Understanding Ozone Measurement Terms

The question asks us to identify which of the given terms are associated with the measurement of ozone. Let's examine each term to understand its relevance.

Analysis of Each Term and Its Relation to Ozone Measurement

(A) Dobson

The term "Dobson" is strongly associated with ozone measurement in two key ways:

• The Dobson unit (DU) is the most common unit used to measure the total amount of ozone in a vertical column of the atmosphere. One Dobson unit is equivalent to the amount of ozone that would form a layer 0.01 millimeters thick at standard temperature and pressure (STP).
• The Dobson spectrophotometer is a ground-based instrument designed specifically to measure the total column ozone using the differential absorption of ultraviolet (UV) light by ozone.

Therefore, "Dobson" is directly associated with ozone measurement.

(B) Spectrophotometer

A spectrophotometer is a general instrument that measures the intensity of light as a function of wavelength. Many methods for measuring ozone, both from the ground and from space, rely on the principle of spectrophotometry. Ozone absorbs UV light very effectively. By measuring the absorption of UV light at specific wavelengths using a spectrophotometer, the amount of ozone can be determined. As mentioned above, the Dobson spectrophotometer is a specific type used for ozone.

Therefore, "Spectrophotometer" is associated with ozone measurement.

(C) Pyranometer

A pyranometer is an instrument used to measure broadband solar radiation flux density. It measures the total solar radiation received on a surface over a wide spectrum, typically from 0.3 to 3 µm. Pyranometers are used in meteorology, climate research, and solar energy applications, but they are not used to directly measure ozone.

Therefore, "Pyranometer" is not associated with ozone measurement.

(D) Planimeter

A planimeter is a mechanical or electronic instrument used to measure the area of an arbitrary two-dimensional shape drawn on a map or plan. It is a tool used in fields like surveying, engineering, or cartography. It has no connection to atmospheric measurements like ozone.

Therefore, "Planimeter" is not associated with ozone measurement.

(E) Anemometer

An anemometer is an instrument used for measuring wind speed. It is a common tool in weather stations and for studying air movement. It does not measure ozone concentration or amount.

Therefore, "Anemometer" is not associated with ozone measurement.

Identifying the Correct Combination for Ozone Measurement

Based on the analysis:

• (A) Dobson is associated with ozone measurement (unit and instrument).
• (B) Spectrophotometer is associated with ozone measurement (principle and instrument type).
• (C) Pyranometer measures solar radiation.
• (D) Planimeter measures area.
• (E) Anemometer measures wind speed.

The terms associated with ozone measurement are (A) Dobson and (B) Spectrophotometer.

Revision Table: Key Measurement Instruments

Additional Information on Ozone Measurement

Measuring atmospheric ozone is crucial for monitoring the health of the ozone layer, which protects life on Earth from harmful ultraviolet (UV) radiation. Apart from ground-based instruments like the Dobson spectrophotometer, ozone is also measured from satellites using various sensors that employ spectrophotometric principles by observing how the atmosphere absorbs or emits radiation at different wavelengths. Examples include instruments on NASA's Aura satellite or the European Space Agency's Sentinel missions. Ozonosondes, which are balloon-borne instruments, can also measure the vertical profile of ozone concentration in the atmosphere.