Geoscience Reference
In-Depth Information
6.7 SIGOONS - France
Significant Weather Object Oriented Nowcast System (SIGOONS) is a component of the
Synergie workstation (Brovelli et al, 2005). Thunderstorm cells are identified using the RDT
(Rapidly Developing Thunderstorms) technique by Hering et al (2005) and are represented
as objects. This database is updated every five minutes and is automatically quality
controlled against other observational data. The objects may have deterministic and
probabilistic attributes and have a time dimension - they can grow and decay. Products are
automatically generated and tailored according to pre-defined customer requirements.
Discrepancies are brought to the attention of the forecaster who can select persistence over
linear extrapolation nowcasts. The forecaster can take additional initiative. The attributes of
the weather objects can be manipulated and altered by forecasters.
6.8 THESPA and TIFS, Australia
Within the Bureau of Meteorology, forecasters use RAPIC to interactively interrogate the
data. The innovation is the radar data is loaded on the graphics memory of the client
computer and extremely rapid response of the display is achieved. To avoid dual-PRF
dealiasing errors, only single PRF data is used resulting in a Nyquist interval of 16 m/s. This
implies considerable forecaster training is required to interpret highly aliased Doppler data.
Thunderstorm Strike Probability (THESPA, Dance et al, 2010) generates probabilistic
nowcasts. Using the historical statistics of the nowcast position errors as a function of lead
time and detected storm properties, storm motion is modeled as a bivariate Gaussian
distribution on storm speed and direction. For a given geographical point, the strike
probability from all possible thunderstorms is computed for the forecast period (Fig. 14).
The algorithm is embedded in the Thunderstorm Interactive Forecast System (TIFS, Bally
2004). The Beijing Olympics provided an opportunity to explore and prototype new
nowcasting techniques (Wang et al, 2010). TIFS was modified to ingest the storm locations and
tracks from the CARDS, SWIRLS, WDSS and TITAN to create a poor man's ensemble. From
each of the storms and tracks, THESPA was used to compute a consensus or ensemble strike
probability (Fig. 14b). A warning product would be automatically generated. The analyst (B08
Forecast Demonstration Project team member) would evaluate the product and determine if
intervention was needed. The analyst could then use the graphical interface and add, delete or
modify cells or tracks. The analyst could view and modify any of the ensemble members and
the strike probability display would update. Accepting the change would regenerate the
automated warning product, be disseminated and overwriting the fully automated product.
6.9 NoCAWS - SMB
The Shanghai Meteorological Bureau's NoCAWS system was one of the nowcast systems
used for the World Expo on Nowcasting Services (WENS) component of the Multi-hazard
Early Warning Service project (MHEWS). It integrates observations, mesoscale models and
nowcasts to host data displays; analysis tools, severe weather alerting tools to generate
automatic forecasts and warning for forecasters. It covers the scales from outlooks to
warnings. An innovative feature is lightning forecasts. COTREC winds are used to nowcast
cell motions. Advection and statistical relationships between lightning and reflectivity are
used to nowcast lightning (Fig. 15)
