2 years of SMOS and Aquarius Brightness Temperatures Intercalibration.
Cabot, Francois1; Kerr, Yann1; Lagerloef, Gary2; Anterrieu, Eric3

SMOS mission has celebrated 3 years in orbit in early November 2012. Throughout these 3 years, it has been made clear that final quality of the geophysical retrieved products, both over land and ocean, highly depends on the brightness temperature map quality.
And because of the very specific way SMOS is acquiring brightness temperature measurements; careful attention has been given to the image reconstruction process. Yet, absolute radiometric accuracy is also a major contributor to overall performance budget at level 2, especially for ocean salinity.
Since June 2011, SMOS has been joined on orbit by Aquarius, more dedicated to ocean surface issues.
In order to prepare for joint products, one needs to guarantee a very good consistency between the brightness temperatures retrieved by the two instruments and first experiments to this end have already been conducted over oceans [1], [2].

The comparison relies on two approaches:
i) Making use of a stable target to assess the consistency and stability of both data sets. This is done over the area surrounding Dome Concordia in Antarctica. After careful selection and filtering, statistics of the comparison are retrieved along with long term trends in both data sets.
ii) Once every so often, both satellites overpass the same area within a very short time period. Due to different inclinations these alignments occur essentially along the equator, but over different surfaces, giving access to wide dynamic range in brightness temperature. This method has been introduced and tested over limited data sets and extended in the present paper. [3]

This presentation will summarize the results of these comparisons over the whole lifetime of both missions, giving special attention to comparison methods.

Various improvements have been incorporated in processing on either side. Impact of these improvements and effectiveness of the successive processor versions can be evidenced through these comparisons.
Complete results of these comparisons over ice, land and ocean will be detailed and analyzed.
Performance assessment of both instruments will also be presented based on these results.

[1]. Lagerloef, G., Kerr, Y., Anterrieu, E., Jackson, T., Bindlish, R., Kao, H., Aquarius Status And SMOS Cross-Calibration Over Oceans, EGU General Assembly 2012, 22-27 April, 2012, Vienna, Austria.
[2]. Anterrieu E., Kerr Y., Cabot F., Lagerloef G., LeVine D., A synergy between SMOS & AQUARIUS: Resampling SMOS maps at the resolution and incidence of AQUARIUS. IGARSS 2011, 24-29 July 2011, Vancouver, Canada.
[3]. Cabot F., Anterrieu E., Picard G., Macelloni G. and Kerr Y., Validating SMOS brightness temperatures over land, MicroRAD2012, 5-9 March 2012, Frascati, Italy.