Carbon tetrafluoride (CF4) from MIPAS measurements
Chiara Piccolo(1) and Anu Dudhia(2)
(1) University of Oxford, Clarendon Laboratory, OX1 3PU Oxford, United Kingdom
(2) University of Oxford, Clarendon Laboratory, OX1 3PU, United Kingdom
Carbon tetrafluoride (CF4 or FC-14) is produced mainly as a byproduct of
the manufacture of aluminum.
CF4 does not harm the stratospheric ozone layer, but it is a powerful
greenhouse gas due to its absorption characteristics in the infrared.
It is an inert tracer and has a very long lifetime in the stratosphere
(probably many thousands of years).
Thus it is expected to be uniformly mixed both geographically and vertically
around the globe.
Measurements of the fluorocarbon reveal that it is essentially independent of
altitude up to at least 50 km (e.g. ATMOS observations).
The MIPAS experiment, onboard Envisat satellite, launched on 1st March 2002,
is a high resolution Fourier Transform Spectrometer observing infrared
limb emission spectra. From these measurements, profiles of atmospheric
pressure, temperature and several species can be retrieved. MIPAS spectra
contain also information on carbon tetrafluoride.
In the present study we use Envisat-MIPAS to retrieve carbon tetrafluoride
and we quantify its concentration as a function of altitude in the altitude
range 6-68 km. Here we present new measurements of CF4 mixing ratios at high
altitude, where few measurements have been made in the past, based on two years
of MIPAS data.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,