Study is performed of the weekly cycle of temperature indices (its diurnal range, mean, maximum and minimum) as
well as cloudiness, solar radiation and air pollution index based on 1996-2005 surface observations and air pollution
indexes from four big cities over the Yangtze River Delta of China. Results suggest that these temperature variations are
featured by significant weekend effect (WE) in that these temperatures are higher at weekends than on workdays in
summer as opposed to those in other seasons; the WE of diurnal maximum and minimum temperatures is much bigger at
weekends and can be utilized as the WE index; during the long spell of holidays or festivities in China WE is remarkable,
and especially in the Spring Festival and National Day holidays these temperatures are smaller compared to those 7 day
before and after as opposed to the values during, and 7 days before/after, the May Day holidays; the temperature WE
bears a close relation to aerosol concentration thanks to anthropogenic activities; in summer the indirect impacts of
aerosols (aerosol - cloud interactions) due to abundant vapor play a dominant role and at weekends little aerosol is
responsible for reduced cloudiness, allowing more solar radiation to strike the ground for the rise in all the temperatures;
in the other seasons the direct and semi-direct effect of aerosol plays a predominant part, with the concentration of
aerosols declining at weekends for reducing its ability to heat air and increasing cloudiness, thus leading to the decrease
in all the temperature elements.
Using Doppler radar products from three intense convective precipitation events occurring on
the night of June 12, early morning and night on July 12, 2006 over the Tianjin area, a comparative study
is made, showing that typically, the radial velocity field changes earlier than does the echo-intensity field
at the initial and mature stages of precipitation, such that much attention should be paid to the variation in
the velocity field in doing nowcasts of rainfall, and the Doppler velocity variation in conjunction with
Auto-Nowcaster predictions helps determine the change in radar echo intensity and its movement
direction, thereby improving the accuracy of nowcasts of strongly convective precipitation.
Based on 1979-2005 typhoon data and NCEP/DOE AMIP-II reanalysis, a study is performed of behaviors of tropical
cyclones generated in the monsoon trough (MTTC hereinafter) in the western North Pacific as well as effects of the
monsoon trough strength on their production. Evidence suggests that (1) during this period the MTTC yearly number
experiences stages as follows: normal (1979~87), more MTTCs (1988~94), and fewer MTTCs (1995~2005); MTTC
variation is marked by quasi-4 and -2 yearly periods, with 1994 as the change from more to fewer MTTCs in annual
number; (2) in the years of anomalous MTTC number there are great difference in the onset/ending day and genesis
position. In the years of fewer (more) MTTCs in comparison to mean, MTCC starts its activity later (earlier), terminating
on an earlier (later) day, its genesis area is smaller (bigger), located south- (north-) and/or west- (eastward) of mean; 3)
the ITCZ intensity affects the MTTC genesis position and yearly number. When the lower-level western North Pacific
subtropical high is positioned south- (north-) of normal, cross-equatorial flows at Somali and 90~1600E are weaker
(stronger), the monsoon trough is weaker (stronger) with its position south- and/or westward (north- and/or eastward)
with respect to normal. At that time, in the tropopause, the south-Asian high is east- (westward) of mean and the oceanic
upper-air trough is south- and/or westward (north- and/or eastward). And the distribution in the high and lower
troposphere allows the small-value band of vertical wind shear to decrease (increase) for a smaller (bigger) domain for
MTTC genesis, and convection is suppressed (intensified), leading to positive (negative) OLR anomalies over waters
east of the Philippine so that MTTC is generated south- and/or westward (north- and/or eastward) relative to normal and
MTTC annual number is anomalously smaller (greater).
Using the 1961-2001 rainfall datasets from 25 typical stations in Fujian Province treated by means of Empirical Orthogonal Function (EOF), Fast Fourier Function (FFT), Continuous Wavelet Transform (CWT) and Orthogonal Wavelet Transform (OWT) study is made of sequences of flood/drought indices (Z index) in different seasons. Evidence suggests that 1) the regional flood/drought events have significant 2~3 year periods in 1965-1975 and the 1990s; 2) rainfall amount in the south opposite to that in the north shows pronounced 1- and 3~ 4-yearly periods after the mid 1980s; 3) quantitatively, precipitation occurs in the west to middle in an opposite way to the other parts of the province, with noticeable 1~2 yearly periods in 1985 - 1998, and more appreciable 9~13-yearly periods after the 1980s; 4) within the study period (1961-2001) the drought trend is more apparent in the south (east) than in the north (west), particularly in the 1990s; 5) the regional climate is relatively wetter (drier) in the 1960s and 1980s (1970s and 1990s).
Doppler radar, when used in detecting large-scale intense precipitation, has its echo features differing than those from warm or cold advection alone (as an S- or anti-S- form) and than those just from large-scale convergence or divergence (as a bow-like shape) but the features of Doppler velocity resulting from the combination of warm or cold advection with convergence or divergence are called the complex windfield. Analysis of Doppler weather radar data from an extensive, persistent strong rainfall event over the Hai river basin on August 16, 2005 reveals that 1) in the presence of a low-level complex windfield related to the combination of warm advection and convergence, i.e., the Doppler velocity products show that, starting from the radar center, clockwise curvature of a zero-speed line on one side toward the positive velocity zone is more remarkable than the counterpart on the other side towards the negative velocity zone, implying that when the negative speed zone is bigger compared to the maximum positive area, rainfall is reinforced or maintained; 2) in the presence of a low-level complex windfield resulting from warm advection combined with divergence, the precipitation would be weakened or ceased. Therefore, the study on the convergence and divergence in the radar velocity field gives a good indicator of nowcasting prediction of the formation, development, maintenance and decay phases of a large-scale rainfall event.
Co-Pt alloy films with perpendicular magnetic anisotropy and 100 percent remanence ratio were successfully prepared using e-beam coevaporation. A series of vacuum annealing was done on these alloy samples to study their thermal stability. The experimental results were as follows: a) For annealing temperature at 200 to approximately 300 degrees C, the Kerr rotation angle was almost unchanged or presented a slow decrease with the lasting of annealing, and the increase in coercivity was also small; b) For annealing temperature above 300 degrees C, both coercivity and Kerr rotation angle dropped prominently, and in the mean time magnetization became partly in-plane; c) Thermal stability is also probably a problem that needs to be solved for CoPt alloy films. The change of magnetic and magneto-optical properties of Co-Pt alloy films during annealing was considered to be related to the strength variation of different textures in films.
Effects of vacuum annealing on the coercivity in sputtered and evaporated Pt/Co multilayer films were detailedly investigated. Our experimental results showed that the coercivity experienced an initial increase and a subsequent decrease with the process of annealing. The saturation magnetization decreased slowly at initial annealing stage and then dropped drastically when the annealing temperature was further raised. The coercivity variation after vacuum annealing can be explained by the improvement of f.c.c. (111) texture and the reduction of Co layer thickness.
Pt/Co multilayered films were prepared by DC sputtering and electron beam evaporation and grazing angle X-ray reflectivity analysis was used to determine the film structure. It was found that the interfaces of the evaporated samples became flatter and more obscure when the substrate temperature rose. The sputtered samples had relatively flat interfaces and the atoms were more closely packed than the evaporated samples.