Northwest-southeast Direction Research Articles

Imaging contamination surrounding a wastewater dumpsite using 2 terrain conductivity meters

Terrain conductivity meters are effective tools for imaging shallow groundwater and soil contamination; however, the capability of different meters as well as the comparability of their results is a controversial issue. We used the EMP-400 Profiler and EM-31 terrain conductivity meters to investigate the soil and groundwater contamination around a wastewater lake in Wadi Uranah, western Saudi Arabia. Both devices are used simultaneously to collect apparent conductivity data along 19 profiles with a total length of 40 kilometers and the collected data are subjected to similar processing routines and plotting parameters. The results show that despite differences in the absolute conductivity values acquired by both meters, they produce significantly comparable subsurface images of apparent conductivity distribution. The results also show that each meter has a set of advantages and disadvantages. The EMP-400 Profiler is lighter, smaller, and easier to handle and operate in field and has the capability to operate at 3 different frequencies, yielding images at variable depth slices. On the other hand, subsurface apparent conductivity images provided by the EM-31 show apparent conductivity images with more details those of the EMP-400 Profiler. The apparent conductivity maps, collected by both meters, confirm that the flow and accumulation of contaminants in the area are structurally controlled and trending the northeast-southwest direction.

Potensi Timah Primer Daerah Nyelanding Berdasarkan Analisis Data Geomagnet

The village area of Nyelanding is estimated that there are still many regions that have primary tin prospects, this is confirmed by the large number of community mines that are still operating. This research purposes to see the distribution of primary tin mineralization and zones where deposition of tin. This research uses a geomagnetic exploration survey method with back – rover (mobile) system, the length of the track of ±3.5 km. The spacing of 200 m as many as 44 tracks, the direction of the track from south to north with data collection techniques starting from west to east. The data obtained of a magnetic strength value which will then be interpreted into a magnetic anomaly map to determine the location of recommendations. The research method used the Geomagnetic Survey method, of GSM-19 T Magnetometer. The interpretation results, the final map with the lowest magnetic anomaly shows magnetic anomaly values ranging from -7.2 to -3.3 nT at locations 1, 2, 3, the highest magnetic anomaly ranges from -4.6 to 5.0 nT in the southern part which is an area close to community settlements and the village highway of Nyelanding, and the direction of mineral distribution for zone 1 starts from east-west, zone 2 focuses towards the middle which means from southwest-northeast direction or vice versa, zone 3 from southwest-northeast. The upward continuity map 250 and matching the location of samples containing Sn levels around the recommended zone, it is certain that the area has cassiterite minerals in the zone namely zone 1 = (342.760 m2), zone 2 = (4001.770 m2), zone 3 = (372.876 m2).

Remote sensing, geological, and geophysical investigation in the area of Ndlambe Municipality, Eastern Cape Province, South Africa: Implications for groundwater potential

Potentiality for groundwater in the Ndlambe Municipality, comprising of rocks of the Witteberg Group, Cape Supergroup, was investigated using a combination of different approaches. Distribution of lineaments extracted from a satellite image is hardly homogenous; their density varies with different localities. Areas around the western and southwestern parts of the study area have relatively high-density values (≥39) while the northern, eastern and northeastern parts of the area of study are dominated by low-density values (0-39). Boreholes located in the northeastern part appear to be away from the zones of dense lineaments, have dried up, and were found not to be productive. In the northwest parts of the study area, there are several locations displaying intersections of lineaments, these zones of high lineament intersection can be targeted for groundwater exploration. Most of the lineaments in the study area trend in a northeast-southwest direction; this trend would be identical to the orientation of the preferential flow path. Quartz veins and normal faults seen in the field are good indicators for groundwater potential as they are a structural expression of extensional environmentsThe same applies to quartz grains affected by extensional micro-fractures, which resulted from brittle deformation as seen under the microscope. Subsurface geology investigation from borehole logging has depicted fractures in quartzitic sandstones; thus, micro-fractures in quartz grains and quartzitic sandstones enhance secondary porosity and groundwater flow. Low resistivities from the geophysical investigation in the study area were inferred to be weathered moist sandstone. The low resistivities at depth also indicate an overlying zone of fractured sandstone and quartzite, hence possibility of hosting some groundwater. Low resistivity zones between two large bodies suggest that the massive rock bodies are being weathered and fractured, and fractures act as conduits for groundwater.

Spatial-temporal patterns and characteristics of ecological function between 2009 and 2015 in China

Abstract Ecological function reflects the ability of the land to provide ecological goods to support high-quality human production and life. The evaluation of the county-level ecological function across the whole nation is crucial for sustainable land management, which has not been implemented effectively in China. In this study, we proposed a unified system for the assessment of ecological function that would be comparable at the county level, and we applied the system to evaluate the ecological function of 2850 counties across China based on multi-source data. We also examined the spatiotemporal changes in ecological function from 2009 to 2015 using standard deviational ellipses and coefficients of variation. The results showed that the number of counties with high levels of ecological function in China decreased by 8.13% from 2009 to 2012 and then increased by 0.6% from 2012 to 2015. The spatial pattern of the degradation of ecological function shifted from the east-west direction to the southwest-northeast direction and became centralized in the Central Plains area of China. The regional imbalance in ecological function followed the order from high to low of the central, western, northeastern, and eastern areas of China. Targeted policies were proposed to control the degradation of the ecological function in the four regions in China.

Seeds of Life in Space (SOLIS)

Context. Low-mass protostars drive powerful molecular outflows that can be observed with millimetre and submillimetre telescopes. Various sulfuretted species are known to be bright in shocks and could be used to infer the physical and chemical conditions throughout the observed outflows. Aims. The evolution of sulfur chemistry is studied along the outflows driven by the NGC 1333-IRAS4A protobinary system located in the Perseus cloud to constrain the physical and chemical processes at work in shocks. Methods. We observed various transitions from OCS, CS, SO, and SO2 towards NGC 1333-IRAS4A in the 1.3, 2, and 3 mm bands using the IRAM NOrthern Extended Millimeter Array and we interpreted the observations through the use of the Paris-Durham shock model. Results. The targeted species clearly show different spatial emission along the two outflows driven by IRAS4A. OCS is brighter on small and large scales along the south outflow driven by IRAS4A1, whereas SO2 is detected rather along the outflow driven by IRAS4A2 that is extended along the north east–south west direction. SO is detected at extremely high radial velocity up to + 25 km s−1 relative to the source velocity, clearly allowing us to distinguish the two outflows on small scales. Column density ratio maps estimated from a rotational diagram analysis allowed us to confirm a clear gradient of the OCS/SO2 column density ratio between the IRAS4A1 and IRAS4A2 outflows. Analysis assuming non Local Thermodynamic Equilibrium of four SO2 transitions towards several SiO emission peaks suggests that the observed gas should be associated with densities higher than 105 cm−3 and relatively warm (T > 100 K) temperatures in most cases. Conclusions. The observed chemical differentiation between the two outflows of the IRAS4A system could be explained by a different chemical history. The outflow driven by IRAS4A1 is likely younger and more enriched in species initially formed in interstellar ices, such as OCS, and recently sputtered into the shock gas. In contrast, the longer and likely older outflow triggered by IRAS4A2 is more enriched in species that have a gas phase origin, such as SO2.

Atacama Compact Array Measurements of the Molecular Mass in the NGC 5044 Cooling-flow Group

Abstract The fate of cooling gas in the centers of galaxy clusters and groups is still not well understood, as is also the case for the complex processes of triggering star formation in central dominant galaxies, reheating of cooled gas by active galactic nuclei (AGN), and the triggering or “feeding” of supermassive black hole outbursts. We present CO observations of the early-type galaxy NGC 5044, which resides at the center of an X-ray bright group with a moderate cooling flow. For our analysis we combine CO(2−1) data from the 7 m antennae of the Atacama Compact Array (ACA) and the ACA total power array (TP). We demonstrate, using the 7 m array data, that we can recover the total flux inferred from IRAM 30 m single-dish observations, which corresponds to a total molecular mass of about 4 × 107 M ⊙. Most of the recovered flux is blueshifted with respect to the galaxy rest frame and is extended on kiloparsec-scales, suggesting low filling factor dispersed clouds. We find eight concentrations of molecular gas out to a radius of 10″ (1.5 kpc), which we identify with giant molecular clouds. The total molecular gas mass is more centrally concentrated than the X-ray emitting gas, but is extended in the northeast-southwest direction beyond the IRAM 30 m beam. We also compare the spatial extent of the molecular gas to the Hα emission: The CO emission coincides with the very bright Hα region in the center. We do not detect CO emission in the fainter Hα regions. Furthermore, we find two CO absorption features spatially located at the center of the galaxy, within 5 pc projected distance of the AGN, infalling at 255 and 265 km s−1 relative to the AGN. This indicates that the two giant molecular clouds seen in absorption are most likely within the sphere of influence of the supermassive black hole.

P-wave velocity anomalies atop and in the mantle transition zone beneath the northern South China Sea from triplicated waveforms

Broadband P waveforms from the China Digital Seismograph Network are used to image velocity structures of the mantle transition zone (MTZ) and lowermost upper mantle beneath the northern South China Sea. The study area is divided into five profiles from southwest to northeast with an azimuthal interval of 10°, and the best-fit 1-D velocity models are obtained from the observed and synthetic triplicated waveform fitting based on an iterative grid-search procedure. Relative to the Earth model IASP91, our results reveal that there are ubiquitous high-velocity anomalies (HVAs) in the lower part of the MTZ with the P-wave velocity increment of 1.5–3.5% and thickness of 209–219 km. The HVAs show no apparent progressive velocity increments or decrements along the southwest-northeast direction. Combining with previous seismological studies, we suggest that the HVAs provide an implication for the proto-South China Sea north slab remnants. The slight 5 km uplift of the 410 km discontinuity and 5–15 km depression of the 660 km discontinuity further support the low-temperature anomalies related to slab remnants stagnated in the MTZ. We also find a low-velocity layer (LVL) atop the MTZ with a P-wave velocity decrement of 2.0–2.5% and a thickness of 60–75 km, and the LVL can be interpreted by the partial melting induced by upwelling MTZ materials, which are hydrated by the water released from stagnant slab. We infer that small lateral variations of the LVL is relevant to the percolation of the melts under vertical pressure in the mantle.

Cenozoic tectonostratigraphic evolution of the strike-slip Cauto-Guacanayabo Basin, Eastern Cuba

An integrated study of Cauto-Guacanayabo strike-slip basin has allowed establishing its tectonostratigraphic evolution. This work uses subsurface data (wells, seismic and gravimetric) and surface data (digital terrain model and geological mapping) to investigate the relations between sedimentary infill and tectonic activity. In the sedimentary infill, four tectonosequences have been recognized, which are constituted by 19 lithostratigraphic units which range in age from middle Eocene to Holocene, and are delimited by regional unconformities at the basin scale. In seismic reflection profiles, the thickness of the sedimentary record can exceed 2600 ms of double time (TWT), while the thickness cut by the boreholes reaches 2500 m in the northeast part of the basin. Each tectonosequence shows different geometries, thickness and number of depocenters. The predominant geometries in a mapping view are rectangular and elongated in the northeast-southwest direction. This evidences the complexity and compartmentalization of the sedimentary infill in the Cauto-Guacanayabo Basin. The coexistence of extensive and compressive structures, close to each other in the Cauto-Guacanayabo Basin, is associated with local transtensive and transpressive regimes. These regimes have been controlled by the left lateral activity of the Cauto-Nipe strike-slip fault and the Guacanayabo-Nipe tectonic corridor. The compressive structures are mainly located in the southern part to the northeast – southwest and east-northeast – west-southwest directions. In the northeast part of the basin, extensive structures with north – south, northeast – southwest and possibly northwest – southeast directions are common, while in the Gulf of Guacanayabo, there is evidence of lesser deformation. The structural patterns indicate that the most intense activity of the Guacanayabo-Nipe tectonic corridor took place during the middle Eocene. The tectonic activity of the corridor begins to wane in the upper Oligocene, which coincides with the transfer of slip to the Orient Fault, the current boundary between the Caribbean and North American plates.

Full-Scale Crustal Interpretation of Kokkola\u2013Kymi (KOKKY) Seismic Profile, Fennoscandian Shield

The Kokkola–Kymi Deep Seismic Sounding profile crosses the Fennoscandian Shield in northwest-southeast (NW–SE) direction from Bothnian belt to Wiborg rapakivi batholith through Central Finland granitoid complex (CFGC). The 490-km refraction seismic line is perpendicular to the orogenic strike in Central Finland and entirely based on data from quarry blasts and road construction sites in years 2012 and 2013. The campaign resulted in 63 usable seismic record sections. The average perpendicular distance between these and the profile was 14 km. Tomographic velocity models were computed with JIVE3D program. The velocity fields of the tomographic models were used as starting points in the ray tracing modelling. Based on collected seismic sections a layer-cake model was prepared with the ray tracing package SEIS83. Along the profile, upper crust has an average thickness of 22 km average, and P-wave velocities (Vp) of 5.9–6.2 km/s near the surface, increasing downward to 6.25–6.40 km/s. The thickness of middle crust is 14 km below CFGC, 20 km in SE and 25 km in NW, but Vp ranges from 6.6 to 6.9 km/s in all parts. Lower crust has Vp values of 7.35–7.4 km/s and lithospheric mantle 8.2–8.25 km/s. Moho depth is 54 km in NW part, 63 km in the middle and 43 km in SW, yet a 55-km long section in the middle does not reveal an obvious Moho reflection. S-wave velocities vary from 3.4 km/s near the surface to 4.85 km/s in upper mantle, consistently with P-wave velocity variations. Results confirm the previously assumed high-velocity lower crust and depression of Moho in central Finland.

Land subsidence from interferometric SAR and groundwater patterns in the Qazvin plain, Iran

ABSTRACTQazvin plain as one of the important plains in northwest Iran in terms of industrial and agricultural activities, reveals evidence of land subsidence in the last decade. We used a descending ENVISAT dataset during 2003–2006 and two ascending and descending Sentinel-1 tracks acquired during 2014–2016 to study the subsidence in the area. Our time-series analysis of the ENVISAT data reveals that the area is subsiding at an average rate of 40 mm yr−1 with a maximum value of 50 mm yr−1 in the line of sight direction. Moreover, our result for the Sentinel-1 ascending and descending tracks shows that the average subsidence rate reaches 65 mm yr−1 in the line of sight direction. Comparing the obtained mean velocity maps of the two datasets indicates the growing subsidence pattern in the northwest-southeast direction inside the plain. The investigation of the water source reveals that the overexploitation of aquifers caused an approximately 17 m decline in the groundwater level from 2001 to 2011. This drastic drop in the groundwater level has resulted in progressive subsidence over time. The comparison between the extent of subsidence from the image processing and the water level depletion contour map in the Qazvin plain depicts that subsidence is occurring in areas with a high decrease in underground water level. This study suggests that, besides decreasing the number of deep wells as well as their outflow water, the types of agricultural production related to water consumption and irrigation methods in an area such as Iran can play an important role in decreasing the stress on aquifers.

Facies variability within a mixed carbonate–siliciclastic sea-floor fan (upper Wolfcamp Formation, Permian, Delaware Basin, New Mexico)

Sea-floor fans containing both carbonate and siliciclastic detritus are rarely recognized in the rock record but are common within the Permian upper Wolfcamp Formation in the Delaware Basin in southeast New Mexico and west Texas. One such compositionally mixed fan has been studied in detail as part of an unconventional oil and gas exploration and development program in southeast New Mexico. Three cores were collected through an approximately 100-m (∼350-ft)-thick interval that defines the structurally controlled fan. Cores collected represent the frontal to distal fringe, off-axis, and lateral fringe parts of the fan. Unlike siliciclastic fans where axial facies are characterized more by turbidites, the axis, off-axis, and lateral fringe cores in the Wolfcamp are dominated by carbonate debrites. Coarse carbonate deposition decreases toward the frontal fringe areas where core facies are composed of mixed carbonate–siliciclastic mud-rich hybrid event beds and background sedimentation. The core through the lateral fringe differs from the off-axis core in that the debrites in the lateral fringe are thinner and commonly rheologically stratified with finer grained debrites sitting directly on top of coarse-grained debrites, suggesting a genetic link in their formation. The axial facies appear to be dominated by thick amalgamated debrites. Changes in carbonate content from axis to frontal fringe appear to be gradual but rapid from axis to lateral fringe over a 3-km (2-mi) distance. The carbonate-rich part of the fan trends at least 55 km (34 mi) in a northeast-southwest direction and extends 18 km (11 mi) northwest-southeast across.

Waveform Cross-Correlation Relocation and Focal Mechanisms for the 2019 Ridgecrest Earthquake Sequence

Abstract I present a high-precision earthquake relocation catalog and first-motion focal mechanisms before and during the 2019 Ridgecrest earthquake sequence in eastern California. I obtain phase arrivals, first-motion polarities, and waveform data from the Southern California Earthquake Data Center for more than 24,000 earthquakes with the magnitudes varying between −0.7 and 7.1 from 1 January to 31 July 2019. I first relocate all the earthquakes using phase arrivals through a previously developed 3D seismic-velocity model and then improve relative location accuracies using differential times from waveform cross correlation. The majority of the relocated seismicity is distributed above 12 km depth. The seismicity migration along the northwest–southeast direction can be clearly seen with an aseismic zone near the Coso volcanic field. Focal mechanisms are solved for all the relocated events based on the first-motion polarity data with dominant strike-slip fault solutions. The Mw 6.4 and 7.1 earthquakes are positioned at 12.45 and 4.16 km depths after the 3D relocation, respectively, with strike-slip focal solutions. These results can help our understanding of the 2019 Ridgecrest earthquake sequence and can be used in other seismological and geophysical studies.

Assessment of Local Site Condition on Seismic Ground Motion in Arak, Using Experimental Measurements and Numerical Modeling

In order to estimate the seismic site response of alluvial deposits in Arak, spectral analysis of microtremor data in 20 locations (in northwest–southeast and northeast–southwest sections) has been performed. Using horizontal-to-vertical spectral ratio (H/V) on the recorded data, natural periods and corresponding amplification factors of soil layers, and using Rayleigh wave inversion techniques, the thickness of the soil layers and depth of seismic bedrock were estimated. In addition, 1D numerical analyses using DEEPSOIL software and 2D modeling using PLAXIS program, linearly at low strain levels, were performed and the results were compared to experimental technique. The comparison of microtremor results with 1D and 2D numerical modeling results shows a 25% difference in NW–SE direction. This difference can be attributed to the magnitude of seismic waves in a one-dimensional and two-dimensional analysis of this study. While in the northeast–southwest directions, the results are fairly consistent indicating one-dimensional site behavior in this direction.

Petrographical, petrochemical characteristics of Hòn Rồng massif granitoids, Cam Ranh, Khánh Hòa

Hòn Rồng massif granitoid has a high mountainous terrain, with an absolute height of 728 m, relatively equal, slightly extended in the Northwest-Southeast direction, occupying an area of ​​about 29 km2. Petrographical composition is mainly medium - grained biotite granite (phase 2), minor is fine- grained biotite granite (phase 3), vein rocks are aplite granite and pegmatite and a little of xenolith of granodiorite in medium - grained biotite granite. Medium-grained biotite granite: major mineral composition (%): plagioclase (oligoclase) 25–35, quartz 30, orthoclas 25, biotite 5 - 8 and few hornblend; fine-grained granite (%): plagioclase (oligoclase) 30 - 35; quartz 30 - 35; feldspar kali (orthoclase, and microclin) 30, biotite 3 - 5; accessory mineral is zircon, orthite, apatite, sphen, and very little ore minerals (about ​​2%); epimagmatic minerals including: chlorite, epidot, kaolinite, sericite, carbonate, sausorite-replaced association. Rocks are altered alkalization strongly (albitization and microlinization), and minor are chloritization, epidotization and sericitization. Averaged chemical compositions (%)SiO2: 69.07–72.07; total alkali(K2O+Na2O) 7.35–7.96. Ratio of K2O/Na2O 1.04, low TiO2 (0.24–0.37). Ratios of A/CNK 1.02–1.09, Rb/Sr: 0.27–1.62; Ba/Sr: 1.82–2.56, Ba/Rb: 1.58–7.13; K/Rb: 0.42–0.62; Ca/Sr: 0.21–0.47; the value of Eu anomalies is low. Granite belongs to calc-alkaline, aluminum content is from medium to high; K-Na alkaline series, I-granite type. Granitoid had been formed in plutonic - volcanic arc of subduction-zone. Compared with the granitoid formations in South Vietnam territory, Hòn Rồng massif granitoid belongs to phase 2 (main) and phase 3 (minor) of Đèo Cả complex with late Kreta age.

Frequency-content parameters of the ground motions from the 2017 Mw 7.3 Ezgeleh earthquake in Iran

This study aims at providing the spatial contours of frequency-content parameters of ground motion records obtained during the 2017 Mw 7.3 Ezgeleh–Kermanshah earthquake in Iran. For this purpose, three scalar frequency-content parameters named the mean period $$ (T_{\text{m}} ) $$, the average spectral period $$ (T_{\text{ave}} ) $$, and the smoothed spectral predominant period $$ (T_{0} ) $$ are calculated. Sixty earthquake records with the closest site-to-source distances in the range of 5–330 km were used to make several high-resolution frequency-content maps for the study area. In addition, a new practical framework is presented to estimate soil condition maps based on a simplified ground motion records analyzing which could be used in rapid loss evaluation after earthquakes. As a new idea, the main features of the horizontal-to-vertical spectral ratio curves including amplification amplitude and peak frequency that can identify resonance effect are automatically considered in the proposed regional soil class map. The consistency between frequency-content maps with the anticipated soil condition map is discussed. Prepared maps showed that very long period range extends in the northwest–southeast direction, far from the epicenter.

A Subsurface Geologic Feature Inferred from Relocation of Local Earthquakes in Al-Refaei District, Southern Iraq

For the last two decades, the District of Al-Refaei, southern Iraq, experienced several small to moderate size earthquakes that seem to be clustered in a relatively small area. The initial locations of these earthquakes from the available local and international bulletins show scattered events without any clear structural patterns. A seven-elements seismic array was installed for the period 2014 to 2018 to monitor this activity. Each element of the array consists of three-component Geospace GS11d high-frequency (4.5 Hz) geophone, a solar system power source, and telemetry communications system to transmit data to a central recording station. During the period of monitoring, the array recorded more than 56 earthquakes having a range of magnitude between 1.5 ML to 4.7 mb. Large number of the low magnitude earthquakes were not detected by other monitoring agencies; however, they were recorded by the array. Fifty-six of the most clearly recorded earthquakes were screened for relocation and analysis. Out of the 56 screened earthquakes, 35 were detected by the array alone. The majority of the selected earthquakes having their initial locations within the array. This improves the relocation process and increase accuracy. The relocated earthquakes express a clear pattern of a linear feature which strikes in the northwest-southeast direction. The direction of the newly inferred pattern coincides with the general tectonic setting of Iraq as it is parallel to Zagros suture zone and the general stress regime of the Arabian Plate. The depth of the relocated earthquakes ranges from about 3.9km to 8.9km. This indicates that these earthquakes occur along a shallow subsurface fault that was not mapped before.

Morphological variation of leaf traits in the Ternstroemia lineata species complex (Ericales: Penthaphylacaceae) in response to geographic and climatic variation.

Variation in leaf morphology is correlated with environmental variables, such as precipitation, temperature and soil composition. Several studies have pointed out that individual plasticity can largely explain the foliar phenotypic differences observed in populations due to climatic change and have suggested that the environment plays an important role in the evolution of plant species by selecting for phenotypic variation. Thus, the study of foliar morphology in plant populations can help us identify the environmental factors that have potentially influenced the process of species diversification. In this study, we analyzed morphological variation in the leaf traits of the Ternstroemia lineata species complex (Penthaphylacaceae) and its relation to climatic variables across the species distribution area to identify the patterns of morphological differentiation within this species complex. Based on the collected leaves of 270 individuals from 32 populations, we analyzed nine foliar traits using spatial interpolation models and multivariate statistics. A principal component analysis identified three main morphological traits (leaf length and two leaf shape variables) that were used to generate interpolated surface maps to detect discrete areas delimited by zones of rapid change in the values of the morphological traits. We identified a mosaic coarse-grain pattern of geographical distribution in the variation of foliar traits. According to the interpolation maps, we could define nine morphological groups and their geographic distributions. Longer leaves, spatulate leaves and the largest foliar area were located in sites with lower precipitation and higher seasonality of precipitation following a northwest–southeast direction and following significant latitudinal and longitudinal gradients. According to the phenogram of the relationships of the nine morphological groups based on morphological similarity, the putative species and subspecies of the T. lineata species complex did not show a clear pattern of differentiation. In this study, we found a complex pattern of differentiation with some isolated populations and some other contiguous populations differentiated by different traits. Further genetic and systematic studies are needed to clarify the evolutionary relationships in this species complex.

Three new archaeological sites in the Upper Euphrates region: Köteriç/Kotaric, Indere, and Obrukbaşı

The archaeological researches of the 2018 ‘Iron Age and Hellenistic Period Tunceli survey’ were concentrated within the limits of the Mazgirt district, to the southeast of Tunceli. One of the focal points of the research is the İndere Valley, located between Güneyharman (Köteriç), Karabulut (Sorek), and Obrukbaşı (Lemk) villages, 39 km southeast of the Mazgirt district centre of Tunceli province. The 3.5 km long and 0.8 km wide valley extends in a southeast-northwest direction and displays a deep and sheltered geographical landscape. While the slope and hill settlements are seen on the outer borders of the İndere Valley, the prehistoric period rock shelters, rock-cut tombs, a large Iron Age settlement and a medieval church were identified inside the valley. Güneyharman (Köteriç) and Obrukbaşı settlements are also associated with the valley. The aim of this study is to localise the medieval place name ‘Citharizon’ in Köteriç. It is known as Kotarič in other medieval sources. After a few archaeological surveys, it became clear that the history of İndere Valley and its environs goes back to the prehistoric periods, and continues from the Early Bronze Age till the late Middle Ages.

Characteristics of Atmospheric Heat Sources in the Tibetan Plateau-Tropical Indian Ocean Region

Investigating the temporal and spatial distributions of the atmospheric heat sources (AHS) over the Tibetan Plateau-Tropical Indian Ocean (TP-TIO) region is of great importance for the understanding of the evolution and development of the South Asian summer monsoon (SASM). This study used the Japanese 55-year Reanalysis (JRA-55) data from 1979 to 2016 and adopted statistical methods to study the characteristics of the AHS between the TP and TIO, and theirs link to the SASM on an interannual scale. The results indicated that the monthly variations of the AHS in the two regions were basically anti-phase, and that the summer AHS in the TP was obviously stronger than that in the TIO. There were strong AHS and atmospheric moisture sink (AMS) centers in both the eastern and western TP in summer. The AHS center in the east was stronger than that in the west, and the AMS centers showed the opposite pattern. In the TIO, a strong AHS center in the northwest-southeast direction was located near 10°S, 90°E. Trend analysis showed that summer AHS in the TIO was increasing significantly, especially before 1998, whereas there was a weakening trend in the TP. The difference of the summer AHS between the TP and TIO (hereafter IQ) was used to measure the thermal contrast between the TP and the TIO. The IQ showed an obvious decreasing trend. After 1998, there was a weak thermal contrast between the TP and the TIO, which mainly resulted from the enhanced AHS in the TIO. The land-sea thermal contrast, the TIO Hadley circulation in the southern hemisphere and the SASM circulation all weakened, resulting in abnormal circulation and abnormal precipitation in the Bay of Bengal (BOB).

Multi-scale ionosphere responses to the May 2017 magnetic storm over the Asian sector

We investigate multi-scale ionospheric responses to the May 27, 2017, geomagnetic storm over the Asian sector by using multi-instrumental observations, including ground-based global navigation satellite systems (GNSS) network, constellation observing system for meteorology, ionosphere and climate radio occultation, the FengYun-3C (FY-3C) GNSS occultation sounder electron density profiles and in situ plasma density observations provided by both Swarm and defense meteorological satellite program missions. This geomagnetic storm was an intense storm with the minimum symmetric horizontal component reaching − 150 nT and was caused by a coronal mass ejection released on May 23. The main observations are summarized below: (1) two ionospheric positive storm periods were observed. The first one was observed in the noon–afternoon sector during the main phase of the storm on May 28, with nearly 120% TEC enhancement. The second one was of a smaller scale and occurred on the nightside during the recovery phase of the storm on May 29. The first dayside positive storm was initiated by the interplanetary magnetic field (IMF) Bz southward turning and eastward penetration electric field, while the second nightside one was terminated by a later southward turning of the IMF Bz since the Asian sector was on the nightside and the penetration electric field changed westward. (2) A negative storm occurred from 00:00 to 12:00 UT on May 30 over the Asian sector, nearly 2 days after the main phase, which was due to the thermospheric composition change, i.e., decrease in the O/N2 ratio, as shown in the TIMED/GUVI measurements. (3) A band-like TEC enhancement was observed aligning in the northwest–southeast direction and propagated slowly southwestward from 15:00 to 20:00 UT (23:00–04:00 LT, near midnight) on May 28 during the recovery phase of the storm. In situ density observations from the Swarm B and DMSP F15&16 satellites confirmed the density enhancement at 510 km and 850 km, respectively, and revealed that this band-like TEC enhancement structure resembles the so-called plasma blob. The similarities of the observed plasma blob characteristics in terms of spatial structure, propagation trend and temporal evolution with the nighttime traveling ionospheric disturbance (TID) are consistent with the TID-blob theory.