Eastward Movement Research Articles

Vapor kinetic energy for the detection and understanding of atmospheric rivers

Poleward water vapor transport in the midlatitudes mainly occurs in meandering filaments of intense water vapor transport, spanning thousands of kilometers long and hundreds of kilometers wide and moving eastward. The water vapor filaments are known as atmospheric rivers (ARs). They can cause extreme wind gusts, intense precipitation, and flooding along densely populated coastal regions. Many recent studies about ARs focused on the statistical analyses of ARs, but a process-level understanding of ARs remains elusive. Here we show that ARs are streams of air with enhanced vapor kinetic energy (VKE) and derive a governing equation for Integrated VKE to understand what contributes to the evolution of ARs. We find that ARs grow mainly because of potential energy conversion to kinetic energy, decay largely owing to condensation and turbulence, and the eastward movement is primarily due to horizontal advection of VKE. Our VKE framework complements the integrated vapor transport framework, which is popular for identifying ARs but lacks a prognostic equation for understanding the physical processes.

ENSO‐Modulated Variability in Winter Shelf Circulation of the Northern South China Sea

AbstractWe combined long‐term observational data from 1999 to 2021 with numerical simulations to study the seasonal changes in the currents along the continental shelf in the Northern South China Sea (NSCS) during winter and how these changes relate to the El Niño‐Southern Oscillation (ENSO). Our results indicate that during El Niño events, the eastward movement of the warm pool in the tropical Pacific Ocean not only leads to colder sea surface temperatures and a stronger Kuroshio current intrusion but also significantly affects the formation of a high‐pressure system in the subtropics over the NSCS. In El Niño years, an anomalous anticyclonic wind stress curl in the South China Sea weakens the northeast winter monsoon, which in turn weakens the cyclonic shelf circulation. The first principal component from the multivariate empirical orthogonal function decomposition, which accounts for 49.02% of the total variance, shows a significant correlation of 0.64 with the Niño 3.4 index, indicating the circulation's sensitivity to tropical climate changes. Our analysis of the winter shelf circulation, based on the along‐isobath depth‐integrated vorticity equation, reveals that the exchange of water across the isobaths over the shelf is mainly controlled by the nonlinear advection of relative vorticity, with wind stress curl and bottom stress curl playing a less significant role in regulating the structure of these exchanges. The combined effect of baroclinic forces and topography likely governs the dynamics over the slope.

Morphotectonic analysis of strike-slip faults in the Sayan-Tuva Upland (North Mongolia and South Siberia): Age and displacement rates

The Sayan-Tuva Upland is the northernmost positive relief of Central Asia, associated with the India-Asia collision. It formed on the boundary of the Siberian Craton in late Miocene-early Pliocene time and is characterized by uplift and shear displacement of lithospheric blocks. In this study, we answer the question of how deformation is distributed within the Sayan-Tuva Upland and what are the rates and age of horizontal displacements. Using morphotectonic and palaeoseismological analyses, we have calculated the displacement rates and onset of activation of three faults: Erzin-Agardag, Sayan-Tuva and Kaakhem, which are fragments of large strike-slip fault systems that cut across the entire Sayan-Tuva Upland. For the Erzin-Agardag Fault, the rate of left-lateral displacement is 0.7–1.4 mm/yr and the age of strike-slip reactivation is estimated to be 2.1–1.1 Ma. For the Sayan-Tuva and Kaakhem faults, the minimum horizontal displacement rates are 0.9 ± 0.1 and 0.6 ± 0.1 mm/yr, and the maximum ages of the onset of strike-slip displacements are 2.4 Ma and 5 Ma, respectively. We propose that 1.1–2.1 Ma ago there was a kinematic change that activated left-lateral strike-slip faults, leading to the formation of the modern kinematic model, characterized by eastward movement of lithospheric blocks along inherited fault systems between the Hangay Dome and the Siberian Craton. Analysis of slip distribution and trenching across the Erzin-Agardag Fault allowed estimating the mean recurrence interval of the ∼ M7.8 earthquakes between 9.4 and 4.7 ka. The Erzin-Agardag Fault has produced multiple displacements with an amplitude of ∼ 6.6 m and follows a characteristic slip model.

Low-velocity middle-and-lower crustal materials blocked by the red river fault in the SE margin of the Tibetan plateau

The ongoing collision between the Indian and Eurasian plates propels the eastward movement of the Tibetan plateau (TP), leading to substantial crustal deformation around the southern Sichuan-Yunnan block (SYB). Using ambient noise data from multiple temporary seismic arrays and permanent stations, we construct a high-resolution regional crustal azimuthally anisotropic Vs model in the SYB. Our new model reveals two significant low-velocity anomalies with strong azimuthal anisotropy near the block boundary faults in the middle-and-lower crust. The extensive low-velocity anomalies around the middle-south segment of the Xiaojiang Fault (XJF) possibly result from partial melting due to spontaneous deformation caused by crustal thickening and increased felsic components, as well as the superimposition of shear heating faults and local upwelling asthenosphere. The N‒S trending low-velocity anomaly at the northwest end of the Red River Fault (RRF) may be associated with weak material migration from the TP, potentially serving as a conduit for mantle upwelling. The azimuthal anisotropy along the block boundary faults exhibits spatial variations linked to segmented distortion resulting from southeastward crustal movement and various geological activities. A key finding is that the crustal channelized low-velocity along the XJF is clearly blocked by the RRF, instead of going through. Notably, the azimuthal anisotropy in the E‒W direction, observed above the Moho and at depths deeper than 30 km in the intersection end, implies the potential intrusion of localized mantle materials into the lower crust. Therefore, lithospheric deformation is significantly affected by block boundary faults and the properties of the crust and mantle.

Pre-shortening reconstruction of the adria microplate: Balanced and restored cross-sections through the Southern Apennines–Dinarides (Central Mediterranean Sea)

The Adria plate and/or microplate has accommodated the differential eastward motion of Africa, Europe-Iberia, since the Jurassic times, and the subsequent convergence between Africa and Eurasia from Middle Cretaceous onwards. Its complex tectonic deformation, responsible of the development of the opposing Apennines and Dinarides thin- and thick-skinned fold and thrust belts, remains poorly constrained, fueling an ongoing debate on the original position of Adria, its pre-compressional continental width, and crustal structure. Here we tackle these uncertainties by analyzing and integrating published structural cross-sections, subsurface data and 2D lithospheric numerical models to build a 758 km long regional balanced and restored cross-sections along a SW-NE transect through the Southern Apennines and Southern Dinarides. Employing the line length method for the sedimentary cover and assuming the preservation of the pre-Triassic continental crustal area, we reconstruct the pre-compressional continental width of Adria. The unfolding of the sedimentary cover along the SW-NE cross-section results in an undeformed continental Adria microplate width of approximately 1050 km, slightly under previous estimations (1175 to 1670 km). The minimum total shortening results in 291 km: 148 km across the Southern Apennines and 143 km across the Southern Dinarides. We then calculate the Adria microplate continental crustal thickness during Middle-Late Jurassic time assuming local isostatic balance, obtaining 23 km for the eastern and central Adria sectors, based on shallow water carbonate sequences. In contrast, the western Adria sector at the Southern Apennines results in a restored pre-Triassic continental crustal thickness of only 7 km, suggesting that the middle and lower crustal layers in this sector may have been partially removed, possibly by mantle delamination during Neogene to Quaternary collisional processes. The results strongly support that the Adria microplate was located to the east of the Pelagian Basin and formed part of the African Plate around the Permian–Triassic boundary interval.

Kinematics Along the Qingchuan Fault and Deformation Pattern in the Eastern Tibetan Plateau

AbstractThe accommodation of the substantial eastward crustal motion of the Bayan Har block characterizes the dynamics of faults located at the eastern Tibetan Plateau. However, uncertainties persist concerning the manner and amount of deformation distributed on these faults, with slip senses and rates constituting critical factors. In the northeastern segment of the Longmenshan thrust zone, the contentious activity and the unknown geologic slip rate present challenges. This study, focusing on the Qingchuan fault, the predominant fault within the northeastern Longmenshan, employed satellite imagery interpretation, displaced fluvial terraces surveying, displacement measurements, and chronological analysis to comprehensively characterize its fault activity. Our investigation robustly demonstrates the Qingchuan fault has been active since the late Quaternary, and is primarily marked with a pronounced dextral slip at a rate of 0.6–1.0 mm/year. By quantitatively assessing the deformation rates of the faults at the eastern Tibetan Plateau, we propose that they sufficiently accommodate the entire eastward crustal movement of the Bayan Har block; thereby no additional deformation propagates beyond the Qingchuan fault. Furthermore, we introduce a subblock model to elucidate the regional crustal deformation pattern, wherein the eastward movement of the Bayan Har block transfers to the northeastward movement of the Bikou subblock. This movement results in reverse slip patterns for the Minjiang and Huya faults, while the Beichuan and Qingchuan faults predominantly experience dextral displacements. The complex strain partitioning within the northern Longmenshan range underscores the observed variations in slip patterns across different segments of the Longmenshan thrust zone, advancing our understanding of fault behavior and the orchestration of crustal deformation in this intricate tectonic framework.

Improving inland precipitation forecast in China through data assimilation of microwave temperature sounding data from a three‐orbit constellation

AbstractMicrowave temperature sounders onboard polar‐orbiting satellites can provide global observation data twice a day, supplying a large amount of temperature information for global data assimilation and serving as a crucial instrument to improve operational numerical forecasts. However, regional numerical forecasts are still subject to a lack of polar‐orbiting satellite data within regional model domains, and even multiple polar‐orbiting satellites may simultaneously miss measurements. Establishing a three‐orbit observation system of polar‐orbiting satellites is crucial to improve the spatiotemporal coverage of polar‐orbiting satellite data. In this study, we investigate the impact of assimilating microwave temperature sounding data from a three‐orbit constellation on precipitation forecasts in inland China based on the data from the US afternoon‐orbit satellite NOAA‐19, the European morning‐orbit satellite Meteorological Operational satellite‐A and the Chinese early‐morning‐orbit satellite Fengyun‐3E (FY‐3E) launched recently. The research results indicate that there are data gaps at 0600 and 1800 UTC in the East Asian region only for the morning‐orbit and afternoon‐orbit satellite observations. The FY‐3E satellite can provide additional microwave temperature sounding observations over the eastern region of China, thus partially compensating for the gap in polar‐orbiting satellite data in China. Moreover, the additional assimilation of the FY‐3E data can further improve numerical forecasts, effectively adjusting the spatial structure and eastward movement of the weather system, thereby considerably increasing the prediction accuracy of rainfall location and intensity. Rolling‐prediction results show that the data from the three‐orbit constellation provide a stable and notable improvement in precipitation forecasts in inland China, especially for forecasts longer than nine hours and amounts of rainfall below 10 mm. These research findings provide valuable insights for optimizing the assimilation application of polar‐orbiting satellite data in regional numerical forecasts.

The impact of evolving synoptic weather patterns on multi-scale transport and sources of persistent high-concentration ozone pollution event in the Yangtze River Delta, China

High-concentration ozone pollution pose threats to ecosystems and human health. However, there is limited research on the impact of the alternating evolution of synoptic weather patterns (SWPs) on the multi-scale transport processes and sources of ozone. From June 14 to 18, 2018, a rare consecutive ozone pollution plagued in Hefei and broader Yangtze River Delta region (YRD). This study investigates the meteorological factors and sources using in-situ observational data and WRF-Chem model simulations. Analysis reveals a northeastern low-pressure system moving from north to south generated a cold front. This moving cold front facilitated the vertical transport of warm air masses carrying high-concentration ozone originating from North China. Subsequently, Ozone-rich air masses (ORMs) were transported over the YRD, influenced by the eastward movement of the Mongolian high-pressure system. Based on WRF-Chem model with NOx tagging mechanisms and WRF-FLEXPART backward simulations, it is confirmed that a notable atmospheric transport originated from North China region (NCR) to Hefei, especially on June 15. As the Mongolian high-pressure weakens and shifts east-southward, it carried ORMs generated by NOx emissions from the YRD, accumulating over the sea within the range of 120°E to 126°E and 25°N to 30°N. Both WRF-chem model results and TRopospheric Ozone and Precursors from Earth System Sounding (TROPESS) Chemistry Reanalysis dataset Version 2 (TCR-2) revealed the existence of ORMs in this geographic range. Subsequently, the ORMs carried out to sea by the weakened high-pressure system were reintroduced inland, influenced by southeast winds brought about by the peripheral circulation of typhoon “Gaemi”. In summary, the alternating evolution of SWPs significantly influences multi-scale ozone transport from both the NCR and the YRD regions, making substantial contributions to this prolonged episode. These findings offer valuable insights for improving regional ozone pollution prevention and control mechanisms.

Estimation of surface deformation in Sikkim and Eastern Nepal Himalaya using PSInSAR technique

The region of the Himalayan arc covering Sikkim and eastern Nepal experiences dominant strike-slip deformation oblique to the convergence direction of the Indian plate. This region is also traversed by transverse structural and tectonic features. The present study is aimed at comprehending the horizontal and vertical deformation rates for this region using the PSInSAR technique. We utilized 70 and 78 Single Look Complex images in ascending and descending passes respectively, spanning from February 2017 to August 2023 for time-series displacement measurement along the radar line of sight (LOS). The results reveal the LOS velocity ranging from −15 to +10 mm/yr for the ascending data and ±20 mm/yr for the descending data. The mean line-of-sight velocities of ascending and descending passes were decomposed to estimate the horizontal (east-west) and vertical components of the deformation vector. These components range from ±15 mm/yr and −12 to +8 mm/yr, respectively, suggesting that the horizontal deformation predominates in the study area. A NW-SE trending boundary coinciding with the Tista lineament sub-divides the study region into the eastern Nepal and the Sikkim blocks based on the patterns of the deformation rates. The eastern Nepal block south of the Main Central Thrust exhibits locked portion of the arc with eastward motion, whereas the Sikkim block exhibits uplift (unlocked with creep) and westward motion. The amplitudes of these deformation rates support dominant strike-slip deformation with minor vertical deformation component. These results suggest that the Tista lineament is a prominent strike-slip fault and probably the most significant active tectonic feature in the region. Together with the seismicity data, we infer that probably the entire crustal block rather than the Himalayan wedge is contributing to the surface deformation, as mapped by the present PSInSAR study.

Trans-Boundary Dust Transport of Dust Storms in Northern China: A Study Utilizing Ground-Based Lidar Network and CALIPSO Satellite

During 14–16 March 2021, a large-scale dust storm event occurred in the northern region of China, and it was considered the most intense event in the past decade. This study employs observation data for PM2.5 and PM10 from the air quality monitoring station, the HYSPLIT model, ground-based polarized Lidar networks, AGRI payload data from Fengyun satellites and CALIPSO satellite Lidar data to jointly explore and scrutinize the three-dimensional spatial and temporal characteristics of aerosol transport. Firstly, by integrating meteorological data for PM2.5 and PM10, the air quality is assessed across six stations within the Lidar network during the dust storm. Secondly, employing a backward trajectory tracking model, the study elucidates sources of dust at the Lidar network sites. Thirdly, deploying a newly devised portable infrared 1064 nm Lidar and a pulsed 532 nm Lidar, a ground-based Lidar observation network is established for vertical probing of transboundary dust transport within the observed region. Finally, by incorporating cloud imagery from Fengyun satellites and CALIPSO satellite Lidar data, this study revealed the classification of dust and the height distribution of dust layers at pertinent sites within the Lidar observation network. The findings affirm that the eastward movement and southward compression of the intensifying Mongolian cyclone led to severe dust storm weather in western and southern Mongolia, as well as Inner Mongolia, further transporting dust into northern, northwestern, and northeastern parts of China. This dust event wielded a substantial impact on a broad expanse in northern China, manifesting in localized dust storms in Inner Mongolia, Beijing, Gansu, and surrounding areas. In essence, the dust emanated from the deserts in Mongolia and northwest China, encompassing both deserts and the Gobi region. The amalgamation of ground-based and spaceborne Lidar observations conclusively establishes that the distribution height of dust in the source region ranged from 3 to 5 km. Influenced by high-pressure systems, the protracted transport of dust over extensive distances prompted a gradual reduction in its distribution height owing to sedimentation. The comprehensive analysis of pertinent research data and information collectively affirms the precision and efficacy of the three-dimensional aerosol monitoring conducted by the ground-based Lidar network within the region.

A Numerical Study of Clear-Air Turbulence over North China on 6 June 2017

On 6 June 2017, four severe clear-air turbulence (CAT) events were observed over northern China within 3 h. These events mainly occurred at altitudes between 8.1 and 9.5 km. The characteristics and possible mechanisms of the CAT events in the different regions are investigated here using the weather research and forecasting (WRF) model. The simulated wind and temperature fields in a 27 km coarse domain were found to be in good agreement with those of the ERA5 (European Centre for Medium-Range Weather Forecasts Reanalysis v5) and the observed soundings of operational radiosondes over northern China. In terms of synoptic features, the region where the turbulence occurred is characterized by a southwest–northeast upper-level jet stream. The upper-level jet stream observed at an altitude of 10.4 km consistently moved eastwards, with a maximum wind speed of 61.7 m/s. Simultaneously, the upper-level front–jet system on the cyclonic shear side of the upper-level jet stream also exhibited an eastward motion. The developed upper-level front–jet system induced significant vertical wind shear (VWS) and tropopause folding in the vicinity of these CAT events. Despite the high stability resulting from tropopause folding, the presence of strong VWS (1.90 × 10−2 s−1–2.55 × 10−2 s−1) led to a low Richardson number (Ri) (0.24–0.88) and caused Kelvin–Helmholtz instability (KHI), which ultimately induced CAT. Although a standard numerical weather forecast resolution of tens of kilometers is adequate to capture turbulence for most CAT events, it is still necessary to use high-resolution numerical simulations (such as 3 km) to calculate more accurate CAT indices (such as Ri) for CAT prediction in some specific cases.

Synoptic Analysis of Flood-Causing Rainfall and Flood Characteristics in the Source Area of the Yellow River

The source area of the Yellow River (SAYR) in China is an important water yield and water-conservation area in the Yellow River. Understanding the variability in rainfall and flood over the SAYR region and the related mechanism of flood-causing rainfall is of great importance for the utilization of flood water resources through the optimal operation of cascade reservoirs over the upper Yellow River such as Longyangxia and Liujiaxia, and even for the prevention of flood and drought disasters for the entire Yellow River. Based on the flow data of Tangnaihai hydrological station, the rainfall data of the SAYR region and NCEP-NCAR reanalysis data from 1961 to 2020, three meteorological conceptual models of flood-causing rainfall—namely westerly trough type, low vortex shear type, and subtropical high southwest flow type—are established by using the weather-type method. The mechanism of flood-causing rainfall and the corresponding flood characteristics of each weather type were investigated. The results show that during the process of flood-causing rainfall, in the westerly trough type, the mid- and high-latitude circulation is flat and fluctuating. In the low vortex shear type, the high pressures over the Ural Mountains and the Okhotsk Sea are stronger compared to other types in the same period, and a low vortex shear line is formed in the west of the SAYR region at the low level. The rain is formed during the eastward movement of the shear line. In the subtropical high southwest flow type, the low trough of Lake Balkhash and the subtropical high are stronger compared to other types in the same period. Flood-causing rainfall generally occurs in areas with low-level convergence, high-level negative vorticity, low-level positive vorticity, convergence of water vapor flux, a certain amount of atmospheric precipitable water, and low-level cold advection. In terms of flood peak increment and the maximum accumulated flood volume, the westerly trough type has a long duration and small flood volume, and the low vortex shear type and the subtropical high southwest flow type have a short duration and large flood volume.

Predominant types of regional cold waves in North China and their historical changes

Cold wave (CW) events in East Asia have a significant impact on the social economy, ecosystems, and human health. Based on daily CW records from October to March during 1980–2019 and K-means clustering, this study identified two types of regional CW (T1 and T2) in China. T1 regional CWs mainly struck Northeast China, whereas T2 regional CWs primarily affected the northern and eastern regions of China. Compared to T1, T2 regional CWs were more intense, lasted longer, and had a broader region of influence. During 1980–2019, there was a significant increase in the frequency of T1 regional CWs, while the frequency of T2 regional CWs showed no trend. Although amplification of the Siberian high was observed in both T1 and T2 regional CW events, there were differences in the wave train patterns in the middle troposphere between the two regional CWs. During T1 regional CW events, a wave train with negative–positive 500-hPa geopotential height anomalies over Siberia–Mongolia weakened the East Asian trough, causing an eastward movement of cold air from Siberia. The increasing trend of T1 regional CW frequency may be attributable to the linear trends of 500-hPa geopotential height caused by global warming. The wave train associated with T2 regional CW events formed ridge–trough–ridge circulation anomalies over the Ural Mountains, Mongolia, and North China. This led to a southeastward intrusion of the cold air. The conclusions of this paper indicate that the Siberian high amplification and mid-tropospheric wave train pattern should be jointly considered in forecasting regional CW events in China.摘要寒潮事件对东亚地区的社会经济, 生态系统和人体健康影响巨大. 根据1980−2019 年间10月至次年3月的每日寒潮记录和K-means聚类, 本文识别出了中国两种不同类型的区域性寒潮(T1 和 T2). T1区域性寒潮主要影响东北地区, T2区域性寒潮则主要影响华北和东部地区. 与T1区域性寒潮相比, T2区域性寒潮强度更强, 持续时间更长, 影响范围更广. 1980–2019年期间, T1区域性寒潮的频率显著增加, 而T2区域性寒潮的频率则没有趋势变化. T1和T2区域性寒潮事件均与西伯利亚高压增强有关, 然而与它们相关的对流层中层波列明显不同. 在T1区域性寒潮事件发生期间, 西伯利亚-蒙古上空出现负-正模态的500-hPa位势高度异常波列, 削弱了东亚大槽, 导致西伯利亚冷空气东移. T1区域寒潮频次增加趋势可能与全球变暖引起的500-hPa位势高度的线性趋势变化有关. 与T2区域寒潮事件相关的波列则在乌拉尔山脉, 蒙古和华北地区形成了脊-槽-脊环流异常, 导致冷空气向东南方向入侵. 本文得出结论, 由于两类区域寒潮影响不同, 西伯利亚高压增强和对流层中层波列模态在我国区域性寒潮事件的预报中应综合考虑.

Dominant circulation pattern and moving path of the Mongolian Cyclone for the severe sand and dust storm in China

Severe sand and dust storm (SDS) is one of the major meteorological disasters in northern China. During 2000–2023, a total of 37 severe SDS events were monitored by the China Meteorological Administration and 34 of them occurred in the boreal spring (March to May). In this study, the 34 cases are analyzed to reveal their spatio-temporal features. The results indicate that there are two high-frequency centers. One is located in the Tarim Basin in northwestern China and the other is located in the central-western part of Inner Mongolia in northern China. In the 21st century, the duration of the severe SDS shows a clear interannual variation with an average of 3.5 days in 2000–2006, 2.7 days in 2007–2015 and 4.6 days in 2016–2023, respectively. Moreover, it occurs mainly in early spring in the third period, whereas it can occur throughout spring in the first and second periods. The composition of the general circulations for these 34 cases indicates that the simultaneous dominant pattern is a “positive-negative-positive” wave structure in the mid-high latitudes of Asia, with a cyclonic circulation (a deep trough) over the southern part of Russia to Mongolia, a major anticyclonic circulation (a ridge) over the eastern Europe to the west of Central Asia and a secondary anticyclonic center over northeastern China to the Korea Peninsula and Japan. The “positive-negative-positive” pattern enhanced the Mongolian Cyclone by increasing the zonal pressure gradients to both its west and east sides. Both the composition and typical case studies indicate that the eastward movement of the Mongolian Cyclone plays a dominant role in causing the severe SDS.

Circulation patterns in the middle and upper troposphere and their relationships with summer precipitation in the Jianghuai River Basin

AbstractThe upper and lower‐level circulations can be divided into four distinct modes based on ERA5 daily reanalysis data. The impact of these patterns on the summer persistent precipitation (SPP) in the Jianghuai River Basin (JRB) is investigated, with the ‘−SR (Silk Road)/+EAP (East Asia‐Pacific)’ mode identified as the most favourable for triggering SPP. The main manifestations are as follows: (1) From 1981 to 2020, 29.4% (30.7%) of extreme precipitation days (the frequencies of persistent extreme precipitation) are related to the ‘−SR/+EAP’ mode, indicating the importance of the ‘−SR/+EAP’ mode to the SPP in the JRB. (2) The ‘−SR’ pattern accelerates the westerly jet, leading to strong divergence over the JRB. Concurrently, the eastward movement of the South Asia High and westward shift of the Western Pacific subtropical high (WPSH) create conditions favourable for SPP in the JRB. (3) Abundant water vapour, facilitated by strong moisture convergence and upward motion, significantly contributes to SPP in the JRB.

Proposal of a West-High–East-Low Hypothetical Theory forthe Longitudinal Distribution of Global Height

In this study, we seek to propose a hypothetical theory of western high-east low and the K&F theory (Kani and Fujii theory), similar to Bergmann's law of north-high and south-low for height, as laws based on latitude and longitude with regard to the trends in global height distribution. Judging from the changes in height over the 100-year span from 1870 to 1970, a composition was suggested in which, taking the European region as the center, height was clearly higher in the west and lower in the east with eastward movement. In other words, it was speculated that diversity decreased as people moved east, leading to slower economic development, lower wealth, and shorter stature. Therefore, we can hypothesize a west-high, east-low composition in the height distribution over longitude. Here, we propose the K&F theory (Kani and Fujii theory) to explain the hypothetical theory of west-high, east-low.

Fault Geometry and Late Quaternary Kinematics Along the Tieluzi Fault: Implications for Tectonic Deformation and Eastward Expansion of the Tibetan Plateau, China

AbstractThe Tieluzi Fault is the largest structure in the East Qinling Mountains, and is considered to be the easternmost continuation of the Altyn Tagh‐Haiyuan‐Qinling Fault System (AHQFS) that allows the eastward extrusion of the Tibetan Plateau and South China Block. We studied the fault geometry and kinematics of the Tieluzi Fault using field investigations, detailed interpretations of high‐resolution satellite imagery and digital elevation models, and late Quaternary dating methods. Paleoseismic investigations indicate that the most recent earthquake along the Tieluzi Fault occurred before 1,500–1,300 cal. BP. Geological and geomorphological observations show that segments west of Lushi County are more active than those to the east. The spatial variations in tectonic activity along the Tieluzi Fault are interpreted to be related to four possible mechanisms: strike change, discontinuity, intersection, and branch. The late Quaternary left‐lateral slip rate is determined to be 0.9 ± 0.1 mm/yr on the Tieluzi Fault. The prominent left‐lateral faulting along the Tieluzi Fault suggests that most of the left‐lateral displacement along the eastern AHQFS has been accommodated by the Tieluzi Fault, which forms the most frontier of the eastward expansion of the Tibetan Plateau. Furthermore, we suggest that the left‐lateral faulting in the East Qinling Mountains is a response to relative eastward motion of the South China block pushed by the Tibetan Plateau with respect to the North China Plain Block. Also, our results indicate that the Tibetan Plateau has undergone a stepwise eastward expansion.

Palaeomagnetic results from Early Mesozoic strata in the Qaidam Basin and their implications for the formation of the Northern China Domain

SUMMARY The Northern China Domain is located between the Central Asian Orogenic Belts to the north and the Kunlun–Qinling belt to the south, and it comprises the North China, Alxa and Tarim blocks. The relationships among the Northern China domain and the southern tectonic elements such as the Qaidam Basin/Terrane are debated because of the major modification by crustal deformation in the late Mesozoic–Cenozoic. To address this issue, we conducted a palaeomagnetic and high-precision radiometric dating study of Triassic volcanic rocks and Middle Jurassic strata in the Qaidam Terrane. Our objective was to determine the relationship between the Qaidam Terrane with the Tarim Block and the North China Block (NCB) during the late Palaeozoic and early Mesozoic. Four volcanic samples yielded zircon U-Pb ages of 236–243 Ma. The characteristic remanent magnetizations (Middle Triassic: D = 40.2°, I = 54.6°, α95 = 3.4°; Middle Jurassic: D = 27.4°, I = 48.0°, α95 = 7.9°) passed the fold and reversal tests, and yielded Middle Triassic and Middle Jurassic palaeopole positions at 57.6° N, 178.2° E, A95 = 4.0° and 65.8° N, 197.6° E, A95 = 7.8°, respectively. Based on these new poles, combined with other reliable data, we compared the apparent polar wander path (APWP) of the Qaidam Terrane with those of the NCB and Tarim Block. The results show that, from the Carboniferous through Early Cretaceous, the APWP of the Qaidam Terrane resembles that of the Tarim Block, but it is quite different from that of the NCB. Combined with other reported evidence, we conclude that the Qaidam Terrane was an independent dynamic unit during the late Palaeozoic until its connection with the Tarim Block, which was followed by continuous eastward motion. During this process, the connection between the Qaidam Terrane and the NCB–Alxa blocks occurred in the Middle Triassic, and subsequently the Qaidam Terrane underwent multiple tectonic responses to collisions with the Qiangtang Terrane, Lhasa Terrane and the India Plate, before the formation of its modern tectonic configuration.

Different influences of La Niña types on the winter sub-seasonal Eurasian cold anomalies linked to Ural blocking

The effects of different types of La Niña on winter sub-seasonal cold anomalies or cold extremes over Eurasia and Siberia are examined through exploring changes in Ural blocking (UB). It is found that the Central Pacific (CP) La Niña can significantly influence surface air temperature over Eurasia mainly by regulating the movement, persistence, zonal scale and location of the cyclonic anomaly associated with the UB. This influence is much greater than that resulting from an Eastern Pacific (EP) La Niña. A long-lived and quasi-stationary cyclonic anomaly with a large zonal scale of UB is induced to the southeast of the Ural Mountains for CP-type La Niña conditions, which leads to a strong warm Arctic-cold Eurasia pattern with an intense sub-seasonal cold anomaly or cold event in the broad region of Eurasia due to strongly reduced downward infrared radiation over Eurasia. In contrast, for EP-type La Niña winter the cyclonic anomaly, while still present, is much weaker, short-lived and eastward propagating, resulting in only a very weak cold anomaly or cold event over a small region of Eurasia. The reduced (enhanced) eastward movement and increased (decreased) persistence of the cyclonic anomaly with large (small) zonal scale of UB are shown to be associated with reduced (enhanced) meridional potential vorticity gradient in the midlatitudes (30o-50oN) to the east of 60°E during the CP-type (EP-type) La Niña winter.

Diversity of the Austral Summer Quasi-Biweekly Oscillation in the Southwestern Indian Ocean

Abstract The 10–20-day quasi-biweekly oscillation (QBWO) is active in the southwestern Indian Ocean (SWIO) during austral summer. Compared with comprehensive analyses of the QBWO in the Asian monsoon regions during boreal summer, studies focusing on the austral summer QBWO in the SWIO are relatively scarce. In this study, the diversity of the austral summer QBWO in the SWIO is examined based on K-means cluster analysis, which objectively classifies two distinct modes: an eastward-propagating mode (EM) and a poleward-propagating mode (PM). For the EM (PM), an active convection center originates from the subtropical ocean (tropical ocean) and exhibits an eastward (poleward) propagation path. Moisture budget analysis reveals that positive moisture time tendency anomalies show a phase-leading relationship relative to both QBWO convection centers. This phase leading in moisture tendency anomalies is mainly due to horizontal moisture advection. Further analysis demonstrates that meridional moisture transport (i.e., the summer mean moisture advected by the meridional quasi-biweekly wind) is fundamentally responsible for moisture phase leading in both QBWO modes in their mature phases. The combined scale interaction among low frequency, quasi-biweekly, and high frequency contributes to the initial movement for both modes in the growing phases. Although the two modes in the SWIO are initiated in different regions and exhibit distinct evolutionary features, they are regulated by similar moisture dynamics: the northerlies (northeasterlies) of the cyclonic wind response bring higher mean moisture levels east (south) of the convective center, which leads to the eastward (southward) movement of the EM (PM). Significance Statement The quasi-biweekly oscillation (QBWO), which can affect extreme weather events, such as extreme precipitation and heat waves, is active in the southwestern Indian Ocean (SWIO) during austral summer. Compared with previous studies of the QBWO in the Asian monsoon regions during boreal summer, studies focusing on the austral summer QBWO in the SWIO are relatively scarce. Specifically, we objectively classify the austral summer QBWO in the SWIO into two distinct modes: an eastward-propagating mode (EM) and a poleward-propagating mode (PM). Through moisture tendency diagnosis, we find that the two QBWO modes are regulated by similar moisture dynamics, although they are initiated in different regions and exhibit distinct evolutionary features. This improved understanding may provide insights into the monitoring and prediction of the QBWO.