Why do we celebrate this day?

Over three decades ago, protection of the depleting ozone layer was made a global priority and the “Montreal Protocol” was introduced. This international protocol was designed so that the production of various chemicals released into the atmosphere, mainly chlorofluorocarbons (CFCs) would be phased out in order to halt further depletion.

According to the United Nations (UN), the Montreal Protocol has:

led to the phase-out of 99 percent of ozone-depleting chemicals in refrigerators, air-conditioners and many other products.

The ozone layer acts like a ‘shield’, filtering the Sun’s ultraviolet radiation and protecting us from its harmful effects. Ozone depletion was first observed by scientists in the late 1970s and resulted in a ban on the manufactured chemicals which cause it, eventually resulting in the introduction of the treaty which has been ratified by all of the world’s 197 countries.

As a result of this international agreement, ozone depletion has stopped and the ozone layer is slowly recovering. It is therefore important to recognise this occasion by marking it as a special day to be celebrated, but also to continue to educate the public and remind world leaders, large corporations, and key decision makers to stay vigilant on issues such as the health of our atmosphere.

Kenneth Holmlund, Chief Scientist at EUMETSAT commented:

This outcome demonstrates the capabilities we have to act and affect our environment in a positive manner. Recent studies, however, revealed an unexpected and persistent increase in global emissions of ozone-depleting CFC-11, which subsequent analysis attribute to CFC-sources in Eastern Asia. It is therefore imperative to stay vigilant and to continue monitoring our environment, in this case the ozone layer.

How do we monitor ozone?

Satellites such as EUMETSAT’s Metop series of three polar-orbiting weather satellites play a key role in monitoring global ozone.

With their on-board Global Ozone Monitoring Experiment–2 (GOME-2) instrument, the Metop satellites are able to get a detailed picture of the total atmospheric content of ozone and the vertical ozone profile in the atmosphere.

Federico Fierli, Atmospheric Composition Training Officer at EUMETSAT discusses the GOME-2 instrument:

In the GOME-2 images below, you can see the current ozone status compared with one year ago. This year, the polar vortex where the ozone hole takes place was disturbed and displaced with respect to the South Pole. This is due to an unusual warming in the stratosphere that weakens the winter circulation, resulting in a weaker ozone depletion up until now. 

For additional details, take a look at this article by the Copernicus Atmosphere Monitoring Service (CAMS).

Data taken from the GOME-2 instrument on board both Metop-A & -B and compiled by the AC-SAF database.

He continued:

A long-term observation programme is crucial to understand and monitor the ozone evolution. The Intergovernmental Panel on Climate Change (IPCC) – which is the United Nations body for assessing the science related to climate change – integrate ozone trends in their reports that constitute the basis for world-scale decisions on the climate. An example report shows the evolution of the ozone hole in the Southern Hemisphere with a fast drop observed by satellites, including GOME, in the 80s and 90s and with a stabilisation in the last two decades (see below image).

Monitoring of the ozone layer using EUMETSAT data

The EUMETSAT Satellite Application Facility on Atmospheric Composition Monitoring (AC SAF) is part of the distributed EUMETSAT ground segment. It is responsible for developing retrieval algorithms, processing and archiving data as well as disseminating data to users.

Seppo Hassinen, AC SAF Project Manager said:

The data measured with GOME-2 and the Infrared Atmospheric Sounding Interferometer (IASI) instruments form long, continuous data records starting from 2007 and continuing, with EUMETSAT Polar System – Second Generation (EPS-SG) data, until sometime in the late 2030s. These data records can be used to monitor the recovery of the ozone layer in the future.

The Antarctic ozone hole, as seen by the IASI instrument on board the Metop satellites. This animation shows the mean October value for the years 2007-2018. This long-time record clearly shows the year-to-year variations.

This animation shows the EUMETSAT AC SAF GOME-2 total ozone data, assimilated into the ROSE 3D Chemistry-Transport Model at the German Aerospace Center (DLR). This animation reveals the ozone hole development over Antarctica for the years: 2015, 2016, 2017 and 2018.

These large, yearly variations are caused by meteorological and dynamical conditions. The large minimum area over Antarctica is due to stable polar-wind circulation around this continent and thus, long continuing ozone depletion inside the area. In the Northern Hemisphere, the dynamical field is more chaotic and so, a similar, stable situation cannot normally be formed.

AC SAF
The AC SAF develops, produces, archives, validates and disseminates ozone and atmospheric chemistry products, to support the services of the EUMETSAT Member States in weather forecasting, as well as monitoring of ozone depletion, air quality and surface UV radiation.

The AC SAF consortium members develop radiative transfer calculation methods and other algorithms for creating atmospheric remote-sensing data from the polar-orbiting satellites Metop-A, -B and -C. They also validate the data products and provide associated dissemination and user services.

AC SAF produces near real-time and offline data products including total ozone, trace gas total columns (for example CO, NO2, SO2, HCHO and BrO), tropospheric NO2 and O3, coarse and high-resolution ozone profiles, absorbing aerosol index and photolysis and UV radiation.

Improving future capabilities and tackling the future

The EPS-SG satellites will follow in the Metop heritage-footsteps by providing global monitoring of ozone and other atmospheric trace gases with enhanced accuracy. The EPS-SG satellites are expected to be operational for approximately 15 years, ensuring future long-term monitoring of the planet.

Meteosat Third Generation (MTG) is EUMETSAT’s next generation of geostationary satellites. The MTG-S (sounding) line will establish a world first, hyper spectral infrared sounding (IRS) capability in geostationary orbit that will deliver vertical profiles of temperature and moisture every 30 minutes over Europe.

MTG is one of the most innovative satellite systems under development in Europe and aims to deliver new capabilities for the real-time monitoring of atmospheric profiles, air quality (e.g. tropospheric ozone and carbon monoxide) and dispersion of atmospheric pollution.

EUMETSAT will generate products derived from MTG and EPS-SG satellite data for the benefit of society and the planet.

32 Years and Healing

This year’s theme reminds us why it is so important to work together in order to achieve positive results – this is only possible if we collaborate on a global scale and make big changes.

The UN also stated that:

The latest Scientific Assessment of Ozone Depletion completed in 2018, shows that, as a result, parts of the ozone layer have recovered at a rate of 1-3% per decade since 2000. At projected rates, Northern Hemisphere and mid-latitude ozone will heal completely by the 2030s.

The Southern Hemisphere will follow in the 2050s and Polar Regions by 2060. Ozone layer protection efforts have also contributed to the fight against climate change by averting an estimated 135 billion tonnes of carbon dioxide equivalent emissions, from 1990 to 2010.

According to CAMS, the “2019 ozone hole could have the smallest area of any Antarctic ozone hole since the mid-eighties”. Read more here.

The planet has a remarkable way of recovering – if we let it.

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Posted by Natalie Lunt

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