Image gallery: SCIAMACHY/WFM-DOAS Methane
Image gallery: SCIAMACHY/WFM-DOAS Methane |
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Here we show some pictures of the greenhouse gas methane (CH4) retrieved from the near-infrared nadir spectra of reflected and backscattered solar radiation measured by the SCIAMACHY instrument onboard the European environmental satellite ENVISAT using the retrieval algorithm WFM-DOAS developed at the University of Bremen. For more information please visite the WFM-DOAS main web page.
Carbon dioxide (CO2) and methane (CH4) are the two most important anthropogenic (man-made) greenhouse gases and contribute to global warming. The reliable prediction of future atmospheric greenhouse gas concentrations and associated climate change requires an adequate understanding of their (natural and anthropogenic) sources and sinks. SCIAMACHY on ENVISAT is the first satellite instrument whose measurements contain information on the vertical columns of both gases due to high measurement sensitivity down to the Earth surface where the major sources and sinks of these greenhouse gases are located. The vertical column of a gas is the number of molecules of this gas located in an air column which extends from the Earth's surface to the top of the atmosphere per surface area (unit: molecules/cm2). For the greenhouse gases (CH4 and CO2) we normalize the greenhouse gas columns with the corresponding (measured) number of air molecules (obtained, e.g., using oxygen (O2) measurements) to get dry air column-averaged mixing ratios or mole fractions of the greenhouse gases (unit: ppb for CH4 and ppm for CO2).
Here we show some results based on a new data set covering the years 2003-2005 generated with the retrieval algorithm WFM-DOAS version 1.0 (Schneising et al., 2008b, see list of publications ).
High values typically indicate a major source region. Methane sources are wetlands, rice, ruminants, waste handling, coal mining, and many others. As methane is long-lived atmospheric transport is very important. Therefore, high values may also appear far from source regions, especially when the region is poorly sampled for example due to persistent cloud cover. Interpretation of the maps is therefore not straight forward and is typically done using complex models.
Global map of atmospheric methane (2003-2005): Clearly visible are major methane source regions such as wetlands (e.g. Siberia, tropics) and rice fields (e.g. China):
Global map of atmospheric methane (2003):
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North polar view maps of atmospheric methane: Clearly visible are elevated methane mostly due to emissions from northern hemispheric wetlands especially during the warm summer months:
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The global distribution of atmospheric methane during 2003 (0.5 deg x 0.5 deg, shown are all data for which the WFM-DOAS quality flags indicates a successful (= high quality) measurement):
The global distribution of atmospheric methane during 2003 shown using a different color scale:
The global distribution of atmospheric methane during April-June 2003:
The global distribution of atmospheric methane during July-September 2003:
Methane over China and India:
Methane over Africa:
Methane over South America:
Methane over Australia:
Methane over North America (note: nearly no data during winter because of very strict quality filtering due to clouds and low sun elevation):
Methane over Europe and Asia (note: nearly no data during winter because of very strict quality filtering due to clouds and low sun elevation):
Methane globally:
Methane Russia:
Last modification: 16-Mar-2010
Author: Michael.Buchwitz@iup.physik.uni-bremen.de
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