Effect of condensational heating over the Bay of Bengal on the onset of the South China Sea monsoon in 1998

Summary In this study, the authors analyse the observational features of the onset of the South China Sea (SCS) monsoon in 1998 shown in reanalysis data and use a numerical model to understand the mechanisms responsible for these features.The onset of SCS summer monsoon in 1998 occurred around 21 May. Prior to this period, monsoon depression activity was strong over the Bay of Bengal (BOB) and warm temperature anomalies appeared at the mid-upper troposphere over the northern BOB. In the meantime, warm horizontal thermal advection occurred over the northern Indo-China peninsula and South China. This warm advection seemed to play an important role in the winter-to-summer transition of the patterns of mean meridional temperature gradient in the 500–200-mb layer over South Asia.The PSU/NCAR Mesoscale Model Version 5 (MM5) is used to understand the physical link between the latent heating associated with the monsoon depression over BOB and the establishment of SCS monsoon. Full-physics simulations, for a 6-day period coinciding with the onset of the observed monsoon, reproduce realistically the evolution of the monsoon depression and monsoon onset process. It is found that the condensational heating over BOB is important for the formation of large-scale circulation pattern that favors the establishment of SCS monsoon. In an experiment without latent heating, the winter-to-summer reversal of meridional temperature gradient over South Asia was delayed and the onset of SCS summer monsoon did not occur during the simulation period.     

Under the billiard table: Animality,anecdote and the tiger's subversive significance at the Raffles Hotel

At the turn of the twentieth century, when tigers were already becoming extinct in Singapore, a living specimen was discovered under the Billiard Room of the Raffles Hotel. This paper attempts to discuss the significance of the tiger in relation to an architectural space – the Billiard Room of a Southeast Asian colonial hotel – by examining how its anecdotal forms – as propaganda, fact, myth and satire – have influenced perceptions of this space across different milieu. It argues that the tiger anecdote, while ontologically remote from the physical materiality of that building, has inevitably become inseparable from its architectural epistemology. Under these terms, it is impossible to talk about the architecture of the Billiard Room without incurring discussion about the factual, fictional and propagandistic aspects of the animal anecdote. As a subtext to these narratives, the location of the hotel in a tropical clime is key. Amidst the civil calm of the genteel Billiard Room, it is the tiger, which ably performs, or re‐enacts, the risk of the tropics. Yet, what is unusual about this tiger is that a reading of its anecdotal forms ultimately transgresses the stereotypes associated with colonialism, indigenous culture, tropical living and wildlife, and subsequently, these too affect interpretations of the architectural space. Drawing on original archival and historical material, the paper contributes to a theoretical and historical understanding of why the tiger under the Billiard Room at the Raffles' continues to be a spatially compelling idea.     

Potential benefits of increased application of water to paddy fields in Taiwan

The potential benefits of increased application of water to paddy fields in Taiwan are investigated in this paper. A conceptual model is used to represent the hydrological system of the paddy field. A technique is presented to estimate the parameters of the model. Field experiments also are performed for parameter estimation and model verification. The simulated results are in good agreement with the observed during model verification. With parameters estimated from the field data, the model is used to simulate the effects of applying water beyond current practice. The simulation results show that the downward percolation increases when the irrigation water increases. However, the percolation reaches a capacity rate no matter how large the amount of water applied. This phenomenon results from the existence of a hard layer below the paddy field. The effects of raising the height of levees around paddy fields are also studied. Copyright © 2001 John Wiley & Sons, Ltd.     

Contaminant transport in fractured media: analytical solution and sensitivity study considering pulse,Dirac delta and sinusoid input sources

The analytical solution of one‐dimensional transport for a single species radioactive nuclide, considering the decay term in a single fracture for pulse, Dirac delta, and single sinusoid input sources, has been studied using the Laplace transform method. The dimensionless concentration of the radioactive nuclide in the fracture appears to be a function of space, elapsed time, dispersivity, retardation factor, half‐life of the nuclide, and release time. By comparing different values of groundwater velocity, retardation factor, dispersivity, and release time, the results show that the c/c₀ ratio agrees with the nature of the physical and chemical characteristics of the nuclide in fracture transportation. The dimensionless concentration peak value from a small retardation factor is found to be more sensitive, within a time frame ranging from 10 years to a few hundreds years, than the case with a larger retardation factor for H‐3. Except for a small variation in the peak value, the result is almost the same for pulse and sinusoid inputs when considering the H‐3 nuclide. Analytical solutions during the preliminary screening phase are suitable for performance assessment on radioactive waste disposal sites under a one‐dimensional single fracture condition. Copyright © 2002 John Wiley & Sons, Ltd.     

Application of spectral analysis to determine hydraulic diffusivity of a sandy aquifer (Pingtung County,Taiwan)

The study demonstrates spectral relationships in the time–frequency domain for one‐dimensional groundwater flow in aquifers bounded by fluctuating boundaries. By nature, the solutions of spectral equations are non‐linear complex functions. To determine hydraulic diffusivity in the governing equations, it is required that the data are collected from the spectra of water levels at the fluctuating boundaries and observation wells. Hydraulic diffusivity thus can be obtained by an iterative inverse approach. This paper presents an application in Pingtung County of Taiwan to determine the hydraulic diffusivity of a sandy aquifer under confined conditions. Spectral density function of water level obtained from tidal boundaries and observation wells are used to approximate hydraulic diffusivity, which yields an averaged value of 1·26 × 10⁶ m²/h. Copyright © 2004 John Wiley & Sons, Ltd.     

Assessment of apparent earth pressure for braced excavations in anisotropic clay

Acta Geotechnica - The evaluation of strut forces is critical to ensure the system stability of braced excavation in urban areas. The most common empirical approach to determine the forces in the...     

Modeling fresh water lens damage and recovery on atolls after storm-wave washover

The principal natural source of fresh water on scattered coral atolls throughout the tropical Pacific Ocean is thin unconfined groundwater lenses within islet substrates. Although there are many threats to the viability of atoll fresh water lenses, salinization caused by large storm waves washing over individual atoll islets is poorly understood. In this study, a mathematical modeling approach is used to examine the immediate responses, longer-term behavior, and subsequent (partial) recovery of a Pacific atoll fresh water lens after saline damage caused by cyclone-generated wave washover under different scenarios. Important findings include: (1) the saline plume formed by a washover event mostly migrates downward first through the top coral sand and gravel substrate, but then exits the aquifer to the ocean laterally through the more permeable basement limestone; (2) a lower water table position before the washover event, rather than a longer duration of storm washover, causes more severe damage to the fresh water lens; (3) relatively fresher water can possibly be found as a preserved horizon in the deeper part of an aquifer after disturbance, especially if the fresh water lens extends into the limestone under normal conditions; (4) post-cyclone accumulation of sea water in the central depression (swamp) of an atoll islet prolongs the later stage of fresh water lens recovery.     

Heavy Metal Concentrations in the Intertidal Gastropod Nerita lineata and Their Relationships to Those in Its Habitats： A Case Study in Dumai Coastal Waters

Concentrations of heavy metals in the intertidal gastropod Nerita lineata collected from 4 sampling stations in the intertidal zone of Dumai coastal waters have been analyzed and correlated with the respective metal concentrations in their habitat. The objective of this study was to evaluate the possible relationships between heavy metal concentrations in the N.lineata with metal concentrations in their habitat, which include seawater, algal mat, suspended particulate matter, and surface sediment. The results showed that heavy metal concentrations in the sediment, N.lineata, suspended particulate matter, algal mat and surface seawater were found to be higher in stations closed to Dumai city center which has more industrial and anthropogenic activities. The mean concentrations of Cd, Cu, Pb, Zn, Ni and Fe in the N.lineata collected from Dumai intertidal area were 4.14 μg/g, 5.90 μg/g, 44.43 μg/g, 3.74 μg/g, 20.73 μg/g, 24.91 μg/g in shell; 4.16 μg/g, 7.31 μg/g, 51.78 μg/g, 17.63 μg/g, 23.52 μg/g, 30.60 μg/g in operculum and 0.71 μg/g, 15.09 μg/g, 9.41 μg/g, 94.42 μg/g, 5.10 μg/g, 398.24 μg/g dry weight in the total soft tissue, respectively. Cd, Pb and Ni concentrations of parts of the N.lineata were in the order: that of operculum>shell>soft tissue whilst Cu, Zn and Fe concentrations of parts of the N.lineata in the order: that of soft tissue>operculum>shell. This suggested that N.lineata could be used as biomonitoring agent for Cu, Zn and Fe (soft tissues) and for Cd, Pb and Ni (operculum). However, the shell had significant correlations (P<0.05) with metal concentrations in the sediment, algal mat, suspended particulate matter and seawater. Bioconcentration factor (BCF) values of the shell also revealed greater capacity for non-essential metals bioaccumulation from all environmental phases. This might suggest that the shell of N.lineata could be better used as biomonitoring agent for heavy metal pollution.