Observation of large and all-season ozone losses over the tropics

TL;DR

This study identifies a large, persistent ozone hole over the tropics since the 1980s, comparable in depth to the Antarctic ozone hole, with significant implications for global UV exposure and climate.

Contribution

It reveals the existence of a large, all-season tropical ozone hole and links it to the cosmic-ray-driven electron reaction model, suggesting a common mechanism with Antarctic ozone depletion.

Findings

Tropical ozone hole area is about seven times larger than Antarctic O3 hole.

Approximately 80% of normal ozone is depleted at the tropical O3 hole center.

The tropical O3 hole can affect 50% of Earth's surface area with increased UV radiation.

Abstract

This paper reveals a large and all-season ozone hole in the lower stratosphere over the tropics (30degN-30degS) since the 1980s, where an O3 hole is defined as an area of O3 loss larger than 25% compared with the undisturbed atmosphere. The depth of this tropical O3 hole is comparable to that of the well-known springtime Antarctic O3 hole, whereas its area is about seven times that of the latter. Similar to the Antarctic O3 hole, approximately 80% of the normal O3 value is depleted at the center of the tropical O3 hole. The results strongly indicate that both Antarctic and tropical O3 holes must arise from an identical physical mechanism, for which the cosmic-ray-driven electron reaction (CRE) model shows good agreements with observations. The whole-year large tropical O3 hole could cause a serious global concern as it can lead to increases in ground-level ultraviolet radiation and affect 50% of Earth's surface area, home to approximately 50% of the world's population. Moreover, the presence of the tropical and polar O3 holes is equivalent to the formation of three 'temperature holes' observed in the stratosphere. These findings will have significances in understanding planetary physics, ozone depletion, climate change, and human health.