Principles of Instrumentation and Measurement

Questions and Answers

Which type of measurement employs direct contact between the sensing device and the medium being measured?

Remote sensing

Meteorological measurement

Indirect measurement

In-situ measurement (correct)

What is the primary characteristic of indirect measurement?

It infers data through interpretation from a device. (correct)

It only measures time.

It requires direct measurement of mass.

It uses physical contact with the subject.

Which of the following is an example of a device used for indirect measurement?

An anemometer (correct)

A ruler

A balance scale

A protractor

What type of observation involves obtaining measurements without direct contact with the subject?

Remote sensing Signup and view all the answers

Which method would likely be used to gather atmospheric profiles without physically touching the atmosphere?

S-band and Ka-band S-PolKa Radar Signup and view all the answers

What type of measurement is made when using a device that interprets electromagnetic radiation?

Remote sensing Signup and view all the answers

Which device is a direct measurement instrument?

Liquid-in-glass thermometer Signup and view all the answers

What is a major difference between in-situ measurements and indirect measurements?

Indirect measurements involve interpretation through a device. Signup and view all the answers

What is the main reason sites for global climate monitoring should be located far from urban environments?

To prevent the influence of the heat island effect Signup and view all the answers

Which of the following best defines a measurand in atmospheric studies?

The measured property of the atmosphere Signup and view all the answers

What do scanning Doppler weather radars primarily measure?

Radial velocities and reflectivity Signup and view all the answers

Which organization maintains a radar network database for international data exchange?

WMO Signup and view all the answers

Which of the following components is NOT required in the characterization of an atmospheric instrument?

Environmental insulation Signup and view all the answers

What system do commercial aircraft use to report weather observations during flight?

ACARS or AMDAR Signup and view all the answers

What does a sensor typically convert in atmospheric instruments?

Mechanical pressure into electrical voltage Signup and view all the answers

In the context of a sensor, what is a transducer?

A sensor that converts one form of energy to another Signup and view all the answers

What type of satellites can sample the exosphere in situ?

Low-Earth Orbiting (LEO) satellites Signup and view all the answers

What is typically the output of a sensor used in atmospheric measurements?

Electrical property like voltage or resistance Signup and view all the answers

Which type of sensing do geostationary satellites primarily use?

Passive sensing Signup and view all the answers

How do satellites observe Earth and its atmosphere?

Via remote sensing techniques Signup and view all the answers

Which component of a sensor is responsible for having a measurable property dependent on the atmospheric property being measured?

Sensing element Signup and view all the answers

Which of the following is NOT a function of scanning Doppler weather radars?

Monitoring satellite data Signup and view all the answers

Which of the following measurands could be classified as a derived property?

Radar reflectivity Signup and view all the answers

What is a key benefit of radar networks established worldwide?

They assist with radio-frequency spectrum allocation. Signup and view all the answers

What is the primary function of rawinsondes?

To collect observations of temperature, humidity, and wind. Signup and view all the answers

Which statement about profiling networks is true?

Data from profiling networks is used to analyze weather patterns. Signup and view all the answers

At what times are rawinsondes typically launched for synoptic soundings?

Twice daily at 00 and 12 UTC. Signup and view all the answers

What do radars primarily detect in the atmosphere?

Reflective particles like precipitation and clouds. Signup and view all the answers

What role do soundings play in weather forecasting?

They provide essential data for weather maps and forecasts. Signup and view all the answers

Which instrument continuously measures wind direction and speed?

Wind profilers. Signup and view all the answers

Which of the following is NOT a function of radar in weather forecasting?

Identifying temperature gradients. Signup and view all the answers

What technology enables rawinsondes to measure atmospheric data from ships?

Radiosondes. Signup and view all the answers

What role does the signal processor play in an instrument?

Amplifies and processes the electrical signal for clarity Signup and view all the answers

What is the primary function of the data recorder in an instrumentation system?

To automate the recording of measurements over time Signup and view all the answers

Which component is responsible for converting sensor output to a digital format?

Analog-to-digital converter Signup and view all the answers

Why is it important to assess the quality of measurements with instruments?

To evaluate noise levels and compliance with expected limits Signup and view all the answers

What characteristic of meteorological instruments is crucial for their autonomous operation?

Uncertainty that remains low and uniform over time Signup and view all the answers

What is typically used to display the property being measured?

A digital display or printed paper Signup and view all the answers

What does the term 'calibration' in the context of instruments refer to?

Adjusting the instrument to maintain measurement accuracy Signup and view all the answers

What are two key components of a display and recording system?

Data display and data recorder Signup and view all the answers

Study Notes

Types of Measurement

Direct measurements assess mass, length, and time without intermediaries, e.g., balances for mass.
Indirect measurements involve using devices to interpret measurements, e.g., anemometers for wind speed or thermometers for temperature based on liquid columns.
In-situ measurements require direct interaction between the sensor and the environment, exemplified by mobile radiosondes.
Remote sensing allows observations without physical contact, useful for atmospheric profiling and imagery, using technologies like S-band and Ka-band radars.

Measurand

Measurand refers to the atmospheric property being measured, such as temperature, pressure, or the size distribution of cloud droplets.
Properties can also include radiative energy from solar sources or measured variations due to weather phenomena.

Key Components of Instruments

Atmospheric instruments typically consist of:
- Sensor: Outputs an electrical property (like voltage) related to the atmospheric measurement.
- Data Acquisition/Signal Conditioning: Enhances and interprets sensor signals.
- Display/Recording System: Shows and records the measurement data.
Sensors incorporate:
- Sensing Element: Responds to the measured property.
- Exciter: Devices like wind profilers or rawinsondes that gather atmospheric data.

Profiling Networks

Radiosonde programs began in the 1930s to support weather forecasting, collecting data on temperature, humidity, and wind.
Soundings contribute essential data for weather maps and predictive models, performed twice daily.

Radar Networks

Radars utilize electromagnetic pulses to detect and analyze atmospheric scatterers like precipitation and clouds.
Scanning Doppler radars can assess wind speeds and precipitation rates, which are crucial for forecasting.

Aircraft Observing Systems

Research and commercial aircraft gather and transmit atmospheric data during flights using systems such as ACARS in the U.S. and AMDAR internationally.

Satellite Observations

Satellites provide unparalleled data by utilizing remote sensing to observe Earth from orbit.
Low-Earth Orbiting (LEO) and geostationary satellites use both passive and active sensors for atmospheric measurements, including electromagnetic energy emissions.

Performance Characteristics of Instruments

Instrument reliability is enhanced through assessments of measurement quality, calibration, and noise levels.
Instruments should exhibit low uncertainty over extended periods, essential for accurate meteorological data collection.

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Description

This quiz covers the fundamental concepts of direct and indirect measurements used in various instruments. Learn about the principles of measurement, including examples like balances and anemometers. Understand how observations are made and interpreted in the context of instrumentation.