REASONS FOR THE LATE ONSET AND ANOMALOUS SOUTHWARD PERSISTENCE OF THE SOUTH CHINA SEA SUMMER MONSOON IN 2005

Features of atmospheric circulation and thermal structures are discussed using the NCAR/NCEP data to reveal the reasons for the late onset and anomalous southward persistence of the South China Sea Summer Monsoon (SCSSM) in 2005. The results show that three factors are crucial. First, a strong Arabian High overlaps with a high-latitude blocking high and channels strong cold air to southern Asia. Second, the Tibetan Plateau has a bigger snow cover than usual in spring and the melting of snow cools down the surface. Third, the Somali Jet breaks out at a much later date, being not conducive to convection over Indochina. The former two factors restrict atmospheric sensible heating over the Tibetan Plateau and nearby regions while the third one limits latent heating over Indochina. All of the factors slow down atmospheric warming and postpone the onset of SCSSM. Long after the onset of SCSSM, strong cold air over India advances the Southwest Monsoon northward slowly, resulting in weaker convection and latent heating over the Tibetan Plateau and nearby areas. The negative feedback conversely inhibits further northward movement of Southwest Monsoon.     

The effect of pressure on the chemical potentials of seawater components,on ionic species in seawater,and on calcite saturation levels

The activities of most of the major seawater components at 1,001 bars have been estimated, and values for the ions deduced. Equations giving the effect of pressure on the activities of ionic species in seawater ($\text{S = 35‰}$) have been developed. The species covered are: NaSO₄^?, MgSO₄⁰, CaSO₄⁰, H⁺, the free base (NH₃), the HCO₃^?/CO₃² activity ratio and the ion activity product of calcium carbonate. Comparison of the latter with the “ideal” solubility of calcite (pure solid in equilibrium with a mixed electrolyte solution) indicates a degree of saturation compatible with the trends indicated by in situ measurements.     

Prediction of the partial molal volumes of electrolytes in seawater

A general equation is derived for predicting the partial molal volume (pmv) of an electrolyte in seawater, using binary solution data, and seawater density data. The composition of seawater need not be “average” - prediction can be made for any composition. Simpler equations are derived for “average” seawater. The ranges cover $\text{S = 0–50‰}$, t = 0–30°C and p = 1–1,000 bar, subject to the availability of binary solution data. Estimates of the pmv's of a number of electrolytes are made and compared with experimental values and the summed ionic values.     

Prediction of the heat capacities of seawater and other multicomponent solutions from the Tammann—Tait—Gibson model

Equations are given for estimating the heat capacity of binary and multicomponent electrolyte solutions on the basis of the TTG model. These equations are used to calculate the heat capacity of seawater solutions up to a concentration of 45‰ for the temperature range 0–30°C and up to a concentration of 160‰ at 20°C. The deviations from the experimental values are less than the uncertainties due to smoothing and experimental errors. The results suggest that the heat capacity of other multicomponent solutions, including non-standard seawater solutions, could be predicted to within 0.1% or better, up to an ionic strength of about 3 M.     

Prediction of the refractive index of seawater as a function of temperature,pressure, salinity and wavelength

An equation is given for predicting the absolute refractive index of seawater as a function of wavelength (in the visible region), temperature, pressure and salinity. This equation is based on the pure-water equation of H. Eisenberg, on the Tammann hypothesis and the Tait-Gibson equation of state for seawater. Comparison with experimental results (to 1380 bars) indicate an accuracy of ca. 0.0001 or better is achieved in the $\text{T-P}$ range of oceanographic interest.     

The chemical potentials of seawater components

An equation for the chemical potential of “seasalt” (R T ln a_s) as a function of salinity is derived from isopiestic and potentiometric data, via the Gibbs-Duhem equation and a simple ion-interaction theory. Estimates of the activity coefficients of seasalts and the major ions are listed for salinities 25‰ and 36‰. The direct measurement of ln a_s is considered, and a related quantity, that could be measured in situ, is suggested as a future oceanographic parameter. The results of laboratory measurements on an average seawater sample, using four ion-selective electrodes, serve to illustrate the concepts involved.     

测量平差电算程序中矩阵求逆实现与优化

随着计算机件技术与数学科学的不断发展 ,虽然测量平差技术已经取得了很大的进步 ,但在技术实现方面还存在不少问题。目前 ,市场上推出的测量平差软件或平差大全 ,大都是在PC— 15 0 0机上用QBASIC或FORTRAN语言进行平差处理 ,在使用时常会遇到无法满足现实测绘工作的要求 ,而且很难对其源程序进行改进。本文充分利用矩阵行列式初等变换性质、C语言中指针动态性优于函数递归调用的特性来实现并优化了测量平差电算程序中的关键技术———矩阵求逆     

黄河口凹陷西北部湖底扇的沉积演化及发育模式——以古近纪沙三下亚段为例

湖底扇是黄河口凹陷古近纪一种重要的沉积类型,扇体储集物性和含油性较好,具有勘探价值.研究黄河口凹陷沙河街组沙三下亚段岩心、测井、地震反射特征,认为A区含油砂岩体为在半深湖—深湖环境形成的2种类型湖底扇沉积.低位域时期发育远岸的深水浊积湖底扇;湖扩域和高位域时期发育由三角洲前缘砂体滑塌进入湖底堆积而成的滑塌浊积湖底扇.从空间分布看,深水浊积扇主要发育在低位域湖盆内二阶断裂的下降盘;滑塌浊积扇主要发育在研究区南部的断裂陡坡带,位于扇三角洲前方,且扇体规模较大,发育时间长.湖底扇的发育受沉积坡折和断裂坡折的控制.由于构造背景、湖平面变化及物源供应不同,湖底扇的位置、规模和形态也不尽相同.     

The refractive index of seawater — comparison of experimental values and estimates from binary solution data

The Tait-Gibson parameter, $\text{B}{}^1$, and the refractive index of seawater are estimated from binary solution data. The predicted and experimental values agree closely. The maximum deviations, at $\text{S = 40‰}$, are 1.7 bars for $\text{B}{}^1$ and 0.0001 for the refractive index. The results show that binary solution data, analysed on the basis of the Tammann-Tait-Gibson model for aqueous solutions, can be used to predict the properties of seawater of composition different to that of standard seawater.