Seasonal ozone minimum over India During which month is the total column ozone over India generally observed to be at its lower seasonal level?

Introduction / Context:
Stratospheric and total column ozone exhibit seasonal cycles influenced by stratospheric circulation, photochemistry, and regional meteorology. In tropical and subtropical regions such as India, these cycles lead to months with relatively lower ozone compared to annual means, which has implications for ultraviolet radiation reaching the surface.

Given Data / Assumptions:

• Typical climatology for Indian latitudes (tropical to subtropical).
• Question refers to general seasonal tendency, not an extreme depletion event.
• Answer focuses on broad national pattern rather than a single station anomaly.

Concept / Approach:
In many Indian locations, lower total column ozone is observed during late winter, with values tending to rise into spring. This seasonal minimum often appears around January–February depending on latitude. Among the choices, February best represents that late-winter lower period, while mid-monsoon (July) and late autumn (December) typically do not correspond to the broad national minimum indicated in educational references.

Step-by-Step Solution:

Verification / Alternative check:
Long-term satellite and ground-based records (Dobson/ Brewer) generally show late-winter troughs in total ozone over much of India, consistent with February being a lower month.

Why Other Options Are Wrong:

• July: Monsoon circulation alters patterns; not the canonical minimum month.
• April: Often higher than winter as spring buildup occurs.
• December: Early winter; many regions see lower values slightly later.
• September: Post-monsoon period; not generally the national minimum.

Common Pitfalls:
Confusing Antarctic “ozone hole” timing with tropical seasonal variability; extrapolating single-city data to the entire subcontinent incorrectly.

Final Answer:
February