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Testing of stability indices derived from the Meteosat Third Generation infrared sounder proxy data

Meteosat third generation infrared sounder (IRS) is an instrument that will be a part of MTG Sounding Mission (MTG-S), scheduled for launch around 2021. Its primary goal is to support global and regional numerical weather prediction models over Meteosat coverage area. Furthermore, it will provide vertical profiles of temperature and humidity every 30 minutes for each pixel scanned over the clear sky area, which gives great possibilities of using IRS data for nowcasting purposes. Similar sounding instrument, Infrared Atmospheric Sounding Interferometer (IASI) is presently operating onboard polar-orbiting satellite Metop and its data sets are used as proxy data for IRS, in order to develop and test the IRS system. It has to be noted that IRS will provide data with much better spatial coverage and temporal resolution than the instruments on board polar satellites, which enables utilization of these data for the purpose of monitoring the pre- convective environment. Analysis of stability indices derived from the IRS proxy data based on IASI data onboard Metop polar satellites is performed for days with convective activity. An analysis is done for a broader Adriatic region, including Croatia, Slovenia and northern Italy, during 2012 and 2013. Comparison between IRS proxy data and the data from the radio- soundings showed that the infrared sounder is measuring temperature and humidity more precisely in the mid-troposphere than in the layers close to the ground, or in the upper troposphere. Various stability indices, which are derived from the IRS data around the altitudes where the standard deviation of measured parameters is lower, are compared with ALADIN model data. The locations of the large probability for the development of convection according to the derived IRS indices are verified with the satellite images and lightning data for certain days. This study is demonstrating the benefits of IRS sounder in monitoring the pre-convective environment which can improve nowcasting of location and intensity of convective storms.

MTG-S; IRS; IASI; vertical profiles; stability indices

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