Browsing by Author "Balsley, B.B."
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Item Open Access Determination of maximum age from the probability distribution function of a growth parameter(Instituto Geofísico del Perú, 1990-04-17) Woodman Pollitt, Ronald Francisco; Balsley, B.B.; Mabres, A.The present notes are motivated by the problem of trying to determine the maximum age of trees which we have under study in the northern part of Perú. The final objective of the project is to decipher the occurrence of El Niños in the past, witch should have been registered in its growth rings.Item Restricted On the lack of southern hemisphere polar mesosphere summer echoes(American Geophysical Union, 1995-06-20) Balsley, B.B.; Woodman Pollitt, Ronald Francisco; Sarango, M.; Rodriguez, R.; Urbina, J.; E. Ragaini; Carey, J.; Huaman, M.; Giraldez, A.We report VHF radar observations of the southern high-latitude mesopause region using wind profilers that were installed recently on King George Island, Antarctica, and Ushuaia, Argentina. Briefly, our observations, which were made during January and February 1993, show almost no evidence of so-called polar mesosphere summer echoes, or PMSE. Since these echoes are a predominant feature of the northern high-latitude mesosphere in summer, their absence in the southern hemisphere is both surprising and intriguing. In this paper we present evidence demonstrating the virtual absence of the echoes and demonstrate that our systems were capable of detecting them had they been present. We also outline some of the consequences of this intriguing result, which are supported by observed hemispheric differences in polar mesospheric clouds, mesospheric temperatures, upper atmospheric gravity wave activity, and mean circulation patterns.Item Open Access Report of MSG-6 on the scientific aspects of an international equatorial observatory (IEO)(Instituto Geofísico del Perú, 1983) Balsley, B.B.; Blamont, J.; Forbes, J.M.; Geller, M.A.; Hirota, I.; Vincent, R.A.; Woodman Pollitt, Ronald FranciscoMSG-6 has been set up to study this on the basis that there is need to have observatories very close to the equator so that we may understand equatorial dynamics much more precisely than we do now. Such observatories, which are equipped with MST radars, lidar and other facilities, should be constructed and operated th rough international cooperation. Specific requirements for the observation of equatorial middle atmosphere dynamics were discussed at the Workshop held 10-12 May 1982 at Estes Park, CO, USA, as will be shown in Section 2. MSG-6 has further worked on the problem, obtaining the opinions of each member as to the following questio ns: (1 ) locations of IEOs; (2) specification of the faciliti es at IEOs; and (3) finanical support on the construction and the maintenance of IEOs.The proposed locations for IEOs are, in alphabetical arder, Christmas Island, Galapagos Island, Kourous, Nauru and Tumbes (or Iquitos).Item Open Access Status of the NOAA/CU trans-pacific profiler network(Editor no identificado, 1997) Gage, K.S.; Carter, D.A.; McAfee, J.R.; Balsley, B.B.; Ecklund, W.L.; Williams, C.R.; Riddle, A.C.; Johnston, P.E.; Avery, S.K.; Woodman Pollitt, Ronald FranciscoSince the Sixth MST Radar Workshop held at National Central University, Chung-Li, Taiwan, in August 1993, the NOAA/CU Network of VHF wind profilers has been operated in a routine mode. The network is comprised of VHF wind profilers located at Piura, Peru; Christrnas lsland, Kiribati; Pohnpei, Federated States of Micronesia; and Biak, Indonesia. The Biak wind profiler was completed in early 1992 and has been in continuous operation since March 1992. In addition to the VHF wind profilers named above a 50 MHz wind profiler is operated in Darwin, Australia through a cooperative research agreement between NOAA's Aeronomy Laboratory and the Australian Bureau of Meteorology's Research Centre. The VHF profiler network was described in more detail by Gage et al, (1990) and the VHF profilers are described in Gage et al. (1994a). In addition to the 50 MHz wind profilers, several sites have been instrumented with lntegrated Sounding Systems (ISS) (Parsons et al., 1994) complete with 915 MHz wind profilers (Carter et al., 1995) equipped with RASS and OMEGA Balloon Sounding Systems and a suite of surface instruments to record surface wind, temperature, humidity, pressure, radiation and precipitation. The ISS were developed jointly by the Aeronomy Laboratory and NCAR's Atmospheric Technology Division. VHF wind profilers at Christmas Island, Biak and Darwin have been complemented with 915 MHz wind profilers. In 1994, 915 MHz profilers were deployed at Tarawa, Kiribati; and San Cristóbal in the Galápagos lslands of Ecuador.Item Open Access Status of the trans-Pacific network of wind profilers(Instituto Geofísico del Perú, 1991) Gage, K.S.; Ecklund, W.L.; Carter, D.A.; Balsley, B.B.; Riddle, A.C.; Johnston, P.E.; Woodman Pollitt, Ronald FranciscoSince the last MST Radar Workshop in Kyoto, in November 1988, there has been substantial progress made toward implementation of a Trans-Pacific network of wind profilers (Gage et al, 1989, 1990). As of June 1991, the network is virtually complete with the exception of the 50 MHz wind profiler that is under construction at Biak, Indonesia. The original network of 50 MHz wind-profiling Doppler radars is being funded by NSF and TOGA to support fundamental research on tropical convection, equatorial waves, and large-scale tropical circulation systems. The network as originally conceived was to be comprised of four VHF radars: Piura, Peru; Christmas Island, Kirabati; Pohnpei, Federated States of Micronesia; and Biak, Indonesia. The first three wind profilers are virtually completed and the Biak wind profiler will be installed as soon as site preparations are completed.Item Open Access The on-axis beam at Jicamarca: is it pointing correctly?(Instituto Geofísico del Perú, 1995) Chau Chong Shing, Jorge Luis; Balsley, B.B.; Huamán, M.M.; Castillo, O.; Woodman Pollitt, Ronald FranciscoVertical velocity measurements of atmospheric winds are becoming increasingly important. To obtain the long-term mean vertical motion of the atmosphere is difficult to do, both because of the small velocities involved and because of the finite width of the antenna beam. Since the vertical wind measurement is very sensitive to the tilt of the vertically-directed antenna beam, we decided to get the Jicamarca beam direction by measuring the phase and amplitude of a reference signal at each of the antenna feed points. Our results tell us that, while the antenna pointing direction is already good, there is room for improvement.Item Open Access The ST radar under construction at Piura, Peru (6°S, 81°W)(Instituto Geofísico del Perú, 1989) Balsley, B.B.; Ecklund, W.L.; Carter, D.A.; Gage, K.S.; Mugica, R.; Mabres, A.; Rodriguez, R.; Avery, S.K.; Violette, J.; Woodman Pollitt, Ronald FranciscoThe Piura ST radar currently under construction at the Universite de Piura in Piura, Peru will be a 50 MHz VHF system. This radar will form the easternmost facility in the proposed trans-Pacific network of ST radars that will eventually span the equatorial Pacific. Support for the construction of the Piura radar is being furnished by the U.S. National Science Foundation. The ST radar at Piura is part of a cooperative research program involving NOAA's Aeronomy Laboratory and the University of Colorado in the United States and the Universite de Piura and the Instituto Geofísica del Peru in Peru. The radar is being constructed on the campus of the Universite de Piura. A container filled with antenna cables and radar hardware was shipped from Alaska during the past few months. Site preparations are now underway and the antenna construction will begin about the first of the year. A building will be constructed next to the antenna site to house the radar equipment. A diesel generator has been purchased to provide a continuous source of power to the radar. The first phase of construction will be completed by mid-1989 and the radar will be operated for the first year in a vertical-only mode. During 1990 the radar will be modified so that horizontal as well as vertical velocities can be measured.Item Open Access VHF doppler radar backscatter measurements through the entire neutral atmosphere (15-95 km) above Jicamarca, Peru(Instituto Geofísico del Perú, Radio Observatorio de Jicamarca, 1980) Cornish, C.R.; Balsley, B.B.; Woodman Pollitt, Ronald FranciscoThe Jicamarca 50-MHz radar was used to obtain backscattered echoes through the entire atmosphere (0-100 km). Previous radar observations at VHF have shown a gap near the 35-55 km region, where the lack of echoes is attributed to a lack of radar sensitivity. By using the full Jicamarca antenna array and maximun transmitter power and by optimizing transmitter duty cycle through the implementation of complementary codes, doppler measurements display discernable peaks in the computed spectra from atmospheric signals in the gap region as well as above and below it. The results indicate that a minimum power-aperture threshold in excess of 1010 W-m2 is required in order to obtain backscatter echoes near 50 MHz through the entire neutral atmosphere.Item Restricted Wind-profiling doppler radars for tropical atmospheric research(American Geophysical Union, 1990-12) Gage, K.S.; Balsley, B.B.; Ecklund, W.L.; Woodman Pollitt, Ronald Francisco; Avery, S.K.The past decade has seen a rapid increase in the use of wind profilers in atmospheric research [Gage, 1990]. Briefly, wind profilers are Doppler radars that observe winds from Doppler shifts of "clear air" atmospheric echoes. The atmospheric echoes arise from backscattering from turbulent irregularities in the radio refractive index of the atmosphere. Wind profilers operate at several VHF and UHF frequencies, notably in the vicinity of 50, 405, and 915 MHz. Since they measure the radial component of the wind, they can be used to monitor vertical as well as horizontal motions by using antennas phased to look sequentially in several directions. The wind profilers can be regarded as "all-weather" instruments, although corrections for fall-speed often have to be made during precipitation. In addition to wind measurements, the wind profilers also yield valuable information on turbulence and in sorne cases on atmospheric stability. Using the latest wind-profiling technology wind can be measured throughout the troposphere and into the lower stratosphere. The UHF wind profilers are smaller and consequently easier to install. They are especially well suited for high-venical resolulion observation oí the lower troposphere. The larger, more powerful VHF wind profilers are better suited for observation of the upper troposphere and lower stratosphere. Until recently, most atmospheric research using wind profilers has been carried out with individual radars. With the current widespread acceptance of clear-air radar wind-profiling technology. field programs are increasingly taking advantage of the continuous wind observations available from wind profilers. At the same time, several companies have become active in developing and marketing wind profilers. With the deployment of the 30-station demonstration net-work of wind profilers in the Central United States, we are on the threshold of a new era in which wind profilers will become an integral pan of the next generation weather-observing system.