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Methane (CH4)
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Tropospheric
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monitoring |
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NO2
- global - central Europe CH2O - global CO - global |
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UV
- UV index - UV dose |
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related gases |
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Ozone
- total column - global field - ozone bulletin - ozone profiles BrO - global field |
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Aerosol
- AOD - aerosol index Methane - global Clouds - cloud info |
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emissions |
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Volcanic plume
- SO2 & AAI |
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23 January 2004
Product services of TEMIS: Contents of this page:
- NOTE:
-
the data product Methane has been removed
from the TEMIS project.
Methane
Methane, CH4, is a greenhouse gas and the primary gas in Kyoto protocol. Large increases in methane concentration are observed since pre-industrial (a 150% increase, from 750 to 1750 ppb).Methane is going to be a new product: it will be derived from SCIAMACHY near-infrared channels. What will be delivered are total methane columns with an anticipated accuracy of about 1%. As the example below shows, the variability due to the uncertainties in the emissions is a 1-2%, and so detection of emissions is perhaps possible.
Problematic is that there are large uncertainties in the estimates of
methane sources (e.g. fossil fuels, cattle, rice agriculture,
landfills, wetlands) and that methane is a well-mixed gas in the
troposphere.
Another aspect is that the methane column value varies with the
surface pressure (i.e. with the local surface height),
which has to be corrected for to be able to compare column values.
Model example
The following graph shows the result of an explicit modelling of methane emissions for June 1997 in Dobson Units (DU). Note that the step between the contours 20 DU or about 1-2%. The regions of high methane emissions in Eastern Europe and Asia are clearly visible.
The chemistry-transport model that produced the above image was run for 10
days, with the approriate meteorological information. And the same was done
with a 50% increase in the emissions (a reasonable estimate of the
variability of the emissions). The following graphs shows the difference
after 10 days between the methane columns of these two model runs. Note
that the scale runs up to 20 DU or 1% of the total methane column as showns
in the picture above. In other words, the variability in the methane column
due to uncertainties in the methane emissions is around 1%. (The moderately
high values above Central Afrika and South America are due to biomass
burning events.)
Some 10-20% of the methane column is in the stratosphere and its variability
is a few percent, as the following graph shows.
