Global Air Quality An Imperative for Long-Term Observational Strategies (2001) / Chapter Skim
Currently Skimming:
Current Capabilities for Observing Global Air Quality Changes
Current Capabilities for Observing Global Air Quality Changes
Pages 20-31
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From page 20... ...
It also limits the value of the developments cited above, since a strong observational base is needed to test and improve model predictions, and to provide a longerterm context for the observational "snapshots" obtained through intensive field campaigns. Current tropospheric observational programs include global and regional networks designed to measure background atmospheric composition at selected remote sites; regulatory monitoring networks that analyze day-to-day air quality 20
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From page 21... ...
. These networks employ in situ automated measurements as well as flask sampling, which permits centralized analyses of samples from different sites and helps verify the relative calibrations of the in situ measurements.
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From page 22... ...
This issue needs to be addressed in order to make optimal use of existing networks. In the United States and many other countries, air quality monitoring networks provide extensive ambient measurements of pollutant species.2 However, there are at present serious limitations to the use of these data in the study of large-scale atmospheric chemical changes.
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From page 23... ...
Finally, aircraft provide a valuable platform for studying atmospheric chemical composition over a wide range of altitudes. The use of aircraft equipped with a large array of analytical instruments are becoming common in intensive field campaigns for measuring a comprehensive suite of trace gases and reactive species in the upper troposphere and lower stratosphere.
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From page 24... ...
Satellite instruments that could potentially be used for determination of longterm trends in tropospheric chemistry include the Global Ozone Monitoring Experiment (GOME) instruments on the European Space Agency' s ERS-2 satellite and the Eumetsat Metop satellites (ca.
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From page 25... ...
. In situ measurements can provide useful information about which aerosol types predominate in a given region, but there are serious gaps in existing aerosol observational programs.
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From page 26... ...
Sporadic data from airborne field campaigns have been used to help understand the vertical distribution of aerosols, and balloon-borne measurement programs have provided valuable information on mid- and upper-tropospheric
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From page 27... ...
UT column column column column Az=lkm (UT) column Az=lkm column Definitions: UT = upper troposphere; Az is to the instrument vertical resolution; 'column' is the vertically integrated abundance of a species; 'column +' means that some information on vertical distribution is provided in addition to total column abundance; 'limb' and 'nadir' refer to observations made (respectively)
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From page 28... ...
However, it is difficult to obtain quantitative information on aerosol type and mass flux from such images, largely because of the complex and poorly characterized radiative properties of most aerosols. Recognition of the important role played by aerosols in climate forcing and in air quality has led to significant international support for satellite missions aimed at improving current observational capabilities.
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From page 29... ...
Aerosol optical thickness, a common satellite data product, has limited utility as input to models for validation purposes; it is likely that combining satellite information with routine and intensive surface observations will be more useful. Continued investigations into coordination of efforts for example, co-locating satellite validation monitoring sites with existing observational network sites, and ensuring continuity of the longer-term network data should be undertaken and supported.
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From page 31... ...
Coordinating measurements among various remote sensing and in situ platforms, and integrating these measurements with detailed modeling studies presents an immensely complex research challenge. This approach is being developed in focused process studies such as the Southern Hemisphere ADditional OZonesondes project (SHADOZ, which coordinates a network of balloon-borne ozonesondes with TOMS remote sensing measurements)
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