astronomy

Jicamarca Radio Observatory

Jicamarca Radio Observatory is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Jicamarca Radio Observatory rather than just read about it. In short: 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.

Key takeaways

Jicamarca Radio Observatory belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Jicamarca Radio Observatory to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Jicamarca Radio Observatory from memory before moving on to harder problems.

Reference excerpt

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 (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. JRO's main antenna is the largest of all the incoherent scatter radars in the world. The main antenna is a cross-polarized square array composed of 18,432 half-wavelength dipoles occupying an area of approximately 300m x 300m. 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 ) 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 is a dual polarized antenna array that consists of 18,432 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 steered +/- 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, 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.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Jicamarca Radio Observatory

Start with the simplest possible case. Write down what Jicamarca Radio Observatory claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Jicamarca Radio Observatory before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Jicamarca Radio Observatory ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Jicamarca Radio Observatory

In research: Jicamarca Radio Observatory appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Jicamarca Radio Observatory in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Jicamarca Radio Observatory is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1961 establishments in Peru, Astronomy in Peru, Buildings and structures completed in 1961, so understanding it makes those chapters shorter.
In everyday life: Look for Jicamarca Radio Observatory outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Jicamarca Radio Observatory in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Jicamarca Radio Observatory means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Jicamarca Radio Observatory out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Jicamarca Radio Observatory in simple terms?

Why does Jicamarca Radio Observatory matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Jicamarca Radio Observatory?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Jicamarca Radio Observatory.