1. History

2. Facilities
    Main Radar   Radar Components    Radar Modes of Operation   JULIA Radar  Other Instruments 

3. Main Research Areas

4. Coherent scatter echoes

5. Non-conventional Studies

6. Summary of Scientific Contributions and Milestones (since 1961)

7. JRO Directors and Principal Investigators

8. See also

9. References

10. External links

The Jicamarca Radio Observatory (JRO) is the equatorial anchor of the Western Hemisphere chain of Incoherent Scatter Radar (ISR) observatories extending from Lima, Peru to Søndre Strømfjord, Greenland. JRO is the premier scientific facility in the world for studying the equatorial ionosphere. The Observatory is about half an hour drive inland (east) from Lima and 10 km from the Central Highway ({{coord|11|57|05|S|76|52|27.5|W|}}, 520 meters ASL). The magnetic dip angle is about 1°, and varies slightly with altitude and year. The radar can accurately determine the direction of the Earth's magnetic field (B) and can be pointed perpendicular to B at altitudes throughout the ionosphere. The study of the equatorial ionosphere is rapidly becoming a mature field due, in large part, to the contributions made by JRO in radio science.^[1]

JRO’s main antenna is the largest of all the incoherent scatter radars in the world. The main antenna consists of a 300m x 300m square array composed of 18,432 cross-polarized dipoles. The main research areas of the observatories are: the stable equatorial ionosphere, ionospheric field aligned irregularities, the dynamics of the equatorial neutral atmosphere and meteor physics.

The Observatory is a facility of the Instituto Geofísico del Perú operated with support from the US National Science Foundation Cooperative Agreements through Cornell University.

History

The Jicamarca Radio Observatory was built in 1960–61 by the Central Radio Propagation Laboratory (CRPL) of the National Bureau of Standards (NBS). This lab later became part of the Environmental Science Service Administration (ESSA) and then the National Oceanic and Atmospheric Administration (NOAA). The project was led by Dr. Kenneth L. Bowles, who is known as the “father of JRO”.

Although the last dipole was installed on April 27, 1962, the first incoherent scatter measurements at Jicamarca were made in early August 1961, using part of the total area projected and without the transmitter's final stage. In 1969 ESSA turned the Observatory over to the Instituto Geofísico del Perú (IGP), which had been cooperating with CRPL during the International Geophysical Year (IGY) in 1957–58 and had been intimately involved with all aspects of the construction and operation of Jicamarca. ESSA and then NOAA continued to provide some support to the operations for several years after 1969, in major part due to the efforts of the informal group called “Jicamarca Amigos” led by Prof. William E. Gordon. Prof. Gordon invented the incoherent scatter radar technique in 1958.

A few years later the National Science Foundation began partially supporting the operation of Jicamarca, first through NOAA, and since 1979 through Cornell University via Cooperative Agreements. In 1991, a nonprofit Peruvian organization—called Ciencia Internacional (CI)—was created to hire most observatory staff members and to provide services and goods to the IGP to run the Observatory.

Since 1969, the great majority of the radar components have been replaced and modernized with “home made” hardware and software, designed and built by Peruvian engineers and technicians. More than 60 Ph.D. students, many from US institutions and 15 from Peru, have done their research in association with Jicamarca.

Facilities

Main Radar

JRO’s main instrument is the VHF radar that operates on 50 MHz (actually on 49.9 MHz ^[1]) and is used to study the physics of the equatorial ionosphere and neutral atmosphere. Like any other radar, its main components are: antenna, transmitters, receivers, radar controller, acquisition and processing system. The main distinctive characteristics of JRO’s radar are: (1) the antenna (the largest of all the ISRs in the world) and (2) the powerful transmitters.

Radar Components

• Antenna. The main antenna consists of 18432 cross-polarized half-wavelength dipoles occupying an area of 288m x 288m. The array is subdivided in quarters, each quarter consisting of 4x4 modules. The main beam of the array can be manually steer +/- 3 degrees from its on-axis position, by changing cables at the module level. Being modular, the array can be configured in both transmission and reception on a variety of configurations, allowing for example: simultaneous multi-beam observations, applications of multi-baseline radar interferometry as well as radar imaging, etc.
• Transmitters. Currently,{{when|date=August 2016}} JRO has three transmitters, capable of delivering 1.5 MW peak power each. Soon a fourth transmitter will be finished to allow the transmission of 6 MW as in the early days. Each transmitter can be fed independently and can be connected to any quarter section of the main array. This flexibility allows the possibility of transmitting any polarization: linear, circular or elliptical.
• Other. The remaining components of the radar are constantly being changed and modernized according to the technology available. Modern electronic devices are used for assembling the receivers, radar controller and acquisition system. The first computer in Peru came to JRO in the early 1960s. Since then, different computer generations and systems have been used.

Radar Modes of Operation

The main radar operates in mainly two modes: (1) incoherent scatter radar (ISR) mode, and (2) coherent scatter (CSR) mode. In the ISR mode using the high power transmitter, Jicamarca measures the electron density, electron and ion temperature, ion composition and vertical and zonal electric fields in the equatorial ionosphere. Given its location and frequency of operation, Jicamarca has the unique capability of measuring the absolute electron density via Faraday rotation, and the most precise ionospheric electric fields by pointing the beam perpendicular to the Earth's magnetic field. In the CSR mode the radar measures the echoes that are more than 30 dB stronger than the ISR echoes. These echoes come from equatorial irregularities generated in troposphere, stratosphere, mesosphere, equatorial electrojet, E and F region. Given the strength of the echoes, usually low power transmitters and/or smaller antenna sections are used.

JULIA Radar

JULIA stands for Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere, a descriptive name for a system designed to observe equatorial plasma irregularities and neutral atmospheric waves for extended periods of time. JULIA is an independent PC-based data acquisition system that makes use of some of the exciter stages of the Jicamarca main radar along with the main antenna array. In many ways, this system duplicates the function of the Jicamarca radar except that it does not use the main high-power transmitters, which are expensive and labor-intensive to operate and maintain. It can therefore run unsupervised for long intervals. With its pair of 30 kW peak power pulsed transmitters driving a (300 m)^2 modular antenna array, JULIA is a formidable coherent scatter radar. It is uniquely suited for studying the day-to-day and long-term variability of equatorial irregularities, which until now have only been investigated episodically or in campaign mode.

A large quantity of ionospheric irregularity data have been collected during CEDAR MISETA campaigns beginning in August, 1996, and continuing through the present. Data include daytime observations of the equatorial electrojet, 150 km echoes and nighttime observations of equatorial spread F.

Other Instruments

Besides the main radar and JULIA, JRO hosts, and/or helps in the operations of, a variety of radars as well as radio and optical instruments to complement their main observations. These instruments are: various ground-based magnetometers distributed through Peru, a digital ionosonde, many GPS receivers in South America, an all-sky specular meteor radar, a bistatic Jicamarca-Paracas CSR for measuring E region electron density profile, scintillation receivers in Ancon, a Fabry–Perot Interferometer in Arequipa, a small prototype of AMISR UHF radar, …

Main Research Areas

The main research areas of JRO are the studies of: the equatorial stable ionosphere, the equatorial field aligned irregularities, equatorial neutral atmosphere dynamics, and meteor physics.

Here are some examples of the JRO topics

• Stable ionosphere
  • Topside: What controls the light ion distribution? Why are the equatorial profiles so different from those at Arecibo? What is the storm time response of the topside?
  • F region: Do current theories fully explain electron and ion thermal balance? Do we understand the electron collision effects on ISR theory now? What is the effect of F-region dynamics near sunset on the generation of ESF plumes? What are the effects of N-S winds on inter-hemispheric transport?
  • E region: What are the basic background parameters in the equatorial E region? What is the morphology of the density profiles in this difficult to probe region? How does this morphology affect the E-region dynamo?
  • D region: What effects do meteor ablation and mesospheric mixing have on the composition in this region?
• Unstable Ionosphere
  • F region: What are the fundamental plasma processes, including nonlinear processes, that govern the generation of plasma plumes? What are the precursor phenomena in the late afternoon F region that control whether or not an F-region plume will be generated after sunset?
  • Daytime Valley echoes (or so-called 150 km echoes). What are the physical mechanisms causing them? (still a puzzle after more than 40 years!).
  • E region: What are the nonlinear plasma physics processes that control the final state of the equatorial electrojet instabilities? To what extent do these instabilities affect the conductivity of the E region, and by extension, the conductivity of the auroral zone E region, where similar, but stronger and more complicated, instabilities exist?
  • Neutral atmosphere dynamics. What are the tidal components at low latitudes for the different seasons and altitudes? How strong are the wind shears in the mesosphere? What are the characteristics of gravity waves? Can we see evidence of lower atmosphere gravity wave coupling with the ionosphere?
  • Meteor physics. Where are the meteoroids coming from? What are the mass and size of the meteoroids? What is the equivalent visual magnitude of meteors detected at JRO? Can we use meteor echoes to diagnose the atmosphere/ionosphere at altitudes where they occur?

Coherent scatter echoes

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