The Advances in Targeted Observations for Tropical Cyclone Prediction Based on Conditional Nonlinear Optimal Perturbation (CNOP) Method - Data Assimilation for Atmospheric, Oceanic and Hydrologic Applications - page 575

a b c

39N
35N
31N
27N
23N
19N
15N

39N
35N
31N
27N
23N
19N
15N

39N
35N
31N
27N
23N
19N
15N

CNOP - A CNOP - B CNOP - C

1.3
1.1
0.9
0.7
0.5

108E113E118E123E128E133E138E 108E113E118E123E128E133E138E 108E113E118E123E128E133E138E

d e f

39N
35N
31N
27N
23N
19N
15N

39N
35N
31N
27N
23N
19N
15N

39N
35N
31N
27N
23N
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15N

CNOP - D CNOP - E CNOP - F

1.3
1.1
0.9
0.7
0.5

108E113E118E123E128E133E138E 108E113E118E123E128E133E138E 108E113E118E123E128E133E138E

g h i

39N
35N
31N
27N
23N
19N
15N

39N
35N
31N
27N
23N
19N
15N

39N
35N
31N
27N
23N
19N
15N

CNOP - G CNOP - H CNOP - I

1.3
1.1
0.9
0.7
0.5

108E113E118E123E128E133E138E 108E113E118E123E128E133E138E 108E113E118E123E128E133E138E

Fig. 24.3 The sensitive areas denoted by the vertically-integrated energies of CNOPs with
schemes ( a )A,( b )B,( c )C,( d )D,( e )E,( f )F,( g )G,( h )H,and( i ) I respectively. The rectangles
are the verification areas. The “ ˚ ” symbol indicates the initial best position of the cyclone (From

Zhou and Mu 2011 )

of the verification area are considered; the designs are shown in Fig. 24.2 c. Scheme
G is designed with small variations (Fig. 24.2 c, solid rectangle). Schemes H and I
have even larger variations: Scheme H has a bigger domain, and scheme I has a
smaller domain (Fig. 24.2 c, dashed rectangle and dotted rectangle, respectively).
Generally, different verification area designs may result in different sensitive
areas (Fig. 24.3 ). From the comparisons of schemes A, B, and C, it is seen that a
small position change of the verification area has minimal influence on the sensitive
areas. In addition, the inclusion of the best final position of the cyclone seems more
important because its exclusion would result in very different sensitive areas. From
the comparisons of schemes B, D, E, and F, it is found that the CNOP is sensitive to
the large position changes of the verification area, which results in large differences
among the identified sensitive areas. The comparisons of schemes G and B shows
that the small variations in both size and position also affect the CNOP sensitive
areas little, but a large variation in size or position would result in much different
CNOP sensitive areas (comparing the schemes B, H, and I). Besides, although
the verification area for scheme H includes almost all of the verification areas for