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N. K. Wagner

The time constant of the sensing elements prevents the radiosonde from indicating the exact height, thickness and gradient of temperature and humidity discontinuity layers in the atmosphere. The error in the indicated value of these layer parameters is derived as a function of layer thickness and time constant. The importance of the assumptions and the ability to determine accurately the time constant of the temperature and humidity sensors are briefly discussed. It is concluded that significant improvement in the accuracy of these layer parameters could be obtained by correcting this source of error.

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N. K. Wagner

A number of meteorological measurements during the early stage of a relatively small tornado permitted the calculation of surface-pressure and wind-speed distributions employing the conservation of momentum and the cyclostrophic wind equation. Of particular interest is the cycloid trajectory of a small cubical building which allowed an estimation of the radial wind component within the tornado.

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N. K. Wagner

Abstract

The ability of the bead thermistor currently used in meteorological sounding rockets to measure the ambient kinetic temperature of the environment is examined theoretically. A non-steady state heat transfer environment including forced convection, infrared and solar radiation, compressional heating, lead wire conduction and internal heating is considered, along with normal variations to be expected in this environment. The average temperature measurement error is found to range from less than 5C at heights below 50 km to 33.5C at 65 km. Correction for this error should yield ambient temperature values to within ±2 per cent up to 60 km with the correction accuracy decreasing to ±3.8 per cent at 65 km. The correction accuracy deteriorates rapidly above 65 km suggesting that either a different type sensing element or a different sounding technique will be necessary for temperature measurement above this level.

Although the theoretical temperature error was computed on the basis of mean model atmospheric temperature distributions, it is shown that the results may be applied to individual soundings as long as abrupt changes in algebraic sign of the environmental lapse rate do not occur.

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N. K. Wagner

Abstract

The time constant for a ten-mil-diameter, spherical-bead thermistor is determined as a function of height in a standard atmosphere from sea level to 100 km. Evaluations are made for continuous, slip, and free-molecular flow conditions with the transition from one flow regime to another being a function of sensor size and the mean free path length of the air molecules. The ventilation speed of the sensor is dictated by the fall velocity of the parachute from which the element is suspended. Computed values for the time constant are 0.32 sec at sea level, 0.62 set at 2.5 km, 2.0 set at 50 km, 70 sec at 80 km and 720 sec at 100 km. A discussion of the errors which might be contained in these determinations is also given.

These results are then used in computations of the radiation error of the thermistor from sea level to 100 km. Variations in the radiation error which result from changes in various physical parameters of the sensor and its environment are also shown in the 20 to 60 km altitude interval. It is concluded that this sensor should generally provide temperature information which is accurate to ±5C up to about 55 km with no correction necessary. Above this level, corrections to the measured temperature are necessary because of possible variations in the physical parameters of the sensor and its environment. The magnitude of these corrections becomes quite uncertain above 65 or 70 km.

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W. T. Echols and N. K. Wagner

Abstract

Wind profile observations obtained at two sites near the upper Texas coast during onshore winds in June 1968 are used to determine local toughness parameters. Values of 3–4 cm are obtained at a 32 m tower site 90 m inland and 0.81–1.5 cm at 4.8 km inland; both are in close agreement with results of others for similar terrain. The portion of the wind profile obtained at heights between 6.7 and 27 m near the beach is extrapolated downward to obtain a roughness between 0,0001 and 0.0003 cm for the Gulf of Mexico.

An internal boundary layer was detected from the data obtained 90 m inland. The mean height was observed to he 6.7 m— a value associated with a mean slope of about 1:13 for an internal boundary originating at the upwind shoreline roughness discontinuity. Daytime values for the internal boundary height are somewhat higher than the mean, averaging 7.2 m, while the nighttime mean is 5.9 m. The data also suggest a wind speed dependence on the height of the internal boundary layer.

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BRIAN J. BUTTERWORTH, ANKUR R. DESAI, STEFAN METZGER, PHILIP A. TOWNSEND, MARK D. SCHWARTZ, GRANT W. PETTY, MATTHIAS MAUDER, HANNES VOGELMANN, CHRISTIAN G. ANDRESEN, TRAVIS J. AUGUSTINE, TIMOTHY H. BERTRAM, WILLIAM O.J. BROWN, MICHAEL BUBAN, PATRICIA CLEARY, DAVID J. DURDEN, CHRISTOPHER R. FLORIAN, TREVOR J. IGLINSKI, ERIC L. KRUGER, KATHLEEN LANTZ, TEMPLE R. LEE, TILDEN P. MEYERS, JAMES K. MINEAU, ERIK R. OLSON, STEVEN P. ONCLEY, SREENATH PALERI, ROSALYN A. PERTZBORN, CLAIRE PETTERSEN, DAVID M. PLUMMER, LAURA RIIHIMAKI, ELICEO RUIZ GUZMAN, JOSEPH SEDLAR, ELIZABETH N. SMITH, JOHANNES SPEIDEL, PAUL C. STOY, MATTHIAS SÜHRING, JONATHAN E. THOM, DAVID D. TURNER, MICHAEL P. VERMEUEL, TIMOTHY J. WAGNER, ZHIEN WANG, LUISE WANNER, LOREN D. WHITE, JAMES M. WILCZAK, DANIEL B. WRIGHT, and TING ZHENG

CAPSULE SUMMARY

A regional-scale observational experiment designed to address how the atmospheric boundary layer responds to spatial heterogeneity in surface energy fluxes.

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Brian J. Butterworth, Ankur R. Desai, Philip A. Townsend, Grant W. Petty, Christian G. Andresen, Timothy H. Bertram, Eric L. Kruger, James K. Mineau, Erik R. Olson, Sreenath Paleri, Rosalyn A. Pertzborn, Claire Pettersen, Paul C. Stoy, Jonathan E. Thom, Michael P. Vermeuel, Timothy J. Wagner, Daniel B. Wright, Ting Zheng, Stefan Metzger, Mark D. Schwartz, Trevor J. Iglinski, Matthias Mauder, Johannes Speidel, Hannes Vogelmann, Luise Wanner, Travis J. Augustine, William O. J. Brown, Steven P. Oncley, Michael Buban, Temple R. Lee, Patricia Cleary, David J. Durden, Christopher R. Florian, Kathleen Lantz, Laura D. Riihimaki, Joseph Sedlar, Tilden P. Meyers, David M. Plummer, Eliceo Ruiz Guzman, Elizabeth N. Smith, Matthias Sühring, David D. Turner, Zhien Wang, Loren D. White, and James M. Wilczak

Abstract

The Chequamegon Heterogeneous Ecosystem Energy-Balance Study Enabled by a High-Density Extensive Array of Detectors 2019 (CHEESEHEAD19) is an ongoing National Science Foundation project based on an intensive field campaign that occurred from June to October 2019. The purpose of the study is to examine how the atmospheric boundary layer (ABL) responds to spatial heterogeneity in surface energy fluxes. One of the main objectives is to test whether lack of energy balance closure measured by eddy covariance (EC) towers is related to mesoscale atmospheric processes. Finally, the project evaluates data-driven methods for scaling surface energy fluxes, with the aim to improve model–data comparison and integration. To address these questions, an extensive suite of ground, tower, profiling, and airborne instrumentation was deployed over a 10 km × 10 km domain of a heterogeneous forest ecosystem in the Chequamegon–Nicolet National Forest in northern Wisconsin, United States, centered on an existing 447-m tower that anchors an AmeriFlux/NOAA supersite (US-PFa/WLEF). The project deployed one of the world’s highest-density networks of above-canopy EC measurements of surface energy fluxes. This tower EC network was coupled with spatial measurements of EC fluxes from aircraft; maps of leaf and canopy properties derived from airborne spectroscopy, ground-based measurements of plant productivity, phenology, and physiology; and atmospheric profiles of wind, water vapor, and temperature using radar, sodar, lidar, microwave radiometers, infrared interferometers, and radiosondes. These observations are being used with large-eddy simulation and scaling experiments to better understand submesoscale processes and improve formulations of subgrid-scale processes in numerical weather and climate models.

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