The variability of eddy ki/netic energy in the South China Sea deduced from satellite altimeter data

We used fifteen years （1993-2007） of altimetric data, combined from different missions （ERS-1/2, TOPEX/Poseidon, Jason-l, and Envisat）, to analyze the variability of the eddy kinetic energy （EKE） in the South China Sea （SCS）. We found that the EKE ranged from 64 cm2/s2 to 1 390 cm2/s2 with a mean value of 314 cm2/s2. The highest EKE center was observed to the east of Vietnam （with a mean value of 509 cm2/s2） and the second highest EKE region Was located to the southwest of Taiwan Island （with a mean value of 319 cm2/s2）. We also found that the EKE structure is the consequence of the superposition of different variability components. First, interannual variability is important in the SCS. Spectral analysis of the EKE interannual signal （IA-EKE） shows that the main periodicities of the IA-EKE to the east of Vietuam, to the southwest of Taiwan Island, and in the SCS are 3.75, 1.87, and 3.75 years, respectively. It is to the south of Taiwan Island that the IA-EKE signal has the most obvious impact on EKE variability. In addition, the IA-EKE exhibit different trends in different regions. An obvious positive trend is observed along the east coast of Vietnam, while a negative trend is found to the southwest of Taiwan Island and in the east basin of Vietnam. Correlation analysis shows that the IA-EKE has an obvious negative correlation with the SSTA in Nifio3 （5°S-5°N, 90°W-150°W）. E1 Nifio-Southem Oscillation （ENSO） affects the 1A-EKE variability in the SCS through an atmospheric bridge--wind stress curl over the SCS. Second, the seasonal cycle is the most obvious timescale affecting EKE variability. The locations of the most remarkable EKE seasonal variabilities in the SCS are to the east of Vietnam, to the southwest of Taiwan, and to the west of Philippines. To the east of Vietnam, the seasonal cycle is the dominant mechanism controlling EKE variability, which is attributed primarily to the annual cycle there of wind stress curl. In this area, the maximum EKE is observed in autumn. To the southwest of Taiwan Island, the EKE is enlarged by the stronger SCS circulation, which is caused by the intrusion branch from the Kuroshio in winter. Finally, intra-annual and mesoscale variability, although less important than the former, cannot be neglected. The most obvious intra-annual and mesoscale variability, which may be the result of baroclinic instability of the background flow, are observed to the southwest of Taiwan Island. Sporadic events can have an important effect on EKE variability.

Intratree Variability of Cleavage Resistance of Chinese Fir from Plantation

This paper studied the variation of cleavage resistance of Chinese fir wood from plantation. Six trees of 36 years old were investigated, and the cleavage resistance properties for 672 samples made of the trees were tested. The samples were cut from the sapwood and heartwood at different directions (south and north) and heights (1.3, 3.3, 5.3 and 7.3 m) of the trees. The result showed that: tangential cleavage resistance was higher than radial one, and cleavage resistance of sapwood was higher than that of heartwood, but there was no significant difference in cleavage resistances between sections of the north and the south of the trees. There was a little variation in cleavage resistance between the radial and tangential from butt to top log, which shows a little decrease with the height from 1.3 to 5.3 m , but a rise in the top of the trees.