Southeastern Coast Of China Research Articles

Semi-automatic mapping of dyke and dyke-related fractures using UAV-based photogrammetric data: A case study from Sijiao Island, coastal Southeastern China

Mapping dyke and dyke-related fractures is important for magma propagation and emplacement mechanisms analysis. Here, we propose a semi-automatic workflow for dyke and fracture mapping using unmanned aerial vehicle (UAV)-based photogrammetric data. Our workflow integrates mean-shift and GrabCut in one cut (GCOC) algorithms to segment dykes, and harnesses the phase symmetry algorithm and a series of follow-up actions to detect fractures. Sijiao Island of Zhejiang Province (SE China) is examined as a case study to validate the approaches. With our workflow, the generated dyke map attains more than a 97% recall rate when compared with the results of expert interpretation, and the ratio of the number of detected false fracture segments to the number of total segments is less than 18%. The dyke strike and fracture strike calculation match well with field measurements. Moreover, by combining visual interpretation and the resulting geometric information, our results manifest that dyke magma invaded along pre-existing fractures to form dykes on Sijiao Island, and the difference between dyke fractures and host rock fractures may be because of the effect of major changes of regional stress. This workflow has great potential for high-resolution terrestrial mapping.

Analysis of the Power Plant Breakwater Failure Subjected to Typhoon Mangkhut Based on Model Experiment

Growing social concern regarding the environmental and visual impacts associated with coastal structures due to climatic change is leading to a reduction in breakwater failures. After Typhoon Mangkhut passed through the southeastern coast of China on September 16 in 2018, the breakwater of a Power Plant was serious failure. As a case study based on model test, the failure process and causes of breakwater were explored in this paper. The wave height and water level were used as the wave parameters, which were accurately extracted by the GOHS system when the typhoon transits, and the breakwater failure process was reproduced based on the typhoon wave forces action at that time. By the experimental result investigating, it was found that the joint of the caisson breakwater and the mound breakwater was firstly failure, then the armor blocks and stones near the seawalls became to be unstable, the seawall was collapsed finally. Based on the analysis of the experiment, the distribution in time and space of the damage of the protective blocks are obtained and divided into different damage areas according to the degree of failure. The wave energy concentration as a important factor were proposed in this paper and the conclusion would be provide as a reference for the study of breakwater engineering.

The origin and population genetic structure of the \u2018golden tide\u2019 seaweeds, Sargassum horneri, in Korean waters

In recent years, drifting and inundating brown seaweed (Sargassum horneri) biomass, called ‘golden tides’, has frequently drifted and accumulated along the southern coastlines of Korea, causing devastating impacts on the local economy and coastal ecosystems. In this study, based on combined analyses of mitochondrial DNA cox3 gene and seven microsatellites, we investigated the genetic makeup of the floating S. horneri populations (N = 14) in comparison to Korean benthic populations (N = 5), and tracked their genetic sources. Given a shared mtDNA haplotype and oceanic circulation systems, the floating populations may have been originated from the southeastern coast of China (e.g. Zhoushan, Zhejiang province). Population structure analyses with microsatellites revealed two distinct genetic clusters, each comprising floating and benthic populations. High levels of inter-population differentiation were detected within Korean benthic samples. The floating populations from the same periods during a 2015–2018 year were genetically more different from one another than those from different periods. These results suggest that the floating populations might be of multiple genetic sources within geographic origin(s). This study will inform management efforts including the development of “S. horneri blooming forecasting system”, which will assist in mitigating ecological and economic damages on the Korean coastal ecosystems in the future.

Coordination of urbanization quality and resource utilization in inclusive perspective: Taking 288 cities in China as an example.

To explore the coordination between urbanization quality and resource utilization and its influencing factors from the perspective of inclusiveness is conducive to expanding the connotation of urbanization quality, which could provide guidance for improving the quality of urbanization. By integrating the concept of inclusiveness into the connotation of urbanization quality and resource utilization, we analyzed the spatial pattern of the coordination of urbanization quality and resource utilization in 288 cities above prefecture level in China with the GIS technology and coordination degree model, with the potential causes being discussed. The results showed that the inclusive level of China's urbanization development was low, which was characterized by unequal development opportunities, scattered distribution of high-level cities and large-scale centralized distribution of low-level cities. The overall utilization of resources was at the middle level. The agglomeration chara-cteristics of high- and low-level cities were significant and bounded by Hu Huanyong line. The average coordination degree of urbanization quality and resource utilization was 0.59, which belonged to the medium level, with the grade-difference and the east-west gradient pattern. Urban distribution with high coordination level fitted southeast coastal urban agglomerations well. The distribution of cities above the middle level was in good agreement with that of the "T" type axial belt in China formed by the southeastern coast of China and the Yangtze River economic belt. The lower level cities were concentrated in the middle and upper reaches of the Yellow River, Jiangnan hills, north-west part of the Northeast and Yungui Plateau. The level of urban administration and the level of economic development were positively related to the coordination between urbanization quality and resource utilization. There was a significant correlation between the urban scale and the level of coordination in the city with more than 3 million population.

An improved method for assessing vegetation cooling service in regulating thermal environment: A case study in Xiamen, China

Quantitatively evaluating vegetation cooling service has become an important issue in current ecosystem service assessment, especially for urban area. Based on a previous method proposed on the energy exchanging theory, this study developed an improved method to generate a spatially explicit evaluation of the vegetation cooling service by introducing fractional vegetation cover (FVC) and the daily length of vegetation cooling service provision. Using remote sensing data from Landsat-8 and MODIS-Terra observations and field measurements from local meteorological stations, the method was successfully applied in Xiamen, a city located on the southeastern coast of China. The results showed that surface elevation and FVC had profound impacts on the length of vegetation cooling service provision and the vegetation cooling ability, respectively. For the vegetation surfaces of total 799.48 km2 in Xiamen, the annual heat absorption was 2.73 × 109 MJ/a in 2015 with an average length of cooling service provision of 1954.04 h. A more reasonable spatial distribution of vegetation heat absorbing capacity can be found with the differences not only among different vegetation types but also within the same vegetation type. Thus, this study emphasized the impacts of vegetation coverage and cooling length on providing cooling service, which has practical implications for vegetation planning in urban areas.

Weather research and forecasting model simulations over the Pearl River Delta Region

Pearl River Delta (PRD), located in south-eastern coast of mainland China, is one of the regions affected by heavy particulate matter (PM) levels. Notwithstanding the potential use of meteorological and air quality modelling to characterize the air pollution problems, little attention has been paid to meteorological model configuration and its impact on air quality modelling applications over the region. Aiming to find the most suitable set of parameterization schemes of the Advanced Research Weather Research and Forecasting (WRF-ARW) model for air quality modelling applications over the PRD region, a performance experiment was performed. Three tests, with different combinations of parameterization schemes, were created and evaluated. For the best configuration modelling setup, meteorological simulations for a winter (i.e. January) and summer (i.e. July) periods are provided. The meteorological model showed a clockwise deviation for the wind direction and tends to overestimate the temperature and wind speed. It is expected that the present work could reduce the meteorological and air quality modelling uncertainty over the PRD region.

Influence of ENSO on frequency of wintertime fog days in Eastern China

The influence of El Nino–Southern Oscillation (ENSO) on wintertime fog days in eastern China was investigated through the analysis of fog station data in China and the National Centers for Environmental Prediction reanalysis data during the period of 1954–2007. A composite analysis shows distinctive anomaly patterns of fog days in early and late winter during ENSO. More frequent fogs appear in Central and North China (around 30°–40°N) in November–December (ND), while more frequent fogs occur over Middle Reach of Yangtze River (27°–32°N) and less frequent fogs appear over 32°–40°N in January–February (JF) during El Nino. The cause of this distinctive sub-seasonal evolution feature is discussed as the following. Actually we analyzed all meteorological fields during El Nino and La Nina, and found that they are approximately in a mirror image. To reduce the number of figures, we presented the difference fields in most of cases. We found that anomalous southwesterlies associated with El Nino penetrate into North China (up to 40°N) in ND. The northward moisture transport leads to near-surface air saturation over the region. Moreover, atmosphere becomes convectively unstable in South China (20°–30°N), which leads to a positive precipitation anomaly there. The local convergence leads to an anomalous divergence and subsidence north of 30°N. Both the saturated air and stable stratification lead to more frequent fog days in 30°–40°N. Compared to ND, anomalous southwesterly flow in JF is weaker, and can only transport moisture up to Central China (near 30°N). As maximum precipitation anomaly is confined near the southeastern coast of China, anomalous divergence and subsidence appear north of 27°N. This stable stratification together with the anomalous moisture transport causes the increase of fog over Central China but decrease of fog in North China (33°–38°N) due to the subsidence induced dryness.

Leaf anatomical traits determine the 18 O enrichment of leaf water in coastal halophytes.

Anatomical adaptations to high-salinity environments in mangrove leaves may be recorded in leaf water isotopes. Recent studies observed lower 18 O enrichment (ΔL ) of leaf water with respect to source water in three mangrove species relative to adjacent freshwater trees, but the factors that govern this phenomenon remain unclear. To resolve this issue, we investigated leaf traits and ΔL in 15 species of true mangrove plants, 14 species of adjacent freshwater trees, and 4 species of semi-mangrove plants at five study sites along south-eastern coast of China. Our results confirm that ΔL was generally 3-4‰ lower for mangrove species than for adjacent freshwater or semi-mangrove species. We hypothesized that higher leaf water content (LWC) and lower leaf stomatal density (LS) both played important roles in reducing ΔL in mangroves relative to nearby freshwater plants. Both differences acted to elongate effective leaf mixing length (L) in mangroves by about 200% and lower stomatal conductance by about 30%. Péclet models based on both LWC and LS could accurately predict ΔL . Our findings highlight the potential species-specific anatomical determinants of ΔL (or L), which has important implications for the interpretation of environmental information from metabolites produced by leaf water isotopes in palaeoclimate research.

An asymmetric rainfall response to ENSO in East Asia

This study explores the impact of El Nino and La Nina events on precipitation and circulation in East Asia. The results are based on statistical analysis of various observational datasets and Geophysical Fluid Dynamics Laboratory’s (GFDL’s) global climate model experiments. Multiple observational datasets and certain models show that in the southeastern coast of China, precipitation exhibits a nonlinear response to Central Pacific sea surface temperature anomalies during boreal deep fall/early winter. Higher mean rainfall is observed during both El Nino and La Nina events compared to the ENSO-Neutral phase, by an amount of approximately 0.4–0.5 mm/day on average per oC change. We argue that, in October to December, while the precipitation increases during El Nino are the result of anomalous onshore moisture fluxes, those during La Nina are driven by the persistence of terrestrial moisture anomalies resulting from earlier excess rainfall in this region. This is consistent with the nonlinear extreme rainfall behavior in coastal southeastern China, which increases during both ENSO phases and becomes more severe during El Nino than La Nina events.

Source identification of PM2.5 at a port and an adjacent urban site in a coastal city of China: Impact of ship emissions and port activities

Daily PM2.5 samples were collected simultaneously at an urban site (UB) and a nearby port-industrial site (PI) on the coast of southeastern China from April 2015 to January 2016. The PM2.5 mass concentration at the PI (51.9μgm−3) was significantly higher than that at the UB. The V concentration at the PI was also significantly higher and well-correlated to the urban value, which suggests that shipping emissions had a significant impact on the PI and, to a lesser extent, on the urban area. A positive matrix factorization (PMF) analysis showed that secondary aerosols were the dominant contribution of PM2.5 at both sites (36.4% at the PI and 27.2% at the UB), while the contribution of industry and ship emissions identified by V, Mn, and Ba at the PI (26.1%) were double those at the UB. The difference in each source contribution among the trajectory clusters that included significant differences and insignificant differences from the UB to the PI provided insight into the role of local impacts. With regards to the UB, local potential sources play important roles in industry and ship emissions, traffic emissions, fugitive dust, and in their contributions to secondary aerosols. A conditional probability function further revealed that the ship emissions and port activities distributed in the NE, E, and SSE wind sectors were responsible for the source contributions of industry and ship emissions and secondary aerosols at the UB. This study provides an example of investigating the impact of ship emissions and port activities on the surrounding air environment using land-based measurements.

Relationship between South China Sea summer monsoon onset and landfalling tropical cyclone frequency in China

Between 1979 and 2015, the anticorrelation between the frequency of landfalling tropical cyclones (LTCs) in mainland China from June to October and the South China Sea summer monsoon (SCSSM) onset date can be attributed to variations in the western North Pacific subtropical high (WNPSH) and monsoon trough (MT) that correspond to the SCSSM onset. When the SCSSM onset is early, the WNPSH shrinks northeastwards and the MT becomes increasingly strong and exhibits a northwards shift. These features lead to anomalous lower‐level cyclonic circulation around Luzon Island and a mid‐tropospheric easterly anomaly over the Chinese coastal regions, which favour the generation of TCs in the western part of the North Pacific that makes landfall on the southeastern coast of China. In contrast, the circulation anomaly prohibits landfalling TCs in mainland China when the SCSSM onset is delayed. The SCSSM onset has the potential to be an indicator of TC landfall frequency in mainland China.

Hydrocarbon potential of the Lower Cretaceous mudstones in coastal southeastern China

The Cretaceous hosts the highest hydrocarbon potential among all geological stratigraphic sequences worldwide, and the Lower Cretaceous in coastal southeastern China, with the development of black mudstones and shales, has potential for hydrocarbon generation. This potential, therefore, is of significance to regional hydrocarbon exploration both onshore and offshore; however, it has not been investigated in detail. Here, we address this issue based on the results of integrated organic geochemistry and petrology of four representative outcrop sections in the region. Results show that there are two possible source rock sequences in the Lower Cretaceous of coastal southeastern China, that is, a lower sequence represented by the Bantou Formation black mudstones in the Fujian Province and an upper interval represented by the Guantou Formation black mudstones or calcareous mudstones in the Zhejiang Province. The organic matter abundance of these two formations reaches levels of poor to good source rocks. The kerogen is dominated by type III, whereas type II can also be found locally in the northwestern Fujian Province. Most samples are highly mature to overmature, except for the samples with less influence of volcanism in the northern Guangdong Province. Comparatively, the organic matter abundance of the early-stage source rocks is higher than for the late-stage rocks, and the kerogen type is less favorable; however, the maturity shows little correlation with age and is largely related to volcanism. Therefore, the Lower Cretaceous in coastal southeastern China seems to have hydrocarbon potential (gas in particular) in local areas, including the northern Guangdong Province and its analog in offshore basins for the early stage and the northwestern Fujian Province and its analog in offshore basins for the late stage. These results and understanding provide insights for expanding new hydrocarbon exploration targets in southeastern China both onshore and offshore and may also have implications for understanding the regional Cretaceous geology.

Evolution of the Lian River coastal basin in response to Quaternary marine transgressions in Southeast China

The coastal basin deposit in the Lian River plain is among the thickest Quaternary sequences along the southeastern coast of China. The clastic sediment accumulated in a variety of environmental settings including fluvial, channel, estuary/coastal and marine conditions. Detailed investigation of lithofacies, grain-size distributions, magnetic susceptibility, microfossils and chronology of marine core CN01, compared with regional cores, and combined with offshore seismic reflection profiles, has allowed us to correlate the spatial stratigraphy in the inner and outer plain and the seismic units. Grain size distribution analysis of core CN-01 through compositional data analysis and multivariate statistics were applied to clastic sedimentary facies and sedimentary cycles. Results show that these methods are able to derive a robust proxy information for the depositional environment of the Lian River plain. We have also been able to reconstruct deltaic evolution in response to marine transgressions. On the basis of dating results and chronostratigraphy, the estimated age of the onset of deposition in the Lian River coastal plain was more than 260 kyr BP. Three transgressive sedimentary cycles revealed in many regional cores support this age model. Detailed lithological and microfossil studies confirm that three marine (M3, M2 and M1) and three terrestrial (T3, T2 and T1) units can be distinguished. Spatial correlation between the inner plain, outer plain (typical cores characterized by marine transgression cycles) and offshore seismic reflectors reveals coherent sedimentary sequences. Two major boundaries (unconformity and erosion surfaces) can be recognized in the seismic profiles, and these correspond to weathered reddish and/or variegated clay in the study core, suggesting that Quaternary sediment changes on the Lian River plain were largely controlled by sea-level variations and coastline shift during glacial/interglacial cycles.

Experimental study of wind loads on gable roofs of low-rise buildings with overhangs

Gable roofs with overhangs (eaves) are the common constructions of low-rise buildings on the southeastern coast of China, and they were vulnerable to typhoons from experience. The wind pressure distributions on gable roofs of low-rise buildings are investigated by a series of wind tunnel tests which consist of 99 test cases with various roof pitches, height-depth ratios and width-depth ratios. The block pressure coefficients and worst negative (block) pressure coefficients on different roof regions of low-rise buildings are proposed for the main structure and building envelope, respectively. The effects of roof pitch, height-depth ratio, and width-depth ratio on the pressure coefficients of each region are analyzed in detail. In addition, the pressure coefficients on the roofs for the main structure and building envelope are fitted according to roof pitch, height-depth ratio and width-depth ratio of the low-rise building. Meanwhile, the rationality of the fitting formulas is verified by comparing the fitting results with the codes of different countries. Lastly, the block pressure coefficients and worst negative pressure coefficients are recommended to guide the design of low-rise buildings in typhoon area and act as references for the future’s modification of wind load codes.

Asian monsoon variations revealed from stable isotopes in precipitation

To further our understanding of the Asian monsoon system, particularly the onset dates of monsoon sub-systems over their respective East Asian domains, we present an 8-year (2007–2014) dataset of oxygen isotopes of precipitation (δ18Op) from three stations, Lulang and Nuxia in southeastern Tibetan Plateau (SETP) and Guangzhou in southeastern coastal China (SECN). The general agreement between isotopically identified monsoon onset dates with those identified by the meridional temperature gradient suggests that the initially sustained isotopic depletion is sensitive to the evolving thermal contrast between the Eurasian continent and the Indian Ocean. The 850 hPa meridional wind over nearby oceans is an efficient bridge linking isotopic variations in both regions with their respective monsoon sub-systems. The intensity of the South Asian High and tropical cyclone frequencies show stronger effects on isotopic depletion in the SECN than in the SETP and on monsoon onset timing over the South China Sea. Tibetan Plateau snow cover anomalies are significantly correlated with δ18Op in both regions on monthly timescales.

The distribution, hydrocarbon potential, and development of the Lower Cretaceous black shales in coastal southeastern China

Lower Cretaceous black shales in coastal southeastern China are of significance to the geological study of the Tethys and Pacific realms and to hydrocarbon exploration of southeastern China and East China Sea. However, the stratigraphic correlation, distribution patterns and hydrocarbon potential of the black shales have not been well constrained so far. In this study, the zircon U–Pb ages, organic petrologic and geochemical analyses were performed for representative outcrop sections in the region. Zircon U–Pb ages demonstrate that the Lower Cretaceous black shales in coastal southeastern China can be divided into two regional-scale sets. The first set was deposited during the early stage of the Early Cretaceous (K11, Berriasian–Hauterivian). The second set was deposited during the late stage of the Early Cretaceous (K12), and might extend to the Taiwan Strait. Detailed organic geochemical analyses including organic matter abundance, type and maturity of the Lower Cretaceous black shales demonstrate that the organic matter abundance of the sources reached medium to good quality by the hydrocarbon source rock standards, and the average TOC values and the chloroform bitumen “A” of the K11 black shales are higher. The type of organic matter is mainly type III, type II can also be found from the K12 black shales. The thermal maturity of most samples is high to overmature. A relatively comprehensive hydrocarbon resource evaluation indicates that favorable regions are in the northern Guangdong Province for the K11 and in the coastal region of Zhejiang Province and the western Fujian Province for the K12. Sedimentology studies on the Shipu section for the K11 black shales illuminated that the K12 black shales in coastal southeastern China were mainly deposited during transgressive period. The relative sea level changes controlled the sequential development pattern of the K12 black shales.

Geochronology, geochemistry, and petrogenesis of the late Mesozoic Luoyang volcanics: Implications for the geodynamic evolution of the Zhejiang–Fujian region, SE China

The Zhejiang–Fujian region, situated along the southeastern coast of China and in the eastern part of the Cathaysia Block, is characterized by large volumes of late Mesozoic granitoid volcanics. We present new zircon U–Pb ages, whole‐rock geochemistry, and Sr─Nd─Hf‐isotope data for 3 rhyolite porphyries from the Luoyang region (LY‐1, LY‐2, and LY‐3). We identify 2 magmatic events. In Stage 1 (146 Ma), rhyolite porphyry LY‐1 was produced by the partial melting of Proterozoic Mayuan Group amphibolites and metasediments. In Stage 2 (130–126 Ma), rhyolite porphyries LY‐2 and LY‐3 were generated by the continued melting of amphibolites but with only a minor contribution from metasedimentary rocks. The fractionation of plagioclase, biotite, titanite, and allanite (degree of fractionation 0.7–0.5) from an LY‐2 parent magma produced LY‐3. Our new data, together with other published data, indicate that minor volcanism, related to the initial northwestward subduction of the Paleo‐Pacific Plate beneath SE China, occurred in a continental arc setting in the Zhejiang–Fujian coastal region from 160 to 140 Ma but that the major period of volcanism took place from 140 to 120 Ma in a back‐arc setting and occurred because of rollback of the subducting slab.

Impacts of Meteorological Conditions, Aerosol Radiative Feedbacks, and Emission Reduction Scenarios on the Coastal Haze Episodes in Southeastern China in December 2013

AbstractFujian Province in southeastern coastal China is a relatively clean region with low emissions, as its high altitude isolates it from the rest of the country. However, the region experienced haze episodes on 3–14 December 2013. The authors performed simulations using the Weather Research and Forecasting Model coupled with chemistry (WRF-Chem) to examine the impacts of meteorological conditions, aerosol radiative feedbacks (ARFs; including aerosol direct and nearly first indirect effect), and internal and external emissions reduction scenarios on particulate matter smaller than 2.5 μm (PM2.5) concentrations. To the best of the authors’ knowledge, this is the first time the WRF-Chem model has been used to study air quality in this region. The model reasonably reproduced the meteorological conditions and PM2.5 concentrations. The analysis demonstrated that the highest-PM2.5 event was associated with a cold surge that promoted the impingement of northern pollutants on the region, and PM2.5 concentrations were sensitive to the emissions from the Yangtze River delta (16.6%) and the North China Plain (12.1%). This suggests that efforts toward coastal air quality improvement require regional cooperation to reduce emissions. Noticeably, ARFs were unlikely to increase PM2.5 concentrations in the coastal region, which was in contrast to the case in northern China. ARFs induced strong clean wind anomalies in the coastal region and also lowered the inland planetary boundary layer, which enhanced the blocking of northern pollutants crossing the high terrain in the north of Fujian Province. This indicates that ARFs tend to weaken the haze intensity in the southeastern coastal region.

Contemporary kinematic models and moment deficit of Chinese mainland

There are lots of achievements about kinematics of Chinese mainland and its vicinity determined from historic earthquake data, Quaternary fault rates and geodesy observations, which provide basic data for analysis of seismic hazard in study areas. Based on impreciseness in using energy of 47 earthquakes with magnitude greater than 7.0 in previous study, we firstly collected source parameters, surface ruptures and displacements of major earthquakes carefully, and divided them into small segmentations with these data gathered. Secondly, we determined contemporary deformation field from latest earthquake mechanisms, Quaternary fault slip rates and geodesy observations. Finally, we evaluated moment deficit of study areas from historic earthquake data and predicted deformation field, and removed 10 percent of aseismic deformation. Combining with previous results, we analyzed the seismic hazard of study areas. The results show that there are some areas with large moment deficit in Chinese mainland. There are also large moment deficit areas, including regions around the Ordos Block, southeastern coast of China and the Bakal rift zone. Previous studies show that there may be some potential earthquakes in the near future in parts of areas mentioned above.

Interdecadal Changes in the Relationship between ENSO, EAWM, and the Wintertime Precipitation over China at the End of the Twentieth Century

Abstract The current study investigates the interdecadal changes in the relationship between the winter precipitation anomalies in southeastern China, El Niño–Southern Oscillation (ENSO), and the East Asian winter monsoon (EAWM) at the end of the twentieth century. It appears that the relationships between the interannual variability of the southeastern China winter precipitation and ENSO as well as EAWM are obviously weakened after 1998/99. The possible mechanisms accounting for this interdecadal change in the relationship have been examined by dividing the data into two subperiods [1980–98 (P1) and 1999–2015 (P2)]. The results indicate that, without the linear contribution of EAWM, ENSO only play a limited role in the variability of winter precipitation in southeastern China in both subperiods. In contrast, in P1, corresponding to an ENSO-independent weaker-than-normal EAWM, anomalous southerlies along coastal southeastern China associated with an anticyclone over the northwestern Pacific transport water vapor to China. However, in P2 the impact of EAWM on winter precipitation in southeastern China is weakened because of the regime shift of EAWM. The EAWM-related positive SLP anomalies over the North Pacific move eastward in P2, causing an eastward migration of the associated anomalous southerlies along its western flank and therefore cannot significantly contribute to the positive winter precipitation anomalies in southeastern China.