Topological structure of coronal-interplanetary magnetic field     

Tyan Yeh 《Solar physics》1978,56(2):439-447

The topological structure of the coronal-interplanetary magnetic field is determined by the arrangement of the neutral lines at the coronal base. It is characterized by nested separatrices, which are interfaces between closed and open field lines or between oppositely directed open field lines, in the coronal-interplanetary space. In the neighborhoods of these separatrices there are important electric currents. These currents form the basis for the sheet-current model.The National Center for Atmospheric Research is sponsored by the National Science Foundation.  相似文献   

Three-dimensional V_P and V_S structural models associated with the active subduction and collision tectonics in the Taiwan region     

Kwang-Hee Kim  Jer-Ming Chiu  Jose Pujol  Kou-Cheng Chen  Bor-Shouh Huang  Yih-Hsiung Yeh  Peng Shen 《Geophysical Journal International》2005,162(1):204-220

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Influence of river channel geometry in stream flow modelling and guidelines for field investigation          下载免费PDF全文

Hongbo Zhang  Fan Zhang  Xiaonan Shi  Chen Zeng  Dong‐Sin Shih  Gour‐Tsyh Yeh  Daniel R. Joswiak 《水文研究》2014,28(4):2630-2638

Fully physics‐based, process‐level, distributed fluid flow and reactive transport hydrological models are rarely used in practice until recent years. These models are useful tools to help understand the fundamental physical, chemical, and biological processes that take place in nature. In this study, sensitivity analyses based on a mountain area river basin modelling study are performed to investigate the effect of river channel geometric characteristics on downstream water flow. Numerical experiments show that reduction in the river channel geometric measurement interval may not significantly affect the downstream water stage simulation as long as measurement accuracy at special nodes is guaranteed. The special upstream nodes include but are not limited to 1) nodes located close to the observation station, 2) nodes near the borders of different land covers with considerable riverbed roughness changes, 3) nodes at entering points of tributaries causing discharge jump and 4) nodes with a narrow cross‐section width that may control the flow conditions. This information provides guidelines for field investigation to efficiently obtain necessary geometric data for physics‐based hydrological modelling. It is especially useful in alpine areas such as the Tibetan Plateau where field investigation capability is limited under severe topography and climate condition. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Erratum to: Analysis of pumping test data for determining unconfined-aquifer parameters: Composite analysis or not?     

Hund-Der Yeh  Yen-Chen Huang 《Hydrogeology Journal》2010,18(8):1983-1983

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Reactive transport codes for subsurface environmental simulation     

C. I. Steefel  C. A. J. Appelo  B. Arora  D. Jacques  T. Kalbacher  O. Kolditz  V. Lagneau  P. C. Lichtner  K. U. Mayer  J. C. L. Meeussen  S. Molins  D. Moulton  H. Shao  J. Šimůnek  N. Spycher  S. B. Yabusaki  G. T. Yeh 《Computational Geosciences》2015,19(3):445-478

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Review: Optimization methods for groundwater modeling and management     

William W-G Yeh 《Hydrogeology Journal》2015,23(6):1051-1065

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Combined effect of El Niño-Southern Oscillation and Pacific Decadal Oscillation on the East Asian winter monsoon   总被引：1，自引：0，他引：1  

Ji-Won Kim  Sang-Wook Yeh  Eun-Chul Chang 《Climate Dynamics》2014,42(3-4):957-971

Using long-term observational data and numerical model experiments, the combined effect of the El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) on the variability of the East Asian winter monsoon is examined. In the observations, it is found that when the ENSO and PDO are in-phase combinations (i.e., El Niño/positive PDO phase and La Niña/negative PDO phase), a negative relationship between ENSO and East Asian winter monsoon is significantly intensified. In other words, when El Niño (La Niña) occurs with positive (negative) PDO phase, anomalous warm (cold) temperatures are dominant over the East Asian winter continent. On the other hand, there are no significant temperature anomalies when the ENSO and PDO are out-of-phase combinations (i.e., El Niño/negative PDO phase and La Niña/positive PDO phase). Further analyses indicate that the anticyclone over the western North Pacific including the East Asian marginal seas plays an essential role in modulating the intensity of the East Asian winter monsoon under the changes of ENSO–PDO phase relationship. Long-lasting high pressure and warm sea surface temperature anomalies during the late fall/winter and following spring over the western North Pacific, which appear as the El Niño occurs with positive PDO phase, can lead to a weakened East Asian winter monsoon by transporting warm and wet conditions into the East Asian continent through the southerly wind anomalies along the western flank of the anomalous high pressure, and vice versa as the La Niña occurs with negative PDO phase. In contrast, the anomalous high pressure over the western North Pacific does not show a prominent change under the out-of-phase combinations of ENSO and PDO. Numerical model experiments confirm the observational results, accompanying dominant warm temperature anomalies over East Asia via strong anticyclonic circulation anomalies near the Philippine Sea as the El Niño occurs with positive PDO phase, whereas such warming is weakened as the El Niño occurs with negative PDO phase. This result supports the argument that the changes in the East Asian winter monsoon intensity with ENSO are largely affected by the strength of the anticyclone over the western North Pacific, which significantly changes according to the ENSO–PDO phase relationship.  相似文献   

Special issue “Grand celebration: 50th anniversary of the Korean meteorological society”     

Song-You Hong  Sang-Wook Yeh  Sang-Woo Kim 《Asia-Pacific Journal of Atmospheric Sciences》2014,50(1):1-1

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Recent progress on two types of El Niño: Observations,dynamics, and future changes     

Sang-Wook Yeh  Jong-Seong Kug  Soon-Il An 《Asia-Pacific Journal of Atmospheric Sciences》2014,50(1):69-81

The climate community has made significant progress in observing, understanding and predicting El Niño and Southern Oscillation (ENSO) over the last 30 years. In spite of that, unresolved questions still remain, including ENSO diversity and extreme events, decadal modulation, predictability, teleconnection, and the interaction of ENSO with other climate phenomena. In particular, the existence of a different type of El Niño from the conventional El Niño has been proposed. This type of El Niño has occurred more frequently during the recent decades and received a great attention in the climate community. This review provides recent progresses on dynamics, decadal variability and future projection of El Niño, with a focus on the two types of El Niño.  相似文献   

ENSO nonlinearity in a warming climate   总被引：1，自引：1，他引：0  

J. Boucharel  B. Dewitte  Y. du Penhoat  B. Garel  S.-W. Yeh  J.-S. Kug 《Climate Dynamics》2011,37(9-10):2045-2065

The El Niño Southern Oscillation (ENSO) is known as the strongest natural inter-annual climate signal, having widespread consequences on the global weather, climate, ecology and even on societies. Understanding ENSO variations in a changing climate is therefore of primordial interest to both the climate community and policy makers. In this study, we focus on the change in ENSO nonlinearity due to climate change. We first analysed high statistical moments of observed Sea Surface Temperatures (SST) timeseries of the tropical Pacific based on the measurement of the tails of their Probability Density Function (PDF). This allows defining relevant metrics for the change in nonlinearity observed over the last century. Based on these metrics, a zonal “see-saw” (oscillation) in nonlinearity patterns is highlighted that is associated with the change in El Niño characteristics observed in recent years. Taking advantage of the IPCC database and the different projection scenarios, it is showed that changes in El Niño statistics (or “flavour”) from a present-day climate to a warmer climate are associated with a significant change in nonlinearity patterns. In particular, in the twentieth century climate, the “conventional” eastern Pacific El Niño relates more to changes in nonlinearity than to changes in mean state whereas the central Pacific El Niño (or Modoki El Niño) is more sensitive to changes in mean state than to changes in nonlinearity. An opposite behaviour is found in a warmer climate, namely the decreasing nonlinearity in the eastern Pacific tends to make El Niño less frequent but more sensitive to mean state, whereas the increasing nonlinearity in the west tends to trigger Central Pacific El Niño more frequently. This suggests that the change in ENSO statistics due to climate change might result from changes in the zonal contrast of nonlinearity characteristics across the tropical Pacific.  相似文献