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Bats alter their echolocation in response to changes in ecological and behavioral conditions, but little is known about how they adjust call structure in response to changes in altitude. We examined altitudinal variation in the echolocation of Brazilian free-tailed bats, Tadarida brasiliensis, a species known to fly to altitudes of 3,000 m above the ground. From 50.2 h of recordings, we analyzed 113 high-quality echolocation call sequences recorded from 0 to 862 m above ground level. Bats flying near the ground used shorter, higher-frequency, broader-bandwidth calls compared to bats at higher altitudes, an effect likely due to the greater levels of echo-producing clutter (i.e., vegetation, buildings) found near the ground. When ground-level recordings are excluded, bats continue to shift towards the use of longer-duration, lower-frequency, narrower-bandwidth calls with increasing altitude. We propose that the observed high-altitude changes in call structure are a response to changing acoustic attenuation rates and/or decreasing insect densities at higher altitudes.

A new in situ measurement system and lidar processing algorithms were developed for improved measurements of boundary layer profiles. The first comparisons of simultaneous Doppler lidar–derived profiles of the key turbulence statistics of the two orthogonal horizontal velocity components (longitudinal and transverse) are presented. The instrument requirements for accurate observations of stably stratified turbulence were determined. A region of stably stratified low turbulence with constant gradients of temperature and velocity was observed above the nocturnal boundary layer using high-rate sensors. The important turbulence parameters were estimated, and turbulence spectra were consistent with new theoretical descriptions of stratified turbulence. The impact of removing the larger-scale velocity features in Doppler lidar estimates of turbulent velocity variance and length scales was investigated. The Doppler lidar–derived estimates of energy dissipation rate ε were found to be insensitive to spatial filtering of the large-scale atmospheric processes. The in situ and lidar-derived profiles were compared for the stable boundary layer in a suburban environment.

Boundary layer profiles of mean temperature, velocity, and small-scale turbulence from in situ sensors, Doppler lidar, sodar, and rawinsondes are intercompared for an urban environment. A new Doppler lidar algorithm is presented to produce high-resolution profiles of small-scale velocity statistics. The lidar-derived profiles are robust and accurate even for challenging conditions such as stable boundary layers with a low-level jet, low turbulence, and low wind speed. Similar results are expected for other locations and convective conditions.

Experimental equipment : A supplement to The Summertime Arctic Atmosphere: Meteorological measurements during the ArcticOcean Experiment 2001 (AOE-2001)

Carbon dioxide is the most important greenhouse gas other than water vapor, and its modulation by the biosphere is of fundamental importance to our understanding of global climate change. We have developed a new technique for vertical profiling of CO2 and meteorological parameters through the atmospheric boundary layer and well into the free troposphere. Vertical profiling of CO2 mixing ratios allows estimates of landscape-scale fluxes characteristic of approximately100 km2 of an ecosystem. The method makes use of a powered parachute as a platform and a new Tedlar bag air sampling technique. Air samples are returned to the ground where measurements of CO2 mixing ratios are made with high precision (< or =0.1%) and accuracy (< or =0.1%) using a conventional nondispersive infrared analyzer. Laboratory studies are described that characterize the accuracy and precision of the bag sampling technique and that measure the diffusion coefficient of CO2 through the Tedlar bag wall. The technique has been applied in field studies in the proximity of two AmeriFlux sites, and results are compared with tower measurements of CO2.

The probability density function (PDF) and spatial statistics of both the energy dissipation rate ϵ and the temperature structure constant C2T are determined for the shear region of a nocturnal jet. The PDF of ϵ and C2T are approximately lognormal. In addition, the joint probability density function of ϵ and C2T is approximately a joint lognormal distribution. The one-dimensional spatial spectra of ϵ and C2T in the inertial region have a k−0.5 and k−0.6 dependence, respectively, where k is the horizontal spatial wavenumber.

Using the unprecedented observational facilities deployed duringthe 1999 Cooperative Atmosphere-Surface Exchange Study (CASES-99),we found three distinct turbulent events on the night of 18October 1999. These events resulted from a density current,solitary wave, and internal gravity wave, respectively. Our studyfocuses on the turbulence intermittency generated by the solitarywave and internal gravity wave, and intermittent turbulenceepisodes associated with pressure change and wind direction shiftsadjacent to the ground. Both the solitary and internal gravitywaves propagated horizontally and downward. During the passage ofboth the solitary and internal gravity waves, local thermal andshear instabilities were generated as cold air was pushed abovewarm air and wind gusts reached to the ground. These thermal andshear instabilities triggered turbulent mixing events. Inaddition, strong vertical acceleration associated with thesolitary wave led to large non-hydrostatic pressure perturbationsthat were positively correlated with temperature. The directionaldifference between the propagation of the internal gravity waveand the ambient flow led to lateral rolls. These episodic studiesdemonstrate that non-local disturbances are responsible for localthermal and shear instabilities, leading to intermittentturbulence in nocturnal boundary layers. The origin of thesenon-local disturbances needs to be understood to improve mesoscalenumerical model performance.

Finescale temperature and velocity measurements with multiple vertically spaced cold-wire and hot-wire sensors on the Cooperative Institute for Research in the Environmental Sciences (CIRES) tethered lifting system (TLS) were produced during the Cooperative Atmosphere–Surface Exchange Study-1999 (CASES-99). The various calibration methods are presented as well as algorithms to extract high-resolution estimates of the energy dissipation rate ϵ and the temperature structure constant C2T. The instrumentation is capable of measurements of ϵ ≈ 10−7 m2 s−3 and C2T ≈ 10−6 K2 m−2/3.

During the Cooperative Atmosphere‐Surface Exchange Study-1999 (CASES-99) campaign in southeastern Kansas in the fall of 1999, the University of Colorado’s Cooperative Institute for Research in Environmental Sciences (CIRES) made a series of vertical profiling measurements using the CIRES tethered lifting system (TLS). The results reported here began during a period when the nocturnal boundary layer (NBL) was characterized by a low-level jet (LLJ) peaking at 120 m and a temperature profile that increased smoothly with height to a point slightly above the height of the LLJ peak. Then, within a period of less than 30 min, the character of the NBL changed abruptly, with the breakdown of the well-defined LLJ and the appearance of a surprisingly steep temperature change of some 3.5 K around 180‐190 m AGL. Part of this inversion was extremely sharp, with the steepest portion showing a temperature change of 1 K over an altitude range of only 5 cm, corresponding to a vertical temperature gradient in excess of 20 K m 21. The general shape of this steep gradient was maintained—albeit with slightly reduced values—for at least 20 min. It is understood that the magnitude of the steepest portion of this gradient exceeds all previously observed atmospheric gradients by over an order of magnitude, although comparable gradients—albeit under very disparate conditions—have been observed in the ocean. A second surprising feature apparent in these results was the steepness of the gradients in turbulence structure at the top of the NBL and within the residual layer (RL), the region above the NBL that is usually slightly stably stratified and extends upward to the height marked by the vestiges of the previous day’s capping inversion. At the NBL top, energy dissipation rates and temperature structure parameters dropped sharply by more than one order of magnitude over a distance of only a few meters. At higher altitudes within the RL, a 60-m-thick region of very weak turbulence was observed. This low-turbulence region also exhibited sharp edges, where energy dissipation rates and temperature structure parameters changed by at least an order of magnitude over vertical distances of only a few meters.

Vertical profiles of carbon dioxide were measured within and above the atmospheric boundary layer at a tropical forest site in the Peruvian Amazon during July 1996 using a tethered balloon sampling platform. Flask samples were collected within and above the mixed layer and analyzed off-site for carbon dioxide by nondispersive infrared spectrophotometry. Ozone and temperature vertical profiles were used to determine the boundary layer heights and growth rates. The mean values for methane, carbon monoxide, hydrogen, carbon-13, and oxygen-18 ratios were determined within and above the mixed layer. Daytime carbon dioxide flux values were calculated using the budget method. Nocturnal fluxes were estimated by integrating the carbon dioxide mixing ratios as a function of height from the ground to the inversion layer and dividing the total accumulated carbon dioxide by the time since sunset. The daytime carbon dioxide flux of −13 ± 2 μmol C m−2 s−1 and the nocturnal flux of +5.0 ± 1.0 μmol C m−2 s−1 are in good agreement with previous studies in the Brazilian Amazon.

This paper presents the capabilities and limitations of using state-of-the-art kites for atmospheric research. A brief historical review of the subject is first presented, followed by an outline of the current status of kite-borne measurement technology. The utility of the technique is then illustrated by presenting a series of recent measurements made using kite-borne technology. A summary of the advantages and limitations of kite-based measurements relative to other technologies is provided for reference.

As part of the 1993 North Atlantic Regional Experiment (NARE), we initiated a program to obtain vertical profiles of temperature, pressure, humidity, and ozone concentration. We describe the technique, including the payload-transporting WindTRAM (Tethered Rover for Atmospheric Measurements) device used for the first time during this campaign, and present vertical profiles of temperature, humidity, and ozone concentration that were obtained during the August 1993 campaign. A number of ozone concentration profiles were obtained in southern Nova Scotia during NARE. Good preliminary agreement was found with concurrent profiles obtained by nearby aircraft when they were available. The profiles exhibited a strong variability in structure and intensity throughout the campaign period. 2 refs., 2 figs.

Synopsis Existing information on the activity of bats in the aerosphere is restricted almost exclusively to altitudes that are within a few tens of meters above the ground. We report a total of 50.2 h of ultrasonic recordings made using radio microphonic bat detectors suspended from free-floating helium balloons and from kites. The data include a total of 22 353 echolocative calls from ground-level to 1118 m above ground level (AGL). These calls are attributed to Brazilian free-tailed bats based on acoustic features and the large numbers and high-altitude aerial dispersion of these bats over the local landscape. Bat activity varied significantly throughout the air column and was greatest at 400–500 m AGL and near ground level. Feeding buzzes, indicating feeding on aerial prey, were most abundant near ground level and at 400–500 m, and were detected to altitudes of � 900 m AGL. The peak activity of bats at 400–500 m AGL is concordant with the altitude of the atmospheric boundary layer and the seasonal formation of the low-elevation southerly wind jet that has been identified as a major aeroecological corridor for the nocturnal dispersal of noctuid moths and other insects.

New results of the (temperature) refractive index structure parameter (CT2), Cn2 are presented from fast response sensor observations near the ground and also using a kite/tethered blimp platform and an aircraft, at the Edward Air Force Base in Mojave Desert, California. Additional optical measurements include near-ground scintillation observations over horizontal paths. Atmospheric turbidity were also calculated from direct beam solar radiation measurements using pyrheliometer. Comparisons were made of the observed profiles of refractive index structure parameters (Cn2) with theoretical modeled profiles, and two derived quantities such as transverse coherence length (r0) and isoplanatic angle (θ0) for a slant path are discussed. All of these parameters are the major indicators of turbulence and are important to design an aircraft or space-craft-based free-space laser communication and high resolution optical synthetic-aperture imaging systems. Non-isotropic turbulence observations from some of the data will be pointed out. Probability density functions (PDF) of the distribution of Cn2 will be described using histograms. Fundamental limits imposed by atmospheric effects in high data rate communication and optical synthetic-aperture imaging systems will be discussed.

*Power system reliability is critical to the performance of modern aircraft. Reliability issues must be considered from the beginning of the power system design process. Addressing these issues can complicate a design flow. To manage this complexity, design teams must use an organized approach based on proven design principles. A Robust Design methodology provides this organized approach. This paper investigates the Robust Design process as it pertains to system design. General Robust Design principles are introduced and related to the development of aircraft power systems. Design tasks are outlined as they apply to the Robust Design process. These tasks are then related to the capabilities that design tools must have to help design teams improve system reliability. A basic 3-phase, 230VACto-28VDC converter is analyzed using the Saber® simulator from Synopsys, Inc. The analysis follows the steps of a Robust Design-based flow and includes a nominal analysis to establish a performance baseline for the system, a sensitivity analysis to investigate which design parameters have the most affect on system performance, a parametric analysis to evaluate system performance while key design parameters are swept through selected values, a statistical analysis to analyze the system’s performance as parameter values are allowed to randomly change within their tolerance range, a stress analysis to evaluate stresses placed on system components, and a failure modes analysis to examine system performance as individual components fail. Establishing simulation techniques for implementing a Robust Design flow is the primary focus of this paper. Understanding detailed converter design is left as an exercise for the reader.

Results of a campaign to measure boundary layer/lower troposphere turbulence quantities over New Mexico's Tularosa basin are described in a companion paper. The present contribution outlines the technical developments that enabled these measurements. Basically, instrumented 'payloads' were carried aloft using either a relatively large aerodynamic blimp or a large parafoil kite. The choice between these platforms was dictated by wind velocity. The kite size was determined by the payload weight and the wind velocity. In addition to providing a brief history in CU involvement in kite/blimp atmospheric measurements, we will outline launching methods, tether winching techniques, and payload attachment schemes that were used during the WSMR campaign. Although very low wind conditions during the New Mexico test precluded the use of payloads up and down the kite tether under reasonable wind conditions. We also describe (1) the instrument package designed to measure in- situ temperature and velocity fluctuations, and (2) the 'basic payload' that measures standard atmospheric variables. System operation is illustrated via examples of the resulting data set.

Results of the refractive index structure parameter (CT2), Cn2, and the eddy dissipation rate, (epsilon) , derived from the velocity structure parameter, Cv2, are presented from high speed fluctuation measurements taken using a kite/tethered-blimp platform in the Tularosa Basin at White Sands Missile Range, NM during the spring of 1998. Comparisons of different sensor measuring the same parameter are displayed and discussed. Salient features of the sensors and the kite and blimp platforms are outlined. Long term measurements of high speed fluctuations of temperature and velocity are shown and intermittency of turbulence is discussed. The nature and statistics of turbulence inside, outside, and at the boundary of a turbulent layer are also shown and interpreted. Observations in the entrainment zone at the top of the planetary boundary layer are shown and similarities of characteristics found in the tropopause region with these boundary layer features is discussed. The diurnal variation of turbulence is presented with particular emphasis on the transition period from the end of daytime convection to development of the stable nocturnal boundary layer. Results are displayed as profiles and histograms of Cn2 and (epsilon) for daytime, near sunset, and nighttime conditions.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Inclusion body myositis (IBM) is a separate class of the inflammatory myopathies with recently proposed clinical and pathological diagnostic criteria. An association between inflammatory myopathies and malignancy has been questioned in the literature. Recent reviews of the inflammatory myopathies suggest that only dermatomyositis is associated with malignancy. The largest study to date of patients with IBM found that 15% had a malignancy (6 of 40). We report the first documented case of IBM and concurrent transitional cell carcinoma of the bladder. We suggest that a causal relationship between IBM and malignancy may exist because of significantly improved functional strength gained after tumor removal.

Results of the (temperature) refractive index structure param- eter (CT ), Cn , and the eddy dissipation rate e derived from the velocity structure parameter Cv are presented from fast response sensor obser- vations using a kite/tethered-blimp platform in the Tularosa Basin at White Sands Missile Range, New Mexico, during the spring of 1998. Comparisons of different sensors (fine-wire probes and pitot tubes) mea- suring the same parameter are displayed and discussed while salient features of all sensors (standard and fast response) and the kite and tethered-blimp platforms are outlined. The nature and statistics of turbu- lence, including intermittency, under different stability conditions is dis- cussed, including those found in the residual layer above the nocturnal boundary layer and the entrainment zone at the top of the daytime plan- etary boundary layer. In addition to displaying time series of temperature C n and e results obtained at specific altitudes and times, histograms of all daytime and nighttime Cn and e values are compared to log-normal distributions. Examples of profiles ofC n and e for daytime, near sunset, and nighttime conditions are shown and discussed. The relationship of Cn with e is displayed for all data as well as sorted by daytime and nighttime. These results are explained in terms of potential and kinetic energy considerations under different atmospheric stability conditions. © 2000 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(00)03209-8) Subject terms: turbulence; refractive index structure parameter; atmospheric propagation; meteorology; velocity; temperature; sensors.