Browsing by Author "Balsley, Ben B."
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Item Restricted A statistical comparison of horizontal winds obtained by a variety of spaced antenna techniques using the Jicamarca VHF radar(American Geophysical Union, 1998-11) Chau Chong Shing, Jorge Luis; Balsley, Ben B.We have used the Jicamarca radar system to measure horizontal winds by a variety of time domain and frequency domain spaced antenna techniques. Horizontal wind comparisons for two orthogonal components are carried out in a statistical sense, i.e., using correlation coefficients, mean differences, standard deviation of differences, and percentage of failures. We find that a simple technique that assumes horizontally isotropic scattering compares very closely with the more complicated full correlation analysis techniques. Techniques that attempt to correct for turbulence appear to be very sensitive to the way we estimate the width of the cross‐correlation/spectra functions. This is particularly true above 15 km, where discrepancies in the wind speed are apparent. In general, all techniques give essentially the same wind direction.Item Restricted A statistical comparison of VHF techniques to study clear-air vertical velocities in the lower atmosphere using the Jicamarca radar(American Geophysical Union, 1998-11) Chau Chong Shing, Jorge Luis; Balsley, Ben B.We compare two types of VHF vertical velocity measurement techniques using a special configuration of the Jicamarca 50-MHz radar antenna. Zenith (vertically directed single-beam) techniques and spaced antenna (SA) techniques are compared using a 54-hour concurrent data set. We compare two different zenith techniques using different antenna beam widths (0.85° and 3.5°). In addition, we compare vertical velocities measured by a “quasi” Doppler beam swinging (QDBS) technique and a SA approach that incorporate either “inferred” or “corrected” vertical velocities. All of the results are compared in terms of statistical basis. Results are presented for both quiet (low wind, low variability) and active (high wind, high variability) conditions. We use the results of the narrow-beam zenith technique as a reference profile and discuss its validity as a reference. Our comparisons show that relative to the reference, (1) the use of corrected values (i.e., correcting for horizontal leakage) gives better results than the wide-beam zenith technique, although mean differences of ∼−3 and ∼4 cm s−1 are still observed below 12 and above 15 km, respectively, (2) QDBS results give the closest mean value agreement of all the techniques, and (3) most of the vertical velocity discrepancies are seen as variations in the mean values.Item Open Access Examination of various techniques for measuring wind velocities using clear-air radars, with emphasis on vertical wind measurements(University of Colorado, 1998) Chau Chong Shing, Jorge Luis; Balsley, Ben B.In this work, I examine various techniques for measuring wind velocities using clear-air radars. Special emphasis has been given to the vertical wind measurements. All the observations were obtained in the lower atmosphere (below 20 km) using the Jicamarca 50 MHz radar system near Lima, Peru. I have concentrated my efforts on: (a) examining: different radar techniques for horizontal wind estimation, (b) improving the understanding of angle-of-arrival radar measurements, and (c) comparing a number of techniques for the measurement of the vertical wind velocities. I have measured horizontal wind velocities by a variety of both time- and frequency-domain spaced antenna (SA) techniques. Comparisons of these techniques for both zonal and meridional components have been carried out in a statistical sense. Two sets of data were analyzed under both "quiet" (low wind, low variability) and "active" (high wind, high variability) conditions. I have found that the simpler techniques that assume horizontally isotropic scattering compare well with the more complicated full correlation analysis techniques. Briefly, while all SA techniques give essentially the same horizontal wind direction, considerable discrepancies are apparent in the wind speed, particularly above 15 km. With regard to technique comparisons for vertical velocity, two types of measurement techniques using a concurrent data set are compared. Both Zenith (i.e., using a vertically-directed single beam) techniques and spaced antenna (SA) techniques are compared using a concurrent 5-day data set obtained with a special configuration of the Jicamarca 50 MHz radar antenna. Two separate Zenith techniques are implemented using different antenna beam-widths (a 0.85º and a 3º beam-width). Different SA approaches are also implemented using a: "quasi" Doppler beam swinging (DBS) approach and four "classical" SA approaches. "Classical" SA approaches make use of horizontal wind and AOA measurements to get 'corrected' vertical velocities. Statistical results are presented for both quiet and active conditions.Item Restricted Fine-scale characteristics of temperature,wind, and turbulence in the lower atmosphere (0–1,300 m) over the south Peruvian coast(Springer, 2012-10-12) Balsley, Ben B.; Lawrence, Dale A.; Woodman Pollitt, Ronald Francisco; Fritts, David C.We report results of preliminary high-resolution in situ atmospheric measurements through the boundary layer and lower atmosphere over the southern coast of Perú. This region of the coast is of particular interest because it lies adjacent to the northern coastal edge of the sub-tropical south-eastern Pacific, a very large area of ocean having a persistent stratus deck located just below the marine boundary layer (MBL) inversion. Typically, the boundary layer in this region during winter is topped by a quasi-permanent, well-defined, and very large temperature gradient. The data presented herein examine fine-scale details of the coastal atmosphere at a point where the edge of this MBL extends over the coastline as a result of persistent onshore flow. Atmospheric data were gathered using a recently-developed in-house constructed, GPS-controlled, micro-autonomous-vehicle aircraft (the DataHawk). Measured quantities include high-resolution profiles of temperature, wind, and turbulence structure from the surface to 1,300 m.Item Open Access First observations of PMSE in Antártica(Ciências espaciais e da atmosfera na Antártica, Transtec Editorial, 1995) Woodman Pollitt, Ronald Francisco; Balsley, Ben B.; Aquino, Freddy; Flores, Luis; Vazquez, Edilberto; Sarango, MartínA 50 Mhz radar, with 25 kW average power, has been installed at the Peruvian base in St. George lsland, Antarcitc. A search far PMSE echoes were made during its first year of operatlon, with negative results. These resutts have already been reported In the literature. Here we report our results during the summer of the second year of operation. This time the observations were made starting earlier, closer to the summer solstice. On this occaslon PMSE have been observed, albeit much weaker that what one would expect based on the Poker Flat radar results at comparable latitudes In the Northern Hemlsphere. The asymmetry, therefore, remains. lt is explained in terms of subtle differences in temperatura in the mesopause region of both polar regions. The potential of the technique to monitor global changes n temperatura is discussed.Item Open Access Inter-hemispheric differences in PMSE: are they due to differences in mesopause temperatures?(Editor no identificado, 1995) Balsley, Ben B.; Woodman Pollitt, Ronald FranciscoRecent observations using the Peruvian\U.S. Profiler at Machu Picchu Base in Antarctica show that PMSE are vastly weaker in the southern hemisphere relative to the north. The difference in average echo strength in the two hemispheres is of the order 23-33 dB. Since the PMSE occurrence is closely associated with the extremely low temperatures that are a well-know feature of the high-latitude summer mesopause region, the most obvious explanation for this discrepancy is that the mesopause temperatures are wanner in the southem hemisphere than they are in the north.Item Open Access Interpretation of angle-of-arrival measurements in the lower atmosphere using spaced antenna radar systems(American Geophysical Union, 1998-05) Chau Chong Shing, Jorge Luis; Balsley, Ben B.On the basis of scattering theory, we present four different contributions to angle-of-arrival (AOA) measurements using spaced antenna (SA) radar systems. We show that the measurement of the scattering parameters is needed to estimate most AOA contributions (e.g., tilt angle of layers). We analyze a general SA system (i.e., receiving antennas not necessarily symmetrically placed about the transmitter) and show, theoretically, that such systems can be used for vertical velocity corrections without explicitly knowing the scattering parameters (e.g., correlation lengths). The theoretical AOA expressions are compared with lower atmospheric data (3–21 km) obtained with the Jicamarca VHF radar system in Perú. We compare the AOAs obtained by a time and a frequency domain method, giving both methods essentially the same information. While the results are comparable, frequency domain AOAs tend to exhibit more outliers. From examination of time series of these AOA measurements, we find some short, but predominantly long-period oscillations (12 hours) with amplitudes of -1.Item Open Access Ionospheric drift velocity measurements at Jicamarca, Peru (July 1967 - March 1970)(World Data Center A, 1971-10) Balsley, Ben B.; Woodman Pollitt, Ronald FranciscoThis report is a collection of measurements of electrón drift velocity in the E and F regions of the equatorial ionosphere, made at the Jicamarca Radar Observatory (dip latitude ~1°N). The data consist of about eighty days of observations during the period July 1967 to March 1970. The measurements consist of (1) the vertical component of the electrón drift velocity in the F región, and (2) the east-west component of the electrón drift velocity in the E región. Other components of the drifts have been measured but the data are sparse and have not been included here. The horizontal component (H trace) of the magnetic field strength records of Huancayo, Perú, has also been included for reference. The purpose of this report is to make these data available to the scientific community. Comparison between these measurements and other geophysical phenomena should aid in the understanding of a variety of ionospheric and magnetospheric processes. This type of data continúes to be taken at JRO from time to time. For information regarding the more recent data, we suggest contacting either of the authors of this report. The data included in this report are also available in digital form on magnetic tape and punched cards.Item Open Access Observaciones ionosféricas y atmosféricas con el radar desatendido de Jicamarca (JULIA)(Instituto Geofísico del Perú, 2000) Sarango, Martin F.; Woodman Pollitt, Ronald Francisco; Balsley, Ben B.; Hysell, David L."En este artículo se describen las observaciones que se realizan en el ROJ, con un sistema de procesamiento y de transmisión-recepción de baja potencia desarrollado en Jicamarca para realizar los experimentos mencionados arriba (y/o, posiblemente, otros experimentos). Este radar, denominado JULIA (por Jicamarca U nattended Long-term studies of the lonosphere and Atmosphere) [Sarango, et. al, 1998], proporciona a los usuarios del ROJ la capacidad de realizar experimentos de larga duración con menor potencia total (10-13dB menos), pero utilizando la gran antena de Jicamarca (300x300m). Se incluye una breve descripción del radar JULIA; así como la descripción y ejemplos de varios experimentos de observación realizados durante los primeros años de operación del sistema."Item Open Access Observaciones recientes de PSME en la Antártida con los radares VHF de Machu-Picchu y Humboldt(Instituto Geofísico del Perú, 2000) Woodman Pollitt, Ronald Francisco; Sarango, Martin F.; Briceño, Jorge A.; Balsley, Ben B.; Villegas, S.; Torres, Luis A.; Flores, Luis A.En el presente trabajo mostramos los resultados de las observaciones recientes, que incluyen observaciones alrededor del máximo esperado cerca del Solsticio de Verano. Estos resultados corroboran nuestras conclusiones previas respecto a que existe una gran asimetría en la intensidad de los PMSE entre los hemisferios Norte y Sur [Balsley, et. al, 1995 y Woodman, et. al, 1999].Item Restricted Observations of E-region irregularities with ST-Radar in Piura Perú(Instituto Geofísico del Perú, 1993) Woodman Pollitt, Ronald Francisco; Rodriguez, Rodolfo; Balsley, Ben B.During a short period around the first days of february the ST radar located in the campus of the Universidad de Piura, Piura (5°S. 80,5° w), Perú, was pointed in a direction perpendicular to the magnetic field. The goal was to make a quick evaluations of the instrument as a tool to study the E-region at this altitudes. The radar has an antenna of 100m x 100m, with a transmitter with a peak power of 50 kW. A pulse width of 8 usec was used giving a range resolution of 1.2 km. The radar interpulse period was set at 1 msec, given a maximum Nyquist frequency corresponding to a doppler shift of 150 m/sec. The observations lasted several days, but only the last were successful. The first trials were made centered at noon time, influenced by our experience with the E-region echoes at the equator, since this is the time at which the equatorial echoes are the strongest. We obtained no echoes during this trials.Item Restricted On the control of the F-region drift velocity by the E-region electric field: experimental evidence(Elsevier, 1969) Balsley, Ben B.; Woodman Pollitt, Ronald FranciscoExperimental evidence is presented which shows a good correlation between velocity variations of 1. (1) the vertical motions of the F-region electrons in the equatorial ionosphere, and 2. (2) the horizontal motions of electrons in the underlying E-region. This observation supports the theory that the E-region electric fields are projected into the F-region along the electrically equipotential magnetic field lines.Item Restricted On the plasma instability mechanisms responsible for Esq(American Geophysical Union, 1976-03-01) Balsley, Ben B.; Rey, Augusto; Woodman Pollitt, Ronald FranciscoEvidence is presented showing that the gradient drift (type 2) irregularities are the most probable scatterers responsible for equatorial sporadic E (Esq) echoes observed on conventional equatorial ionograms and that the two‐stream (type 1) irregularities are not detectable at ionosonde wavelengths (1–10 MHz).Item Open Access Simultaneous observations of structure function of refractive index using a high-resolution radar and the DataHawk small airborne measurement system(European Geosciences Union (EGU), 2016-09-16) Scipión, Danny; Lawrence, Dale A.; Milla, Marco; Woodman Pollitt, Ronald Francisco; Lume, Diego A.; Balsley, Ben B.The SOUSY (SOUnding SYstem) radar was relocated to the Jicamarca Radio Observatory (JRO), near Lima, Peru in 2000, where the radar controller and acquisition system were upgraded to state-of-the-art parts to take full advantage of its potential for high-resolution atmospheric sounding. Due to its broad bandwidth (4 MHz), it is able to characterize clear-air backscattering with high spatial resolution (37.5 m). A campaign conducted at JRO during July 2014 aimed to characterize the lower troposphere with a high temporal resolution (8.1 Hz) using the DataHawk (DH) small unmanned aircraft system, which provides in-situ atmospheric measurements at scales as small as 1 m in the lower troposphere, and can be GPS-guided to sample within the beam of the radar. This was a unique opportunity to make coincident observations by both systems, and to directly compare their in-situ and remotely sensed parameters. Because SOUSY only points vertically, it was only possible to directly retrieve changes in the refractive index as a function of height through the structure function of refractive index Cn2 . Profiles of Cn2 from the DH are obtained by combining pressure, temperature, and relative humidity measurements along the helical trajectory and integrated at the same scale as the radar range resolution. Excellent agreement is observed between the Cn2 estimates obtained from the DH and SOUSY in the overlapping measurement regime from 1200 m up to 4200 m above sea level, and this correspondence provides the first accurate calibration of the SOUSY radar for measuring Cn2.Item Open Access Status of the NOAA/CU wind profiler at Piura, Peru(6th Workshop on Technical and Scientific Aspects of MST Radar (Evento), 1992) Balsley, Ben B.; Woodman Pollitt, Ronald Francisco; Mabres, Antonio; Gage, Kenneth S.The wind profiler at Piura, Peru (81°West, 6° South) has been in almost continuous operation since January 1989. The profiler is operated jointly by the University of Colorado (CIRES), NOAA's Aeronomy Lab, and the University of Piura (Peru). It is the eastern-most profiler in a chain of profilers extending across the tropical Pacific.Item Open Access The early history of the Jicamarca Radio Observatory and the incoherent scatter technique(Copernicus Publications, 2019-10-02) Woodman Pollitt, Ronald Francisco; Farley, Donald T.; Balsley, Ben B.; Milla, MarcoThe purpose of these historical notes is to present the early history of the Jicamarca Radio Observatory (JRO), a research facility that has been conducting observations and studies of the equatorial ionosphere for more than 50 years. We have limited the scope of these notes to the period of the construction of the observatory and roughly the first decade of its operation. Specifically, this period corresponds to the directorships under Kenneth Bowles, Donald Farley, and Tor Hagfors and the first period of Ronald Woodman, i.e., the years between 1960 and 1974. Within this time frame, we will emphasize observational and instrumental developments which led to define the capabilities of the Jicamarca incoherent scatter (IS) radar to measure the different physical parameters of the ionosphere. At the same time, we partially cover the early history of the IS technique which has been used by many other observatories built since. We will also briefly mention the observatory’s early and most important contributions to our understanding of the physical mechanisms behind the many peculiar phenomena that occur at the magnetic Equator. Finally, we will put special emphasis on the important developments of the instrument and its observing techniques that frame the capabilities of the radar at that time.