Question

What is the standard unit used to measure Total Column Ozone?

• A. Pascal
• B. Dobson Unit
• C. Parts per million
• D. Millibar

Hint:

\textbf{Ozone layer thickness} is measured in \textbf{Dobson Units (DU)}.

Answer 1

The Correct Option is B

Concept: Total Column Ozone refers to the total amount of ozone present in a vertical column of the atmosphere above a given location.
Step 1: Understanding measurement of ozone.
Ozone concentration across the atmospheric column is measured in a specialized unit called the Dobson Unit (DU).
Step 2: Definition of Dobson Unit.
1 Dobson Unit represents a layer of ozone that would be \(0.01 \, \text{mm}\) thick under standard temperature and pressure.
Step 3: Eliminating incorrect options.

• Pascal and millibar measure pressure.
• Parts per million measures concentration, not total column ozone.

Conclusion:
Thus, the correct answer is Dobson Unit.