Triple-Hot-Film Anemometer Performance in Cases-99 and A Comparison With Sonic Anemometer Measurements

Two levels of triple-hot-film and sonic anemometers were deployed on a 5.5-m towerduring the Cooperative Atmospheric Surface Exchange Study (CASES-99) in October1999. Each triple-hot-film probe was collocated 50 mm from the sonic sensing path ona common boom. Various problems with using triple-hot-films in the atmosphere toresolve wind components are addressed including the derivation of a yaw angle correction using the collocated sensors. It was found that output voltage drift due to changes in environmental temperature could be monitored and corrected using an automated system. Non-unique solutions to heat transfer equations can be resolved using a collocated sonic anemometer. Multi-resolution decomposition of the hot-film data was used to estimate appropriate day and night averaging periods for turbulent flux measurements in and near the roughness sub-layer. Finally, triple-hot-film measurements of mean wind magnitude (M), turbulent kinetic energy (TKE), sensible heat flux (H), and local friction velocity (u_*) are compared to those of the collocated CSAT3 sonic anemometers. Overall, the mean wind magnitudes measured by the triple-hot-film and the collocated sonic sensorswere close, consistent and independent of stability or proximity to the ground. The turbulent statistics, TKE, u_*, and H, measured by the two sensor systems were reasonably close together at z = 5 m. However, the ratio of sonic measurement/hot-film measurement decreased toward the ground surface, especially during stable conditions.     

Process-oriented modeling studies of the 5500-km-long boundary flow off western and southern Australia

While the unique character of the coastal current system off the western and southern coasts of Australia has been recognized, this vast 5500-km-long boundary flow has been studied far less than other current systems of the world. Recent observational studies from satellite altimetry and climatology are consistent with a continuous current extending from its origin at the North West Cape to the southern tip of Tasmania. To date, coastal modeling studies have focused on either the western Australian coast to Esperance or on southern Australia. There has been no process-oriented modeling study of the entire region that would allow the systematic exploration of the two independent forcing mechanisms (i.e., wind-forcing and thermohaline gradients) and their interactions that have been noted to act in a synergistic manner to maintain the longest continuous coastal current system in the world.     

Surface and downhole shear wave seismic methods for thick soil site investigations

Shear wave velocity–depth information is required for predicting the ground motion response to earthquakes in areas where significant soil cover exists over firm bedrock. Rather than estimating this critical parameter, it can be reliably measured using a suite of surface (non-invasive) and downhole (invasive) seismic methods. Shear wave velocities from surface measurements can be obtained using SH refraction techniques. Array lengths as large as 1000 m and depth of penetration to 250 m have been achieved in some areas. High resolution shear wave reflection techniques utilizing the common midpoint method can delineate the overburden-bedrock surface as well as reflecting boundaries within the overburden. Reflection data can also be used to obtain direct estimates of fundamental site periods from shear wave reflections without the requirement of measuring average shear wave velocity and total thickness of unconsolidated overburden above the bedrock surface. Accurate measurements of vertical shear wave velocities can be obtained using a seismic cone penetrometer in soft sediments, or with a well-locked geophone array in a borehole. Examples from thick soil sites in Canada demonstrate the type of shear wave velocity information that can be obtained with these geophysical techniques, and show how these data can be used to provide a first look at predicted ground motion response for thick soil sites.     

Generating an Image of Dispersive Energy by Frequency Decomposition and Slant Stacking

We present a new algorithm for calculating an image of dispersive energy in the frequency-velocity (f-v) domain. The frequency decomposition is first applied to a shot gather in the offset-time domain to stretch impulsive data into pseudo-vibroseis data or frequency-swept data. Because there is a deterministic relationship between frequency and time in a sweep used in the frequency decomposition, the first step theoretically completes the transform from time to frequency. The slant stacking is then performed on the frequency-swept data to complete the transform from offset to velocity. This simple two-step algorithm generates an image of dispersive energy in the f-v domain. The straightforward transform only uses offset information of data so that this algorithm can be applied to data acquired with arbitrary geophone-acquisition geometry. Examples of synthetic and real-world data demonstrate that this algorithm generates accurate images of dispersive energy of the fundamental as well as higher modes.     

Reducing capture zone uncertainty with a systematic sensitivity analysis

The U.S. Environmental Protection Agency has established several methods to delineate wellhead protection areas (WHPAs) around community wells in order to protect them from surface contamination sources. Delineating a WHPA often requires defining the capture zone for a well. Generally, analytical models or arbitrary setback zones have been used to define the capture zone in areas where little is known about the distribution of hydraulic head, hydraulic conductivity, or recharge. Numerical modeling, however, even in areas of sparse data, offers distinct advantages over the more simplified analytical models or arbitrary setback zones. The systematic approach discussed here calibrates a numerical flow model to regional topography and then applies a matrix of plausible recharge to hydraulic conductivity ratios ( R / K ) to investigate the impact on the size and shape of the capture zone. This approach does not attempt to determine the uncertainty of the model but instead yields several possible capture zones, the composite of which is likely to contain the actual capture zone. A WHPA based on this composite capture zone will protect ground water resources better than one based on any individual capture zone. An application of the method to three communities illustrates development of the R / K matrix and demonstrates that the method is particularly well suited for determining capture zones in alluvial aquifers.     

Water balance modeling over variable time scales based on the Budyko framework – Model development and testing

Partitioning of precipitation into evapotranspiration and runoff is controlled by climate and catchment characteristics. The degree of control exerted by these factors varies with the spatial and temporal scales of processes modeled. The Budyko framework or the “limits” concept was used to model water balance at four temporal scales (mean annual, annual, monthly and daily). The method represents a top-down approach to hydrologic modeling and is expected to achieve parsimony of model parameters. Daily precipitation, potential evapotranspiration, and streamflow from 265 catchments in Australia were used. On a mean annual basis, the index of dryness defined as the ratio of potential evapotranspiration to precipitation was confirmed to be a dominant factor in determining the water balance with one model parameter. Analysis of the data, however, suggested increased model complexity is necessary on finer time scale such as monthly. In response, the Budyko framework for mean annual water balance was extended to include additional factors and this resulted in a parsimonious lumped conceptual model on shorter-time scale. The model was calibrated and tested against measured streamflow at variable time scales and showed promising results. The strengths of the model are consistent water balance relationships across different time scales, and model parsimony and robustness. As result, the model has the potential to be used to predict streamflow for ungauged catchments.     

Concentration of Ciprofloxacin in Brazilian Hospital Effluent and Preliminary Risk Assessment: A Case Study

This study was carried out to evaluate the occurrence of the fluoroquinolone antimicrobial agent ciprofloxacin (CIP) in the effluent of the Hospital of the Federal University of Santa Maria (HUSM). Measured environmental concentrations (MECs) of CIP in the hospital wastewater, both before (P1) and after (P2) cesspit/filter system treatment (CFTS), were determined by means of solid phase extraction and reversed‐phase liquid chromatography with fluorescence detection (LC‐FLD) and reversed‐phase liquid chromatography with mass spectrometric detection (LC‐MS/MS). The MECs (n = 7 daily composed samples) were 19 to 155 μg L^–1 (average: 54 ± 21 μg L^–1) and 32 to 99 μg L^–1 (average: 65 ± 45 μg L^–1) in P1 and P2, respectively. No relevant removal was observed from P1 to P2. In a worst case scenario, the final effluent was regarded as MECs of surface water. These MECs were generally 5 to 20,000‐fold higher than what was previously known. If the present data is drawn on to form a model of the situation in developing countries, the picture provides a first rough indication that the environmental risk associated with the use and emission of pharmaceuticals into the environment in developing countries might be higher than in developed countries.