REFIR data
Since only one flight of the MARSCHALS instrument provided useful data, it was decided, in agreement with ESA, to perform instead the analysis of measurements made by an other instrument. The selected instrument is a Fourier transform spectrometer that observes the emission of the atmosphere at nadir from a balloon-borne platform. Spectra are measured in the spectral region from 100 to 1400 cm-1 with a spectral resolution of 0.5 cm-1. The instrument is named REFIR-PAD.
Given the different spectral region and different geometry of observation the MARC code was partially modified in order to make possible its use with the REFIR-PAD measurements. The retrieved quantities are the profiles of temperature and water vapour and the brightness temperature of the Earth surface. Figure 9 and Figure 10 show maps of the vertical distribution of the temperature and water vapour quantities and of their biased/unbiased error wrt the sequence number.
From the retrieval of each scan it is possible to obtain 8 degrees of freedom about temperature from 1 to 33 km and 7 degrees of freedom about water from 1 to 17 km. The temperature measurements do not add significant information to the already existing information provided by ECMWF, but the water vapour measurement can usefully complement ECMWF data.
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Figure 9 . Map of the temperature retrieved profile (top) and of the ratio biased/unbiased error (bottom). White dots indicate the altitude retrieval grid. |
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Figure 10 . Map of the water vapour retrieved profile (top) and of the ratio biased/unbiased error (bottom). White dots indicate the altitude retrieval grid.
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Tanks to the different observation geometries, the measurements of water profile made by REFIR-PAD are complementary to those made by MARSCHALS. Indeed, both instruments made measurements in a tropical region and only 1.6 degrees of freedom of REFIR-PAD measurements are in the altitude range where MARSCHALS makes observations, while the others (about 5.4) are at lower altitudes where MARSCHALS cannot observe because of water vapour absorption.
The developed code provided a robust and reliable analysis of two different instruments with a comprehensive characterisation of their results and with the identification of their future potentialities. Indeed both instruments provide innovative sounding techniques for the study of the lower atmosphere.
