Trend Of Anomalies Research Articles

Effective Elastic Thickness Map Reveals Subglacial Structure of East Antarctica

AbstractEast Antarctica is the least well‐exposed Precambrian shield on Earth. What is known, or surmised, of its geological structure comes from extrapolation over large distances and from geophysics. Here, we present a map of effective elastic thickness, Te, computed from Antarctic bedrock topography and both terrestrial and satellite gravity data. Te is directly related to lithospheric strength and can distinguish domains of differing tectonic history. Our map reveals a broad region of high Te in Wilkes Land, interpreted as a craton, while elsewhere a corridor of low Te meanders between areas of higher Te. The low‐Te belt follows the trend of prominent linear magnetic anomalies identified in the Gamburtsev and Dronning Maud Land provinces, two of which have previously been identified as possible Grenville or Pan‐African age sutures.

An Assessment of the Filling Process of the Grand Ethiopian Renaissance Dam and Its Impact on the Downstream Countries

The Grand Ethiopian Renaissance Dam (GERD), formerly known as the Millennium Dam, has been filling at a fast rate. This project has created issues for the Nile Basin countries of Egypt, Sudan, and Ethiopia. The filling of GERD has an impact on the Nile Basin hydrology and specifically the water storages (lakes/reservoirs) and flow downstream. In this study, through the analysis of multi-source satellite imagery, we study the filling of the GERD reservoir. The time-series generated using Sentinel-1 SAR imagery displays the number of classified water pixels in the dam from early June 2017 to September 2020, indicating a contrasting trend in August and September 2020 for the upstream/downstream water bodies: upstream of the dam rises steeply, while downstream decreases. Our time-series analysis also shows the average monthly precipitation (derived using IMERG) in the Blue Nile Basin in Ethiopia has received an abnormally high amount of rainfall as well as a high amount of runoff (analyzed using GLDAS output). Simultaneously, the study also demonstrates the drying trend downstream at Lake Nasser in Southern Egypt before December 2020. From our results, we estimate that the volume of water at GERD has already increased by 3.584 billion cubic meters, which accounts for about 5.3% of its planned capacity (67.37 billion cubic meters) from 9 July–30 November 2020. Finally, we observed an increasing trend in GRACE anomalies for GERD, whereas, for the Lake Nasser, we observed a decreasing trend. In addition, our study discusses potential interactions between GERD and the rainfall and resulting flood in Sudan. Our study suggests that attention should be drawn to the connection between the GERD filling and potential drought in the downstream countries during the upcoming dry spells in the Blue Nile River Basin. This study provides an open-source technique using Google Earth Engine (GEE) to monitor the changes in water level during the filling of the GERD reservoir. GEE proves to be a powerful as well as an efficient way of analyzing computationally intensive SAR images.

Holocene vegetation and hydrology variations and their associations with climate changes: a multi-proxy analysis of a sediment core from an alpine basin in the middle Tianshan Mountains

We in this paper present a multi-proxy study of a 186-cm-long lacustrine sediment core (i.e., BY Core) obtained from the Youerdusi Basin in the middle Tianshan Mountains in an attempt to disentangle the causal associations among climate changes, ecological responses and hydrological variations. Palynological, assemblages and the associated biome scores indicate that the upper limit of the forest zone was closer to the Youerdusi Basin with a larger wetland extent in the Youerdusi Basin during the early part (i.e., from ~ 10.5 to ~ 5.8 cal. kyr BP) of the data-covering period (i.e., from ~ 10.5 to ~ 2.4 cal. kyr BP). The upper limit of the forest zone was farther away from the Youerdusi Basin with a smaller wetland extent in the Youerdusi Basin during the late part (i.e., from ~ 5.8 to ~ 2.4 cal. kyr BP). The changes of taiga biome score and the AP% ratio indicate a persistent cooling trend during the data-covering period which is well corroborated by various proxy data from nearby sites and the cooling trend is chronologically consistent with the trend of Northern Hemisphere temperature anomalies that was interpreted to be a delayed response to the summer solar irradiance at 50° N. The tundra biome score and the associated percentages of Cyperaceae in the Youerdusi Basin show two major stages of wetland extent variation. The wetland extent variation in the Youerdusi Basin might have been controlled by precipitation and/or by glacier-melting potential that was in turn controlled by both temperature and the extent of remained ice cover in higher elevations. The δ13Corg values obtained from the BY Core indicate a wetting trend during the data-covering period which is reasonably corroborated by various proxy data from nearby sites. We infer that the wetting trend was causally associated with the Holocene increasing trend of the North Atlantic Ocean SST (sea surface temperature) and also with the Holocene increasing trend of the westerlies’ intensity.

Mega-dams and extreme rainfall: Disentangling the drivers of extensive impacts of a large flooding event on Amazon Forests.

Extreme weather events and the presence of mega-hydroelectric dams, when combined, present an emerging threat to natural habitats in the Amazon region. To understand the magnitude of these impacts, we used remote sensing data to assess forest loss in areas affected by the extreme 2014 flood in the entire Madeira River basin, the location of two mega-dams. In addition, forest plots (26 ha) were monitored between 2011 and 2015 (14,328 trees) in order to evaluate changes in tree mortality, aboveground biomass (AGB), species composition and community structure around the Jirau reservoir (distance between plots varies from 1 to 80 km). We showed that the mega-dams were the main driver of tree mortality in Madeira basin forests after the 2014 extreme flood. Forest loss in the areas surrounding the reservoirs was 56 km2 in Santo Antônio, 190 km2 in Jirau (7.4–9.2% of the forest cover before flooding), and 79.9% above that predicted in environmental impact assessments. We also show that climatic anomalies, albeit with much smaller impact than that created by the mega-dams, resulted in forest loss along different Madeira sub-basins not affected by dams (34–173 km2; 0.5–1.7%). The impact of flooding was greater in várzea and transitional forests, resulting in high rates of tree mortality (88–100%), AGB decrease (89–100%), and reduction of species richness (78–100%). Conversely, campinarana forests were more flood-tolerant with a slight decrease in species richness (6%) and similar AGB after flooding. Taking together satellite and field measurements, we estimate that the 2014 flood event in the Madeira basin resulted in 8.81–12.47 ∙ 106 tons of dead biomass. Environmental impact studies required for environmental licensing of mega-dams by governmental agencies should consider the increasing trend of climatic anomalies and the high vulnerability of different habitats to minimize the serious impacts of dams on Amazonian biodiversity and carbon stocks.

Prevalence and Trends of Congenital Anomalies Among Neonates at Jimma Medical Center, Jimma, Ethiopia: A Three-Year Retrospective Study.

IntroductionCongenital anomalies are a major public health problem which is defined as structural or functional anomalies that occur during intrauterine life which can be detected prenatally, at birth, or sometimes may only be detected later in infancy. The impact of congenital anomalies is severe in middle- and low-income countries than in other developed and developing countries.ObjectiveTo assess the prevalence and trends of congenital anomalies among neonates admitted at Jimma Medical Center from 2017 to 2019.MethodsA facility-based retrospective, descriptive crossectional study was conducted among neonates admitted at Jimma Medical Center from 2017–2019. Descriptive analysis (frequency and percentage) was calculated for the variables. The result was present in the table, text, and figure.ResultsFrom a total of 3346 admitted neonates, 199 (5.95%) neonates were diagnosed with congenital anomalies; of which 120 (60.3%), 146 (73.4%), 144 (72.4%) and 30 (15.1%) of neonates were males, urban dwellers, delivered with normal birth weight and had multiple congenital anomalies, respectively. Central nervous system was the most commonly affected body system 56 (28.1%), followed by the gastrointestinal tract 41 (20.1%) and musculoskeletal system 32 (16.1%). The proportion of congenital anomalies was significantly increasing over time.ConclusionThe overall prevalence of congenital anomalies was high and increased from year to year. The proportions observed in the study indicated that a significant number of neonates were affected and suffered from the impacts of congenital anomalies which need immediate preventive actions such as iron folate supplementation during preconception and early pregnancy. Therefore, design strategies to create community awareness and prevention mechanism of congenital anomalies, and strengthening the care and rehabilitation services for affected patients are crucial.

Interpretation of aeromagnetic data of the Sivas Basin in the central eastern Turkey

The Sivas Basin is located in the eastern part of the central Anatolia. In this study, aeromagnetic data in the basin and surrounding area are processed and anomalies are interpreted to determine the approximate locations of the causative bodies and reveal their relationship with the tectonic trends. The sedimentary basin is surrounded by strong magnetic anomalies from the south, east, and northeast. The most apparent anomalies are observed in the E-NE of Zara, SW of Divriği, and north of Kangal. These anomalies do not present significant directional change when they are reduced to the pole process. Causative bodies of the southern anomalies around Divriği and Kangal extend from NE to SW and the northerly anomaly trend (to the north of Kangal) crosses the southern one (Divriği trend) in the analytic signal map. These trends are well-defined by the maxima points of the horizontal derivatives and these maxspots generally follow the boundaries of anomalies in the tilt angle map. The Kangal Fault controls the extensions of the Divriği anomalies through the north and they are not observed in the area to the north of the fault. The Hafik Anomaly in the north of the study area is also differentiated from the anomaly group in the E-NE of Zara precisely, defining that they are created by 2 different causative bodies. Aeromagnetic characteristics of the ophiolites to the south indicate that they have different origin from the northern ophiolites group. Similarly, it is determined that the plutonic rocks in the south and north are also different origin emplacements, considering their aeromagnetic responses, mineral contents, and ore deposit possibilities.

Trends of Temperature Extreme Indices over Arusha and Kilimanjaro Regions in Tanzania

The study aimed at analyzing the trends and variability of temperature extremes over the northeastern highlands in Tanzania, specifically over Arusha and Kilimanjaro regions. Quality controlled mean monthly, daily maximum and minimum temperature data for the period 1961 to 2020, obtained from Tanzania Meteorological Authority, were used in the study. Rclimdex and the National Climate Monitoring Products (NMCP) software, developed by the World Meteorological Organization (WMO), were used for computation of the indices at a monthly, seasonal and annual time scale. The computed indices were also subjected to trend analysis to determine their direction and magnitude of change. Extraction and assessment of the top five highest and lowest maximum and minimum temperatures were also done. Increasing trends of temperature anomalies for seasonal and annual timescales were observed for both Arusha and Kilimanjaro regions. Also, the increasing trends of warm and extreme warm days and nights and relatively increasing trends of cold and extreme cold days and nights were observed for both regions. The highest ever recorded temperatures since the establishment of the two stations were 36.3?C observed on 16th February 2011 and 38.6?C observed on 22nd February 2005 for Arusha and Kilimanjaro respectively. These results indicate that The last two decades have been characterized by enhanced warming, which is consistent with overall global temperature trend patterns as depicted in recent IPCC reports and the report of the State of Climate in Africa.

Prevalence & spectrum of congenital anomalies at a tertiary care centre in north India over 20 years (1998-2017).

Background & objectives:Congenital anomalies lead to significant morbidity and mortality. Systematically published data on the prevalence and spectrum of congenital anomalies from India are scarce. This study was aimed to ascertain the prevalence, spectrum, trend, and outcome of congenital anomalies at a tertiary care centre in north India over two decades.Methods:Electronic records of all live births from January 1998 to December 2017 were retrieved, and the neonates with congenital anomaly were included in this retrospective analysis. International Statistical Classification of Diseases and Related Health Problems, tenth revision (ICD-10) was used for uniformity and international comparison. The further sub-categorization was done as per the WHO birth defects surveillance manual. The prevalence of individual as well as overall congenital anomalies was calculated. Run charts were used to analyze the trends.Results:In the two decades studied (1998-2017), there were 86850 live births, of which 1578 [1.82%, 95% confidence interval (CI): 1.73-1.91%] neonates had a major congenital anomaly. The overall prevalence of anomalies was 182 (95% CI: 173-191) per 10,000 live births. Malformation of the circulatory system was the most common (28.0%) followed by musculoskeletal (18.6%) and urinary system (14.3%). Congenital anomaly-related death rate was 6.78 per 1000 live births. No significant trend was observed in the annual prevalence, individual malformations or contribution of congenital anomalies to overall mortality over the two decades.Interpretation & conclusions:Our results showed a high prevalence of congenital anomalies which could be responsible for significant mortality, warranting the need for a national surveillance programme and birth defect services. It is important to have a national database to know the overall burden and spectrum of congenital anomalies in the country.

Characterizing the Seasonal Cycle of the Northern Australian Rainy Season

AbstractIn this paper we introduce an objective definition for the onset and the retreat of the northern Australian rainy season that overlaps significantly with the Australian monsoon season. We define onset and retreat dates of the northern Australian rainy season as being the first and the last day of the year when the daily rain rate exceeds and falls below the climatological annual mean rain rate, respectively. However, our definition of onset/demise is not as restrictive as the traditional monsoon season that seeks the arrival of the westerlies and the equatorward retreat of the trough at its onset and demise, respectively. As defined in this paper, the length of the rainy season is longer than the monsoon season and includes the pre- and post-monsoon rainfall. It is noted that an early or later onset date of the northern Australian rainy season is associated with a longer or shorter, wetter or drier, and colder or warmer season, respectively. Similar relationship is also observed with demise date variations, which are, however, weaker than the onset date variations. Furthermore, we find that the relationship of the northern Australian seasonal rainfall variations with ENSO variability becomes stronger when we account for variations in the length of the rainy season compared to the fixed (December–February) monsoon season length. We also find a significant linear trend over the time period of the analysis from 1901 to 2015 toward an increasing length of the northern Australian rainy season that influences the corresponding rising trend of seasonal rainfall anomalies.

Types, Characters and Trend of Congenital Anomalies in Thi-Qar / 2 years assessment

Objectives: To assess the extent of NCDs among geriatric people in Al- Nasiriyah city together with an assessment of general health status and the health care services provided to this segment of the population. Methodology: Analytical, cross-sectional study in form of household survey had been conducted in Al- Nasiriyah City, from 1 October 2015 to the end of August 2016. A multistage sampling involving 423 individuals aged ≥ 60 years as a representative sample. Results: The overall prevalence of chronic NCDs was 89%. The top five chronic diseases were hypertension (67%), diabetes (31.2%), musculoskeletal diseases (15.4%), heart diseases (11.1%), and cataract (12.8%). Prevalence of mutimorbidity (patient with two or more chronic diseases) was 59%. The main geriatric symptoms were vision problems (77.8%), feeling sad or depressed (36.4%), hearing problems (31.7%), falls (30%), memory problems (22.9%), and urinary symptoms (11.1%). Conclusion: The overall prevalence of chronic NCDs, mutimorbidity and geriatric problems among geriatric people of Al- Nasiriyah city was high, particularly cardiovascular diseases and diabetes alarming the need for actual and focused efforts in the field of prevention and improvement as well as strengthen the health care system particularly geriatric health care to reduce morbidity and to improve the healthy life years for elderly people.

Types, Characters and Trend of Congenital Anomalies in Thi-Qar / 2 years assessment.

Types, Characters and Trend of Congenital Anomalies in Thi-Qar / 2 years assessment.

Recent changes in heatwave characteristics over Korea

Global warming and abnormal climate change have resulted in an increase in the frequency of severe heatwave events. Recently, a series of extreme heatwave events have occurred in South Korea, and the damage from these events has also been increasing. Thus, it is necessary to analyze the mechanisms for generating and developing heatwaves. In this study, the long-term trend for heatwave events in South Korea was investigated using cluster analysis. Heatwave events in a 38-year period in South Korea were defined, and their synoptic patterns were categorized into three clusters. The number of heatwave days of cluster 2, which is related to the anomalous positive geopotential height (GPH) over the Kamchatka Peninsula, was found to significantly increase in recent years (2000–2018) compared with the past (1981–1999). In contrast, the frequency of cluster 3 associated with a negative GPH anomaly over the Kamchatka Peninsula decreased in the same period. There were five regions, including northern China and the Kamchatka Peninsula, where the mid-level GPH significantly increased between 2000 and 2018. This change in GPH was positively (negatively) correlated with the patterns associated to long-term variability of heatwave days of cluster 2 (cluster 3). The long-term trends of the GPH anomalies over five regions showed a significant correlation with the North Atlantic Oscillation (NAO) index during midsummer. As a result, it is likely that the heatwave events related to cluster 2 (cluster 3) have increased (decreased) in South Korea because the long-term variability of the summer NAO has recently induced a favorable (unfavorable) atmospheric condition for cluster 2 (cluster 3).

Sedimentary geology and geochemical approach to determine depositional environment of the Triassic turbidites bearing Semanggol Formation, NW Peninsular Malaysia

The current study will provide sedimentary and geochemical characteristics of turbidites bearing part of the Triassic Semanggol Formation (SgF) from NW Peninsular Malaysia. Six localities have been studied for detailed lithofacies analysis around Taiping, north Perak, Bukit Merah, north Perak and Kampung Badak, north Kedah, whereas 12 representative samples have been selected for geochemical analysis. A total of nine lithofacies (Fsg1-Fsg9) have been identified which categorized into four facies groups: I-Conglomerate dominate facies (Fsg1-Fsg2), II-Sand dominate facies (Fsg3-Fsg6), III-Chaotic unit of shale/mudstone-siltstone dominate facies (Fsg7), and IV-Mud dominate facies (Fsg8-Fsg9). Sedimentary facies analysis has resulted in recognition of four major genetic units: (1) Channel-fill complex, (2) Levee or over-bank deposits, (3) Distal lobes, and (4) Mass transport complexes (MTCs). These four genetic units were deposited within three proposed laterally contiguous depositional environments which are: (1) inner-fan channel-fill complex, (2) mid-fan levees or over bank complex, and (3) outer-fan distal lobes. The Semanggol Formation turbidites system is considered as a multiple-sourced, shelf-fed, Type III, low efficiency, mixed sand-mud rich depositional system. Multiple geochemical indicators (V/(V+Ni),V/(V+Cr),V/Cr, Sr/Cu, Ce∗, Eu∗ etc) have been utilized which show geochemical anomalies trend increases stratigraphically from bottom to top and corresponds to an upward deepening of depositional environment.

Mantle flow below the central and greater Alpine region: insights from SKS anisotropy analysis at AlpArray and permanent stations

Abstract. The Alpine chain in western and central Europe is a complex orogen developed as a result of the African–Adriatic plate convergence towards the European continent and the closure of several Tethys oceanic branches. Seismic tomography studies detected high-wave-speed slabs plunging beneath the orogen to variable depths and a potential change in subduction polarity beneath the Central Alps. Alpine subduction is expected to leave a significant imprint on the surrounding mantle fabrics, although deformation associated with the Hercynian Orogeny, which affected Europe prior to the collision with Adria, may have also been preserved in the European lithosphere. Here we estimate SKS anisotropy beneath the central and greater Alpine region at 113 broadband seismic stations from the AlpArray experiment as well as permanent networks from Italy, Switzerland, Austria, Germany, and France. We compare the new improved dataset with previous studies of anisotropy, mantle tomography, lithospheric thickness, and absolute plate motion, and we carry out Fresnel analysis to place constraints on the depth and origin of anisotropy. Most SKS directions parallel the orogen strike and the orientation of the Alpine slabs, rotating clockwise from west to east along the chain, from −45 to 90∘ over a ∼700 km distance. No significant changes are recorded in Central Alps at the location of the putative switch in subduction polarity, although a change in direction variability suggests simple asthenospheric flow or coupled deformation in the Swiss Central Alps transitions into more complex structures beneath the Eastern Alps. SKS fast axes follow the trend of high seismic anomalies across the Alpine Front, far from the present-day boundary, suggesting slabs act as flow barriers to the ambient mantle surrounding them for hundreds of km. Further north across the foreland, SKS fast axes parallel Hercynian geological structures and are orthogonal to the Rhine Graben and crustal extension. However, large splitting delay times (>1.4 s) are incompatible with a purely lithospheric contribution but rather represent asthenospheric flow not related to past deformational events. West of the Rhine Graben, in northeastern France, anisotropy directions are spatially variable in the proximity of a strong positive seismic anomaly in the upper mantle, perhaps perturbing the flow field guided by the nearby Alpine slabs.

Strengthening of the Kuroshio current by intensifying tropical cyclones.

A positive feedback mechanism between tropical cyclones (TCs) and climate warming can be seen by examining TC-induced energy and potential vorticity (PV) changes of oceanic geostrophic eddies. We found that substantial dissipation of eddies, with a strong bias toward dissipation of anticyclonic eddies, is directly linked to TC activity. East of Taiwan, where TCs show a remarkable intensifying trend in recent decades, the ocean exhibits a corresponding upward trend of positive PV anomalies. Carried westward by eddies, increasing numbers of positive PV anomalies impinge on the Kuroshio current, causing the mean current to accelerate downstream. This acts in opposition to decreasing basin-scale wind stress and has a potentially important warming impact on the extratropical ocean and climate.

Anomaly detection for large span bridges during operational phase using structural health monitoring data

In view of the limitation of damage detection in practical applications for large scale civil structures, a practical method for anomaly detection is developed. Within the anomaly detection framework, wavelet transform and generalized Pareto distribution (GPD) are adopted for data processing. In detail, to reduce the influence of thermal responses on signal fluctuations induced by anomaly events, wavelet transform is employed to separate thermal effects from raw signals based on the distinguished frequency bandwidths. Subsequently, a two-level anomaly detection method is proposed, i.e. threshold-based anomaly detection and anomaly trend detection. For the threshold-based anomaly detection, the threshold for anomaly detection is determined by GPD analytics, corresponding to a 95% guarantee rate within 100 years. Moreover, the threshold is periodically updated by incorporating the latest monitoring data to model the increase of traffic volumes and gradual degradations of structures. For the anomaly trend detection, the moving fast Fourier transform is adopted for discussion. Finally, the mid-span deflection of Xihoumen Suspension Bridge is selected as the index to validate the effectiveness of the proposed methodology. Two types of anomaly events are assumed in the case study, i.e. the overloading event and structural damage. The two-level anomaly detection is implemented. It is indicated through the case study that the proposed anomaly detection approach (without the influence of temperature) is able to detect three 100 ton overloaded vehicles and damages in main cables. However, the assumed cases subject to 100 ton vehicle and damages in stiffening girders are hardly detected by using the deflection index, owing to the sensitivity of the index to each anomaly event. In the future studies, a structural health monitoring-based multi-index anomaly detection system is promising to ensure the operational and structural safety of large span bridges.

과표본추출 기반의 블록체인 이상탐지 방법에 관한 연구

Despite the characteristics of reliable blockchain, there are an increasing trend of anomalies in its network. Recent crime reports show that bitcoins can be used in illegal transactions such as drug trafficking, money laundering and frauds. Thus, it is crucial to detect illegal transactions earlier to secure credibility of blockchain network. We extracted features from both each users and their transactions after building a database. In particular, transaction data are of a network structure, so features are extracted using the network analysis. Owing to unbalance property of the transaction data, the borderline SMOTE is used as the oversampling method. Finally, the analysis and comparison are performed using support vector machine (SVM), random forest (RF), XGBoost, and logistic regression to evaluate their performances. We apply the proposed method to the real data set of bitcoin transaction data, and find that XGBoost shows the best performance in detecting anomal transactions. The proposed oversampling-based methods show a potential in detecting anomal transactions earlier.

Crustal architecture and rift tectonics across the Visakhapatnam Bay basin, central-east Indian margin: Insights from multichannel seismic and potential field data

The Visakhapatnam Bay (VB) basin is a passive margin rift basin located at the non-basinal segment of the Eastern Continental Margin of India (ECMI) and formed during the rift–drift events associated with the breakup of eastern Gondwanaland. In the present study, integrated analysis of potential field and multi-channel seismic reflection (MCS) data were carried out to understand the rift tectonics, crustal configuration and onshore–offshore structural continuity across this basin. The study revealed the following: (i) crustal models derived through joint gravity-magnetic modelling show limited stretching with 36–40 thick crust below the Eastern Ghat Mobile Belt (EGMB) thinning down to 16–20 km at the Ocean Continent Transition (OCT), (ii) extension of Charnockitic basement associated with the Eastern Ghat Mobile Belt (EGMB) into the offshore region. Comparison of the crustal configuration across the VB basin with that across the adjacent thick sedimentary area of the Krishna–Godavari shows that upper crustal configuration is significantly different in the VB area. The observed limited rift related structuration (horst-graben morphology), the mapped high angle break-away fault with large offset in the seismic data and narrow width (70–90 km) of extended crustal domain in VB basin suggests that this segment acts as transfer zone between Krishna–Godavari and Mahanadi rift zones. Further, long curve-linear trend of magnetic anomalies associated with Pudimadaka Lineament (PKL) demarcate the VB basin from the adjacent Krishna–Godavari rift zone.

Geology of the Gobi and Mongol Altai junction enhanced by gravity analysis: a key for understanding of the Mongolian Altaides

ABSTRACT The geological map L-47-V at a scale 1:500,000 covers part of Mongolian Altaids with ophiolite fragments in southern Central Asian Orogenic Belt in SW Mongolia. This region has a basin and range topography with Neoproterozoic and Palaeozoic units exposed at NW–SE trending ranges rising along major intracontinental faults and with intermontane basins filled by Mesozoic and Cenozoic sediments in between. The map shows clear N–S tectonic zonation featuring the northerly Precambrian Baidrag microcontinent, the lower Palaeozoic Lake Zone in the centre and the southerly Palaeozoic Gobi-Altai and Trans-Altai zones. Gravity highs are located in the SW part of the map and low to intermediate Bouguer anomalies in the NE part. NW–SE trends of gravity anomalies correlate well with the contact between the Trans-Altai and the Gobi-Altai zones but the important first-order geological boundary between the Lake and Gobi-Altai zones cannot be delineated by the gravity gradients.

Reconstructed 3-D Ocean Temperature Derived from Remotely Sensed Sea Surface Measurements for Mixed Layer Depth Analysis

The mixed layer depth (MLD) is generally estimated using in situ or model data. However, MLD analyses have limitations due to the sparse resolution of the observed data. Therefore, this study reconstructs three-dimensional (3D) ocean thermal structures using only satellite sea surface measurements for a higher spatial and longer temporal resolution than that of Argo and diagnoses the decadal variation of global MLD variability. To simulate the ocean thermal structures, the relationship between the ocean subsurface temperature and the sea surface fields was computed based on gridded Argo data. Based on this relationship, high spatial resolution and extended periods of satellite-derived altimeter, sea surface temperature (SST), and wind stress data were used to estimate the 3D ocean thermal structures with 0.25° spatial resolution and 26 standard depth levels (5–2000 m) for 24 years (1993–2016). Then, the MLD was calculated using a temperature threshold method (∆T = 0.2 °C) and correlated reasonably well (>0.9) with other MLD datasets. The extended 24-year data enabled us to analyze the decadal variability of the MLD. The global linear trend of the 24-year MLD is −0.110 m yr−1; however, from 1998 to 2012, the linear trend is −0.003 m yr−1 which is an order of magnitude smaller than that of other periods and corresponds to a global warming hiatus period. Via comparisons between the trends of the SST anomalies and the MLD anomalies, we tracked how the MLD trend changes in response to the global warming hiatus.