Studying the chemistry of the atmosphere

Atmospheric weather testing. Photo: Dan Smale
30 October 2023

New Zealand scientists have been measuring atmospheric chemistry at Arrival Heights in Antarctica for four decades. They have been instrumental contributors to international assessments on ozone depletion and climate change. New Zealand's scientists are at the forefront of atmospheric science, and their datasets hold vital importance worldwide.

Antarctica is a unique location for studying atmospheric gases because it is isolated from sources of local pollutants. This means that any shifts in the chemistry arise primarily from anthropogenic causes originating elsewhere in the world. A prime example of this is the ‘Ozone Hole’. NIWA has a suite of remote sensing and air sampling instruments at Scott Base and Arrival Heights, Antarctica, that collect data on the ozone layer, atmospheric chemistry processes, and greenhouse gases. The oldest instrument has been in operation since 1982 to the present day.

The ozone layer, an invisible protective shield encircling the planet, absorbs nearly all of the sun's harmful ultraviolet light (UV radiation). Ozone molecules in the stratosphere, a layer positioned 30 to 50 kilometres above the Earth's surface, absorb the majority of this radiation. Without ozone, the sun's intense UV radiation would sterilize the Earth's surface, endangering all creatures and plants that inhabit it.

If you live in New Zealand, you will have surely felt the effects of the ozone hole in the form of scarlet-red, sunburned skin from the summer sun at least once in your lifetime. The ozone hole is a thinned area in the ozone layer above Arrival Heights, Antarctica, that forms every year in spring and then closes again in summer. It was formed due to Chlorofluorocarbons (CFCs), chemicals that were once prevalent in products worldwide. CFCs led to accelerated rates of ozone destruction, disrupting the natural balance of ozone and resulting in higher UV levels, which in turn led to high rates of skin cancer in New Zealand. CFCs were banned in 1987 as part of the international Montreal Protocol, one of the most successful environmental actions taken by the international community.

The data collected at Arrival Heights is one of the crown jewels of Antarctic atmospheric research. The ground-based observations look at the ozone hole and associated chemistry. The instruments function like upside-down satellites; instead of looking down, they look up. Data gathered from these instruments helps to illustrate the changes and evolution of the ozone, used to validate satellite measurements, inform the public of risks, and measure the current environmental events’ effects on the ozone.

The ozone layer is considered one of the nine planetary boundaries for Earth, a threshold beyond which humankind cannot survive. This means that if the ozone threshold is crossed, it will lead to irreversible changes in the environment and jeopardize human survival.

Currently, escalating greenhouse gases from climate change pose a threat to ozone and UV levels. The stratosphere is sensitive to changing temperature and greenhouse gases, such as water vapour, which creates a cooling effect, promoting ozone depletion through the formation of clouds. Ozone also influences surface winds via effecting large scale weather patterns (such as the Southern Annular mode). Changes in wind leads to changes in ocean upwelling and carbon uptake, eventually impacting on climate change, oceanic ecosystems and the food chain.

Ozone plays a massive role in maintaining life on Earth at sustainable levels. Therefore, continuous, long-term datasets like these are absolutely vital for understanding and monitoring, and to assist policymakers in implementing accurate measures to protect this planetary boundary!

Information on the instruments and data collected by NIWA has just been added to Antarctica New Zealand's metadata catalogue (antcat) and is accessible here.

Image: ‘Chocks way!’ Penny Smale (NIWA) launches a balloon, from Scott Base, with scientific equipment dangled beneath to measure the amount of ozone, water vapour and particulate matter in the stratosphere. Photo: Dan Smale