The mechanism of growth of the low-frequency East Asia–Pacific teleconnection and the triggering role of tropical intraseasonal oscillation

2015 ◽  
Vol 46 (11-12) ◽  
pp. 3965-3977 ◽  
Author(s):  
Jiabao Wang ◽  
Zhiping Wen ◽  
Renguang Wu ◽  
Yuanyuan Guo ◽  
Zesheng Chen
2020 ◽  
Vol 33 (17) ◽  
pp. 7643-7662
Author(s):  
Shu Gui ◽  
Ruowen Yang

AbstractThe study reported in this paper used ERA-Interim reanalysis data to investigate the intraseasonal variability of the Bay of Bengal (BOB)–East Asia–Pacific teleconnection (BEAP) during the summer between 1979 and 2016. Over this period, the intraseasonal oscillation of the BEAP fell mainly within the quasi-biweekly oscillation (QBWO) band. Variations in atmospheric circulation and precipitation, which may contribute to extreme weather events, showed a significant correlation with the phase transition of the BEAP from the BOB to East Asia and the Pacific. The evolution of the BEAP–QBWO is closely associated with the westward propagation of convective anomalies to the southwestern BOB. Dynamical analysis revealed that anomalous vertical motion coupled with anomalous convective activity over the southern BOB plays an important role in leading the phase propagation of the BEAP–QBWO, and that the horizontal advection anomalies can strengthen the BEAP–QBWO. Linear baroclinic model experiments confirmed that variations in convection over the southern BOB play a leading role in the BEAP–QBWO phase changes. Further research suggests that the boreal summer intraseasonal oscillation can trigger the BEAP–QBWO through downstream propagation of convective disturbances to the southern BOB. This study provides insights into the cause and effect of the BEAP–QBWO, which will help to improve understanding of flood and drought patterns in the Asia–Pacific region.


2020 ◽  
Vol 33 (22) ◽  
pp. 9849-9862
Author(s):  
Mengmeng Lu ◽  
Zhiming Kuang ◽  
Song Yang ◽  
Zhenning Li ◽  
Hanjie Fan

AbstractEurasian snow, one of the most important factors that influence the Asian monsoons, has long been viewed as a useful predictor for seasonal monsoon prediction. In this study, observations and model simulations are used to demonstrate a bridging role of the winter snow anomaly over northern China and southern Mongolia (NCSM) in the relationship between the East Asian winter monsoon (EAWM) and the East Asian summer monsoon (EASM). Enhanced snow in NCSM results in local surface and tropospheric cooling, strengthening the EAWM through cold-air intrusion induced by northerly wind anomalies. In turn, the stronger EAWM provides a favorable condition for enhanced snowfall over East Asia to the south, indicating an active snow–EAWM interaction. The continental cooling could be maintained until summer due to the memory effect of snowmelt and moistening as well as the snow–monsoon interaction in the spring, causing changes in the meridional temperature gradient and associated upper-level westerlies in the summer. The interaction between the strengthened westerlies over the northern Tibetan Plateau and the topography of the plateau could lead to anomalous downstream convergence and compensating divergence to the south. Therefore, anomalous cyclonic circulation and increased rainfall occur over northeastern China and the Korean Peninsula, but anticyclonic circulation and decreased rainfall appear over the subtropical East Asia–Pacific region. Moreover, limited analysis shows that, compared to sea surface temperature feedback, the direct impact of snow anomaly on the EAWM–EASM connection seems more important.


2016 ◽  
Vol 60 (3) ◽  
pp. 58-71
Author(s):  
A. Fedorovskii

The article deals with the prospects for Russia’s “pivot to the East” taking into account main chances as well as risks in the context of growing challenges in East Asia. The author stresses that national and regional misbalances in East Asia are the results of the dynamic development of East Asian countries during the last 15 years. “Middle class trap” is at the agenda as the main common problem in China and ASEAN member countries. The analysis focuses also on such issues as broad scaled corruption and state-controlled legal system, quality of political, social institutions and social lifts, role of nationalism and culture. Regional misbalances in infrastructure and R&D as well as the crisis of regional institutions are characterized as new challenges to integration trends in East Asia and Asia-Pacific area in general. According to the author’s view, there are three different types of policies to meet the domestic challenges and to overcome “middle class trap”: Japanese, South Korean and Chinese. Prime Minister Ikeda’s “income-doubling plan” accompanied by public activity is described as an effective reform-oriented policy. South Korea’s transition from dictatorship to democratic society and more flexible economy is another type of positive reform policy. According to China’s modern domestic strategy, a lot of attention is paid to administrative measures against corruption, modification of social policy, reforms of banks, etc. At the same time, public activities and legal system, in spite of some improvements, are still under rigid administrative control. Meanwhile, the role of law will be crucial factor of successful development of East Asian countries at the stage of “middle class economy”. To a large scale, the prospects for regional integration depend on growing creative role of China (for example, investments into regional infrastructure and establishment of special bank, initiations of the Asia-Pacific Free Trade Area). At the same time, China will continue cooperation and dialogue with other countries, first of all with the USA. ASEAN members increase their activity to improve sub-regional cooperation and relations with United States and Japan in order to couterbalance China’s influence in East Asia. Finally, the author describes Russia’s policy towards East Asia and the Pacific, including brief history, main trends and key priorities at the current stage. “Free Vladivostok port” and some other initiatives to realize more flexible economic strategy towards East Asia and Pacific will give opportunity for Russia to promote its integration into the Pacific Area. Transition of Russia’s export structure from resources and energy to innovation goods and services is at the agenda.


2019 ◽  
Vol 85 (1(I)) ◽  
pp. 64-71 ◽  
Author(s):  
M. M. Gadenin

The cycle configuration at two-frequency loading regimes depends on the number of parameters including the absolute values of the frequencies and amplitudes of the low-frequency and high-frequency loads added during this mode, the ratio of their frequencies and amplitudes, as well as the phase shift between these harmonic components, the latter having a significant effect only with a small ratio of frequencies. Presence of such two-frequency regimes or service loading conditions for parts of machines and structures schematized by them can significantly reduce their endurance. Using the results of experimental studies of changes in the endurance of a two-frequency loading of specimens of cyclically stable, cyclically softened and cyclically hardened steels under rigid conditions we have shown that decrease in the endurance under the aforementioned conditions depends on the ratio of frequencies and amplitudes of operation low-frequency low-cycle and high-frequency vibration stresses, and, moreover, the higher the level of the ratios of amplitudes and frequencies of those stacked harmonic processes of loading the greater the effect. It is shown that estimation of such a decrease in the endurance compared to a single frequency loading equal in the total stress (strains) amplitudes can be carried out using an exponential expression coupling those endurances through a parameter (reduction factor) containing the ratio of frequencies and amplitudes of operation cyclic loads and characteristic of the material. The reduction is illustrated by a set of calculation-experimental curves on the corresponding diagrams for each of the considered types of materials and compared with the experimental data.


2019 ◽  
Vol 124 (8) ◽  
pp. 4395-4412 ◽  
Author(s):  
Ruowen Yang ◽  
Shu Gui ◽  
Jie Cao

2021 ◽  
Vol 25 ◽  
pp. 233121652110101
Author(s):  
Dmitry I. Nechaev ◽  
Olga N. Milekhina ◽  
Marina S. Tomozova ◽  
Alexander Y. Supin

The goal of the study was to investigate the role of combination products in the higher ripple-density resolution estimates obtained by discrimination between a spectrally rippled and a nonrippled noise signal than that obtained by discrimination between two rippled signals. To attain this goal, a noise band was used to mask the frequency band of expected low-frequency combination products. A three-alternative forced-choice procedure with adaptive ripple-density variation was used. The mean background (unmasked) ripple-density resolution was 9.8 ripples/oct for rippled reference signals and 21.8 ripples/oct for nonrippled reference signals. Low-frequency maskers reduced the ripple-density resolution. For masker levels from −10 to 10 dB re. signal, the ripple-density resolution for nonrippled reference signals was approximately twice as high as that for rippled reference signals. At a masker level as high as 20 dB re. signal, the ripple-density resolution decreased in both discrimination tasks. This result leads to the conclusion that low-frequency combination products are not responsible for the task-dependent difference in ripple-density resolution estimates.


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