|Title||ECMWF study to quantify the interaction between terrestrial and space-based observing systems on Numerical Weather Prediction skill|
|Year of Publication||2012|
|Authors||Radnóti, G, Bauer, P, McNally, A, Horanii, A|
|Secondary Title||Technical Memorandum|
The subject of the present study is the evaluation of the interaction between terrestrial and spacebased observing systems and thus focuses on the inter-dependence that is common to all current operational NWP systems.The study also addresses selected recommendations that were issued by the WMO expert team on the evolution of the global observing system (ET-EGOS) at its meeting in December 2009. To reach this goal different Observation System Experiments (OSEs) have been perfomed and evaluated. The main work packages presented in the study are: 1. Investigation of the impact of a thinned terrestrial observing system on radiance bias correction anchoring (OSEs with and without GPSRO and with full and less dense conventional observing system) with special focus on: the synergy between radiosondes and GPSRO as anchors (with resepect to temperature); the question of what radiosonde coverage is needed in the stratosphere, to which height, and for which latitude ranges; the synergy between ships/buoys and GPSRO as anchors (with respect to surface pressure). 2. Investigation of the impact of a reduced conventional observing system on NWP following the most successful scenarios (3b) and (4) of an earlier Upper Air Network Redesign Study (Radnoti, 2010). In this scenario (3b) 06, 12 and 18 UTC radiosonde ascents are reduced by removing soundings of sites which are in the vicinity of in a 100 km radius in the vicinity of airports in Europe. In scenario (4) the horizontal spacing of sites is 250 km, all other settings are similar to scenario (3b). 3. Investigation of the impact of ASAP radiosondes over the Northern Atlantic region.