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P. B. Chilson, C. W. Ulbrich, M. F. Larsen, P. Perillat, and J. E. Keener


This paper describes an investigation of a thunderstorm that occurred in the summer of 1991 over the National Astronomy and Ionosphere Center in Arecibo, Puerto Rico. Observations were made using collinear dual-wavelength Doppler radars, which permit virtually simultaneous observation of the same pulse volume using transmission and reception of coherent UHF and VHF signals on alternate pulses. This made it possible to directly measure the vertical wind within the sampling volume using the VHF signal while using the UHF signal to study the nature of the precipitation. The observed storm showed strong similarities with systems observed in the Global Atmospheric Research Program's Atlantic Tropical Experiment study. Since this experiment can determine the various microphysical parameters, such as the vertical air velocity, the mean fall speeds of the precipitation, and the reflectivity, the relationships between these parameters that have been postulated in past studies can be tested. For example, in this paper, the method of using reflectivities to deduce the fall speeds of precipitation particles is studied. The method is found to be unreliable when used in turbulent environments.

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Phillip B. Chilson, Winifred F. Frick, Jeffrey F. Kelly, Kenneth W. Howard, Ronald P. Larkin, Robert H. Diehl, John K. Westbrook, T. Adam Kelly, and Thomas H. Kunz

Aeroecology is an emerging scientific discipline that integrates atmospheric science, Earth science, geography, ecology, computer science, computational biology, and engineering to further the understanding of biological patterns and processes. The unifying concept underlying this new transdisciplinary field of study is a focus on the planetary boundary layer and lower free atmosphere (i.e., the aerosphere), and the diversity of airborne organisms that inhabit and depend on the aerosphere for their existence. Here, we focus on the role of radars and radar networks in aeroecological studies. Radar systems scanning the atmosphere are primarily used to monitor weather conditions and track the location and movements of aircraft. However, radar echoes regularly contain signals from other sources, such as airborne birds, bats, and arthropods. We briefly discuss how radar observations can be and have been used to study a variety of airborne organisms and examine some of the many potential benefits likely to arise from radar aeroecology for meteorological and biological research over a wide range of spatial and temporal scales. Radar systems are becoming increasingly sophisticated with the advent of innovative signal processing and dual-polarimetric capabilities. These capabilities should be better harnessed to promote both meteorological and aeroecological research and to explore the interface between these two broad disciplines. We strongly encourage close collaboration among meteorologists, radar scientists, biologists, and others toward developing radar products that will contribute to a better understanding of airborne fauna.

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P. Klein, T. A. Bonin, J. F. Newman, D. D. Turner, P. B. Chilson, C. E. Wainwright, W. G. Blumberg, S. Mishra, M. Carney, E. P. Jacobsen, S. Wharton, and R. K. Newsom


This paper presents an overview of the Lower Atmospheric Boundary Layer Experiment (LABLE), which included two measurement campaigns conducted at the Atmospheric Radiation Measurement (ARM) Program Southern Great Plains site in Oklahoma during 2012 and 2013. LABLE was conducted as a collaborative effort between the University of Oklahoma (OU), the National Severe Storms Laboratory, Lawrence Livermore National Laboratory (LLNL), and the ARM program. LABLE can be considered unique in that it was designed as a multiphase, low-cost, multiagency collaboration. Graduate students served as principal investigators and took the lead in designing and conducting experiments aimed at examining boundary layer processes.

The main objective of LABLE was to study turbulent phenomena in the lowest 2 km of the atmosphere over heterogeneous terrain using a variety of novel atmospheric profiling techniques. Several instruments from OU and LLNL were deployed to augment the suite of in situ and remote sensing instruments at the ARM site. The complementary nature of the deployed instruments with respect to resolution and height coverage provides a near-complete picture of the dynamic and thermodynamic structure of the atmospheric boundary layer. This paper provides an overview of the experiment including 1) instruments deployed, 2) sampling strategies, 3) parameters observed, and 4) student involvement. To illustrate these components, the presented results focus on one particular aspect of LABLE: namely, the study of the nocturnal boundary layer and the formation and structure of nocturnal low-level jets. During LABLE, low-level jets were frequently observed and they often interacted with mesoscale atmospheric disturbances such as frontal passages.

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Howard B. Bluestein, Robert M. Rauber, Donald W. Burgess, Bruce Albrecht, Scott M. Ellis, Yvette P. Richardson, David P. Jorgensen, Stephen J. Frasier, Phillip Chilson, Robert D. Palmer, Sandra E. Yuter, Wen-Chau Lee, David C. Dowell, Paul L. Smith, Paul M. Markowski, Katja Friedrich, and Tammy M. Weckwerth

To assist the National Science Foundation in meeting the needs of the community of scientists by providing them with the instrumentation and platforms necessary to conduct their research successfully, a meeting was held in late November 2012 with the purpose of defining the problems of the next generation that will require radar technologies and determining the suite of radars best suited to help solve these problems. This paper summarizes the outcome of the meeting: (i) Radars currently in use in the atmospheric sciences and in related research are reviewed. (ii) New and emerging radar technologies are described. (iii) Future needs and opportunities for radar support of high-priority research are discussed. The current radar technologies considered critical to answering the key and emerging scientific questions are examined. The emerging radar technologies that will be most helpful in answering the key scientific questions are identified. Finally, gaps in existing radar observing technologies are listed.

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