Browsing by Author "Sarango, Martin F."
Now showing 1 - 9 of 9
Results Per Page
Sort Options
Item Restricted A multi-DSP signal processing and control system for MST radar(IEEE, Institute of Electrical and Electronics Engineers, 1995) Sarango, Martin F.; Woodman Pollitt, Ronald Francisco; Ragaini, Enrico; Vásquez, Edilberto H.This paper describes a signal processing and control system for atmospheric sounding rardars, with improved characteristics with respect to formerly used architectures. We refer especially to wind profiling as an important and interesting application. The system allows up to 4 receiver signals to be processed at the same time, with 60 range gates and 300 m height resolution. The use of two DSPs working in parallel allows the use of a single PC for real time data processing and system control. Some experimental results and reported.Item Open Access Investigación ionosférica y mesosférica utilizando el radar VHF a bordo del B.I.C. Humboldt(Instituto Geofísico del Perú, Radio Observatorio de Jicamarca, 1999) Woodman Pollitt, Ronald Francisco; Sarango, Martin F.; Soldi, HéctorEste artículo describe el radar coherente VHF instalado a bordo del Buque de Investigación Científica B.I.C. Humboldt. El sistema fue diseñado y construido en el Radio Observatorio de Jicamarca. El instrumento cuenta con un arreglo de antenas tipo COCO de 24x2 l m, especialmente diseñado para su instalación en un buque. Se presenta una descripción del instrumento, así como los primeros resultados de las observaciones de Ecos Mesosféricos Polares de Verano (PMSE) en la Antártida y del Electrochorro Ecuatorial a lo largo de la costa Sur del Perú.Item Open Access Jicamarca radar observations of the diurnal and semidiurnal tide in the troposphere and lower stratosphere(American Geophysical Union, 2002-04) Riggin, Dennis M; Kudeki, Erhan; Feng, Zhaomei; Sarango, Martin F.; Lieberman, Ruth S.The mesosphere-stratosphere-troposphere (MST) radar at Jicamarca, Peru (12S, 77W), made extended (15 day or longer) observations of the horizontal and vertical winds that were used to infer the diurnal and semidiurnal tides. The measurements were made during several months from mid-1997 through mid-1998 and using a higher-power transmitter and finer range resolution during 10 days of August 1998. The three-component winds are used to estimate amplitudes, phases, and momentum fluxes associated with the tides. Thermal forcing of the diurnal tide is also examined with diurnal water vapor heating rates calculated using data from the NASA Water Vapor Project (NVAP). For the region near Jicamarca the calculations from NVAP showed the temporal variability of the diurnal heating to be dominated by an annual cycle with maximum around the summer solstice. When projected into tidal modes, about 25% of the total water vapor heating rate amplitude near Jicamarca is found to be nonmigrating. The meridional amplitude of the semidiurnal tide was found to be generally greater than the zonal amplitude, although tidal theory predicts that the zonal amplitude should be much greater at the latitude of Jicamarca (assuming the tide was migrating). The phase of the semidiurnal tide lagged (by about 3 hours) the phase expected from surface pressure climatologies. According to tidal theory the migrating semidiurnal tide should transport little meridional momentum flux. However, substantial southward fluxes (vw ∼ −1 × 10−3 m2 s−2) were observed at Jicamarca, and the meridional component of momentum flux was typically larger in magnitude than the zonal component was. The diurnal tide was somewhat weaker, was less coherent, and transported less momentum. The semidiurnal tide had a very long vertical wavelength throughout the troposphere and into the lower stratosphere, while the diurnal tide was only observed to propagate at heights above the tropopause with a much shorter (∼10 km) vertical wavelength. Below the tropopause the dominant diurnal motions were not traveling waves, but rather convective motions that exhibited little phase progression with altitude. These motions were broadly peaked in frequency around 24 hours and were presumably standing oscillations with no horizontal propagation and probably with small horizontal scale. Despite the lack of coherence of these quasi-diurnal motions, the associated vertical wind amplitudes were sizable (∼0.02 m s−1), and thus the fluctuations can presumably transport significant horizontal momentum.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 Open Access PC-DSPs-based signal processing and control system for MST radars(Instituto Geofísico del Perú, 1996) Sarango, Martin F.; Woodman Pollitt, Ronald Francisco; Ragaini, Enrico; Vásquez, EdilbertoThis paper describes a signal processing and control system, designed and built for the Peruvian MST radar installed in the "Machu-Picchu" Scientific Station, Antarctica (62 º05'5 S, 58º28' W). System architecture, based in a single PC and two DSP boards, and design considerations are discussed. Toe system allows up to 4 receiver signals to be processed in parallel, with 60 range gates and 150 m maximum height resolution. System evaluation and sorne experimental results are reported.Item Open Access Ship-borne VHF radar for mesospheric and ionospheric research(Instituto Geofísico del Perú, Radio Observatorio de Jicamarca, 2000) Woodman Pollitt, Ronald Francisco; Sarango, Martin F.This paper describes a VHF coherent radar installed on board the Peruvian research vessel "Humboldt". The system has been designed and developed at Jicamarca Radio Observatory. The radar's antenna is a COCO array of 21 x 24m, specially designed to be installed on a ship. System description is included, as well as first results from observations of Polar Mesospheric Summer Echoes (PMSE) in Antarctica, and Equatorial Electrojet along the southern Peruvian coast.Item Open Access Synthetic aperture radar observations with the Humboldt VHF ship-borne radar(Instituto Geofísico del Perú, 2001) Sarango, Martin F.; Woodman Pollitt, Ronald FranciscoMotivated by the interest to study PMSE in Antarctica and Equatorial Electrojet along the southern Peruvian coasts, a VHF radar was developed and installed in 1998 by the Jicamarca Radar Observatory group on board the Peruvian research vessel BIC Humboldt (see description on a companion paper by Woodman, et. al). During the test runs of this radar, very strong echoes from the Andes were observed. In order to obtain profiles of the mountains and other facing targets, as glaciers in Antarctica, sorne efforts have been carried out to observe and process these echoes using Synthetic Aperture Radar (SAR) techniques SAR is a well known airborne (or spaceborne) radar mapping technique for generating high resolution maps of surface target areas and terrain. SAR applications include topographic mapping, surface deformation studies related to seismic activity and extraction of oíl and ground water, glaciology, and determination of Earth surface characteristics, including Jand surface, snow, oceans, sea ice and land ice. The Humboldt radar has been used to determine coastlines along the South American coasts for evaluation purposes. We also plan to use the same idea to perform observations using a radar on a truck. Ship-borne SAR cannot be used for surface mapping, because facing targets darken the targets behind them. However, this type of measurements become highly interesting when the coastline to be observed changes dynamically as in the case of glaciers and because of its low operational cost.Item Restricted Tropospheric and stratospheric momentum flux measurements from radar wind data collected at Jicamarca(Elsevier, 2004-02-01) Riggin, Dennis M.; Kudeki, Erhan; Sarango, Martin F.Tropospheric and stratospheric radar wind data obtained at Jicamarca, Perú (11.95S, 76.87°W) during August 17–26, 1998 have been used to estimate the momentum flux of short-period wind fluctuations together with the estimation uncertainties. As a result of our study we conclude that momentum flux estimates exceeding the measurement uncertainties can be obtained after about one day of integration.