Improved use of atmospheric in situ data
Ingleby, Bruce ; Isaksen, Lars ; Kral, Tomas ; Haiden, Thomas ; Dahoui, Mohamed
Atmospheric in situ observations from surface stations, aircraft and radiosondes are important both for direct use in the ECMWF data assimilation system and for diagnostics. Radiosonde and surface observations also help to control biases in the assimilation system. However, like other Earth system data, in situ observations can be complex to interpret and close attention to quality control, observation uncertainty and in some cases bias correction is needed to optimise their use. This article describes a range of recent improvements in the use of atmospheric in situ observations at ECMWF. One of these has been made possible by the gradual transition in reporting such observations from alphanumeric codes (such as TEMP and SYNOP) to Binary Universal Format for the Representation of meteorological data (BUFR): extra information in BUFR enables balloon drift to be taken into account in the assimilation of radiosonde data. A change to this effect will be implemented in the next upgrade of ECMWF's Integrated Forecasting System (IFS Cycle 45r1). Other improvements in the next IFS upgrade include better bias correction and reduced thinning of aircraft data. ECMWF has also begun to use varying uncertainty estimates for different types of radiosondes. All these changes improve the quality of ECMWF's forecasts. Further current developments include the use of solar radiation measurements from surface stations to verify predicted surface fluxes and the monitoring of radiosonde descent reports to see what use can be made of them.
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