National Physical Laboratory


Environmental Monitoring - History

A history of environmental monitoring at NPL.

How Concorde launched NPL's research into stratosperic ozone depletion and climate change


Environmental research began at NPL over 25 years ago when the Anglo-French Concorde took to the skies - the first aircraft to fly directly in the stratosphere. At that time there were plans for 'fleets' of these aircraft to fly the lucrative transatlantic routes, however the USA became very concerned that these would pollute the global stratosphere and cause irreparable ozone depletion. As a result, DTI funded NPL to use newly developed far-infrared spectrometry to make measurements in the stratosphere from the 'prototype' Concorde during its round the world promotional cruises - in order to enhance the European science base. This involved challenging measurement technology applied to stratospheric science, also coupled with requirements to arrange liquid nitrogen in difficult locations worldwide. Part of Concorde 002 still has a special fused silica window installed by NPL from this era to provide infrared transmission.

Stratospheric Ozone Depletion

This issue of Concorde pollution, however, soon became marginalized by the much more serious issue of ozone depletion due to chlorofluorocarbons (CFCs-freons), which were ubiquitous in developed countries in refrigeration, foam blowing etc, which were predicted to cause serious stratospheric ozone depletion. NPL continued to provide an essential UK contribution, by using sensitive cryogenically-cooled spectrometers for high altitude balloon-borne measurements, in an increasingly international research effort. A much better awareness of the chemical complexity of stratospheric ozone depletion emerged as a result of this research, and the question of greenhouse gases and climate change began to emerge as an important related global long-term issue. The measurements obtained at this time were used underpin complex global 3-D computer models being developed to enable future predictions. However, such models were flawed at that time, did not contain all the key physio-chemical ingredients, and failed to provide valid predictions. Instead, it was left to measurement science, in which NPL continued to play an important role, to set atmospheric science back onto a sounder footing.

About this time, the Antarctic 'Ozone Hole' was measured by UK scientists, ironically after the USA had programmed a satellite deployed to monitor global ozone depletion to ignore results on ozone depletion if they were outside pre-specified limits - another example of where scientific preconceptions have been modified by measurement science. The experimental results obtained in the Antarctic produced a new generation of atmospheric science - bringing in 'heterogeneous chemistry' on particles as the main cause of major ozone depletion. International protocols emerged rapidly as the scientific research pointed at CFCs as the main cause. This led to present day key issues of stratospheric ozone depletion at northern polar and mid-latitudes caused by man-made pollution and the related on-going scientific issue of global warming - which is now subject to international protocols.

NPL currently plays a wide role in these issues. We have developed advanced spectroscopic instrumentation including a reference travelling standard FTIR for the Network for Detection of Stratospheric Change. This is a global network of research groups around the world making continuous long-term (20+ years) ground based atmospheric measurements, to monitor trends and use for satellite validation. This reference instrumentation uses a well characterised high resolution spectrometer to measure the concentration profiles of a wide range of key atmospheric species involved in stratospheric and climatic change, and NPL's research ensures that these measurements are accurate, and intercomparable, and can be used for detecting long-term trends.

Climate Change - Global Warming

NPL also employed other optical remote sensing technologies developed at NPL to provide DETR with a robust inventory for the emissions of greenhouse gases from all UK landfill sites. This has fed into expert Working Groups of the Intergovernmental Panel on Climate Change (IPCC), which is committed to reducing emissions. Recently, the connection between stratospheric ozone depletion and climate change have been the focus of a number of large international scientific campaigns, and in the most recent THESEO 2000, new flexible, lightweight NPL spectroscopic instrumentation was used for high spatial resolution measurements of stratospheric tracers and greenhouse gases - yielding new insights into the chemistry of ozone depletion and into large scale atmospheric transport processes, and providing data which is being used to feed into and validate three-dimensional predictive computer models.


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