A STUDY OF SOME CARTOGRAPHIC TECHNIQUES
USED BY BRITISH OCEANOGRAPHERS
by
A nn R
ic h a r d s o n
Hydrographic Department, Taunton, United Kingdom .
This study was carried out as part o f an investigation o f the cartogra­
phic techniques em ployed by oceanographers and was presented to the
ICA W o r k in g Group on Oceanic Cartography at its m eeting held in conjunc­
tion with the Seventh International Conference on Cartography, Madrid,
April 1974. A n exam ination was made of the oceanographic literature,
especially D e e p Sea R e sea r ch , since 1970 and additional ideas and in fo rm a ­
tion were obtained by personal contact and from correspondence with
British oceanographers.
Cartographic methods used by British oceanographers to illustrate
their w o rk appear to fall into two main categories. T h e y either show
relationships between (and spatial variations in) parameters and describe
processes at any given point in tim e; or they indicate the variations o f
these parameters and processes over an interval o f time, or the frequency
of occurrence o f particular phenomena.
Firstly, those maps or diagrams w hich aim to show the situation at
a given time — although all the observations and acquisition o f data
illustrated would not necessarily have taken place simultaneously.
Th e simplest diagram in use is the graph, used to relate tw o dependent
variables, and readily lending itself to automatic plotting. Since the wellknown line graph is m ore usually em ployed w ith time as an independent
variable, scatter graphs appear to be m ore appropriate fo r the instantaneous
picture. P i n g r e e and P l e v i n (1971, figure 1) show the com m on salinity
temperature diagram w ith scatter values distinguished b y different form s
of symbol to illustrate the depths at w hich observations were taken.
Sigma-t lines have been superimposed. L i n d e n (1973, figure 2) has used
the scatter technique to determine the exact relationship between the
width o f salt fingers and temperature gradients w ith in them. Lo g a rith m ic
scales have been used, being particularly suitable for showing rates of
increase rather than absolute changes in quantity.
B a r g raphs, on the other hand, emphasise actual quantities in com par­
ing separate elements, rather than variations or relationships. J o n e s (1971,
figure 3) uses this technique to show the composition o f core samples.
Th e best-known medium for the illustration o f processes and distributions
SALINITY %.
I ' io . 1. —
T e m p e r a t u r e and
salin ity
v a lu e s f o r th e u p p e r 100 m
4 July u m .
between
10 Ju n e
and
K.D. P i n g r e e a n d J. P l e v i n . A d e s c r i p t i o n o f the u p p e r 100 m at Ocean W e a t h e r
S t a t io n “ J u l i e t t ” , fig. 7(b). D e e p Sea R e s e a r c h , J a n u a r y 1972, P e r g a m o n P res s L td .
05
1.0
2.0
TZi°C/cm .
3.0
4.0 5.0
F ig . '1. — T h e w i d t h o f th e f i n g e r s L p l o t t e d a g a in s t the t e m p e r a t u r e g r a d i e n t T . in the
fingers.
T h e li n e is a f i t to th e data w i t h s lo p e — 1/4.
P.F. L i n d e n . On th e s tr u c t u r e o f salt fin g e r s , f ig . 5. D e e p Sea R e s e a r c h , A p r i l
P e r g a m o n P re s s L t d .
1973.
I ’ ui. :s. — (C omposition o f the s a n d -s iz e d acid in so lu b le m a t e r i a l in cor es 1)01)38 and
1)562((. T h e serie s o f cu rv es f o r 1)5()38 a r e p res e n ted on t h e r i g h t h a l f o f the d i a g r a m
w i t h those f o r D5K20 on th e le ft . S e v e r a l h u n d r e d g ra in s w e r e c ou n te d in each s a m p l e and
the results ar e d is p l a y e d in p er centage s.
T h e f u l l w i d t h o f each c o lu m n r e p r e s e n t s 5 0% .
T.A . D a v i e s an d E .J.W . J o n e s . S e d i m e n t a t i o n in th e area o f P e a k e a n d I-’ re en Deep s
( m i d - A t l a n t i c R i d g e ) , f i g . 7. Dee p Sea R e s e a r c h , June 1971, P e r g a m o n P res s L td.
spatially is, of course, the ma p. T h e simplest fo rm restricts itself to two
dimensions only, usually showing the locations o f stations or ships’
tracks or the quantitative distribution o f parameters w ith the use of isopleths. A n y attempt to introduce the third dimension o f depth must involve
a further technique. F or instance, C o o p e r (1960, figure 4) in his descrip­
tion o f streamline patterns uses the thickness o f line to show whether
the streams are sinking or rising. L a n g h o r n e (1973, figure 5 ) spaces his
sounding lines sufficiently far apart to be able to have them plotted,
automatically, as vertical sections in situ, facilitating the further stage
of superimposing morphological zones. A method o f obtaining a good
three-dimensional effect, which has become feasible with the advent of
automatic plotting, is the anaglyph m a p , e.g. the map o f the bathym etry
of the Gulf o f Aden by L a u g h t o n (1970) [1 ], Each contour has been drawn
twice, in red and green, the red contours being displaced to the right and
the green contours to the left, or vice versa when depicting relief on land.
T h e amount o f displacement is proportional to the actual depth or height
of the contour, and when viewed through red and green spectacles the
7”
6°
S”
4"
F k i . 4. — T h e p a t t e r n o f s t r e a m l i n e s o f t h e d e e p e r w a t e r in A u g u s t 1950. T h e d ir e c t io n
o f m o v e m e n t is f r o m th e s o u t h - w e s t t o w a r d s the north. A t t e n u a t i o n o f th e lin e in d i c a t e s
si nk in g, s t r e n g t h e n i n g o f th e l i n e in d ic a t es r i s i n g o f a w a t e r str a tu m .
L. H .X . C o o p e r . W a t e r f l o w in t o th e E n g l i s h C h a n n e l f r o m
.1. M a r . l l i o l . Ass. U . K . (196(0, V o l . 39, pp. 173-208.
impression is one o f a
dimensional effect is also
salinity sections (figure 6 )
along the ship’ s track in
t h e S o u t h - W e s t , f ig .
12.
three-dimensional model. A successful threegiven by C a s t o n (1969) by means o f a series of
with a k ey map (figure 7) o f the stations occupied
the G olfe du Lion.
V ertica l sections themselves are an extrem ely comm on method of
showin g m eridional or zonal circulation or distribution o f parameters.
G ii.l (1971, figure 8 ) uses them to show circulation in a model ocean as
calculated from numerical experiments. He has used logarithmic scales
to accommodate the relatively large vertical range in depth. C o o p e r
(1960, figure 9) shows the zonal distribution o f density west o f Ushant
and distinguishes the separate w ater masses by variations in intensity of
stippling.
Another technique in the depiction of three dimensions is the block
usually in sim plified fo rm illustrating the characteristics of
water masses, as in C o o p e r ’ s representation o f the twisting o f a streamline
as it passes north-west o f Ushant (1960, figure 10). Since few o f the rather
intangible oceanographic parameters lend themselves to this particular
technique block diagrams are not com m on ly used.
diagram ,
T h e illustration o f processes rather than quantifiable parameters can
be achieved by f l o w charts — a sim plified method o f showing successive
Fi<i. 5. — S pa tia l d ia g r a m o f the s a n d w a v e f i e l d w i t h s u p erim p o s ed m o r p h o l o g i c a l zones.
V e r t ic a l to h o r iz o n t a l scale r a t i o 20/1. ( R o m a n n u m e ra ls I - V I lo c a tio n s o f sidc-scan
so n a r re co rd s ).
D.N. L a n c h o h n e .
G eo log y, Feb. 1973.
A
sandwave
field
in the
O u ter
Thames
Estua ry ,
fig .
3.
M arine
Fin. (i. —
G.
G aston .
S a l i n i t y sec tio ns in the G o l f e du L io n .
In s titu te o f O c ea n o gr ap h ic Sciences, 1969.
Km. 7.
S h ip ’ s truck and o c e a n o g r a p h i c s tatio ns , G o l f e du L io n ,
(i.
C aston .
In s t i t u t e o f O c e a n o g r a p h ic Sciences, 1!)69.
movements through a process, e.g. M a u c h l i n e (1972, figure 11) demonstrat­
ing the transfer of nutrients. A nother interesting method is the succession
o f profiles and pictorial diagrams indicating the stages o f a process used
by W o o d s and W i l e y (1972, figure 12) to illustrate billow mixing.
This idea of a series o f diagrams or maps depicting the situation at
different stages or times is the simplest form used in the s eco n d category
o f cartographic methods, which is concerned with showing h o w parameters
vary with time.
S t e e l e , B a i r d , and J o h n s t o n (1971, figures 13A and 13B) use two
successive series o f maps o f the same area to show observations o f fo ur
parameters taken on two separate occasions, twelve days apart. A lthough
a graded series of shading has been used to enhance the visual effect, the
technique is not completely successful since the sequence and values o f
shading vary fro m parameter to parameter and between successive observa­
tions o f the same parameter. H owever, the choice o f black to represent the
m axim u m values of salinity and nitrate and the m inim um values o f
temperature and chlorophyll effectively shows the correlation between
them.
Another w a y o f solving the temporal problem is by the use o f a
Here, vectors at one point, fo r exam ple where
p ro g r ess iv e vector diagram.
LA TI T UD E
LA TITU D E
Fir.- 8. — M e r i d i o n a l c i r c u l a t io n in the m o d e l ocean l o r cases (a) I 4 - I (closed bas in ),
(b ) 15-1 (d ee p g_.p, li n e a r s u r f a c e - t e m p e r a t u r e d i s t r i b u t i o n ) , (c) 16-1 (d e e p gap, curved
s u r f a c e - t e m p e r a ^ u r e d i s t r i b u t i o n ) , and ( d ) 18-1 ( s h a l l o w gap, l i n e a r s u r f a c e -t e m p e r a t u r e
d istribu tion).
A. E . G i i .l a n d K. B r y a n . Effec ts o f g e o m e t r y on th e c i r c u l a t i o n o f a th r e e - d im e n s io n a l
s o u t h e r n - h e m i s p h e r e ocean m o d e l, fig. 6. D e e p Sea R e s e a rc h , J u l y 1971. P e r g a m o n Press
L td .
Fid. 9. — D e n s ity (a,) sectio n w e s t
w i t h d e s tin a t io n s o f th e w a t e r in
e n t e r th e E n g lish Ch an n el east o f
c a p it a l letters, w h e r e a s l o w e r case
o f U s h a n t a lo n g l a t it u d e 4 8 " 2 0 ' N o n 7 A u g u s t 1950
and b e l o w th e t h e r m o c lin e . W a t e r s w h i c h w e r e to
a lin e d r a w n f r o m U s h an t to S c i l l y ar e d e n o t e d h v
le tte rs in d ic a t e w a te r s w h i c h w e r e n o t t o e n t e r th e
Ch a n n e l.
L . H .N . C o o p e r . W a t e r flow- in to th e E n g l i s h Channel, f ig . 9. J. M a r . B i o l . .Ass. U . K .
(1960), V o l. 39, pp. 173-208.
J'ii;. II). ■— A b l o c k d i a g r a m to s h o w h o w w a t e r l y i n g h o r i z o n t a l l y in th e thei-moclinc
w e s t o t I s h a n t tw is t s in a v e r t i c a l p la n e t h r o u g h a r i g h t a n g le as it passes n o rth -w e s t
o f I s h a n t to o c c u p y the s u h t h e r m o c lin e v e r t ic a l c o lu m n in m i d -C h a n n e l (s ta tio n 21)1
and at E.I. T h e l o w e r c o n t o u r p asses t h r o u g h the p o s i t i o n o f stat io n 25 at 50 in depth.
T h e u p p e r c o n t o u r, h o w e v e r , passes not t h r o u g h sta tio n 25 but th r o u g h a p o s itio n some
m il e s to th e n o r th -w e s t.
L.H .X . Cooi'EH. W a t e r f l o w
(19611). Vol. 39, pp. 173-2(18.
in to the E n g lis h Ch an n e l, f ig . 8. J. M a r . B i o l . *4ss. I ' . K .
a current meter is situated, are joined in succession. S w a l l o w ' (1971,
figure 14) has used a computer-generated vector diagram for readings from
current meters on the Biscay Slope — changes in rate and direction may
be determined, but there is a false impression o f spatial movement. He has
also illustrated water movement in the Golfe du Lion by means of a film
technique, the frames consisting o f successive diagrams of data from
current meters and floats. One set of diagrams represents readings at
12-hourly intervals, broken lines showing vectors at each current meter
and solid lines the movement of each float. T h e second set o f diagrams
shows the same situation at 2-hourly intervals by the use o f coloured dots
which appear to move outwards from each meter station. Fig. 15 is a
composite of the first set of diagrams.
The most usual w ay of showing variations o f characteristics with time
is by the use o f line gritphs. P i t t , C a h s o n and T u c k e r (1973, figure 16)
have shown how wind and current speeds altered over ten days and the
relationship between them, by superimposing the graphs o f the two para­
meters, which are distinguished by different line symbols; the velocities
are also correlated with changes in their directions, which are indicated
by arrows above. The different velocity units can conveniently be applied
to a single set o f sub-divisions on the vertical axis. Multiple line graphs
F i g . 11. — M e c h a n is m f o r th e t r a n s f e r o f n u t r i e n t s p ro d u ce d b y p h y t o p l a n k t o n t o the
b e n t h ic h a d a l e n v i r o n m e n t . H, v e r y s m a l l h e r b i v o r e s ; O, s m a ll o m n i v o r e s ; 0/C, l a r g e r
o m n i v o r e s , p r o b a b l y b ia s e d t o w a r d s a c a r n i v o r o u s d i e t ; C, l a r g e c a r n i v o r e s . A l l th e s e
a n i m a l s can m i g r a t e v e r t i c a l l y and h o r i z o n t a l l y to m e e t the o n e s a b o v e a n d b e l o w t h e m .
J. M a i c h l i x e . T h e b i o l o g y o f b a t h y p e l a g i c o r g a n is m s , e s p e c i a l l y Cru stac ea ,
D ee p Sea R e s e a r c h , N o v . 1972. P e r g a m o n P r e s s L td .
fig.
11.
D ensity g r o d itn t p ro fil*
--------
F i g . 12. —
X ~ 15 h -----------H
S ta ges in the e v o l u t i o n o f a b i l l o w
J.D. W o o u s a n d R . L . W i l e y . B i l l o w tu rb u le n c e an d
D e e p S e a R e s e a r c h , Feb. 1972. P e r g a m o n P r e s s L td .
m i x i n g e ve n t.
ocea n
m ic r o s t r u c t u r e ,
fig.
1.
o»
is*
M*
n*
ig||
lilr
NITR ME M o t I4
Fir..
13A.
—
O b se rv a tio n s at 3 m on f i r s t s u r v e y ( n o t e : th e s o lid b la c k
te m p e r a t u r e a n d c h l o r o p h y l l i n d ic a t e m i n i m u m v a lu e s ).
a r ea s
for
Km:. Klli. - O b s e r v a tio n s at
111 on second s u r v e y (n o t e : the th ic k li n e to th e n o r th e a s t
s ep ara te s the d i f f e r i n g c h l o r o p h y l l v a l u e s at the start and end o f th e s u r v e y ) .
J.H. S t e b i - e , I.E. B a i r d an d 1¾. J o h n s t o n . E v i d e n c e o f u p w e l l i n g o n
fig s 2 an d 3. D e e p Sea R e s e a rc h , Feb. 1971. P e r g a i n o n Pre ss L td .
Kockall
Bank,
F
ig.
14. —
H e a d in g s f r o m c u rre n t m e te rs on
J.C. S w a l l o w .
llis ca y Slope.
I n s t i t u t e o f O c e a n o g r a p h ic Sciences, 1971.
are c o m m on ly used for comparison between separate sets of values, although
different vertical ranges m ay necessitate multiple sub-division o f the vertical
axis. R a y m o n t (1971, figure 17) has used this to illustrate variations in
composition o f zooplankton over 11 months, although the topmost graph
is far removed from the time scale and the month limits have been produced
onto each line. T o represent variations in relative proportions o f three
m ajo r constituents over the same period he has used a series of divided
rectangles (figure 18). Since absolute values are not involved, the columns
representing 100 per cent are of standard size and are divided on a per­
centage basis, carbohydrate, lipid and protein being distinguished by
shading. T h e example has no intervening spaces between successive months
and it therefore shows a “ battleship” profile.
A further common requirement is to show frequency o f occurrence, and
divided diagrams, in this case divided circles or pie diagrams, can be used
most effectively. A r m s t r o n g [2] uses this technique : the pie diagrams
are based on observations o f sea ice o f the U.S.S.R. since 1850 and are
related to the station positions on a map o f the area. A colour code
F i g . 15. —
C o m p o s i t e o f suc ce ss iv e f i l m f r a m e s s h o w i n g d a t a f r o m c u r r e n t m e t e r s and
f lo a ts . G o l f e du L io n .
J.C. S w
12
13
. In s t i t u t e
o f O c e a n o g r a p h i c Sciences, 1970.
14
15
16
17
18
knots
or cm
11
a ll o w
F ig . 16. —
E.G .
P i t t , R .M .
C h a n ge s in w i n d an d c u r r e n t speed an d d i r e c t i o n .
Carson
a n d M.J. T
ucker
. N .I.O .
I n t e r n a l R e p o r t A62, f ig . 1. 1973.
F i g . 17. —
M e g a n y c t i p h a n e s n o r v é g ie n . V a r i a t i o n s in p r o t e in , lip i d , c a r b o h y d r a t e , ash
a n d c h i t i n , e x p r e s s e d as p e r c e n t a g e d r y w e ig h t , a n d w a t e r c o n t e n t e xp re s s e d as p e r c e n t a g e
w e t w e i g h t . M ea ns a r e g i v e n f o r eac h m o n t h t o g e t h e r w i t h l i m i t s o f v a r i a t i o n .
J.E.G. R a y m o n t , R .T . S r i n i v a s a g a m a n d J.K.B. R a y m o n t . B i o c h e m i c a l studies on
m a r i n e z o o p l a n k t o n V I I I , fig. 2. D e e p Sea R e s e a r c h , D e c e m b e r 1971, P e r g a m o n P res s L td .
^ ( c a r b o h y d r a te
ÜÜ L ip id
C H P rote in
Fig. 18. — M e g a n y c t i p h a n e s n o r v é g ie n . T h e p r o p o r t i o n s o f th e t h r e e m a j o r b i o c h e m i c a l
c on s tit u e n t s , p r o te in , l i p i d and c a r b o h y d r a t e , as p erc e n t a g e s o f t o t a l o r g a n ic m a t t e r
t h r o u g h o u t e le v e n m o n th s .
J.E.G. R a y m o n t , R . T . S r i n i v a s a g a m and J .K .B . R a y m o n t . B i o c h e m i c a l studie s o n
m a r i n e z o o p l a n k t o n V I I I , fig. 5. D e e p Sea R e s e a r c h , D e c e m b e r 1971, P e r g a m o n P res s L t d .
represents four levels o f severity of ice cover, and fo r each fo rtn igh tly
period between May and December the relative sizes o f the differently
coloured segments show the proportion o f observations o f each type o f
ice to the total number o f observations available. Refinem ents by H e a p [3 ]
include the addition o f the number o f the station and the total number
o f observations taken, in the centre o f each circle.
A
popular method fo r showing frequ ency is the h is to g r a m , e.g.
histograms (1968) fo r percentage occurrence o f crossing periods
of waves (figure 19). A n extension o f this is G o u l d ’ s diagram (1971,
figure 20 ) which compares three histograms o f temperature gradients over
vertical distances o f 10 m, 30 m, and 40 m at a given station.
D r ape r ’s
T h e overall cartographic problem o f oceanographers is one o f repre­
senting fou r dimensions on two, in black and white. T h e film technique,
however, i f developed, w ill readily extend the dimensions o f presentation
to three to include, above all, time. Colours can also be used, expense
apart, to enhance the appearance and clarity o f maps and diagrams. T h e
increasing use o f computer output devices, such as automatic plotters, m a y
be expected to have a profound effect on both the content and style o f
graphics produced by, or for, oceanographers.
30m
•j)
ni
0)
.Q
E
u
40m
0
F ig . 19. — P e r c e n t a g e o c c u r re n c e o f
c r o s s in g p e r io d s o f w a v e s .
L.
f ig .
D r a p e r . N .I.O .
7.
1968.
I n t e r n a l R e p o r t A33,
1
2
3
t/lOOm
Fid. 20. — T e m p e r a t u r e g r a d ie n ts o v e r
v e r t ic a l distan ce s o f 10 m, 30 m, and 40 m
at a sta tio n.
W .J . G o u l d . In s t i t u t e o f O c e a n o g r a p h ic
Sciences , 1971.
ACKNOWLEDGEMENTS
Th an k s are due to Sir George D e a c o n F RS, fo rm e rly Director of the
Institute o f Oceanographic Sciences, W o r m le y , and Dr John S w a l l o w FRS,
D r A.S. L a u g h t o n , and Mrs Gillian C a s t o n o f the same Institute; Dr G. de
Q. R o b i n , Director o f the Scott P o la r Research Institute, Cambridge; and
D r L.H .N. C o o p e r , FRS, of the Ply m ou th Laboratories of the Marine B io­
logical Association o f the U.K. I am also grateful to Mr Derek N e w ts o n ,
Chief Civil Hydrograp hic Officer in the H ydrographic Department, Taunton,
and U.K. m em ber o f the IC A Oceanic Cartography W o r k in g Group for
his advice and encouragement.
Permission to reproduce the diagrams has been kin d ly given by the
authors and publishers concerned.
REFERENCES
[1 ]
L aughton,
A.S. : Red Sea Discussion, Fig. 13. P h il. Trans. R o y . Soc.,
Vol. 267, 1970.
[2]
A rm strong,
[3 ]
Heap,
T. : Sea Ice North o f the U.S.S.R., Part I. Hydrographic
Department, London, 1958.
J.A. : Sea Ice distribution
Department, London, 1963.
in
the
Antarctic.
Hydrographic