Impact of adjusting the times of radiosonde launches Proposed studies: Impact of adjusting the times of radiosonde launches John Eyre, on behalf of Stuart Goldstraw, Chair WMO/CBS ET-SBO WMO Impact Studies Workshop; Shanghai, China; 10-13 May 2016 © Crown copyright 2007

Proposed studies: Impact of adjusting the times of radiosonde launches Background Possible NWP impact studies © Crown copyright 2007

Background (1) Under present WMO regulations, radiosondes are launched mainly at 00 and 12 UTC Implementation Plan for the Evolution of Global Observing Systems (EGOS-IP) says: Action G10: Investigate possibility to optimize the radiosonde network … to make upper-air conventional observation coverage more uniform … taking into account all user requirements in terms of space and time distribution; … and make relevant recommendations to the CBS for updating Technical Regulations accordingly. © Crown copyright 2007

Background (2) Expected impact on WMO Application Areas of changing radiosonde launch times: Nowcasting – positive – launch times adjusted to be most favourable to support the forecasting of local meteorological phenomena. This will vary widely around the world. NWP – neutral/positive? [see next slide] Climate monitoring – potentially negative – some stations must be protected Other applications areas? Costs – potentially positive for some countries (staff time) © Crown copyright 2007

Background (3) Expected impact on NWP - issues: Global NWP is now relatively insensitive to observation times … if they are distributed approximately uniformly in time. HOWEVER, other observations are not uniform in time … e.g. minimum in AMDAR data around local midnight, AND SO what is the impact on NWP of changing launch times?: to complement other observation types for NWP, to improve impact on other applications and/or costs. © Crown copyright 2007

Possible NWP impact studies Data denial studies – possible in regions where there are currently more than 2 launches per day Special campaigns – launch additional sondes for a period of time – study their impact OSSEs Others? © Crown copyright 2007

Summary Question: If NMSs had the freedom to optimise cost:benefit of radiosonde launch times, … what would be the impacts on applications of these observations, … including NWP? NWP impact studies encouraged to address this question WMO/CBS ET-SBO will be studying this, and they have requested help from NWP centres. © Crown copyright 2007

Thank you! Questions? © Crown copyright 2007