Search Results

You are looking at 1 - 3 of 3 items for

  • Author or Editor: Yuan Kang x
  • All content x
Clear All Modify Search
Boqi Liu, Congwen Zhu, Yuan Yuan, and Kang Xu

Abstract

An advance in the timing of the onset of the South China Sea (SCS) summer monsoon (SCSSM) during the period 1980–2014 can be detected after 1993/94. In the present study, the interannual variability of the SCSSM onset is classified into two types for the periods before and after 1993/94, based on their different characteristics of vertical coupling between the upper- and lower-tropospheric circulation and the differences in their related sea surface temperature anomalies (SSTAs). On the interannual time scale, type-I SCSSM onset is characterized by anomalous low-level circulation over the northern SCS during 1980–93, whereas type-II SCSSM onset is associated with anomalies of upper-level circulation in the tropics during 1994–2014. The upper-tropospheric thermodynamic field and circulation structures over the SCS are distinct between the two types of SCSSM onset, and this investigation shows the importance of the role played by the spring SSTAs in the southern Indian Ocean (SIO) and that of ENSO events in type-I and type-II SCSSM onset, respectively. In the early episode, the warming SIO SSTAs can induce an anomalous low-level anticyclone over the northern SCS that affects local monsoonal convection and rainfall over land to its north, demonstrating a high sensitivity of subtropical systems in type-I SCSSM onset. However, in type-II SCSSM onset during the later episode, the winter warm ENSO events and subsequent warming in the tropical Indian Ocean can influence the SCSSM onset by modulating the spring tropical temperature and upper-level pumping effect over the SCS.

Full access
Kai-Yuan Cheng, Pao K. Wang, and Chen-Kang Wang

Abstract

The ventilation coefficients that represent the enhancement of mass transfer rate due to the falling motion of spherical hailstones in an atmosphere of 460 hPa and 248 K are computed by numerically solving the unsteady Navier–Stokes equation for airflow past hailstones and the convective diffusion equation for water vapor diffusion around the falling hailstones. The diameters of the hailstones investigated are from 1 to 10 cm, corresponding to Reynolds number from 5935 to 177 148. The calculated ventilation coefficients vary approximately linearly with the hailstone diameter, from about 19 for a 1-cm hailstone to about 208 for a 10-cm hailstone. Empirical formulas for ventilation coefficient variation with hailstone diameter as well as Reynolds and Schmidt numbers are given. Implications of these ventilation coefficients are discussed.

Full access
Yun Su, Yuan Kang, Xianshuai Zhai, and Xiuqi Fang

Abstract

Climate change affects relationships between regions. The sequence of peacemaking events between farming and nomadic groups in northern China from the Western Han to the Qing dynasty was constructed based on historical documents. We analyzed the impacts of climate change on ethnic relationships using war and temperature sequence data from previous studies. The main results are as follows: 1) There were 504 peacemaking events between farming and nomadic groups, with an average frequency of 2.4 times per decade. Paying tribute (68.9%) occurred significantly more frequently than intermarriage for pacification (31.1%). The sequences showed different stages. 2) There were more peacemaking events during cold periods and fewer during warm periods. Intermarriage for pacification played a greater role in peacemaking during warm periods, while paying tribute was more important during cold periods. 3) High-incidence stages of war and of peacemaking events alternated. Peacemaking events occurred more frequently during cold periods and wars occurred more frequently during warm periods. 4) During warm periods, farming and nomadic groups had enough power to contend with each other, wars occurred frequently, and intermarriage was often used for peacemaking. During cold periods, agriculture and animal husbandry declined, both sides weakened, and the power difference between them usually increased. Wars rarely occurred, and paying tribute was often used for peacemaking. Ethnic relationships are affected by many factors. As a background factor influencing land productivity, climate indirectly affected conflict-resolution measures between farming and nomadic groups. We can hereby consider ways to manage interregional ethnic relationships under global climate change today.

Restricted access