Geoscience Reference
In-Depth Information
machine or the mono or color graphics terminal. Each innovation increased the capacity to
deliver better products. In today's technology, every button press or mouse click that is
eliminated delivers “a big bang for the buck”. This key innovation allowed the data to be
effectively used in the Sydney Olympic Command Centre (Joe et al, 2004; Keenan et al,
2004).
Similar to the SCIT of WDSS-I, CARDS implemented a fuzzy logic technique to rank storms.
The technique is configurable (see Table 6). It shows the parameters that the users decided
to use and the thresholds that they considered as weak, moderate, strong and severe (see
also Doswell et al, 2006).
In the overlap region, cells are selected from one radar or the other, unlike WDSS-II. Due
to attenuation concerns, lack of experience with the fuzzy logic storm severity technique
and that reflectivity (and reflectivity based products) was still the prime parameter for
determining storm severity; users selected the cell detection with the maximum
reflectivity as the cell for visualization. However, this would likely not be the case
anymore as nearest radar or maximum information or maximum severity ranking would
be chosen today.
Thresholds
Rank
BWER
Meso
Hail
Wdraft Vil
density
Max Z 45 dBZ
(0-8)
ETop
count
m/s/km
cm
m/s
kg m^2 /
km
dBZ
km
0
0
0
0
0
0
0
0
Minimum
1 0-2
5-11
4
0.5
10
2.2
30
5.5
Weak
2 3-4
12-17
6
1.3
15
3
45
8.5
Moderate
3 5-6
18-21
8
2.3
20
3.5
50
10.5
Severe
4 7+
22-26
10
5
25
4
60
12.5
Notes:
Rank:
5-6 means a value of 5 or more but less than 7.
WER:
The number of directions where reflectivity
increases
determines a BWER (with low reflectivity below)
Meso:
Average Pattern Vector Shear (see Zrnic et al, 1985)
Hail:
Average Hail Size
WDRAFT
:
Gust potential in
m/s
Vil Density:
Similar to WDRAFT in pattern
VIL
if VIL for classification then 10 20 30 40 are the thresholds
Max Z:
Max reflectivity in the cell
45 dBZ Echotop Ht:
Reliable echo top parameter
Table 6. Fuzzy Logic Membership Functions for Parameters Used to Rank Storms.
