Inversion problems and data assimilation

Institute for Applied Physics "Nello Carrara"
Italian National Research Council
Department of Earth Observation

Inversion Problems and Data Assimilation

MIPAS on ENVISAT

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is an high resolution Fourier Transform Spectrometer developed by ESA for the detection of limb emission spectra in the upper atmosphere.

MIPAS has been successfully launched on board Envisat-1, on 1^st March 2002. It detects the atmospheric limb emission over a wide spectral interval in the middle infrared region.

Up to now MIPAS mission can be divided in 3 parts:

measurements from June 2002 to March 2004
measurements on August - September 2004
measurements from January 2005 on

The characteristics of the instrument that are common to the different periods of measurements are summarised in the following table:

Type	Parameters
Pointing
Instantaneous Field of View	3 x 30 km^₂ (height per width, at 10 km tangent altitude)
Elevation pointing	5 ... 210 km (tangent altitude)
Spectral
Spectral range	685-970 cm^-1, 1020-1170 cm^-1, 1215-1500 cm^-1, 1570-1750 cm^-1, and 1820-2410 cm^-1
Radiometric
Radiometric sensitivity NESR	50, 40, 20, 6 and 4.2 nW/cm²/sr/cm^-1, respectively for the above spectral ranges

The characteristics distinguishing the measurements in the different periods are the spectral resolution and the # of spectra per standard elevation scan.

The measured middle infrared emission spectra contain features of most atmospheric constituents. Therefore, a series of spectra measured in the limb-scanning configuration can be processed to determine the volume mixing ratio profiles of numerous atmospheric trace species.

The retrieval of pressure and temperature, as well as the volume mixing ratio of six high priority species, namely O₃, H₂O, HNO₃, CH₄, N₂O and NO₂, are routinely performed in near real time.
Official Site: http://envisat.esa.int/instruments/mipas/