Geophysical validation of temperature retrieved by the ESA processor from MIPAS/ENVISAT atmospheric limb-emission measurements M. Ridolfi1, U. Blum2, B. Carli3, V. Catoire4, S. Ceccherini3, H. Claude5, C. De Clercq6, K. H. Fricke7, F. Friedl-Vallon8, M. Iarlori9, P. Keckhut10, B. Kerridge11, J.-C. Lambert6, Y. J. Meijer12, L. Mona13, H. Oelhaf8, G. Pappalardo13, M. Pirre4, V. Rizi9, C. Robert4, D. Swart12, T. von Clarmann8, A. Waterfall11, and G. Wetzel8 1Dipartimento di Chimica Fisica e Inorganica, Università di Bologna, Italy 2Fraunhofer-Institut für Naturwissenschaftlich-Technische Trendanalysen, Euskirchen, Germany 3Istituto di Fisica Applicata "Nello Carrara", Consiglio Nazionale delle Ricerche, Firenze, Italy 4Laboratoire de Physique et Chimie de l'Environnement, CNRS – Université d'Orleans, Orleans, France 5DWD, Observatory Hohenpeissenberg, Germany 6Institut d'Aéronomie Spatiale de Belgique, Bruxelles, Belgique 7Physikalisches Institut, Universität Bonn, Bonn, Germany 8Forschungszentrum Karlsruhe, IMK, Germany 9CETEMPS – Dipartimento di Fisica, Università de L'Aquila, L'aquila, Italy 10Service d'Aeronomie, Institut Pierre Simon Laplace/UVSQ, Verrieres-Le-Buisson, France 11Earth Observation and Atmospheric Science, Space Science and Technology Department, Rutherford Appleton Laboratory, Oxfordshire, UK 12National Institute for Public Health and the Environment, RIVM – LVM, Bilthoven, The Netherlands 13Istituto di Metodologie per l'Analisi Ambientale, Consiglio Nazionale delle Ricerche, Tito Scalo, Potenza, Italy
Abstract. The Michelson Interferometer for Passive Atmospheric Sounding
(MIPAS) has been operating since March 2002 onboard of the
ENVIronmental SATellite of the European Space Agency (ESA). The high
resolution (0.035 cm−1 full width half maximum,
unapodized) limb-emission measurements acquired by MIPAS in the
first two years of operation have very good geographical and
temporal coverage and have been re-processed by ESA with the most
recent versions (4.61 and 4.62) of the inversion algorithms. The
products of this processing chain are pressures at the tangent
points and geolocated profiles of temperature and of the volume
mixing ratios of six key atmospheric constituents: H2O,
O3, HNO3, CH4, N2O and NO2.
As for all the measurements made with innovative instruments and
techniques, this data set requires a thorough validation. In this
paper we present a geophysical validation of the temperature
profiles derived from MIPAS measurements by the ESA retrieval
algorithm. The validation is carried-out by comparing MIPAS
temperature with correlative measurements made by radiosondes,
lidars, in-situ and remote sensors operated either from the ground
or stratospheric balloons.
The results of the intercomparison indicate that the bias of the MIPAS
profiles is generally smaller than 1 or 2 K depending on altitude.
Furthermore we find that, especially at the edges of the altitude
range covered by the MIPAS scan, the random error estimated from
the intercomparison is larger (typically by a factor of two to three)
than the corresponding estimate derived on the basis of error
In this work we also characterize the discrepancies between MIPAS
temperature and the temperature fields resulting from the analyses
of the European Centre for Medium-range Weather Forecasts (ECMWF).
The bias and the standard deviation of these discrepancies are
consistent with those obtained when comparing MIPAS to correlative
measurements; however, in this case the detected bias has a peculiar
behavior as a function of altitude. This behavior is very similar to
that observed in previous studies and is suspected to be due to
vertical oscillations in the ECMWF temperature. The current
understanding is that, at least in the upper stratosphere (above
≈10 hPa), these oscillations are caused by a discrepancy
between model biases and biases of assimilated radiances from
primarily nadir sounders.
Citation: Ridolfi, M., Blum, U., Carli, B., Catoire, V., Ceccherini, S., Claude, H., De Clercq, C., Fricke, K. H., Friedl-Vallon, F., Iarlori, M., Keckhut, P., Kerridge, B., Lambert, J.-C., Meijer, Y. J., Mona, L., Oelhaf, H., Pappalardo, G., Pirre, M., Rizi, V., Robert, C., Swart, D., von Clarmann, T., Waterfall, A., and Wetzel, G.: Geophysical validation of temperature retrieved by the ESA processor from MIPAS/ENVISAT atmospheric limb-emission measurements, Atmos. Chem. Phys., 7, 4459-4487, doi:10.5194/acp-7-4459-2007, 2007.