new doc 2017-10-17 10.48 - thunderridge...
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is s o d itım c h lo r id e . c o m m o n t a b le s a lt .
th a t c o n t r ib u te to th e o c e a n'
s s a lin it y . O M o s t o f th e sa l t in sea w
terity o f s e a w a te r is 3 . 5 % o r 3 5 % o . F ig u r e 1 s h o w s t h e p
r in c ipa l e le m e lı
ty p ic a lly e x p r e s s s a lin it y in p a r t s \ r th o u s a n d (% o ). T h e a v e n ge ral
iï ľs o lv e d s u b s ta n c e s in s e a w a te r is s u c h a s m a ll n u m b e r , o c e a ï ıo g
t a ph er
s(% ), w h ic h is p a r ts p e r h u n d r e d . e B e c a u s e th e p
r o po r tio n o f d i
*th e w a te r s a m p le . M a n
y c o m m o n q u a n t itie s a r e e x p r e s s e d in pe rce
r ıtin w a te r . It is th e r a t io o f th e m a s s o f d is s o lv e d s u b s ta n c e s to th e m ass o
fs a l in ity (s a lin a s =
s a lt) is th e to ta l a m o u n t o f s o lid m a te ń a l d isso lv ed
' "J
s a ıin i · · ·
b e c a u s e th e o c e a n is s o v a s t .
s o lv e d c o m p o n e n ts m a y s e e m s m a ll. T h e a c tu a l q u a n tity is h u g
e
th a t a r e c o lle c tiv e ly te r m e d"
s a lts"
A lth o u g h th e p e rc e n ta ge o f d is
-
S e a w a te r c o n s is t s o f a b o u t 3 . 5 p e r c e n t d is s o lv e d m in e r a l su b sta n ces
O u r o w n b o d y flu id c h e m is t r y is s im ila r to th e c h e m is tr y o f se a w a ter
W a te r is th e m a jo r c o m p o n e n t o f n e a r ly ev e r y l
ife fo r m o n
a r e fu ll o f life a d a p te d to t h is e n v ir o n m e n t .
h igııly c o r r o s iv e to m a n y m a te r ia ls . H o w e v e r . M a n y p a r ts o f th e o cean
u n s u ita b le fo r d r in k in g o r fo r ir r ig a tin g m o s t c r o p s a n d c a u se s it to b e
tr a c e a m o u n t s in s e a w a te r . T h e s a lt c o n te n t o f s e a w a te r m a k es it
e v e r y k n o w n n a t u r a lly o c c u r r in
g ele m e n t is fo u n d d is s o lv e d in a t le a st
s o d iu m c h lo r id e , o t h e r s a lts , m e t a ıs , a n d e v e n d is s o lv e d g a s e s . In fa ct,
s ta n c e s th a t g iv e it a s a lty t a s t e . T h e s e d is s o ıv e d s u b s ta n c e s in c lu d e
th e m o s t o b v io u s d iffe r e n c e s is t h a t s e a w a t e r c o n t a in s d is s o lv e d s u
h a t is th e d if fe r e n c e b e tw e e n p u r e w a te r a n d s e a w a te r ? O n e o fW
厂
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w a t e r a n d 3 5 g r a m s o f v a r io u s
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g ra m s o f s e a w a t e r w it h a s a lin it y
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n lo n g tlrn e ,
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o v e ra ll m a k e u p o f se a w a te r h a s
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o ce a rilc rid g e a t h y d ro th e rm a l
o th e rs łlre e x c łriırrg e d a t th e
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re g io n s .
in te n s ity o f s o la r r a d ia t io n i n h ig h la titu d e s is m u c h
T h e gr a p h in F ig u r e 3 s h o w s th is r p ln l in n qh i
p . T he
s o la r r a d ia t io n r e c e iv e d , w h i c h is p ń m a r il y a ħ rn c t io n o f la titu d E
e T h e o c e a n's s u r f a c e w a t e r t e m
pe r a h ır e v a ń e s w i t h t h e a m o n t f
O c e a n T e m p e r a t u r e V a r ia t io n
r e la tiv e ly fr e s h w a te r d ilu te s th e s o lu t io n a n d s a lin it y d e c r e a se s .
se a w a te r in c r e a s e s . In s u m m e r w h e n s e a ic e m e lts , t h e a d d iū o n o r
n o t b e c o m e p a r t o f th e ic e . T h e re fo r e , t h e s a l i n i ty
o f t h e r c m a j
m a tio n a n d m e ltin g o f s e a ic e . W n e n s e a w a te r fr e e z e s in w in te r, s a lßdo
S u r fa c e s a lin ity in p o la r r e g
io n s v a r ie s s e a s o n a lly d u e to th e fm ·
th e s e e x a m p le s a re s h o w n o n th e g r a p h in F ig u r e 3 .
in th e m id - la t it u d e s a n d n e a r th e e qu a t o r , s a l i n it
y i s l o w e r . B o th o F
]n a r e a s w h e r e la r ge a m o u n ts o f
pr e c ip
ita tio n d ilu te o c e a n \y a le rs, a s
e v a p o ra tio n r a te s a re h ig h , a s is th e c a s e in th e d r y s u b t r o p ic a l reg io n s .
fo r m a t io n o f s e a ic e . H ig h s a lin itie s , fo r e x a m p le , a r e f o u n d w here
w a te ı, in c r e a s in g s a lin it y
. T h e s e p ro c e s s e s in c lu d e e v a p o r a tio n a n d th e
O th e r p r o c e s s e s r e m o v e la r ge a m o u n ts o f fr e s h w a te r fr o m s .
te m p e r a tu r e h ig h e s t ? W h y ?
s u rfa c e s a lin ity (lo . E r c u . e ) .
te m p e ra t u re (to p c u rv e ) a n d
v a ria t io n s in o c e a n s u r fa c e
F ig u r e 3 T h is g ra p h s h o w s t h e
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O ce a n W a te r a n d O c e a n Lij 4 2 S
ıa t it u d e s ?
th e r m o d in e a b s e n t in t h e h ig h
A p p ıy in g C o n c e p t s W iry i s t h e
la t it u d e a n d h ig h - la t it u d e r e g i
t e m p e r a t u r e w it h d e p th f o r ıo w
th e v a ria t io n s in o c e a n w a t e r
F ig u r e 4 T h e s e g r a p h s s h o w
has h ig h sa lin ity is s o m e o f th e h ig h e s t - d e n s ity
w a te r in th e w o r ld .
c o n sta n tq o e s s a lin ity s ig n ific a n tly affe c t d e n s ity . C o ld w a te r th a t a ls o
artas o f th e o c e a n -
w h e r e te m p e r a tu re s a r e lo w a n d r e m a in r e la t iv e ly
are g re a te r th a n s a lin it y
v a r ia t io n s . In fa c t , o n ıy in th e e x tre m e p o la r
sea w a t e r d e n s ity b e c a u s e v a r ia t io n s in s u r fa c e s e a w a te r te m p e r a t u r e
seah ate r d e n s ity . T e m p e r a t u r e h a s th e g r e a te s t in flu e n c e o n s u r fa c e
in seaw a te r d e n s ity . A n in c r e a s e in te m p
e r a tu r e re s u lts in a d e c r e a s e in
in crease in sa lin ity a d d s d is s o lv e d s u b s ta n c e s a n d r e s u lts in a n in c r e a s e
sity is in flu e n c e d b y tw o m a in fa c to r s s a lin it y a n d te m p e r a tm e . A n
Fa cto rs A f f e c t ın g s e a w a t e r D e n s ıt y O s e a w a te r d e n -
below th e fre sh w a te r .
staw a te r is a d d e d to lo w - d e n s it y fr es h w a te * th e d e n s e r s e a w a te r s in k s
cau se larg e a r e a s o f o c e a n w a t e r t o s in k o r fıo a t . W ħe n h i
gh - d e n s ity
m in e s th e w a te r'
s v e r t ic a l p o s it io n in t h e o c e a n . D e n s ity d i f f e r e n c e s
D en sity is a n im p o r ta n t p r o p e r t y o f o c e a n w a te r b e c a u s e it d e te r -
size, s u c h a s c e m e n t , m o s t m e t a ls , o r a la r ge c o n ta in e r fu ll o f w a te r .
pack in g , o r a s u r fb o a rd . A n o b je c t th a t h a s h ig h d e n s it y is h e a v y fo r its
that h as lo w d e n s ity is ligh tw e i
g h t fo r it s s iz e , s u c h a s a d ry s p o n
g e , fo a 】n
m easu re o f h o w h e a v y so m e th in g is fo r its s iz e . F o r e x a m p le , a n o b je c t
D en sity is d e fin e d a s m a s s p e r u n it v o l u m e . It c a n b e th o u g h t o f a s a
O c e a n D e n s it y V a r ia t io n
i
Te ◆ p e rd u re (C °
)- T e m p e ï a t u r e (C l -
Lo w la liM d e $ H ig h l a t i t u d
ıl ê - o t is th e th e r m o c lin e ?
(oıu m n is iso th e r m a l ( is o-
s a m e , t lıe r m o - h e a t) .
not p re se n t in h ig h la titu d e s . In s te a d , t h e w a te r
chan g e o f te m p e r a tu r e w it h d e p th . A th e r m o c lirıe is
Ce , so the c u r v e r e m a in s v e r t ic a l . T h e re is n o r a
p id
tem peratu re o f th e w a te r is s im ila r to t h a t a t t h e s u r -
Itc w ith a lo w te m p e r a tu r e . D e e p e r in th e o c e a n , t h e
than in lo w la titu d e s , s o t h e c u r v e b e g in s a t th e s u r -
w a te r te m p
e r a tu re s in h ig h la t it u d e s a r e m u c h c o o le r
difïerent p
a tte r n fro m th e lo w - la titu d e c u r v e . S u r fa c e
The h ig h - la titu d e c u r v e in F i \ r e 4 s h o w s a v e r
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o n ly a b o u t 2 p e rc e n t o f o c e a n w a te r .
e x te n «l k ) a d e p th o f 4 5 o m e te rs . T h e s u r fa c e m ix e d z o n e a c co u n t
s lo rs e a s o n . T h c z o n e u s u a lly e x te n d s to a b o u t 3 o o m c te f s ,
b u t it n aÝ
d e p th a n d tc m p c ra tu rc o f th is la y e r v a r h d e p e n d in g o rl ıa titu d e d
re n ts , a n d tid e s . T h e m ix e d n »n c h a s n e a r ly un ifo r m te m p
e ra tu r es . The
is th e a rc a o f th e s u r fa c e c re a te d b y th c m ix in 8 o f w a te r b y
w a v e s , c t«
'
fa c e , it is h e re th a t w a te r te m p e ra tu re s a re w a r m e s t . T h e m ix e d ı'o o ¢
S u r f a c e Z o n e lļ c c a u s c s o la r e n e r g y is re c e iv e d a t th e o c e a n su r
tr a n s it io n z o n e , a n d a d e e p z o n e . T h e s e z o n e s a re s h o w n in F igu re 6 .
In m o s t p a r ts o f th e o p e n o c e a n a s h a ııo w s u r fa c e m ix e d z o n ¢, a
O O c e a n o g r a p h e r s g e n e r a ıly r e c o
g n iz e a t h r e e - ıa y e r e d str u d u re
ra tio n , t h e h ig h e s t - d e n s ity w a te r is fo u n d a t th e gre a te s t o c e a n d ep
th
b e lo w , Iıx c e p t fo r s o m e s h a llo w in ıa n d se a s w ith a h ig h ra te o f e v a p o
d e n s ity w a te r e x is ts n e a r th e s u r fa c e , a n d h ig h e r - d e n s ity w a te r o ccu rs
T h e o c e a n , like R a r th'
s in tc r io r * is la y e re d a c c o rd in 吕 to d m s ity
Lo w 。
O c e a n L a y e r ın g
in s te a d , t h e w a te r c o lu m n is a b o u t th e s a m e d e n s ity th ro u g h o u t.
h igh- d e n s ity w a te r b e lo w , A p yc n o c lin e is n o t p re s e n t in h ig h la titu d es
c a n t l»a r r ie r to m ix in g b e tw e e n lo w - d e n s ity w a te r a b o v e a n d
a r a p id c h a n g e o f d e n s ity w ith d e p th . A p y c n o c lin c p re s e n ts a sig n ili ·
o c e a n w a te r b e tw e e n a b o u t 3 0 0 m e te r s a n d ı 0 0 0 m e te r s w h e re th eT¢ i$
T h c p y c n o c ıin e (p y ć n o - d e n s ity , ć lin e = s ıo p e ) is th e la y er of
4 2 6 C ha p te r 15
th ıs d k ın n c o o c c u r?
h ig h · łıtıtu d · g rıp h ? W h y d o e s
w h a " ' " e d k ·r ın ' " ' " ' "
Ë= gæı. . ) H X Xp ' " ' " o lle ' " h e d ¢. N r
ın t · rp m t ın g D ln g r n m a
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stra tific a tio n .
d o n o t e x h ib it th e sa m e p a tte rn o f w a te r
ın c ıu d e a n e x p ıa n a t io n o f w h y p o ıa r re g io n s
istic s o f th e th re e z o n e s o f th e o p e n o c e a n .
g ra p h th a t d e s c rib e s th e d iffe re n t c h a ra c te r -
D e s c r ıp t ıv e P a r a g r a p h W rite a p a ra -
W r i t i n g S c
ıa titu d e o c e a n s .
o f te m p e ra tu re v a ria tio n w ith d e p th in ıo w -
8 . S u m m a r ız ın g E x p ıa in t h e g e n e ra ı p a t t e r n
re m a in re la tiv e ıy c o n sta n t o v e r tim e ?
7 . ın f e r r ın g W h y d o e s t h e s a ıin it y o f s e a w a te r
C r ıt ıc a ı T h ın k ın g
o p e n o c e a n ?
6 . e w ha t a re th e t h re e m a in z o n e s o f th e
w a te r?
S, e W ha t fa c to rs a « e c t th e d e n s iw o f o c e a n
a n d se a su rfa c e te m p e ra tu re .
4 . e Ex p la in th e re ıa tio n s h ip be tw e e n ıa titu d e
3, e w ha t a re th e so u rc e s o f s a ıt in o c e a n w a te r?
in se a w a te r?
2. e w ha t a re th e s ix m o s t a b u n d a n t e ıe m e n ts
e xp re ss th e s a ıin iw o f o c e a n w a te r?
1. e w ha t is sa lin ity ? w h a t u n its a re u se d to
Re v ıe w ıng C o n c e p t s
Sectio n . 1 A s s e s s m e n t
te m p e ra t u r e a n d s a ıin it y .
w a t e r d e n s it y , w h i c h v a r i e s w i t h
m a in z o n e s o f t h e o c e a n b a s e d o n
O c e a n o g r a p h e rs r e c o g n iz e t h re e
F ig u r e 6 0 c e a n Z o n e s
cılssed in C h a p te r 1 6 .
e su rface , s in k s , a n d in it ia te s d e e p-
o c e a n c u r r e n ts , w h ic h a r e d is -
occu r in h ig h - la titu d e r e g io n s . H e r e , c o ld h ig h- d e n s ity w a te r fo r m s a t
Therefo re , go o d v e r tic a l m ix in g be tw e e n s u r fa c e a n d d e e p
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lhere is n o r a pid c h a n g e in te m p e r a tu r e o r d e n s ity
w ith d e p th .
does n o t ex ist a s s e e n in F ig u r e 6 . T h e th r e e la ye r s d o n o t e x is t b e c a u s e
ın h ig h la titu d e s , t h is th r e e - la y e r e d s t r u c t u r e o f th e o p e n o c e a n
The d eep zon e in c lu d e s a b o u t 8 0 p e r c e n t o f o c e a n w a te r .
above fie e zin g . A s a r e s u lt , w a t e r d e n s ity re m a in s c o n s ta n t a n d h igh .
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Dee p Z o n e B e lo w th e t r a n s it io n z o n e is th e d e e p z o n e . S u n li
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acco u n ts fo r a b o u t 1 8 p e rc e n t o f o c e a n w a te r .
ıone includes a th e r m o c lin e a n d a s s o c ia t e d p y c n o c lin e . T h is z o n e
lace lay er a b o v e a n d th e d e e p z o n e o f c o ld w a te r b e lo w . T h e t r a n s itio n
distin ct laye r c a lle d th e tr a n s itio n z o n e e x is ts b e tw e e n th e w a r m s u r -
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w ith d ep th a s w a s s e e n in F ig u re 4 . H e r e , a
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4 4 8 C h a p te r 1 6
th e g e n e r a l c ir c u la tio n p a tte r n o f th e a tm o s p h e re .
m a jo r h o r iz o n ta l m o v e m e n ts o f s u r fa c e w a te r s a re closely related
to
m o r e p e r m a n e n t a n d e x te n d o v e r la r g e p o r tio n s o f th e o c e a lls . Thes
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r e s p o n s e s to lo c a l o r s e a s o n a l in flu e n c e s . O th e r s u r fa c e c u r re nts a
re
la s t lo n g , a n d th e y a fŘ c t o n ly s m a ll a re a s . S u c h w a te r m o v e m e iıts ale
th e w in d th a t b lo w s a c r o s s it s s u r fa c e . S o m e o f th e s e c u r re n ts d o n ot
◆ S m fa c e c u r r e n t s d e v e lo p ħ o m f r ic t io n b e tw e e n th e o c ea iı aitd
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s s u r face ·
S u r f a c e C u r r e n t s s u r fa c e c u iT e n ts a r e m o v e m e n ts o f w a te r that
e r a te d in v o ıv e w a te r m a s s e s in m o t io n .
b e s imp le o r c o m p le x . In a ll c a s e s . H o w e v e r , t h e c lır re n ts th a t a re g
en ·
c a n b e a t th e s u r fa c e o r d e e p b e lo w . T h e c r e a t io n o f th e se c u rr e n ts can
a n o th e r . T h e a m o u n t o f w a te r c a n b e la rg e o r s m a ll . O c e a n c u rre n ts
O c e a n c u r r e n t s a r e m a s s e s o f o c e a n w a te r t h a t flo w fr o m o n e pla ce to
S u r f a c e C ir c u ıa t io n
fo r o c e a n m ix in g a n d r e c y c lin g n u t r ie n t s .
fe r e n c e s c r e a te d e e p-
o c e a n c ir c u la tio n . T h is c ir c u la t io n is im p o rtan t
s h o re s , w h e r e t h e ir im p a c t e r o d e s t h e la n d . In s o m e a re a s . Density
F ig u r e 1 . S o m e w a v e s c a r r y e n e rg y f r o m p o w e r fu l s t o r m s to d istaiıt
c o a s ta l c lim a te . W in d s a ls o p r o d u c e w a v e s lik e t h e o n e s sh o w n in
fo r c e s . W in d s , fo r e x a m p le . G e n e r a te s u r f a c e c u r r e n ts , w h ic h influence
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sy s te m s . T h e W e s t W in d D r if t
flo w s a ro u n d t h e c o n t in e n t
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the S o u th A tla n tic G y r e , a n d th e In d ia n O c e a n G y r e . F in d th e s e g p e s
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called T e s ({W o s -
a c ir c le ) . T h e r e a r e tiv e m a in o c e a n g )T e s th e
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s h o w n in g re e n , b lu e . A n d p
u rp
l e .
s u r r o u n d in g c o ld e r w a t e r s a r e
a n d t h e C a r o lin a s . T h e
a lo n g t h e e a s t c o a s t o f F lo r id a
a r e s h o w n in r g d a n d o r a n g e
w a r m w a t e r s o f t h e G u lf S t r e a m
c o u r s e o f t h e G u lf S t r e a m . T h e
s u r f a c e t e m p e r a t u r e s s h o w s t h e
c o lo r s a t e llit e im a g e o f s e a
F ig u r e 3 G u ıf S t r e a m T h is f a ls e -
w a t e r fr o m d ep th s o f 5 o to 3 o o m e te r s b r in
g s w a te r th a t is c o o le r th ai
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C o r io lis e f fe c t c a u s e s u r fa c e w a te r to m o v e a w a y fr om s h o re . M th
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th e eq u a to r a n d
p a r a lle l to th e c o a s t . C o a s ta l w in d s c o m b in e d w ith th ť
C o a s ta l u p w e llin g o c c u r s in t h e s e a r e a s w h e n w in d s b lo w to wad
W e s t A fr ic a .
c o n tin e n ts , m o s t n o t a b ly a lo n g c a l ifo r n ia , w e s t e r n s o u th A n ie rica , an d
c a lle d c o a sta l u p w e llin g , is m o s t c h a r a c te r is tic a lo n g th e w e s t c o a sts of
a c o m m o n w in d - in d u c e d v e r tic a l m o v e m e n t . O n e ty p e o f u p \, e l】in g
w a te r fr o m d e ep e r la
y e r s to rep la c e w a r m e r s u r fa c e w a te r . u p w eu in g
is
a ls o c a u s e w r tic a l w a te r m o v e m e n ts . u p w e llin g is th e r is in g o f co ld
U P w e ııın g In a d d itio n to p r o d u c ing s u r fa c e c u r r e n ts , w in d s a n
W in d s t r a n s p o r t th e r e m a in ing th r e e -
q u a r te r s .
w a te r m o v e m e n t a c c o u n ts fo r a b o u t a q u a r te r o f th is h e a t tra m po R
is a n e x c e ss o f h e a t, t o t h e p o la r r e
g io n s , w he r e le s s h e a t e x is ts . o cean
b a la n c e . T h e y d o th is b y tr a n s fe r r ing h e a t fr o m th e tropi w h e ï e m
O c e a n c u r r e n ts a ls o p la
y a m a jo r ro le in m a in ta in in g E a r t h h a t
re n ts a r e s h o w n in F ig u r e 2 .
w e s t c o a s t o f S o u th A m e r ic a . A n d th e C a lifo r n ia C u r r e n t. T h « e cu r ·
B e ng u e la C u r r e n t a lo n
g w e s t e r n A f r ic a , t h e p e r u C u r r e n t a lo n g th e
w a r m t e m p e r a t u r e s o f a d ja c e n t l a n d a r e a s . S u c h is th e c a se fo r th e
w a t e r c u r r e n t s t r a v e l to w a r d t h e eq u a t o r , th e y h e ıp m o d e r a te th e
itu d e s . C o ld c u r r e n ts b e g in in c o ld h ig h
- la titu d e r eg io n s . O A s co ld
is m o s t fe lt in th e tr o p ic s o r d u r ing s u m m e r m o n t h s in t h e m id d le la t.
m id d le la titu d e s in w in t e r . In c o n t r a s t , t h e i n f l t ım r p o f c o ld c u n en ls
T h e e ffe c ts o f t h e s e w a r m o c e a n c u r r e n ts a r e k lt m o s tly in ıħe
w h ic h lie s 1 2 d e gr e e s la titu d e fa r t h e r s o u t h .
Ja n u a r y te m p e r a t u r e s im ila r to th a t e xp e r ie n c e d a t N e w Y o rk C i
%
e x a m p le , B e rlin , G e r m a n y ( 5 2 d e g r e e s n o r th la t ih ıd p ), h a s a n a v eï age
p r e v a iling w e s te r ly w in d s c a r r y t h is w a r m in
g e ffe c t fa r in la n d . Fo r
w h ic h a re s im ila r to th e la titu d e s o f A la s k a a n d N e w fo u n d la n d . TIE
w in te r th a n o n e w o u ld e x p e c t fo r th e ir la titu d q
o f n o r th w e s te r n E u r o p e to b e w a r m e r d u ring tht
Stre a m . T h is c u r r e n t a llo w s G r e a t B r ita in a n d m ,jc h
A tla n tic C u r r e n t , w h ic h is a n e x te n s io n o r th e G ulf
U P to th e N o r h
w a te r c u r r e n t s h o w n in F ig u r e 3 , is a n a ĺ c e lle n l
c o o l t l a s n E h . ıh e G u lf S tre a m , a w a r ln
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of a w ater M a s s , s c ie n tists a r e a b le to m a p th e s lo w c ir c u la -
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ljjn e it is in th e d e e p o c e a n . B e c a u s e o f th is , o c e a n o g r a p h e r s
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s ic a l
e nough , it sin k s , in itia tin g d e e p
-
o c e a n d e n s ity c u r r e n ts .
hcteases a s se a ic e fo r m s . w ħe n th is w a te r b e c o m e s d e n s e
these reg io n s , s u r fa c e w a te r b e c o m e s c o ld , a n d its s a lin ity
density cu rr e n ts b e g in s in h igh ıa t it u d e s a t th e s u r fa c e . In
Hlsh La t ıt u d e s M o s t w a te r in v o lv e d in d e e p- o c e a n
rem ain s lo w a n d r e la t iv e ly
c o n s t a n t .
POrtant in v e ry h ig h la t it u d e s , w h e r e w a te r te m p e r a tu r e
ice m elting . D e n s it y c h a n g e s d u e to s a lin ity
v a r ia tio n s a r e
Precip ita tio n , r u n o ff fro m la n d , ic e b e r g s m e lt in g , a n d s e a
ice. Pro c e sse s th a t d e c r e a s e t h e s a lin ity o f w a te r in c lu d e
iof w a te r in c lu d e e v a p o r a t io n a n ą th e fo r m a tio n o f s e a
oran in cr e a s e in s a lin it y . P r o c e s se s th a t in c r e a s e th e s a lin -
w ter d e n s it y c a n b e c a u s e d b ya d e c r e a s e in t e m p e r t u r e
\ 油 o u t b e n e a th th e s u r fa c e . e A n in c r e a s e in s e a -
am o ng
w a te r m a s s e s . D e n s e r w a te r s in k s a n d s lo w ly
ren ts o f o c e a n w a t e r t h a t r e s u lt f r o m d e n s ity
d if fe r e n c e s
Den sıty (u r r e n t s D e n s it y c u r r e n ts a r e v e r t ic a l c u r -
to u p w e ılin g n u t r ie n ts .
p h o t «»s y n t h e s is , w h ic h is l i n k e d
re d , i n d i c a t e h i
gh a m o u n t s o f
c h ıo ro p h y ıı c o n c e n t ra t io n s , i n
s o u t h w e s t c o a s t o f A f r ic a . H ig hc o n c e n t ra t io n a lo n g t h e
s a t e lıit e s h o w s c h lo ro p h y ıl
T h is im a g e f ro m t h e S e a s t a r
F ig u r e 4 E Ħ e c ts o f U p w e ııin g
accou n ts fo r th e th o r o u g h m ix in g o f d e e p-
w a te r m a s s e s .
dew c e a n c ir c u la t io n h a s a s ig n ific a n t v e r t ic a l c o m p o n e n t . It
In con tr as t to th e la r g e ly h o r iz o n t a l m o v e m e n t s o f s u r fa c e c u r r e n ts ,
Dee p- O c e a n C ãr c u ıa t io n
d w h a t is u p w e w n g ?
M uđiv ityd u e to c o a s t a l u
pw e ll in
g o ft th e s o u th w e s t c o a s t o f A fr ic a .
orher m a rin e o rg a n is m s . F ig u re 4 is a s a te llite im a
g e th a t s h o w s h ig h
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m o n th s , t h is w a te r flo w s o u t o f th e M e d ite r r a n e a n S e a in to th e A n tic
h a v e a s a lin ity o f a b o u t 3 8 o , o o (p a r ts p e r th o u s a n d ) . In th e w in tđ
w a t e r in c r e a s e s . T h e s u r fa c e w a te r s o f t h e e a s t e r n M e d ite r 】a n e a iı Sa
w a te r e v a p o r a t e s , s a lt is le ft b e h in d , a n d th e s a lin it y o f th e re m a in in g
o f e v a p o r a t io n c o m p a r e d t o th e a m o u n t o f p r e c ip ita tio n . w h e n
w e s t w in d a n d s u n ny d a
y s . T h e s e c o n d it io n s le a d to a n a n n u a l e x cesi
C lim a te c o n d it io n s in th e e a s te r n M e d ite r r a n e a n in c lu d e a d q n o rth .
th e s u r fa c e t h a t s in k s a n d e v e n t u a lly flo w s in t o t h e A tıa n t ic O c m
c o n d it io n s e x is t th a t le a d t o t h e fo r m a t io n o f a d e n s e w a te r m a ss a
ity o f o c e a n w a t e r d u e to e v a p o r a t io n . In th e M e d ite 】T a n e a n S a
E v a p o r a t io n D e n s it y c u lr e n t s c a n a ls o r e s u lt fr o m in c r e a se d
fa c e fo r a n a v e r a g e o f 5 0 0 to 2 0 0 0 y e a r s .
fr o m th e s u r fa c e o f th e o c e a n , d e e p w a te r s w ill n o t re a p p e a r a t th e słn -
it m o v e s th ro u g h o u t th e o c e a n b a s in s in s lo w c u r r e n ts . A fte r \
in th e w o r ld . T h is c o ld , s a lty w a te r s lo w ıy s in k s to th e se a flo o c w h en
N e a r A n ta rc tic a , s u r fa c e c o n d it į o n s c r e a te th e h ig h e s t d m sity w a ra
fo r m e d b y d e n s it y c u r r e n t s .
w a t e r c irc u la t io n o f w a t e r m a s s e s
A t la n t ic O c e a n s h o w s t h e d e e p
Ħg u r e 6 T h is c r o s s s e c tio n o f t h e
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d o e s th is p ro c e s s le a d to t h e
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th e G u « S tr e a m w h e n s a ilin g to A m e ric a .
Fig u re 2 to e x p la in h o w s a iıo rs c o u ld a v o id
p a ra g ra p h e x p la in ing w h y t h is is t ru e . U s e
S tre a m w a s delang th e s h ip s . W rite a
En g la n d . ït w a s d e te rm in e d t h a t t h e G u K
to tra v e l t h e s a m e ro u te fm m A m e ric a t o
ıo n g e r to g o fro m E n gla n d to A m e ric a th a n
n o te d th a t it to o k th e s h ip s tw o w e e k s
b e tw e e n E n g ıa n d a n d A m e ric a . It w a s
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a re a s o ff th e c o a s t o f P e ru . H o w m ig h t t h ķ
u p w e ııin g o f c o ld , n u t ń e n t-
r ic h w a te r s to p s in
ın f e r r ın g D u ń n g a n E ı N iñ o e v e n t t h e7 .
b e tw ee n th e s e a re a s a t t h e s a m e la t itu d e .
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