Adiabatic density surface,neutral density surface, potential density surface,and mixing path

In this paper,adiabatic density surface,neutral density surface and potential density surface are compared.The adiabatic density surface is defined as the surface on which a water parcel can move adiabatically,without changing its potential temperature and salinity.For a water parcel taken at a given station and pressure level,the corresponding adiabatic density surface can be determined through simple calculations.This family of surface is neutrally buoyant in the world ocean,and different from other surfaces that are not truly neutrally buoyant.In order to explore mixing path in the ocean,a mixing ratio m is introduced,which is defined as the portion of potential temperature and salinity of a water parcel that has exchanged with the environment during a segment of migration in the ocean.Two extreme situations of mixing path in the ocean are m=0(no mixing),which is represented by the adiabatic density curve,and m=1,where the original information is completely lost through mixing.The latter is represented by the neutral density curve.The reality lies in between,namely,0<m<1.In the turbulent ocean,there are potentially infinite mixing paths,some of which may be identified by using different tracers(or their combinations)and different mixing criteria.Searching for mixing paths in the real ocean presents a great challenge for further research.

Review of Global Ocean Intermediate Water Masses: 1.Part A, the Neutral Density Surface (the ‘McDougall Surface’) as a Study Frame for Water-Mass Analysis

This review article commences with a comprehensive historical review of the evolution and application of various density surfaces in atmospheric and oceanic studies. The background provides a basis for the birth of the neutral density idea. Attention is paid to the development of the neutral density surface concept from the nonlinearity of the equation of state of seawater. The definition and properties of neutral density surface are described in detail as developed from the equations of state of seawater and the buoyancy frequency when the squared buoyancy frequency N2 is zero, a neutral state of stability. In order to apply the neutral density surface to intermediate water-mass analysis, this review also describes in detail its practical oceanographic application. The mapping technique is focused for the first time on applying regularly gridded data in this review. It is reviewed how a backbone and ribs framework was designed to flesh out from a reference cast and first mapped the global neutral surfaces in the world’s oceans. Several mapped neutral density surfaces are presented as examples for each world ocean. The water-mass property is analyzed in each ocean at mid-depth. The characteristics of neutral density surfaces are compared with those of potential density surfaces.

Limiting stand density and basal area projection models for even-aged Tecomella undulata plantations in a hot arid region of India

This paper presents equations for estimating limiting stand density for Z undulata plantations grown in hot desert areas of Raj asthan State in India. Five different stand level basal area projection models, belonging to the path invariant algebraic difference form of a non-linear growth function, were also tested and compared. These models can be used to predict future basal area as a function of stand variables like dominant height and stem number per hectare and are necessary for reviewing different silvicultural treatment options. Data from 22 sample plots were used for modelling. An all possible growth intervals data structure was used. Both, qualitative and quantitative criteria were used to compare alternative models. The Akaike＇s information criteria differ- ence statistic was used to analyze the predictive ability of the models. Results show that the model proposed by Hui and Gadow performed best and hence this model is recommended for use in predicting basal area development in 12 undulata plantations in the study area. The data used were not from thinned stands, and hence the models may be less accurate when used for predictions when natural mortality is very significant.

Regional Variation in Carbon Sequestration Potential of Forest Ecosystems in China

Enhancing forest carbon(C) storage is recognized as one of the most economic and green approaches to offsetting anthropogenic CO_2 emissions. However, experimental evidence for C sequestration potential(C_(sp)) in China's forest ecosystems and its spatial patterns remain unclear, although a deep understanding is essential for policy-makers making decisions on reforestation. Here, we surveyed the literature from 2004 to 2014 to obtain C density data on forest ecosystems in China and used mature forests as a reference to explore C_(sp). The results showed that the C densities of vegetation and soil(0–100 cm) in China's forest ecosystems were about 69.23 Mg C/ha and 116.52 Mg C/ha, respectively. In mature forests, the C_(sp) of vegetation and soil are expected to increase to 129.26 Mg C/ha(87.1%) and 154.39 Mg C/ha(32.4%) in the coming decades, respectively. Moreover, the potential increase of C storage in vegetation(10.81 Pg C) is estimated at approximately twice that of soil(5.01 Pg C). Higher C_(sp) may occur in the subtropical humid regions and policy-makers should pay particular attention to the development of new reforestation strategies for these areas. In addition to soil nutrients and environment, climate was an important factor influencing the spatial patterns of C density in forest ecosystems in China. Interestingly, climate influenced the spatial patterns of vegetation and soil C density via different routes, having a positive effect on vegetation C density and a negative effect on soil C density. This estimation of the potential for increasing forest C storage provided new insights into the vital roles of China's forest ecosystems in future C sequestration. More importantly, our findings emphasize that climate constraints on forest C sequestration should be considered in reforestation strategies in China because the effects of climate were the opposite for spatial patterns of C density in vegetation and soil.Enhancing forest carbon(C) storage is recognized as one of the most economic and green approaches to offsetting anthropogenic CO2 emissions. However, experimental evidence for C sequestration potential(Csp) in China's forest ecosystems and its spatial patterns remain unclear, although a deep understanding is essential for policy-makers making decisions on reforestation. Here, we surveyed the literature from 2004 to 2014 to obtain C density data on forest ecosystems in China and used mature forests as a reference to explore Csp. The results showed that the C densities of vegetation and soil(0–100 cm) in China's forest ecosystems were about 69.23 Mg C/ha and 116.52 Mg C/ha, respectively. In mature forests, the Csp of vegetation and soil are expected to increase to 129.26 Mg C/ha(87.1%) and 154.39 Mg C/ha(32.4%) in the coming decades, respectively. Moreover, the potential increase of C storage in vegetation(10.81 Pg C) is estimated at approximately twice that of soil(5.01 Pg C). Higher Csp may occur in the subtropical humid regions and policy-makers should pay particular attention to the development of new reforestation strategies for these areas. In addition to soil nutrients and environment, climate was an important factor influencing the spatial patterns of C density in forest ecosystems in China. Interestingly, climate influenced the spatial patterns of vegetation and soil C density via different routes, having a positive effect on vegetation C density and a negative effect on soil C density. This estimation of the potential for increasing forest C storage provided new insights into the vital roles of China's forest ecosystems in future C sequestration. More importantly, our findings emphasize that climate constraints on forest C sequestration should be considered in reforestation strategies in China because the effects of climate were the opposite for spatial patterns of C density in vegetation and soil.

The relation between the Mindanao Current and Mindanao Undercurrent on seasonal scale

The ocean general circulation model for the earth simulator（OFES） products is applied to estimate the transports of the Mindanao Current（MC） and the Mindanao undercurrent（MUC） and explore the relation between them on seasonal scale. In general, the MUC is composed of the lower part of the Southern Pacific Tropical Water（SPTW）and Antarctic Intermediate Water（AAIW）. While the deep northward core below 1 500 m is regarded as a portion of MUC. Both salinity and potential density restrictions become more reasonable to estimate the transports of MC/MUC as the properties of water mass having been taken into consideration. The climatological annual mean transport of MC is（37.4±5.81）×10~6 m^3/s while that of MUC is（23.92±6.47）×10~6 m^3/s integrated between 26.5 σ_θ and 27.7 σ_θ, and（17.53±5.45）×10~6 m^3/s integrated between 26.5 σ_θ and 27.5 σ_θ in the OFES. The variations of MC and MUC have good positive correlation with each other on the seasonal scale： The MC is stronger in spring and weaker in fall, which corresponds well with the MUC, and the correlation coefficient of them is 0.67 in the OFES.The same variations are also appeared in hybrid coordinate ocean model（HYCOM） results. Two sensitive experiments based on HYCOM are conducted to explore the relation between MC and MUC. The MUC（26.5〈σ_θ〈27.7） is strengthening as the MC increases with the enhancement of zonal wind field. It is shown,however, that the main part of the increasement is the deeper northward high potential density water（HPDW）,while the AAIW almost remains stable, SPTW decreases, and vice versa.

The properties of an asymmetric Gaussian potential quantum well qubit in RbCl crystal

With the circumstance of the electron strongly coupled to LO-phonon and using the variational method of Pekar type（VMPT）,we study the eigenenergies and the eigenfunctions（EE） of the ground and the first excited states（GFES） in a RbCl crystal asymmetric Gaussian potential quantum well（AGPQW）.It concludes：（i） Twoenergy-level of the AGPQW may be seen as a qubit.（ii） When the electron located in the superposition state of the two-energy-level system,the time evolution and the coordinate changes of the electron probability density oscillated periodically in the AGPQW with every certain period T0=22.475 fs.（iii） Due to the confinement that is a two dimensional x-y plane symmetric structure in the AGPQW and the asymmetrical Gaussian potential（AGP） in the AGPQW growth direction,the electron probability density presents only one peak configuration located in the coordinate of z 〉 0,whereas it is zero in the range of z 〈 0.（iv） The oscillatory period is a decreasing function of the AGPQW height and the polaron radius,（v） The oscillating period is a decreasing one in the confinement potential R 〈 0.24 nm,whereas it is an increasing one in the confinement potential R 〉 0.24 nm and it takes a minimum value in R = 0.24 nm.

Study and modeling of the transport mechanism in a Schottky diode on the basis of a GaAs semiinsulator

The current through a metal-semiconductor junction is mainly due to the majority carriers. Three distinctly different mechanisms exist in a Schottky diode： diffusion of the semiconductor carriers in metal, thermionic emission-diffusion （TED） of carriers through a Schottky gate, and a mechanical quantum that pierces a tunnel through the gate. The system was solved by using a coupled Poisson-Boltzmann algorithm. Schottky BH is defined as the difference in energy between the Fermi level and the metal band carrier majority of the metal--semiconductor junction to the semiconductor contacts. The insulating layer converts the MS device in an MIS device and has a strong influence on its current-voltage （I-V） and the parameters ofa Schottky barrier from 3.7 to 15 eV. There are several possible reasons for the error that causes a deviation of the ideal behaviour of Schottky diodes with and without an interracial insulator layer. These include the particular distribution of interface states, the series resis- tance, bias voltage and temperature. The GaAs and its large concentration values of trap centers will participate in an increase in the process ofthermionic electrons and holes, which will in turn act on the I-V characteristic of the diode, and an overflow maximum value [NT = 3 × 10^20] is obtained. The I-V characteristics of Schottky diodes are in the hypothesis of a parabolic summit.