Watching the animation of the annual reopening of the Ozone hole in the austral spring reminds us to the damage mankind has caused to our planet’s atmosphere through the industrial release of chlorofluorocarbons in the past. This visualization has been created at DLR from a 25 years long European satellite data series from Global Ozone Monitoring Experiment (GOME) type instruments which are hosted in the archives of EOC. The quarter-of-a-century long data-time-series is now continued by a new satellite starting to deliver data.
Luckily this dataset documents not only damage, but contains as well good causes for hope: Trends derived from this long time-series make DLR scientists today confident, that the measures taken in the past in combined international efforts to protect our globe’s ozone layer proof to be effective. In particular, first signs of recovery of the ozone layer become evident today.
Satellite measured time-series as a key to address complex scientific questions
Ozone shows a strong natural variability and is subject to complex feedback mechanisms between atmospheric dynamics and climate change. That is why trends can only be detected and proofed to be statistically reliable when looking at carefully homogenized long-term time series of satellite measurements like the “GOME-type Total Ozone Essential Climate Variable” (GTO-ECV).
Annual (1995-2019 ) extent of the ozone hole over the Antarctic in October derived from the GTO-ECV data time series: While the large dimension of the ozone hole as it can be seen for the 1990s later is seldom reached, the data clearly document the overall high inter-annual variability of the phenomenon. This makes evident why well-curated long-term time series have such high relevance for monitoring the evolution of the ozone layer.
GOME was the first European atmospheric composition sensor, launched onboard the ERS-2 satellite 25 years ago in April 1995. Since ever then, the torch of continuous monitoring of atmospheric trace gases like ozone has been handed over to ENVISAT and later to the MetOp satellites series, as well as lately to the Copernicus Sentinel-5 Precursor mission. Thus it is good news that MetOp-C, now secures the extension of the GOME-type data record at least until 2025. Since a few days the ozone data of the C-unit are – as part of a pre-release - already feed into the map layers presented at EOC’s Geoservice portal, to allow users to have a ‘first glance’ at them. The MetOp-C full data products currently still undergo a final review. Official release of this products to public is expected within a few weeks.
DLR as a key player in the “GOME team” from the beginning on
DLR-EOC has, together with numerous international partners, been involved into the GOME story right from the beginning and on various levels:
On the technical level, all started in the 1990s when DLR on behalf of ESA overtook responsibility within the development and operation of the payload data ground segment of the GOME type instruments onboard the ERS-2 and ENVISAT missions. Since more than a decade now, DLR is also a key contributor to the Application Ground Segment of the GOME type instruments, within the “Satellite Application Facility on Atmospheric Composition Monitoring” (AC-SAF) run by EUMETSAT.
Moreover, DLR plays an important role in the long-term preservation of GOME-type data in the German Satellite Data Archive (D-SDA), curing them there and delivering them to scientists and the general public: The trace gas and cloud properties data computed from the MetOP satellites get not only pushed to EUMETSAT’s data centre, but are also offered free of cost via DLR’s own catalogue frontends as the ATMOS Portal , the EOWEB GeoPortal and the EOC Geoservice portal.
On the scientific side, DLR has made prominent contributions on retrieval algorithms and processor systems in order to retrieve geophysical quantities from GOME-type instruments. Not the only one, but prominent amongst them is the “GOME-type Total Ozone Essential Climate Variable” GTO-ECV, based on the total ozone from all European UV sensors. DLR is responsible for continuously cross-calibrating and updating this data record in close cooperation with colleagues at the Royal Belgian Institute for Space Aeronomy (BIRA). This way it opens like a key the door to the information contained in the quarter-century spanning GOME-type data record curated and kept open and accessible in DLR archives.