东北极地区构造特征及油气资源潜力分析

东北极地区勘探程度较低，其构造特征及油气潜力研究已被列为国际极地年项目子课题。研究区随着美亚洋盆（加拿大和波德沃德科尼夫-马卡洛夫海盆）于晚侏罗世-早白垩世张开及与欧亚海盆扩张有关的白垩纪-新生代裂陷作用，逐渐形成现今地形地貌。洋盆打开作用导致沿现今北冰洋边缘海的大陆斜坡及陆架，在终北（Hyperborean）克拉通块体和早古生代-中自垩世造山带基底之上形成一系列拉分和裂谷盆地。通过北极地区盆地与大西洋被动大陆边缘盆地类比，认为白垩纪-新生代大陆架和大陆斜坡盆地具有巨大的油气潜力，油气聚集于盆地的沉积盖层及基底之中。

19世纪下半叶至20世纪初俄国极东北地区经济状况与科学考察

俄国极东北地区地处遥远边疆,经济开发较晚,至20世纪初经济发展仍然落后。原始渔猎和养鹿业是该地区土著居民主要经济生活方式,几乎没有工业。19世纪下半叶起,外国企业家、商人的滥捕盗猎行为和经济渗透破坏了该地区原有经济平衡,且愈演愈烈。沙皇政府试图改变极东北地区困境,着手开发其经济,改善其交通运输环境,但收效甚微。20世纪初,极东北地区吸引了各领域研究者们的关注。俄国和国外极地研究者们在极东北陆地和周边海域开展自然生物、地质地理、水文测绘和矿产资源勘探等调查研究工作,形成对极东北地区初步的、较为全面的科学认识。

Synoptic-scale potential vorticity intrusion over northeastern China during winter and its influence on surface air temperature

A regional potential vorticity(PV)intrusion(PVI)(RPVI)index,defined as the sum of the numbers of grids containing PVI within a certain area for each day,is used to reflect the day-to-day PVI variability over northeastern China during winter from 1979 to 2016.The synoptic-scale PVI variations and resultant surface air temperature(SAT)anomalies are identified by comparing the high and low RPVI index cases.In high(low)RPVI cases,significantly strong positive(negative)PV anomalies are found in the stratospheric midlatitudes,which intrude downward mostly within 90°–110°E into the upper troposphere to reach around 300 hPa and extend eastward to the east of 120°E,forcing an anomalous cyclonic(anticyclonic)circulation in the middle and lower troposphere over East Asia,with the anomalous northerlies(southerlies)of the forced lower-tropospheric cyclone(anticyclone)leading to significant negative(positive)SAT anomalies of less(greater)than-0.9°C(0.9°C),especially over northeastern China.In the stratosphere,the positive(negative)midlatitude PV anomalies over northern China are actually associated with a weakening(strengthening)of the polar vortex over the Eurasian continent for the high(low)RPVI cases,resulting mostly from positive(negative)barotropic vorticity anomalies associated with static stability due to the meridional shear of anomalous zonal winds on the southern side of the anomalous Eurasian anticyclone(cyclone).

Impact of Arctic amplification on East Asian winter climate

1.IntroductionThe Arctic region warms about twice as much as the global average,and this so-called Arctic amplification（AA）might increase the moisture flux towards Siberia（Cohen et al.2014）.Furthermore,because of strong radiative cooling over Siberia in winter,AA might enhance the snowfall in that region and reinforce cold spells in East Asia（Wu,Su,and Zhang 2011）.

Reviews and Expectations on the Maiden Voyage of a Chinese Merchant Ship in the Arctic Northeast Route

This paper introduces the preparatory work and conducts an integrated review on the maiden voyage of a Chinese commercial ship on the Arctic Northeast Route. It puts forth expectations on the exploitation and utilization of the Arctic Northeast Route in the aspects of safety, fastness, low costs, low consumption of energy and less pollution, knowledge of maritime law and navigation practice, building seaworthiness ships and making studies on the methods of sailing and maneuvering for navigation in polar waters, training qualified seafarers with navigation experiences in ice waters and establishing a safeguard system for the navigation in this route through the analysis on the weather, temperature, ice condition, route and hydrology encountered in the practice of a Chinese merchant ship in its maiden voyage in the route, and studies on the ice pilotage, convoy by icebreaker, practical condition of communication and navigation equipment in sea areas of high latitude and the economic benefit of the navigation in the Arctic Northeast Route.

An interdecadal decrease in extreme heat days in August over Northeast China around the early 1990s

Northeast China(NEC)witnessed an interdecadal increase in summer extreme heat days(EHDs)around the mid-1990s.The current study reveals that this interdecadal increase only occurs in June and July,while August features a unique interdecadal decrease in EHDs around the early 1990s.Plausible reasons for the interdecadal decrease in EHDs in August are further investigated.Results show that the interdecadal decrease in EHDs in August is due to the deceased variability of daily maximum temperature(Tmax).Overall,the variation of the Tmax over NEC in August is modulated by the Eurasian teleconnection pattern,Silk Road pattern,and East AsiaPacific pattern.However,the influence of the Silk Road pattern dramatically weakens after the early 1990s because the meridional wind variability along the westerly jet significantly decreases.The weakened influence of the Silk Road pattern contributes to the decreased Tmax variability over NEC.Meanwhile,the convection over the western North Pacific,which accompanies the East Asia-Pacific pattern,presents a significant decrease in variance after the early 1990s,further decreasing the Tmax variability over NEC.

A dipole wind curl pattern induced by Taiwan Island and its effect on upper stratification in the northeastern South China Sea

Using hydrographic data sampled during four successive late summer-early autumn cruises in 2004-2007, vertical stratification along transects in the lee of Taiwan Island was analyzed to investigate upper ocean responses to orographically induced dipole wind stress curl (WSC). Results indicate that mixed-layer depth (MLD) and its relationship with thermocline depth varied under different local wind forcings. Average MLD along the transects from the 2004 to 2007 cruises were 18.5,30.7,39.2 and 24.5m, respectively. The MLD along the transects deepened remarkably and resulted in thermocline ventilation in 2005 and 2006, whereas ventilation did not occur in 2004 and 2007. Estimates indicate that frictional wind speed was the major factor in MLD variations. To a large degree, the combined effects of frictional wind speed and Ekman pumping are responsible for the spatial pattern of MLD during the cruises.

Distinct influential mechanisms of the warm pool Madden-Julian Oscillation on persistent extreme cold events in Northeast China

This study investigates whether and how the Madden-Julian Oscillation(MJO)influences persistent extreme cold events(PECEs),a major type of natural disaster in boreal winter,over Northeast China.Significantly increased occurrence probabilities of PECEs over Northeast China are observed in phases 3 and 5 of the MJO,when MJOrelated convection is located over the eastern Indian Ocean and the western Pacific,respectively.Using the temperature tendency equation,it is found that the physical processes resulting in the cooling effects required for the occurrence of PECEs are distinct in the two phases of the MJO when MJO-related convection is consistently located over the warm pool area.The PECEs in phase 3 of the MJO mainly occur as a result of adiabatic cooling associated with ascending motion of the low-pressure anomaly over Northeast Asia.The cooling effect associated with phase 5 is stronger and longer than that in phase 3.The PECEs associated with phase 5 of the MJO are linked with the northwesterly cold advection of a cyclonic anomaly,which is part of the subtropical Rossby wave train induced by MJO-related convection in the tropical western Pacific.

Unprecedented East Asian warming in spring 2018 linked to the North Atlantic tripole SST mode

An unusually warm East Asia in spring 2018,when exceptionally high surface air temperatures were recorded in large areas of Asia,such as northern China,southern China,and Japan,was investigated based on the ERA-Interim reanalysis.The East Asian warming anomalies were primarily attributed to a tripole mode of North Atlantic SST anomalies,which could have triggered anomalous Rossby wave trains over the North Atlantic and Eurasia through modulating the North Atlantic baroclinic instability.Atlantic-forced Rossby waves tend to propagate eastward and induce anomalously high pressure and anticyclonic activity over East Asia,leading to a northward displacement of the Pacific subtropical high.As a result,descending motion,reduced precipitation,and increased surface solar radiation due to less cloud cover appear over East Asia,accompanied by remarkably warm advection from the ocean to southern China,northern China,and Japan.The transportation of anomalously warm advection and the feedbacks between soil moisture and surface temperature were both favorable for the recordbreaking warmth in East Asia during spring 2018.The seasonal‘memory’of the North Atlantic tripole SST mode from the previous winter to the following spring may provide useful implications for the seasonal prediction of East Asian weather and climate.

Preliminary Study on Seismic Anisotropy in the Crust in the Northeast of Hainan

With SAM shear-wave splitting analysis,shear-wave splitting parameters at two stations of the digital seismic network in the northeast of Hainan are obtained based on the data from the Hainan Digital Seismic Network from 2000 to 2013. The results show that the predominant polarization direction of fast share-wave represents the direction of in-situ maximum principal compressive stress. The predominant polarizations of Qixingling( QXL) seismic station are in the NEE direction,which is different from the direction of principal compressive stress of the Hainan area,but same as the strikes of faults in the NE direction,which means that the local tectonics and stress fields are complicated. The predominant polarization of Qingshanling( QSL) seismic station is in the NNE-NS direction,which indicates the tectonic significance of the strikes of NNE-trending faults.At the same time,the study confirms that the predominant polarizations of the stations located on active faults or at the junctions of several active faults are parallel to the strikes of faults which control the earthquakes used in this analysis, and the predominant polarizations are scattered,which indicates the complicated background of fault structures and stress distribution.

Observations of narrow bipolar events during two thunderstorms in Northeast China

Here we report characteristics of more than 100 cases of Narrow Bipolar Events(NBEs)occurred during two thunderstorms on the basis of our analysis of the dataset collected by a GPS based three-station time of arrival(TOA)lightning location system deployed in Northeast China during the summer of 2010.All of the NBEs were of positive polarity and the amplitude of VLF/LF initial pulse of NBE was comparable to that of return strokes.The waveform characteristics of 166 NBEs that occurred within 150 km were consistent with the results of other reports.The average value of initial peak width of the bipolar pulse is 7.8±1.5 μs,full width at half maximum is 4.6±1.0 μs,and the ratio of initial peak amplitude to overshoot peak is 2.1±0.6.The inferred source height of NBEs occurred in two thunderstorms averaged 9.6 and 7.4 km above mean sea level,whereas the corresponding virtual ionosphere heights at two different times were 89 and 78 km,respectively.In NBEproducing thunderstorms,NBEs tended to burst during the active stage of normal lightning;nevertheless,no determinate quantitative relations could be established between them.In Storm 0711,NBEs were inclined to cluster at the proximity of particular convective cores with high radar reflectivity,and NBEs tended to move consistently at the front area of those NBE-producing convective cores during the evolution of thunderstorm.