THORPEX was also motivated by the rapidly growing economic impacts of weather events.
In response to these challenges, THORPEX was established as a 10-yr program of the World Weather Research Program (WWRP) of the World Meteorological Organization (WMO) under the Commission for the Atmospheric Sciences (CAS).
The earliest THORPEX planning was focused on the concept that predictive skill could be improved through employing additional measurements, such as aircraft-deployed dropsondes, in regions where forecast simulations were particularly sensitive to errors in the initial state.
The end of the THORPEX era (2005-14) provides an opportunity to review the successes and shortcomings of targeted observations, and to assess whether the original grand vision has been realized.
The main techniques employed prior to and during the THORPEX era are summarized in Table 1.
Successful examples of the use of the PREVIEW DTS were during the Mediterranean Experiment (MEDEX) and the THORPEX Pacific Asian Regional Campaign (T-PARC).
TIGGE was established to support a range of THORPEX research activities by providing operational ensemble forecast data to the international research community.
The THORPEX program covered three major research areas; predictability and dynamical processes, data assimilation and observing systems, and ensemble forecasting.
The final section of the paper looks beyond the THORPEX program and explores how the achievements of TIGGE should be built on in the future.
THORPEX program, which had focused on components of the forecast system, identified accomplishments including the development and implementation of a new operational hybrid 3D-Var/ensemble Kalman filter data assimilation scheme at NOAA, leadership in international ensemble forecasting (the North American Ensemble Forecast System), field campaigns, and global research initiatives.
THORPEX had been established to achieve similar goals.
WMO/WWRP International THORPEX program (concluded at the end of 2014) www.