Geoscience Reference
In-Depth Information
et al, 1980). Crane (1979) developed the cell identification techniques based on peak detection.
These systems left a legacy for the development of the WSR88D algorithms. McGill developed
SHARP (Bellon and Austin, 1978) for precipitation nowcasting and developed the cross-
correlation method for echo tracking which is still used today. It did not specifically address
severe weather algorithms, which is the focus of this contribution.
6.2 WSR-88D, U.S.A., WSR-98D, China
Many of the innovations for the reflectivity-only algorithms of RADAP-II were adopted and
significantly enhanced for the WSR88D (Crum and Alberty, 1993; Kitzmiller et al, 1995).
Doppler algorithms were developed for mesocyclone and gust front detection (Hermes et al
1993; Uyeda and Zrnic, 1986; Zrnic et al, 1985). Considerable effort has been expended to
improve upon these initial efforts. A search of the American Meteorological Society journal
publications will illustrate that. Initially, the output from the WSR88D Radar Product
Generator was displayed on a dedicated radar-only visualization system called the Principal
User Product (PUP) display for the forecaster and later the forecaster workstation called
AWIPS was used. This integrated all the data and products that the forecaster needed. WSR-
88D algorithms were later deployed on the WSR-98D radars made by MetStar and used in
China, Romania, India, Korea and other places.
A fundamental question arose as to the role of automated guidance products versus manual
interpretation (Andra et al, 2002). It is clear that automated generated products are for
guidance and it should not be mistakenly interpreted that warnings were automatically
generated and issued without an intervening well trained decision-maker. Initially, there
was an extensive radar training program for forecasters, up to 6 weeks for specialists.
Clearly, the expectation was that an expert level of training was needed to interpret Doppler
radar data for severe weather warnings. This was re-enforced by the work of Pliske et al
(1997) who analyzed how to achieve the expected benefits of a modernization program. This
resulted in the development of an on-going training program for decision-making at the
appropriately named, Warning Decision Training Branch of the National Severe Storms
Laboratory. Professionally trained instructors on cognitive principles interactively have the
skills to tailor the material to the appropriate knowledge level, abilities and learning styles
of the student. It is a model for professional training.
6.3 TITAN - NCAR
TITAN (Thunderstorm identification, tracking and nowcasting) was first developed in
South Africa and then later at NCAR for support of weather modification programs. Dixon
and Weiner (1993) described a simple but brilliant threshold technique for the identification
of thunderstorm cell cores. This simplified the peak detection techniques of the Crane (1979)
technique as the latter identified many weak cells and challenged the computing power of
the day. It also described a methodology for tracking. It could be argued that this is the most
widely used system in the world. It is freely available and requires some expertise to
implement. It is used extensively in research environments (Lei et al, 2009). It is a stand
alone system and integrating it into an operational environment has been done but there are
capacity and support issues to consider. For example, it is used at the South African
Weather Service.
