SC/56/IA11

Overview on survey design differences in IDCR/SOWER
between the second and the third circumpolar cruises
Shigetoshi Nishiwaki
Contact email: nisiwaki@cetacean.jp
The Institute of Cetacean Research: 4-5, Toyomi-cho, Chuo-ku, Tokyo 104-0055, Japan

ABSTRACTThis paper outlines the changes in the survey design of IWC/IDCR/SOWER cruises. Changes inthe survey design between the second (CPII) and third (CPIII) circumpolar cruises was made in the
1992/93 cruise in austral summer season. The priority of the survey design in CPII consideredmainly longitudinal coverage and the whole IWC management area was surveyed in a single
season. On the other hand, the survey design of CPIII took precedent latitudinal coverage andconsequently it took two or more season to cover the whole area. The difference in this survey
design was expressed by the survey area per unit of search efforts (SPSE) in the research strata .
The SPSE in CPIII become larger through each research stratum than that in CPII. The negative
correlation was found between the SPSE and the density index (DI). The difference in abundance
estimate between CPII and CPIII could be caused by the following two factors, 1) Northern
expansion of north stratum of research area. 2) Latitudinal expansion of south stratum. In addition,
yearly difference of the shape of the ice edge line could have influenced greatly the abundance
estimation.
KEY WORDS: SURVEY DESIGN, IDCR/SOWER, SOUTHERN OCEAN, ANTARCTICMINKE WHALESINTRODUCTION
This paper presents an overview on survey design differences in the IDCR/SOWER cruises
between CPII and III. The International Whaling Commission/International Decades of Cetacean
Research (IWC/IDCR; 1978/79 until 1995/96) and IWC/Southern Ocean Whale and Ecosystem
Research (IWC/SOWER; since 1996/97) have been conducted in austral summer season. With thestart of the SOWER programme, a blue whale research component was added, but all cruises were
designed for abundance estimation of the Antarctic minke whale (Butterworth et al. 1994).
The first circumpolar serie s, hereafter CPI (i.e. all six management Areas covered
longitudinally) was between 1978/79 and 1983/84, CPII was between 1984/85 and 1990/91, while
CPIII was between 1991/92 and 2003/04. During the early years, there was a major change inemphasis of cruises, with a shift from whale marking to sighting surveys. Procedural modificationin survey design was made in 1992/93 season. Since then the complete coverage in each 10 degree
longitudinal sector between 60 o S and ice edge was aimed because this corresponded to the choiceof “small areas” in the application of the Revised Management Procedure to the Antarctic minke
whales (Rowlett et al .1993).

1

SURVEY ITEM
Research area
First and second circumpolar series
One of the IWC Antarctic Management Areas (Fig.1, see Donovan, 1991) was surveyed during
each cruise in CP I and CPII. In each Area, longitudinal coverage took precedence over latitudinalcoverage. The northern boundary of each Area was established around 60o S-61o S in Areas IV andVI, 62o S-65o S in Areas I and III, and 58o S-59o S in Areas II and V.
Third circumpolar series
During CPIII, on all cruises since the 1991/92 cruise, priority has been given to latitudinalcoverage (from the ice-edge to 60o S) instead of longitudinal coverage (i.e. there was additional
coverage of northern waters compared with the first and second circumpolar cruises). The aim of
the modification was to estimate abundance between 60o S and the northern boundary of earlier
surveys. As a consequence of this modification, the southern stratum was also expanded to thenorth.
Survey design
The transition from CPI to CPIII by the change of the survey design was summarized in Table 1(Matsuoka et al. 2003). A major change of survey design is the shift from whale marking to thesighting. CPI is conducted mainly as the whale marking survey, while CPII and III were conducted
as the sighting survey only. The first year of CP II was spent on an experiment cruise forstandardization of the sighting survey.
Although the Normal Searching Closing mode (NSC) was applied for the whale marking
survey, Independent Observer Passing mode (IOP) was adopted as standard specification of thesighting survey from 1985/86 season by introduction of the second platform.
The sighting experiment was conducted in 1984/85 cruise. The difference in the position of anobserver platform which was different by the type of ship might influence in the collection ofsighting information data. Full-scale sighting survey was started in 1985/86. Shonan-Maru type(SM) vessel was more suitable than Toshi-Maru type (TM) vessel as standard specification, andSM vessels were used in CPII and CPIII series. As for IOP, collection of the data used forpresumption of g (0) in Antarctic Ocean was adopted. NSC and Normal Sighting Passing (NSP)
modes are applied the two primary observers on the top barrel. Two primary observers in IOP were
stationed at the top barrel and one primary observer was an IOP barrel.
Each IWC management area was stratified into two equally east and west sectors. This
stratification was continued until CPIII. The north-south stratification was made into two layers or
three layers depending on the number of research vessels. It was only 1985 / 86 and 1986/87
cruises in CPII which three layers were adopted in east and west sectors (1984 / 85 cruise wasconducted sighting survey on three layers only in the west sector because of sighting experimentyear).
The width of southern stratum from ice to 30n.miles offing, and the northern stratum was froma northern boundary of the southern stratum to 5 degree (300n.miles) in latitude. In 1983/84 cruise,a different research range was set up. 60o S was set as the north-side boundary of the research area.
The research area was stratified north and south at 65o S. The north strata were able to cover in thefirst half of the CPII by three sighting vessels. Then the south- stratum was set up in the range
from ice to 60n.miles offing. The area from the north-side boundary of south strata to 60o S was
divided further to north and south. The north one was called to north stratum and on the south one
was medium stratum. Two sighting vessels were used in the CPII in 1886/87 cruise and afterwards.
The research range was stratified into north and south. In South stratum was set to the range of 60
n.miles offing from ice edge. North stratum was set to the range of 5 degrees latitude from the2

north-side boundary of the south stratum. CPIII aimed into more coverage of longitude than the
coverage of latitude. The full coverage of all six management areas were made around in six years
in CPI and CPII, it will spend 13 years in CPIII.
Sighting survey track line in CPI was parallel to ice edge line in south stratum, and thelattice-like track line was adopted in north stratum. The zigzag track line was adopted both in thenorth and south strata from 1983/84 cruise. The number of sighting survey track line is set up
corresponding to number of research days and the area of research area. The number of sighting
survey track line in each stratum was set up more than four evenly. The lattice-like track line isonly adopted in south strata in 1988/89 cruise through CPII and CPIII. In CPIII, two zigzag tracklines were set up at intervals of the five degrees longitude in south strata and ten degrees longitude
in north strata.
The ice-edge line from 1978/79 to 1986/87 cruises was mapped based on the visual
information by survey vessel. In 1987 /88 cruises and afterwards, it was mapped based on the ice
information by the satellite data.
RESULTS
The distribution of Antarctic minke whale
The distribution of Antarctic minke whales with survey track-lines in each Area was shown in
Figure 5.In Area I, the ice edge line of CPII was located in more south than that of CPIII. The
difference was remarkable in west sector. In east sector, ice edge line turned north in eastern sector
by Antarctic Peninsula. The northern part of south strata in CPIII overlaps the southern part ofnorth strata in CPII. The difference in the position of the ic e edge line between CPII and CPIII has
influenced greatly the distribution of Antarctic minke whale s in research area.
In Area II, shape of ice edge line differs remarkably between CPII and CPIII. The difference inthe shape is remarkable in the western sector. On the eastern sector, south strata in CPIII overlap
with north strata in CPII. A sighting distribution of the minke whale in the southern stratum hasdepended on the difference in shape of ice edge line. The shape and size of the survey area in northstrata differ greatly each other in CPII and III. These differences reflected into a difference insighting distribution of minke whale.
The positions of the ice edge line in Area III differed greatly between CPII and CPIII. For thisreason, the covered area of the western sector in the research area differs remarkably. The south
strata in CPIII overlap north strata in CPII completely. These differences reflected into a differencein sighting distribution of minke whale.
In Area IV, the southern stratum in CPIII overlaps the northern stratum in CPII. The south
strata in CPII were surveyed under the lattice-like track line. A sighting distribution of a minke
whale is concentrated on the south portion of track line in southern stratum, and there is almost nosighting on the north portion of track line. These differences reflected into a difference in sighting
distribution of minke whale.
As for the research area of Area V, the position of ice edge line has jutted out in CPIII
compared with CPII. As for the southern stratum of eastern sector, the research area is remarkably
narrow. The southern stratum of the western sector in CPIII overlaps the northern stratum of that in
CPII. These differences reflected into a difference in sighting distribution of minke whale.
In Area VI, there is no significant difference in the position of ice edge line and the range ofthe research area between CPII and CPIII. There is no substantial difference in the sighting
distribution of a minke whale between CPII and CPIII.
Survey area (n.miles2 )The size of survey area (n.miles) for every circumpolar and research stratum in six Antarctic
management Areas were shown in Figure3 (Branch and Butterworth, 2001). When CPIII is3

compared with CPII, the size of survey areas increased in Areas I, II, III, and V. Conversely, Areas
IV and V were decreased. As for the Areas IV and V, the part of un-surveyed area is not included.
Each research stratum of CPIII has expanded than that of CPII with change of a survey design.
Survey area per unit of search efforts (SPSE)
The survey area per unit of search efforts (SPSE) in each research area was shown in Figure 4.
The Area I show that the value of CPIII is large in north and south strata. The Area II showed thehigh value except for the north-west stratum in each stratum of CPIII. The north-west stratum of
CPII showed the highest value through all IDCR/SOWER cruises. There is no conspicuous
difference SPSE between CPII and CPIII in Areas III, IV, V and VI Areas.
Relation between a density index (DI) and SPSE
Relation between DI and SPSE in each research area were shown in Figure 5(Branch andButterworth 2001). The DI in Area I showed smaller value in CPIII than CPII. As For the SPSE,
CPIII was larger value than CPII.
As for DI in Area II, CPIII showed lower value than CPII except for north-west stratum. As for
SPSE, CPIII showed larger value than CPII except for north-west stratum.
The DI and the SPSE is not different between CP II and CPIII in the Area III. The estimatedmean school size (E(S)) showed the larger value in CPII than CPIII. This might be caused by thedifference in the ice edge line between CPII and CPIII.
The SPSE in the Area IV does not have a difference between CPII and CPIII. As for the DI and
the E(S), CPII showed the value higher than CPIII by south strata. This was caused by thedifference in the design of track line between CPII and CPIII.
About the Area V, the opposite correlation in the SPSE and the DI is shown between CPII and
CPIII. As for the difference in the E(S), position and its shape in the ice edge line might beinfluenced.
The DI and SPSE is no conspicuous difference between CPII and CPII in the Area VI. The E(S)showed the larger value at CPII than CPIII. This has suggested the influence by the difference in
the ice edge line between CPII and CPIII.
DISCUSSION
The change in the survey design between CPII and CPIII cruises was made in the 1992/93 season.
A survey design of CPII took precedence the coverage of longitude and surveyed one area in asingle season. On the other hand, the survey design of CPIII took precedent latitudinal coverageand consequently it took two or more years. The difference in this survey design was expressed by
the SPSE in the research strata. The SPSE in CPIII was suggested to become large through each
sub research area than that of CPII. The negative correlation was shown between the DI and SPSE.
It confirmed that the northern strata of CPII overlapped to the southern strata of CPIII. The survey
design changes of CPIII brought a result which increased survey coverage at lower latitudes in thenorthern strata where most minke whales are solitary and the sea state trends to be worse. This has
suggested that g(0) is changing between CPII and CPIII (Murase et al, 2004 in-prep.).
Further, the ice edge position of CPII located more south rather than CPIII and it might bring a
result lower DI in the southern strata in CPIII. Such difference of ice edge position might influencealso DI in the northern strata and E(S) in the southern strata in CPIII. The difference in abundance
estimate between CPII and CPIII suggests the following two points as a factor related to a survey
design, 1) Northern expansion of north stratum of research area. 2) Latitudinal expansion of south
stratum. These two factors brought decrease in abundance estimate from CPII to CPIII.
It is concluded that direct comparisons of abundance estimates between CPII and CPIII are
difficult. Further analyses are required to remove effect of survey design changes between CPII
and CPIII. Whether such differences in survey design affect on abundance estimate can be4

investigated by simulation studies.
REFFERNCE
Branch, T. A. and Butterworth, D. S. 2001.Southern Hemisphere minke whales: standardized
abundance estimates from 1978/79 to 1997/98 IDCR/SOWER surveys. J. Cetacean Res.
Manage. 3(2):143-74.
Butterworth, D. S. Borchers, D. L., Chalis, S., De Decker, J.B. and Kasamatsu, F. 1994. Estimatesof abundance for Southern Hemisphere blue, fin, sei, humpback, sperm, killer and pilot whales
from 1978/79 to 1990/91 IWC/IDCR sighting survey cruises, with extrapolations to the area
south of 30S for the first five species based on Japanese scouting vessel data. Paper
SC/46/SH24 presented to the IWC Scientific Committee, May 1994 (unpublished). 129pp.
[Paper available from the Office of Journal].
Donovan, G. P. 1991. A review of IWC stock boundaries. Rep. int. whal. Commn (special issue)
13:39-68.
Matsuoka, K., Ensor, P., Hakamada, T., Shimada, H., Nishiwaki, S., Kasamatsu, F. and Kato, H.
2003. Overview of minke whale sighting surveys conducted on IWC/IDCR and SOWER
Antarctic cruises from 1978/79 to 2000/01. J. Cetacean Res. Manage. 5(2):173-201.
Murase, H., Matsuoka, K., Nishiwaki, S., Hakamada, H. and Mori, M. 2004. Effect of observed
covariates (school size, sighting cue, latitude and sea state) on the Antarctic minke whale
abundance estimation parameters in the IWC/IDCR-SOWER surveys. J. Cetacean Res. Manage.

(in-prep.) .
Rowlett, R. A., Nishiwaki, S., Abernethy R. B., Desportes, G., Findlay, K. P., Kira, M., Owada, A.
and Shimada, H. 1993. 1992-93 IWC/IDCR Southern Hemisphere Minke Whale Assessment
Cruise, Area III (00E-40E) “The NEXT GENERATION”. Paper SC/45/SHBa5 presented to
the IWC Scientific Committee, May 1993 (unpublished). 32pp.

5

Table 1. The transition from CPI to CPIII by the change of the survey design（ Data are quoted from Matsuoka et al 2003）

ＣＰⅠ

Circumpolar

ＣＰⅡ

ＣＰⅢ

Year

1978/79−1982/83

1983/84

1984/85

1985/86・1986/87

1987/88

1988/89

1989/90-1990/91

1991/92-

Research activity

Marking > Sighting

Sighting > Marking

Sighting = Experiment

Sighting

Sighting

Sighting

Sighting

Sighting

Toshi-Maru type: one
vessel, Shonan-Marutype: Two vessels

Shonan-Maru type:Two vessels

Shonan-Maru type:Two vessels

Shonan-Maru type:Two vessels

Shonan-Maru type:Two vessels

NSC=IOP

NSC=IOP

VesselToshi-Maru type: one Toshi-Maru type: one
Toshi-Maru type:Two
vessel, Shonan-Maru vessel, Shonan-Maru
vessels
type: Two vessels
type: Two vessels

Sighting survey mode

NSC>NSPNSC>NSPNSC=NSPNSC=IOP

NSC=IOP

NSC=IOP

Stratum of researcharea

Research area wasdivided two sectors,
by the middle positionin the longitudinalrange. These sectors
were further divided
two strata inlatitudinal range.

Research area wasdivided two sectors,
by the middle positionin the longitudinalrange. These sectors
were further divided
two strata inlatitudinal range.

Research area wasdivided two sectors,
by the middle positionin the longitudinalrange. The part ofwestern sector was
further divided threestrata in latitudinalrange.

Research area wasdivided three sectors,
by the middle positionin the longitudinalrange. These sectors
were further divided
two strata inlatitudinal range.

Research area wasdivided two sectors,
by the middle positionin the longitudinalrange. These sectors
were further divided
two strata inlatitudinal range.

Research area wasdivided two sectors,
by the middle positionin the longitudinalrange. These sectors
were further divided
two strata inlatitudinal range.

Research area wasdivided two sectors,
by the middle position
The research areain the longitudinal
was divided two strata
range. These sectors
in latitudinal range.
were further divided
two strata inlatitudinal range.

East and Westsectors: 30 digrees inrange of longitude.
East and WestSouthern stratum: on
sectors: 35 digrees in
the ice-edge and on
range of longitude.
the locus from the 60
Southern stratum: onn.miles from ice-edge.
the ice-edge and on
Northern stratum:
the locus from 65S
these were divided inlatitude line. Northern
mideum range ofstratum: on the locus
latitude between on
from 65S latitude line
the 60 n.miles fromand 60S latitude line.
ice-edge and on thelocus from 60S
latitude.

East and Westsectors: 30 digrees inrange of longitude.
Southern stratum: onthe ice-edge and on
the locus from the 60
n.miles from ice-edge.
Northern stratum:these were divided in
mideum range oflatitude between on
the 60 n.miles from
ice-edge and on thelocus from 60S
latitude.

East and Westsectors: 35 digrees inrange of longitude.
Southern stratum: onthe ice-edge and on
the locus from the 60
n.miles from ice-edge.
Northern stratum: on
the 60 n.miles from
ice-edge and on thelocus from 65S
latitude line.

East and Westsectors: 30 digrees inrange of longitude.
Southern stratum: onthe ice-edge and on
the locus from 65S
latitude line. Northern
stratum: on the locus
from 65S latitude line
and 60S latitude line.

East and Westsectors: 30 digrees inrange of longitude.
Each 10 degree
Southern stratum: on longitudinal sector
the ice-edge and on with inter stratum
the locus from 65S
boundary establishedlatitude line. Northern on fixed latitudinal
stratum: on the locus line.
from 65S latitude line
and 60S latitude line.

Track-line

Soutern stratum:
wriggle line along ice
Southern and Nortern Southern and Norternedge. Northen
strata: zig-zag line
strata: zig-zag line
stratum: lattice shapeline

Southern and Nortern
strata: zig-zag line

Southern and Nortern Southern and Nortern Southern and Nortern Southern and Nortern
strata: zig-zag line
strata: zig-zag line
strata: zig-zag line
strata: zig-zag line

Ice edge line

Estimaton of the
The ice edge was
The ice edge was
The ice edge was
The ice edge wasposition of the icemapped by the
mapped by the
mapped by the
mapped by theedge from saterallite
soutern survey vessel. soutern survey vessel. soutern survey vessel. soutern survey vessel.
information.

East and Westsectors: 30 digrees inrange of longitude.
Southern stratum: onthe ice-edge and on
the locus from the 30
Range of research arean.miles from ice-edge.
Northern stratum: onthe 30 n.miles from
ice-edge and on thelocus from 65S
latitude line.

6

Estimaton of theposition of the iceedge from saterallite
information.

Estimaton of theposition of the iceedge from saterallite
information.

Estimaton of theposition of the iceedge from saterallite
information.

Figure1. The IWC Antarctic Areas for the management of baleen whale species

Figure2-a. The sighting distribution of Antarctic minke whales with survey track-lines in Area I (Left:
CPII. Right: CPIII)

7

Figure2-ｂ. The sighting distribution of Antarctic minke whales with survey track-lines in Area II(Upper: CPII. Lower left: Western sector in CPIII. Lower right: Eastern sector in CPIII)

8

Figure2-ｃ. The sighting distribution of Antarctic minke whales with survey track-lines in Area III(Upper: CPII. Lower left: Western sector in CPIII. Lower right: Eastern sector in CPIII)

9

Figure2-d. The sighting distribution of Antarctic minke whales with survey track-lines in Area IV(Upper: CPII. Lower: CPIII)

10

Figure2-e. The sighting distribution of Antarctic minke whales with survey track-lines in Area V(Upper: CPII. Lower: CPIII)

11

Figure2-ｄ. The sighting distribution of Antarctic minke whales with survey track-lines in Area VI(Upper: CPII. Middle: Eastern sector in CPIII. Lower: Western sector in CPIII)

12

Area I

Area II
400000350000350000Area(n.miles2)

Area(n.miles2)

300000250000200000150000ＳＥ
100000

ＮＷ

50000

ＳＥ

300000250000200000150000ＮＥ

100000

ＮＷ
ＳＥ

50000

ＳＷ

0

ＳＷ

0
CPI

CPII

CPIII

CPI

CPII

CPIII

Area IV

Area III
250000400000350000Area(n.miles)

Area(n.miles2)

200000300000250000200000150000NE

100000

NW
SE

50000

150000100000

ＮＥ

50000

ＮＷ
ＳＥ
ＳＷ

SW
0

0
CPI

CPII

CPIII

CPI

Area V
400000450000350000Area(n.miles2)

Area(n.miles2)

400000350000300000250000200000ＮＥ

150000ＮＷ

100000

ＳＥ

50000
0

300000250000200000ＮＥ

150000ＮＷ

100000

ＳＥ
ＳＷ

50000

ＳＷ
CPII

CPIII

Area VI

500000

CPI

CPII

0

CPIII

CPI

Figure3. The survey area (n.miles2 )

CPII

CPIII

in Antarctic Areas for the management of baleen whale species(Data are quoted from Branch and Butterworth 2001)

13

Area I

Area II
350

250

320

222
300
186

145

142

150

A/L(n.miles2)

A/L(n.miles2)

200

131
115

100
68
50

47

45

36

NE

31

206 208
200
150

127
103

100

83

73

NW
SE

18

250

50

41

25 34

56

48

ＮＥ
ＮＷ
ＳＥ
ＳＷ

SW
0

0
CPI

CPII

CPI

CPIII

CPII

Area IIICPIII

Area IV

200

189

182

180

165

162

180

160

149

155

160

140

142

120
120

A/L(n.miles)

A/L(n.miles)

140

100
100
83

79

80
62

60

109

80

73

83

77

60

60

50

NE
3 1 35

40

32

NW

40

20

SE

20

SW

SW

0

0
CPI

CPII

CPI

CPIII

CPII

Area V
300
210

254
250

170

237
222

216
203

164

A/L(n.miles2)

A/L(n.miles2)

CPIII

Area VI

237

200

150
150
121
100
72 7 3

80
62

49
50

NE
NW

30
19

SE

250

105
95

100

NE

200

150

155

145
120

114

100

NE

NW

38

48

SE

53

50

59

NW
SE

SW

SW

0

0
CPI

CPII

CPIII

CPI

CPII

CPIII

Figure 4. The Coverage Survey area per amount of search Efforts (CSE) in each research area (Dataare quoted from Branch and Butterworth 2001)

14

Area I

Area II
350

250

320

222
300

150

186

A/L(n.miles2)

A/L(n.miles2)

200

145

142
131
115

100
68
50

47

45

36

NE

31

206 208
200
150

127
103

100

83

73

NW
SE

18

250

50

41

25 34

56

48

ＮＥ
ＮＷ
ＳＥ
ＳＷ

SW
0

0
CPI

CPII

CPI

CPIII

CPII

Area ICPIII

Area II

140.0

70.0
122.9

100.0

50.0

n/A*10000

60.0

n/A*10000

120.0

80.0
60.0
42.3
34.7

40.0

NE

57.2

40.0
30.0

26.9
23.0

14.715.3

14.2

20.0
5.6 3.8

5.3 3.4

NE

11.2

SE

10.0

SW

0.5 1.0

20.1

20.0

NW
3.8

1.4

9.8 9.9
1.2 1.4

0.2

NW
SE
SW

0.0

0.0
CPI

CPII

CPI

CPIII

CPII

Area ICPIII

Area II
140.0

250.0

118.9

120.0

204.0

Ssc*n/A*10000

Ssc*n/A*10000

200.0

150.0
113.1
89.1

100.0

NE

100.0
75.9

80.0
62.0

NE

40.0

NW

50.0
20.0
6.2

25.5
9.4 7.7

24.525.6
0.8 1.6

56.7

60.0

25.9
18.2

24.9

SE

20.0

SW

6.2

0.0

2.9

0.4

CPI

CPII

2.0 1.6

0.0
CPI

CPII

CPIII

CPIII

Figure 5-a. Relation between DI and CSE in Areas I and II ( Data are quoted from Branch andButterworth 2001).

15

NW
SE
SW

Area III200

Area IV
189

182

180

165

162

180

160

149

155

160

142

140
120

120

A/L(n.miles)

A/L(n.miles)

140

100
100
83

79

80

105
95

80

62

60

109

100
73

83

77

60

60

50

NE
3 1 35

40

32

40

NW

19

SE
20

SE

20

SW

NE
NW

30

SW

0

0
CPI

CPII

CPI

CPIII

CPII

Area III
45.0

CPIII

Area IV
70.0

41.1
39.8

60.6

40.0

60.0

35.0
50.0

27.3

n/A*10000

n/A*10000

30.4
30.0
25.0
20.0
15.0
9.6

10.0
5.0

NE

0.7

NW
SE

30.0

SW

20.0

SE

2.4

36.0

13.414.3

NW

4.4

2.6 2.6

NE
40.0

10.0

SW

1.5 1.6

6.1 6.8

4.3 3.9

1.3 0.9

1.4 2.2

0.0

0.0
CPI

CPII

CPI

CPIII

CPII

Area IIICPIII

Area IV

180.0
400.0
153.6

160.0

356.8
350.0

129.5

Ssc*n/A*10000

Ssc*n/A*10000

140.0
120.0

96.7

100.0

75.1

80.0
60.0

NE
NW

40.0
20.0

24.8
8.4 6.2

2.8

9.6

25.0
1.6 2.0

300.0
250.0
200.0
150.0
101.2

NE

100.0

NW
48.351.5

SE

SE

50.0

SW

11.910.7

0.0

5.6 3.7

1.8 2.7 7.8 8.6

SW

0.0
CPI

CPII

CPIII

CPI

CPII

CPIII

Figure 5-b. Relation between DI and CSE in Areas III and IV (Data are quoted from Branch andButterworth 2001).

16

Area V
250

Area VI

237

300
210

254
250

200

150
150
121
100

80

72 7 3
62

NE

49
50

216
203

164

A/L(n.miles2)

A/L(n.miles2)

170

237
222

200
155

145

150

120

114

100
NE

NW

38

SE

53 59

48

50

SE

SW

SW

0

0
CPI

CPII

CPIII

CPI

CPII

Area VCPIII

Area VI

40.0

12.0
35.2

10.2

35.0
10.0

25.0

n/A*10000

n/A*10000

9.3

29.3

30.0

23.1

21.7

20.0
15.3

14.7

15.0

11.5
10.0
5.0

NE

8.1

6.0

5.4

4.0

3.0

NE

0.9

SW

SE

0.8

SW

0.0
CPI

CPII

CPI

CPIII

CPII

Area VCPIII

Area VI
30.0

140.0

28.6

118.1
25.0

100.0

Ssc*n/A*10000

Ssc*n/A*10000

NW

1.7 1.9

1.5

2.0

0.0

90.4
73.9

80.0
60.0

52.1

40.0

7.0 7.8

33.2

29.1

25.8
20.0

5.5

4.5

2.4

SE

4.4

3.7 3.1

8.0

NW

0.9

120.0

NW

22.0
8.4

SE

16.8
15.0
9.9
10.0
6.9

SW

5.1 4.5

5.0

SE
2.4

19.1

20.0

3.0

2.1

1.6

SW

0.0

4.6

NE
NW
SE

2.1

SW

0.0

CPI

CPII

CPI

CPIII

CPII

CPIII

Figure 5-c. Relation between DI and CSE in Areas V and VI (Data are quoted from Branch andButterworth 2001).

17