www.sron.nl/data-access-eos-activities-1475/googleearth.html

Google Earth

On March 1, 2002, ESA launched its ENVIronmental SATellite (ENVISAT) with on-board some 10 instruments observing the Earth. One of these instruments is the Dutch-German SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY), a UV-VIS-NIR spectrometer. SRON Netherlands Institute for Space Research developed the detector modules of the instrument and is, together with the Royal Netherlands Meteorological Institute KNMI, involved in retrieval of data and their scientific interpretation.

The primary scientific objective of SCIAMACHY is the global measurement of various trace gases in the troposphere and stratosphere such as ozone, nitrogen dioxide, water vapour, formaldehyde, bromine oxide, sulfur dioxide, carbon dioxide, methane and carbon monoxide.

Combining all kinds of datasets is clearly the future also in atmospheric research. Large datasets of different origin are becoming available very rapidly now, particularly because of the growing amount of satellite data. Google Earth is the platform that makes access to all these datasets extremely easy, so easy anyone can do it. It allows to see correlation between different datasets, and you can view time series of data as movies.

The Google Earth network link below, contains several of these scientific dataproducts as produced at SRON Netherlands Institute for Space Research, and KNMI, the Royal Netherlands Meteorological Institute. If clicking on the network link below does not automatically open in Google Earth (make sure to install the latest version 4), then click 'Add' on the upper-menu, and then 'Network Link...'. Type a Name (suggested 'SCIAMACHY') and paste the link below under 'Link'.

 SCIAMACHY Google Earth network link

Several species (CO, CH4, NO2, AAI) will appear in the 'Places' menu and can be viewed by clicking on them. In order to see the variations over time of a species, select the years you want to view by clicking on the little square box in front of the year and then on the play button next to the time bar in the upper-right of the viewing window. Note this works only in the latest Google Earth version 4, so if you do not see a time-bar, uninstall your current version and reinstall the latest Google Earth.

The scientifically most interesting use of Google Earth is the possibility to instantly compare different data-sets (satellite observations and other geo-data) without having to bother about downloading data from different archives, and trying to read the differently formatted data. Google Earth Layers allows overlaying different datasets with one click on a button.
Several other interesting (external) Google Earth network links are included below, showing more satellite observations from other institutes. Note however as these were not created at SRON, so SRON can not be responsible for their availability.

MODIS Fire Counts, for example, can be easily compared with the amount of carbon monoxide (CO) as measured by SCIAMACHY. One will quickly notice that enhanced carbon monoxide levels coincide with areas suffering from large forest fires. These can be clearly seen over Alaska during the great fires of June-July 2004, or during the entire available period over Africa, where both enhanced carbon monoxide and nitrogen dioxide (NO2) coincides with the forest fires hot spots. For this latter case, also increases in Aerosol Absorbing Index (AAI) can be seen over the fires, but also over sandstorms in the Sahara. Such comparisons allow scientists to determine the (likely) sources of pollution.

Additional interesting cases can be viewed by overlaying the SCIAMACHY data with the extra geo-databases included in the link above. Enhanced methane levels correlate with the location of rice paddy fields (South-East Asia) in the growing season, and NO2 pollution is visible over highly populated areas.

A demonstration video is available here. For more information contact: Krijger"at"sron.nl .

copyright SRON Netherlands Institute for Space Research and KNMI. For more information or data access contact the individual scientists as indicated in the metadata-descriptions.