlorinated biphenyls in the surface and deep waters of the Southern Indian Ocean and Coastal Antarctica

Polychlorinated biphenyl compounds (PCBs) are industrial chemicals whose production was discontinued in the early nineties in most countries. Sill, PCBs are detectable in pristine and remote locations. Occurrence in regions such as Southern Oceans and Antarctica are influenced by the global, and regional, cycling. Here, we studied the surface and deep ocean distribution of indicator- and dioxin-like PCB congeners in the Southern Indian Ocean (SIO), and the coast of Antarctica (COA) during the tenth Indian Southern Ocean Expedition (SOE-10), December 2017–February 2018. ∑21PCBs in SIO surface waters ranged from 3.8 to 167.1 pg L−1 (average ± standard deviation: 35.7 ± 48.4 pg L−1), and in COA from 1.0 to 41.8 pg L−1 (13.8 ± 12.7 pg L−1), respectively. A noticeable gradient was observed, with higher PCBs levels in northern latitudes than southern latitudes in the SIO, and higher levels in the eastern longitudes compared to western longitudes in the COA. Results suggest the influence of secondary sources, or re-emission, of PCBs in the Southern Oceans and Antarctica. Both regions showed notable PCB levels in surface and deep waters (up to 1000 m) due to ongoing surface sources and remineralization processes in deeper waters. Multimedia modeling with the global model (BETR-Global) suggests the SIO act as a net sink for PCBs in the ocean.

On the Crustal Sources of Magnetic Anomalies in the Middle Urals

The 800×500 sq km area of the the Middle Urals, Russia, lying between 56 to 60° northern latitude and 54 to 66° eastern longitude, was studied in terms of the deep crustal structure. The study was based on three-dimensional modeling of the sources of magnetic anomalies in three layers of the Earth’s crust. The studied area covers the folded region of the Urals and adjacent structures of the East European Platform and the West Siberian Plate. The sources modeled in the near-surface layer down to a depth of 5 km make it possible to clarify the position of magnetized massifs, mainly consisting of mafic-ultrabasic rocks, and to trace their connection with mafic-ultrabasic belts in the granite layer and root blocks in the lower basaltic layer of the Earth’s crust. When the sources in the upper crustal layer are compared with those in the lower crustal layer, it is apparent that many belts on the platform have deep-seated roots and are located above the basalt layer protrusions, while most of the massifs in the Urals do not have deep-seated roots. The springs located under the western slope of the Urals allow reliably determining the depth to the basement of the ancient platform and the location of the eastern border of the East European Platform in the lower layer of the Earth’s crust. There were found extended zones of subsidence of the roof of the lower magnetized layer, which probably mark the boundaries of various terrains forming the paleo-island arc sector of the Ural fold system. The most extensive subsidence of the roof of the lower layer occurs to the west of the Tyumen-Chudinovsky fault and is perhaps the eastern deep-seated dividing line between the Ural fold system and the West Siberian Plate.

Transport accessibility and efficiency of PHC location in Kanyakumari district, Tamil Nadu

Transportation is an essential feature of modern economics. In general terms, as an economy grows and develops, it becomes more dependent on its transport sector. The efficient location of any PHC center mainly depends on the network pattern. The study area, Kanniyakumari, is the southernmost district of Tamil Nadu. Kanyakumari District lies between 77°15’ and 77°36’ of eastern longitude and 8°03’ and 8°35’ of northern longitude. The study area has 83 nodes and 120 edges in the transport network system. The main objectives of the paper are to analyze the variation in the degree of connectivity, accessibility, and nodal efficiency of the network pattern and to assess the relationship between road network structure and the location of the PHC center. (Primary Health Care). The present study depends on secondary data. The secondary sources were collected from various transport offices and institutions. Cartography mapping and buffer analysis are used by GIS software. The quantitative research approaches in network analysis were measures to determine the spatial structure, associate number, route development, nodal efficiency, and accessibility of a given PHC location. The Shimbels shortest path matrix was used to identify the health centrality of a node in the network, and its minimum accessibility was found for each PHC center. The detour index was computed based on knowing the route for existing network systems. The present study aims to understand the characteristics of the road transport network in relation to the structural location of the PHC of connectivity, accessibility, and route efficiency in Kanniyakumari district.

A cyclone formation, eastward plume drag, ion-hydration process, and the consequent ionospheric changes following the 2022 Hunga Tonga-Hunga Ha'apai volcanic eruption

In this paper, we investigate the possible mechanism behind the volcanic plume drag and the massive expansion of the ionospheric Total Electron Content (TEC) along the eastern longitudes by using near-field observations of the 15 January 2022 Hunga Tong-Hunga Ha'apai volcanic eruption. The meteorological omega parameter shows a dominant upward/downward movement of the air parcels along the eastern and southern sides of the volcanic eruption. This dominant air convection under the presence of the heavy moisture of volcanic plume and vector winds indicated the formation of a cyclone over and around the Tonga volcano. This cyclone dragged the heavy volcanic plume towards the eastern longitudes (150oE – 180oE). Moreover, we observe that the volcanic plume injected about 5 DU of Sulfur Dioxide (SO2) and 30 kgm−2 of the water content along the total atmospheric column. The chain reactions of Hunga Tonga volcanic trace gases with the gases present in the neutral atmosphere instigated an air ionization process, while under the presence of the heavy water content, these ions underwent an ion-hydration process that contributed to the electrodynamical changes in the region. These electrodynamical changes can be regarded as Atmospheric Chemical Potential (ACP) in the lower atmosphere. We observe a sharp increase in the ACP of ∼0.26 eV along the eastern longitudes (160–180°E) exactly above the dragged volcanic plume area. The long-term TEC changes that have been observed towards the eastern longitudes are the result of the ion-hydration process at the lower atmosphere. The statistical analysis showed a critical change during the day of the event up to ∼48 TECU with an increasing value of 28 and 18 TECU from the lowest and highest ranges before the event over the crater, respectively. Our main findings showed ionospheric anomalies in the near field started from 6:00 to 16:00 UTC. Based on Swarm satellites, the S4 values have significant changes around 0.3–0.6 lasting for tens of minutes.

The Quantitative Morphometric Analysis of the Biggest Basin in Western Plateau of Iraq

The integrative utilization of the remotely sensed extracted data with geographic information system analyzing capabilities is the optimal approach to determine the shape of rivers and valleys basins realistically and to know their morphological and geomorphological characteristics, so it gives an accurate perception of ways to exploit surface or groundwater resources for these basins.The concerned region is the western plateau which located between (38° 45’ 31˝) and (48° 17’ 12.58) eastern longitudes; (34 ° 30’ 10.77) and (29 0’ 38) northern latitudes. The hydrological analysis based on the geographic information system of the region basins showed that the Houran valley basin is the largest basin in the western plateau that described as a fourth-order drain basin that has dendritically and sometimes paralleled drain network.The quantitative analysis of the morphological features showed that longitudinal drain density was 0.1698 km / km2, which reflects a soil quality with high permeability plus a desert climate of arid to semi-arid weather. The circulation ratio is 0.08566, which indicates that the basin is in an early geomorphological stage and that the linear structures control the pattern of its drainage network. The elongation ratio is 0.112, which means that there are significant differences in the hardness of its geological structure, and this would help the use of groundwater in the process of sustainable development of the region. The adoption of quantitative methods based on spatial analysis in hydrological studies supports the optimal use of water resources (from accurate identification of dam sites to realistic planning of irrigation projects), especially in areas with scarce water.

Geomorphological hazards on transportation roads in Sarkapkan township

Sarkapkan sub-district, in terms of administration, belongs to Ranya district in Slemani province. Astronomically, it is located between the located in latitude (northern Longitude °36: ¯28:꓿27-°36: ¯15: ꓿21.) (°45: ¯51: ꓿35- east °45: ¯46: ꓿39)eastern longitudes. It is located in the northwest of Slemani Province. The study area includes a strategically important economic and military road that borders with Warte sub-district in Erbil province, as well as a number of secondary roads that connect human settlements to the urban center, and in physiography is located in a hard mountainous area. The main objective of this study is to identify the environmental characteristics of the study area and draw a specific map for each of them in order to analyze the risks faced by the roads in the study area. The study begins with an analysis of the natural environment in Sarkapkan sub-district and its impact on roads, such as (geology, topography, climate, soil, and vegetation cover). In the second part, we discussed the introduction of road networks in terms of (main, secondary, and village roads) and then the role of humans in destroying the balance of the earth and as a factor in the creation of danger on roads, this is an analysis of each of these natural features and their direct and indirect impact on traffic networks. In the third part, each of the processes (water erosion and movement of materials) is discussed and their impact on the creation of hazards on the roads is examined, and then a morphodynamics map is created to determine the level of morphodynamics risk in the study area. The results of the study show that natural characteristics and human activities play a major role in the creation of geomorphological hazards on traffic networks and their destruction.

Mountain Graticules: Bridging Latitude, Longitude, Altitude, and Historicity to Biocultural Heritage

The interdependence of biological and cultural diversity is exemplified by the new conservation paradigm of biocultural heritage. We seek to clarify obsolescent notions of nature, whereby cultural construction and identity markers of mountain communities need to reflect localized, situated, and nuanced understanding about mountainscapes as they are developed, maintained, managed, and contested in spatiality and historicity. Using the nexus of socioecological theory, we question whether a convergent approach could bridge montological knowledge systems of either different equatorial and temperate latitudes, western and eastern longitudes, hills and snow-capped mountain altitudes, or hegemonic and indigenous historicity. Using extensive literature research, intensive reflection, field observation, and critical discourse analysis, we grapple with the Nagoya Protocol of the Convention of Biological Diversity (COP 10, 2010) to elucidate the benefit sharing and linkages of biocultural diversity in tropical and temperate mountain frameworks. The result is a trend of consilience for effective conservation of mountain socioecological systems that reaffirms the transdisciplinary transgression of local knowledge and scientific input to implement the effective strategy of biocultural heritage conservation after the UN Decade of Biological Diversity. By emphasizing regeneration of derelict mountain landscapes, invigorated by empowered local communities, promoted by the Aspen Declaration, the UN Decade of Ecological Restoration, and the UN International Year of Mountain Sustainable Development, montological work on sustainable, regenerative development for 2030 can be expected.

Modelling of [formula omitted] using artificial neural network over Equatorial Ionization Anomaly (EIA) region stations

The critical frequency of F2-layer in the Equatorial Ionization Anomaly (EIA) region is one of the most challenging ionospheric characteristics to model. We illustrate the efforts to model monthly hourly medians of foF2 using Artificial Neural Network (ANN) over five EIA crest stations between 23.1° N – 30.5° N of Eastern longitudes during 1958–2008 (as per data availability per station). The ANN based model was designed to obtain foF2 values as output by inputting seven parameters defining diurnal (hour), seasonal (month), geographical (latitude & longitude) and solar cycle (year, F10.7 & F10.7P indices) dependency of foF2. With this input space, the model uses a hidden layer of 96 neurons to generate output foF2, producing a mean squared error of less than 1.0MHz2. Additionally, the convergence of the model improved on introducing derived solar radio flux (F10.7P) by 6.0%. After training and validation, the model predicts foF2 values over the locations under study for unseen testing data of 1989, 1998 & 2008 as a representation of high, moderate and low solar activity, respectively. Our ANN based climatological model gave a Root Mean Square Error (RMSE) of 0.956 MHz and goodness of fit, r2=0.929 for the testing data. Data-model comparison with ANN model is better than the International Reference Ionosphere (IRI) estimations of foF2 with CCIR (IRIC) and URSI (IRIU) coefficients. IRIC and IRIU produced RMSE of 1.901 MHz (r2=0.732) and 1.926 MHz (r2=0.716) for the same testing data set, respectively. The designed ANN based model successfully captures the climatological features of foF2 in the EIA region. After necessary modifications, the model may be applied for predicting daily hourly values, particularly in the Asian-longitudinal range over Pakistan, in future.

The Analysis Morphometric Watershed Dolabafra Baisn

Watershed of Dolabfra is one of the branches of little river in Pishder sub-district, this river flows down into The little river in almost three km far away from south of west of Sultanade village, this basic of river is located in latitude (northern Longitude °36: ¯25:꓿00-°36: ¯29: ꓿00.) (°45: ¯03: ꓿00- east °45: ¯13: ꓿00)eastern longitudes. the main resources of watershed is located the land of Kurdistan Region and board of Pishder sub-district, the source of water providing of this river is situated in a valley of Sharueta village. The main aim of this research includes two parts, the first one is recognition of the characteristics of environments of the area of the research and the second one is to design a special map for each one. Thus, for the purpose of analyzing and using the water resources in the area of the research. In the beginning analysis has been presented for the natural environment of the Basin of Dolabfre and its influence on system of the irrigation, such as (geology, topography, weather and soil) thus, this is through analyzing each of the natural characteristics and direct and indirect effect on flowing river. In the second part, the most important morphometric measures for basin has been carried out, in a way that there is a focus on characteristics of the research (square of the area, shape, height and low, net of the flow of the river). The outcome of the research reveals that natural characteristics of the area of research play main role in the richness of water resources and speed of flow of steam, brook and main river of the basin.

Factor analysis of the parameters of the ergatic natural-production system of the carting out of timber assortments

ABSTRACT Factor analysis of 35 factors in 162 experiments was conducted for carting out timber from the forest to a forest products mill using the method of identifying stable patterns. The sampling power of the total correlation matrix was 352 = 1225 values of the correlation index for the identified stable patterns. According to the identified patterns of rank-size distributions and binary relations, the number of pre-selected factors decreased from 35 to 24 in summer (68.57%) and to 25 in winter (71.43%) using the proposed method of factor analysis. Basically, factors with a correlation index of less than 0.3 were excluded. Structural indicators become a system parameter of the set of regularities of binary relations, which decrease with an increase in the “permissible” correlation index. In total there are 1190 pairs of binary relations. According to the research results, among the influencing variables, the factor “type of snow and ice cover” was in first place, “number of the month in the year” was in second place, and “time of operation of the logging truck” was in third place. Among the dependent indicators in comparison with the general correlation matrix and the matrix of strong connections, the first and second places were: “the height of the snow cover (off the road)”; the given eastern longitude. The factor “the wheel formula of the logging truck” was in third place.

Longitudinal Variability of the Vertical Drift Velocity Inferred from Ground-Based Magnetometers and C/NOFS Observations in Africa

This study aims at discussing longitudinal effects on the variability of the vertical E × B drift velocity at low latitudes, specifically over African sector. To this effect, observations from ground-based magnetometers and the Ion Velocity Meter experiment onboard C/NOFS satellite are analyzed in conjunction with equatorial electric field and neutral wind model estimates under geomagnetically quiet conditions in the years 2012-2013. Notwithstanding the limitation in data over Africa, the combination of ground-based and in-situ observations confirmed the existence of longitudinal differences in the E × B between the Atlantic, Western and Eastern African sectors. This was well reproduced by the equatorial electric field model (EEFM) which showed that during noon, the peak of the equatorial electric field (EEF) was the lowest in the Atlantic sector, with an increasing trend towards the Eastern longitude. The Horizontal Wind Model 14 (HWM14) showed that the eastward zonal (poleward meridional) wind velocity was the lowest (highest) in the Eastern sector. Furthermore, the zonal (meridional) wind increased (decreased) from the Eastern to the Atlantic sector. These results highlight the contribution of the neutral wind velocity in driving the longitudinal difference in the vertical drift velocity over Africa.

Effects of novel bioorganic fertilizer application on soil enzymes and bacterial community in multi-site rice paddies in China

Application of a novel bioorganic fertilizer (BIO) has been effectively used to inhibit weeds in rice paddies. To identify changes in soil bacterial community and enzymes in response to BIO treatments, field experiments were carried out in five major rice-growing areas in China. The dominant phylogenetic groups recorded included Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes and Acidobacteria. Anaeromyxobacter, Bacteroides, Bifidobacterium, Escherichia- Shigella, Geobacter and Haliangium were significantly different between BIO-treatment and untreated control and aided in general function (R), amino acid transport, metabolism (E) and transcription (K) clusters. The soil chemical properties and enzyme activities were less affected by BIO at these study sites. RDA analysis showed that soil bacterial community had a significant positive correlations among northern latitude, eastern longitude, exchangeable K, total K, total P, soil pH, and total N, except for organic matter, hydrolytic N and extractable P. Overall, our work showed that application of BIO does not alter the main community structure and functional diversity of soil bacteria in rice paddies and should be encouraged for use as a sustainable weed management strategy.

Anatomical study of Tsushima Warm Current system: Determination of Principal Pathways and its Variation

The Tsushima Warm Current (TWC) forms a chaotic picture of surface currents in the Sea of Japan. This study, based on satellite-based sea surface topography, was conducted to clarify the complicated figures by identifying the main pathways of the TWC system. We specifically examine four main branches based on the initial position at the entrance region and their downstream trajectories. In regions west of 133°E, the four currents mutually flowed independently, whereas the streamlines became scrambled at eastern longitudes. Our analyses revealed that the three branches of TWC, excluding the Subpolar Front Current, showed a confluence in the regions around the Oki Islands and off the Noto Peninsula. The seasonality of those current pathways is also addressed by this study. In the Yamato Basin, the TWC pathways, particularly offshore branches, were affected strongly by the existence and the location of developed mesoscale eddies, where basin-wide anticyclone during winter and cyclone during summer are frequently observed. In the eastern area of the Sea of Japan, the TWC branches showed notable features of meandering during winter, but it was straightforward during summer, mostly exiting towards the Pacific Ocean through the Tsugaru Strait.

Ring Current Proton Dynamics Driven by Wave-Particle Interactions During a Nonstorm Period

Modeling of pitch angle scattering of ring current protons at interaction with electromagnetic ion cyclotron waves during a nonstorm period was considered very seldom. Therefore it is used correlated observation of enhanced electromagnetic ion cyclotron (EMIC) waves and dynamic evolution of ring current proton flux collected by Cluster satellite near the location L = 4.5 during March 26–27, 2003, a nonstorm period (Dst > –10 nT). Energetic (5–30 keV) proton fluxes are found to drop rapidly (e.g., a half hour) at lower pitch angles, corresponding to intensified EMIC wave activities. As mathematical model is used the non-stationary one-dimensional pitch angle diffusion equation which allows to compute numerically density of phase space or pitch angle distribution of the charged particles in the Earth’s magnetosphere. The model depends on time t, a local pitch angle and several parameters (the mass of a particle, the energy, the McIlwain parameter, the magnetic local time or geomagnetic eastern longitude, the geomagnetic activity index, parameter of the charged particle pitch angle distribution taken for the 90 degrees pitch angle at t = 0, the lifetime due to wave–particle interactions). This model allows numerically to estimate also for different geophysical conditions a lifetime due to wave–particle interactions. It is shown, that EMIC waves can yield decrements in proton flux within 30 minutes, consistent with the observational data. The good consent is received. Comparison of results on full model for the pitch angle range from 0 up to 180 degrees and on the model for the 90 degrees pitch angle is lead. For a perpendicular differential flux of the Earth’s ring current protons very good consent with the maximal relative error approximately 3.23 % is received

Petrography and geochemistry of intrusive magmas in Varmaqan – Sardare ghobadi in the west of Iran

The study area is a quadrilateral of 155 km2 between eastern longitude 47˚ and 40 ′ to 47˚ and 52 ′ and northern latitudes 35˚ and 00 ′ to 35˚ and 04 ′ that is located in west of Iran, north of Sonqor city and between Varmaqan and Sardare Ghobadi villages of Kermanshah province. In this range, the intrusive rocks are alkaline granite, granite, granodiorite, tonalite, quartz alkaline syenite, quartz monzonite, quartz monzodiorite, quartz diorite, alkaline syenite, monzonite, diorite, gabbro diorite, gabbro, and olivine gabbro as they were injected in the iron ores of cretaceous which has resulted in contact metamorphism and created hornfels at the site of contact. After comprehensive sampling of all required igneous rocks and according to the thesis objectives, thin sections were prepared and after petrography and some samples were selected for geochemical experiments. XRF analysis, ICP and alkaline fusion were performed on some samples. According to geochemical and petrological studies, the magmas forming these intrusive igneous rocks are from one region and because of magmatic differentiation or fractional crystallization, they from basaltic to acidic terms. Samples of this quadrilateral have a meta-alumina nature and granitoids are in the range of arc islands granites, continental arc granitoids and continental collision granitoids. The mineralogical and chemical composition of the acidic rocks in the area show that the granites in this study are type I.

A Statistical Study of Low-Frequency Solar Radio Type III Bursts

We have studied low-frequency (45 - 410 MHz) type III solar radio bursts observed using the e-CALLISTO spectrometer located at Gauribidanur radio observatory, India during 2013 - 2017. After inspecting the 1531 type III bursts we found that 426 bursts were associated with flares, while the other bursts might have triggered by small scale features / weak energy events present in the solar corona. In this study, we have carried out a statistical analysis of various observational parameters like start time, lower and upper-frequency cut-offs of type III bursts and their association with flares, variation of such parameters with flare parameters such as location, class, onset and peak timings. From this study, we found that most of the high-frequency bursts (whose upper-frequency cut-off $> 350$ MHz) are originated from the western longitudes. We interpret that it could be due to the fact that Parker spirals from these longitudes are directed towards the earth and high-frequency bursts are more directive. Further, we report that number of bursts that reach earth from western longitudes are higher than eastern longitudes.

Phytogeography boundaries between Stone-birch and White-birch forests in the North of the Koryak Region

The distribution boundaries of the two birch species communities: Stone-birch (Betula ermanii Cham.) and White birch (Betula platyphylla Sukacz) forests have been firstly reliably established for the North of the Koryak Region. The remote sensing data, aerial observations, original relevés, and itinerary research data were used. A map of the Stone-birch and White-birch forests allocation in the mainland part of the Koryak Region was compiled. It was shown that Stone-birch groves were found in relatively warmer and wetter areas adjacent to the Bering Sea coast. They occupy Southern and South-Eastern slopes of the Koryak Upland spurs; whereas White birch forests are common in the continental districts. They are found in the valleys of the rivers Penzhina, Talovka, Belaya, Oklan, Apukvayam, on the Penzhinskiy Ridge slopes. Stone-birch forests do not occur North of 62° northern latitude, do not overcome the boggy depression of Parapolsky Dale, and do not occur to the West of 167° 30’ eastern longitude. The natural phytogeographical boundary between the areas of the two birch formations are the Southern and South-Eastern spurs of the Koryak Upland.

Universal time control of the parameters of the electron temperature enhancement zone in the winter subauroral ionosphere

Comparison of the numerical simulation results with experimental data obtained aboard the CHAMP spacecraft has shown that in the eastern longitudes during the local winter period the parameters of electron temperature (Te) enhancement zone in the subauroral ionosphere undergo significant changes depending on the universal time (UT control) as a result of the formation of the shadow region, almost devoid of direct sources of ionization due to the displacement of the geographic and geomagnetic poles. Thus, in the time interval of 04–07 UT in the northern hemisphere and 16–19 UT in the southern hemisphere, a zone of increase of Te in the region of main ionospheric trough can have the greatest length and square, and take a ring-shaped configuration; in the time interval of 16–19 UT in the northern hemisphere and 04–07 UT in the southern hemisphere the length and square of Te enhancement zone decrease, and its configuration becomes crescent. The study has been carried out under the assumption that the main reason for the Te enhancement is the ring current that causes a downward heat flow from the plasmasphere.

Epidemiologic and spatiotemporal trends of Zika Virus disease during the 2016 epidemic in Puerto Rico.

BackgroundAfter Zika virus (ZIKV) emerged in the Americas, laboratory-based surveillance for arboviral diseases in Puerto Rico was adapted to include ZIKV disease.Methods and findingsSuspected cases of arboviral disease reported to Puerto Rico Department of Health were tested for evidence of infection with Zika, dengue, and chikungunya viruses by RT-PCR and IgM ELISA. To describe spatiotemporal trends among confirmed ZIKV disease cases, we analyzed the relationship between municipality-level socio-demographic, climatic, and spatial factors, and both time to detection of the first ZIKV disease case and the midpoint of the outbreak. During November 2015–December 2016, a total of 71,618 suspected arboviral disease cases were reported, of which 39,717 (55.5%; 1.1 cases per 100 residents) tested positive for ZIKV infection. The epidemic peaked in August 2016, when 71.5% of arboviral disease cases reported weekly tested positive for ZIKV infection. Incidence of ZIKV disease was highest among 20–29-year-olds (1.6 cases per 100 residents), and most (62.3%) cases were female. The most frequently reported symptoms were rash (83.0%), headache (64.6%), and myalgia (63.3%). Few patients were hospitalized (1.2%), and 13 (<0.1%) died. Early detection of ZIKV disease cases was associated with increased population size (log hazard ratio [HR]: -0.22 [95% confidence interval -0.29, -0.14]), eastern longitude (log HR: -1.04 [-1.17, -0.91]), and proximity to a city (spline estimated degrees of freedom [edf] = 2.0). Earlier midpoints of the outbreak were associated with northern latitude (log HR: -0.30 [-0.32, -0.29]), eastern longitude (spline edf = 6.5), and higher mean monthly temperature (log HR: -0.04 [-0.05, -0.03]). Higher incidence of ZIKV disease was associated with lower mean precipitation, but not socioeconomic factors.ConclusionsDuring the ZIKV epidemic in Puerto Rico, 1% of residents were reported to public health authorities and had laboratory evidence of ZIKV disease. Transmission was first detected in urban areas of eastern Puerto Rico, where transmission also peaked earlier. These trends suggest that ZIKV was first introduced to Puerto Rico in the east before disseminating throughout the island.

Investigation of global ionospheric response of the severe geomagnetic storm on June 22-23, 2015 by GNSS-based TEC observations

The magnetosphere and ionosphere have a crucial interaction during severe geomagnetic storms. The Global Navigation Satellite System (GNSS) provides high-quality ionospheric observations with high temporal and spatial resolution, is generally preferred to investigate the ionospheric variation. In this study, the storm-time ionospheric response of the June 2015 severe storm (Dstmin = −208 nT) was investigated by the Total Electron Content (TEC) data of the Global Ionosphere Maps (GIMs), COSMIC radio occultation (RO) and a chain of International GNSS Service (IGS) stations. GIMs were used to show the global TEC variation during the storm. COSMIC RO data were also utilized to investigate the TEC variation and electron density profiles in an anomaly area with a limited time interval. GNSS TEC data of the 16 IGS stations were utilized to investigate the ionospheric variability on different latitudes of hemispheres. The results showed that intense positive phases formed in high latitudes of the Southern Hemisphere (SH) and the western longitudes of the Northern Hemisphere (NH), especially over the North Atlantic Ocean until the main phase of the storm. Besides, negative phases were observed in high latitudes and eastern longitudes of the NH. During the recovery phase of the storm, positive phases were seen in the low latitudes of the SH and the ionospheric conditions calmed down in the entire SH after the depletion of these phases. Negative phases were also observed almost wholly covered in the NH, which denser in the European-African sector. As a particular result, the electron density profiles of COSMIC RO showed that the ionospheric phases of the June 2015 storm not only related to TEC values but also the altitude of maximum electron density.