The inflow of solar energy and the irradiance of the

Oceanologia, 15(1933)
P L IS S N 0078-3234
Bogdan WOŹNIAK, Ryszard HAPTER, Barbara MAJ
Polish Academ y of Sciences
Institute of Oceanology — Sopot
THE INFLOW OF SOLAR ENERGY AND THE IRRA­
DIANCE OF THE EUPHOTIC ZONE IN THE REGION
OF EZCURRA INLET DURING THE ANTARCTIC SUM­
MER OF 1977/78 *
1. IN T R O D U C T IO N
Solar energy affects the m ajority of fundamental and com plex processes
occurring in the sea either indirectly or directly. One of the most im ­
portant interactions of light and the marine environment is its influence
'on the aquatic biosphere. Light, affecting the photosynthesis directly,
determines prim ary production o f the biomass in the sea, thus affects
population of all livin g organisms. Responses of the organisms to photic
impulses (phototropism), constituting one of the factors determ ining their
migration and distribution in a basin, are also important.
In this connection it seemed w orth w h ile to include optical measu­
rements of energetic characteristics of the light field in the sea in the
program me of oceanographic and biological research carried out by the
Second Polish Antarctic Expedition in Ezcurra In let during the A n tarc­
tic summer of 1977/78. A s analysis of the results of measurements con­
cerned both w ith the in flu x of the solar radiation to the sea surface and
its diffusion into the w ater body is the subject of this paper.
Both spatial and spectral distributions of solar energy in a basin
v a ry w ith the external solar flu x reaching its Surface (determ ined by
geographical situation, season of the year, tim e of day, optical condi­
* These studieis were carried out under the research program M R II 16 coordinated
by the Institute of Ecology of the Polish Academy oi Sciences. They were spon­
sored in part under research program M R I 15 coordinated by the Institute of
Hy-'dro-Engineerhlg of the Polish Academy of Sciences.
'
tions in the atmosphere etc.) and specific optical properties of the sea,
characteristic for a particular region. As far as the Antarctic v/aters are
concerned, this problem has been little studied. As yet, the investiga­
tions w ere lim ited for all practical purposes to atmospheric actinometric
measurements (w ith the exception of a fe w papers [9, 16] also con­
fined to studies of the optical properties o f the sea in the Antarctic re ­
gion) carried out system atically for several years at m eteorological sta­
tions situated in that region [14]. These actinometric data refer only,
however, to the w hole range of solar energy fallin g on the sea surface.
The main purpose of this w o rk to give a fu ll description of the in flow
of solar energy to the basin studied (in particular to the euphotic zone),
including both the magnitude of the radiant energy fallin g on its sur­
face and that reaching particular depths.
To attain this goal, the actimicimeitiric measurements had to be supplemeneted w ith systematic monitoring of the optical properties of the
sea, in particular the time-space fluctuations of spectral distributions of
the irradiance attenuation coefficient w ith depth. Hence, the results of
the investigations of energetic conditions occurring in the euphotic zone
of Ezcurra In let also shed some light on the environm ental optical pro­
perties of this basin.
A ll energetic and optical characteristics of underwater ligh t fields
presented in this paper w ere restricted to visible light over the w a ve ­
length range of 400— 700 nm. O w ing to strong attenuation of ultraviolet
and infra-red in sea water, this range constitutes the m ajor part of the
solar energy penetrating the w ater body. Furtherm ore, for all practical
purposes this range involves all the energy utilized in the photosynthesis
of organic matter in the sea.
2. MATERIAL AND METHODS
The experim ents w e re carried out in the region of Ezcurra Inlet from
Decem ber 21st, 1977 to March 10th, 1978 (w ith the exception of 22— 26
December, 6— 14 and 28 January) on board the m.s. „A n ton i Garnuszewski” anchored at a fixed position cp=62°10’ S, X=58°32’ W ) w here the
depth was 70— 80 m. This paper presents the results of 65 all-day series
of measurements of alternate above-w ater and underwater energetic cha­
racteristic of the solar radiation flu x and m eteorological observations.
These included:
A)
diurnal variations of irradiance (the definitions of all optical
magnitudes used in the present paper have been discussed in detail in
[2] and [7]), Ep. i.e. the magnitude of the solar energy over the whole
spectral range, reaching the sea surface through the atmosphere. The
measurements w ere carried out b y means of a universal M-80M pyranometer (made in the U.S.S.R.) calibrated in absolute pow er units
(W · cm-2). Tim e variations of E p w ere registered by a recorder or d igi­
ta lly using electronic integrators and recording appliances equipped with
a term inal printer (details of the methods, techniques and apparatus
used for the optical and energetic characteristics of the light field by
the team of optical physicists from the Polish Academ y o f Sciences’
(P A S ) Institute of Oceanology are described in [3, 1*0, 11, 17]). In the lat­
ter case, averaged irradiances over various tim e intervals could be de­
term ined owing to changes of integration times of electric signals from
the pyranom eter;
B) diurnal variations of underwater downward irradiance, E d(X,z)
for the follo w in g seven wavelengths, X, over the visible range: 425, 475,
500, 525, 550, 600 and 675 nm, w ere measured simultaneously at tw o
differen t depths, z, in the sea. These measurements w ere carried out by
means o f tw o multichannel marine spectrophotometers (designed and
made b y the P A S ’ Institute of Oceanology), calibrated in absolute pow er
units (W · cm '2 ■nm"1). The depth o f immersion of the optical sensors cf
the spectrophotometers was changed periodically and most frequ en tly
set at levels Zj » 0 — 7 m and z2 ^ 15 — 25 m. The choice of these depths
was determ ined by the sensitivity thresholds of the sensors and irradia­
tion of the basin, as w e ll as by the desire to carry out the measurements
within as thick a layer of euphotic zone as possible. The photo-currents
from the optical sensors w ere measured in the same manner as in the
case of the E p measurements;
C) diurnal variations of the degree of total cloudiness. These obser­
vations w ere made eve ry hour on the hour G.M.T. diJring the day. Data
obtained by meteorologists on board the m.s. „A n ton i Garnuszewski”
was also utilized.
On the basis o f the above data, other parameters characterizing the
light in flu x reaching the sea surface and light field in the w ater body
w ere determ ined and analysed, such as:
A)
spectra of the downward irradiance attenuation coefficient in
the sea, K d(k). Generally, the K d coefficients also depend on the depth
and can be described by the equation
« [ Tt y ) m —
^_____
Kd ( A . , z )
Ed U , z )
SE (A. , z )
o>z
As the coefficients in this paper w ere determined by irradiance measured
at tw o depths, Zj and z2, they w ere computed from an appropriately
transformed equation (2):
K IA.) ■
ln[EIA- ^ 1 }/ E l ^ . z?>]
<i
(2)
Z2 - 2,
Kence, the K d(X) values can be considered to be the means for the
layer bounded by the depths Zj and z2. The K dCk) values, so determined,
w ere assumed to be representative for the whole euphotic zone, the op­
tical hom ogeneity of this zone being understood in terms of these K d
values;
B ) spectra of downward irradiances, E d(l,z) at various (differen t
from Zi 'and z2) depths in the euphotic zone of the sea. The magnitudes
of these irradiances w ere determined from :
Ed ( A , z )
=
E d ( A.
, z 1 ) e
K d
2 ; f 2 - z 1]
(?)
on the basis of the measured irradiances, E d(X,z1) and mean K d(X) coef­
ficients calculated from eq. 2 fo r the euphotic zone;
w
C) irradiance, E d(z), over the visible range of the spectrum (400—
— 700 nm) at various depths of the w ater body. These magnitudes w ere
determ ined by numerical integration in respect of the w avelength of the |
Ed(X,z) spectra, from the equation:
A.= 70Cinm
Ej ( z ) =
J
(4) |
Ed ( 7 U Z ) d \
A.= A00 nm
D) dose of solar energy over the whole spectral range, reaching the
sea surface, %, and dose of the energy of visible light (400— 700 nm)
W
diffusing into particular depths of the w ater body, r|d(z). These magnitu­
des w ere determ ined by integration over tim e t of temporal variations
of the corresponding irradiances, according to the follo w in g relationships:
V
/ Ep"ldt
(5)
At
J
E j ( 2,t)d t
(6) |
At
D ifferen t time intervals, At, of the integration w ere assumed, depending
on requirem ents (e.g. 1 hour, a w hole day, etc.);
E) absolute transmission coefficients through the atmosphere, T, o f
diurnal doses of solar radiation, These magnitudes w ere determ ined from
known r)p values;
T · ’2 p / 12o.p
P)
where'r]o,p is the dose of the solar energy fallin g on the upper layer of
the atmosphere above the observation site in one day. The r)°, p values
w ere determ ined from the equation:
(8)
ï]o, p=480F[arc cos(-tg<p tg8) sincp s in ô + - ^ ~ s in arc cos (-tgcp tgô) coscp cosô],
w here r\o, p is expressed in joules per unit area, F is the solar constant
expressed in watts per unit area (F = 1380 W · m '2), q> and Ô, expressed in
degrees, are angles of latitude and solar declination, respectively. Equa­
tion (8) is obtained b y integration over the tim e from sunrise to sunset
of the expression fo r the tim e varia b ility of solar irradiation on the top
of the atmosphere: E (t) — F cosflftj, where ü(t) is the time-dependet zenith
distance of the sun;
F) average (for particular days and mean in the surface w ater layer
from 2 = 0 to 30 m ) attenuation coefficients o f irradiance (400— 700 nm)
w ith depth in the sea, K d. These w ere calculated from daily energy do­
ses of light, determ ined for the 0 and 30-m depths from the relationship
I n l E ^ ( z* 0 m ) / ( z
is
w _
d "
_____------------ -----------
~
'
* 3 0 m) ]
(9)
--------——.
a z
w here A z = 3 0 m;
G) average ranges of the euphotic zone for particular days, 2e. In ac­
cordance w ith the optical criterion fo r the range of this zone aaopted
here [2], it is the depth to which 1% of the light energy w ith the w a ve ­
length Xm (im m ediately under the sea surface) reaches. The wavelength
corresponds to the maximum light penetration depth, i.e. to the minimum
value of the attenuation coefficient in the spectrum, KaO-)· In the wafers
investigated the Xm value was 525 nm, Hence, the ranges w ere determ i­
ned from :
=
e
In 100
------- ----------------- -
10)
( A. - 525pm.)
w here K d (X = 525 nm) is the mean daily magnitude of this coefficient;
H) diurnal depth variations, 2c, to which a given quantity o f visible
ID
light penetrates, E d= const. The fixed values of this irradiance assumed
10 — O ceanology N o 15(1983)
w ere 10, 5, 1, 0.1, 0.01 and 0.001 m W -cm '2 and the corresponding depths
w ere determ ined from the equation
E ^ (z c ) = const = E v' ( z =0 ) P ( z c )
^
w h ere P(zc) is a function of light transmission over the 400— 700-nm ran­
ge through a layer lim ited by depths of 0 and Zc metres, described by the
equation ([5], [16]):
700 nm
Ed U , z = 0 ) e:'Kd ( W ' z c d A.
[
A^-AOOnm
p (z c )
=
__________ _
^.2=700 nm
J
~
(12)
-
Ed ( ^ 1 z ~ Zc )
Ed 1 K 1z " 0 1
Ed ( A .,-z-0 ) dA.
^ - 4 0 0 nm
Graphs of variations of the Zc levels corresponding to particular
to
Ed — const values, as a function of time, are referred to as „isophotes” ;
H)
mean degree of cloudiness (in a 0— 1 grade scale) fo r particular
days:
n = N/8
(13)
w h ere N is the mean cloudiness (in a 0— 8 grade scale) taken from re ­
cords made e very hour on the hour from sunrise to sunset.
The above measured and calculated optical properties w ere used to
analyze the in flo w of solar energy to the sea surface and irradiation of
the euphotic zone.
3. RESULTS
The measurements and calculations enabled the determination of both
tem poral fluctuations of magnitudes characterizing diurnal irradiance
field s of the sea surface and euphotic zone, and respective ligh t energy
doses fo r particular days during the research period. Owing to the v o ­
lume of material, however, it is impossible to present it in fu ll here.
Hence, only the most essential parameters have been given, these inclu­
ding diurnal doses of solar energy reaching the sea surface and represen­
tative depths of the euphotic zone, as w e ll as mean optical magnitudes
;Eor the sea and atmosphere on particular days. These results (Table 1),
Table 1, Daily energy doses and mean daily parameters characterizing the inflow
of solar energy to the sea surface and its propagation in the euphotie zone
Of Ezcurra Inlet during the summer of 1977/78
ur
^ p ‘
are the d a ily doses o f solar radiation reaching the sea surlacs and o f the
400—."GO-nm visib le iig th band reaching selected depths, g, in the w a te r body, res­
p e c tiv e ly ;
T — is the absolute transmission co e ffic ien t of the d a ily e n e rg y doses through tha
atm osphere:
« ™r !s the mean d egree o f cloudiness during the day (in the f —1 scale);
^ is the mean attenuation c o e ffic ie n t (in the o—30-m la y er) o f the dow nw ard
irradian ce in tha 409—700 nin visib le ligh t band;
X c — is the m ean range o f the euphotie zone during the day.
Tab.
1,
Dzienne dozy energii i średnie dzienna wartości parametrów charakteryzu­
jących dopływ promieniowania słonecznego do powierzchni morza i jego
propagację w strefie eufotycznej fiordu Ezcurra latem 1977/78
odp ow iedn io dzienne d ozy en ergii prom ieniow ania słonecznego padające­
go na pow ierzchn ię m orza i św iatła w idzialn ego w paśmie 400—70S nm na w ybra n e
głębokości z w ton i w od n ej;
T — b ezw zględ n y w spółczyn n ik transm isji dziennych dóz en ergii przez atm osferę;
n — średni (w dniu) stopień zachm urzenia (w skali 0—i);
j{
średni w w a rs tw ie 0—30 m w spółczynnik osłabiania ośw ietlen ia odgórnego
św iatłem w id zia ln ym w paśmie 400—700 nm;
t , ~ średni (w dniu) zasięg c trę fy eufotyczn ej.
'
Date
Data
[J -W
]
T
* 6
-Yl
X~ SS X=U»
1
21.12.77
27.12.
23.12.
29.12.
30.12.
31.12.
01.01.78
0 2 .0 1 .
03.01.
04.01.
05.0.1.
15.01.
16.01.
17.01.
18.01.
19.01.
20.31.
2 1 .0 1 .
2 2 .0 1 .
23.01.
24.01.
25.01.
26.01.
27.01.
29.01.
30.01.
2
2441
1779
2088
2965
2538
2915
2083
2699
2650
1044
718
1821
3144
232S
1384
1427
1760
2189
1062
1154
2565
1748
1811
1372
2076
351
3
0.57
0.41
0.49
0.69
0.61
0 .6 8
0.49
0.63
0.63
0.25
0.17
0.45
0.78
C.58
0.35
0.36
0.45
0.56
0.28
0.30
0.67
0.46
0.48
0.37
0.57
0 .1 0
4
0,75
5
370
744
867
0.92
0.61 1195
0.79 1064
1197
0 .6 6
863
0.81
0.78 1134
C.75 1104
0.99
437
342
0.97
0.92
761
0.47 1303
967
0.59
574
0.92
0.89
5i<8
729
0 .6 8
901
0.64
439
0.93
480
0.99
0.73 1059
0.57
730
0.72
752
0.96
563
0.93
859
1.00 147
0 ,8 6
6
!
1=223
!
7
47.1
43.2
51.7
85.4
93,2
95.8
63.4
68.9
43.4
19.8
19.7
108
114
70.7
73.9
53.6
58.3
68.3
31.8
37.7
88.5
63.6
63.5
74.2
58.6 '
7.21
2.57
3.31
4.13
8.24
11.5
1 0.6
6.32
5.39
2.34
1.14
1.60
23.1
14.7
8.16
14.6
8.13
7.14
8.53
3.48
4.3Ü
1 0 .6
8.11
9.42
14.5
5.01
0.524
1 7=5*00
1
8
0.155
0.28Î
0.355
0.883
1.56
1.28
0.689
0.450
0.141
0.0710
0.146
5.46
2 .1 1
1.11
3.15
1.52
0.987
1.23
0.431
0.562
1.44
1.14
1.44
3.03
0.645
0.0413
[ w
4]
9
0 288
0.263
0.260
0.240
0.213
0.228
0.238
0.261
0.299
0.291
0.259
0.165
0.214
0.226
0.174
0.199
0 .2 2 0
0 .2 2 0
0.231
0.225
0 .2 2 0
0.215
0.209
0.174
0.240
0.272
o
10
20
21
21
23
£6
24
22
21
13
19
22
30
27
23
28
27
26
24
25
25
26
26
25
S3
23
20
Table 1, cont.; Tab. 1, c.d.
1
31.01.
01.02.78
0 2 .0 2 .
03.02.
04.02.
05.02.
06.02.
07.02.
08.02.
09.02.
1 0 .0 2 .
1 1 .0 2 .
1 2 .0 2 .
13.02.
14.02.
15.02.
16.02.
17.02.
18.02.
19.02.
2 0 .0 2 .
2 1 .0 2 .
2 2 .0 2 .
23.02.
.
24.02.
25.02.
26.02.
27.02.
28.02.
01.03.
02.03.
03.03.
04.03.
05.03.
06.03.
07.03.
08.03.
09.03.
10.03.
2
602
1019
1763
1445
875
1237
1176
1272
2150
1073
1360
1040
1759
1591
1041
1708
1696
1817
2419
2350
1762
1047
1501
1040
851
1950
1240
1115
1750
522
1637
2394
2023
1038
905
1688
1048
212
756
3
0.17
0.29
0.49
0.41
0.25
0.36
0.35
0.38
0.65
0.33
0.42
0.32
0.55
0.51
0.34
0.56
0.56
0.61
0.82
0.80
0.61
0.37
0.53
0.38
0.31
0.72
0.47
0.43
0 .6 8
0.2 1
0 .6 6
0.96
0.84
0.44
0.39
0.73
0.46
0.95
0.35
4
5
1 .0 0
253
422
739
592
366
506
487
534
480
440
564
432
735
657
432
695
706
740
981
956
722
435
621
435
355
799
517
454
716
217
673
964
822
448
378
682
430
865
315
0.83
0.92
0.85
0.91
0.74
0.93
0.87
0 .8 6
0.84
0.87
0 .8 6
0 .8 8
0.83
0.89
0.69
0 .8 2
0.72
0.57
0.67
0.78
0.83
0.87
0.96
0.97
0.73
0.94
0.74
0.47
0.92
0.72
0.25
0.52
0.81
0.93
0.53
0.90
0.71
0.94
6
9.03
11.1
24.6
25.4
2 0 .0
41.1
44.4
28.6
27.8
27.9
38.6
28.0
45.6
38.8
24.4
48.4
89.2
44.1
73.5
90.6
93.4
87.0
66.4
48.9
37.0
56.4
39.9
38.0
61.9
17.4
46.9
61.0
97.2
34.7
32.0
47.0
21.5
43.3
2 2 .8
7
0.471
0.429
1.19
1.59
1.61
5.85
5.94
2 .2 0
2.35
2.58
3.94
2.67
4.07
3,26
1.93
4.90
17.2
3.85
8.30
13.2
18.5
31.0
10.7
5.83
5.51
6.05
4.74
4.92
8.52
2.18
5.22
5.80
18.0
4.11
3.24
5.13
1.74
4.54
3.12
8
9
10
0.0273
0.0184
0.0647
0.304
0.335
0.311
0.286
0.261
0.204
18
16
17
19
0 .1 11
0.144
1 .1 0
0.877
0.190
0.233
0.267
0.446
0.284
0.407
0.305
0.170
0.549
4.01
0.376
1.05
2.17
4.11
1 2 .6
1.92
0.932
1.1 1
0.734
0.633
0.712
1.31
0.304
0.643
0.622
3.85
0.555
0.371
0,603
0.164
0.583
0.578
0 .2 1 1
0.265
0.256
0.247
0.238
0.244
0.250
0.256
0.261
0.238
0.172
0.253
0,228
0.203
0.172
0.118
0.193
0.205
0.192
0.233
0.224
0.215
0 ,2 1 0
0.219
0,232
0.245
0.179
0.223
0.321
0.234
0.262
0.243
0 .2 1 0
21
34
27
21
22
23
24
23
22
22
21
23
30
21
23
26
31
44
28
25
26
22
23
24
25
23
22
21
28
23
?2
21
19
20
23
thus characterize the fluctuation of ligh t fields over the w hole research
period. A s far as the fluctuations of these magnitudes in a single day are
concerned, illustrative situations typical for a particular period and lo ­
cation have been presented, supplemented w ith statistical data on diur­
nal variations of the parameters averaged for observations lasting seve­
ral days and the w h ole research period. A s in the analyses of the varia­
tions of these parameters for the w hole period, neither cyclic regularities
nor sim ilarity of the values of parameters could be found in series of
consecutive days, all statistical calculations referin g to observations la­
sting several days w ere made fo r sets of days in particular month, ir ­
respective o f theiiir number. These results are listed in Tables 2— 5.
Table 2. Averaged (for observations lasting many days in particular months and
the whole research period) daily energy doses and parameters characte­
rizing the inflow of solar radiation to the sea surface and its propagation
in the euphotic zone of Ezcurra Inlet.
The meaning of the symbols iin particular columns is the same as in
Table 1, the corresponding values denoting the means for selected observation
periods. — The mean value is given in the upper fraction of each line
and the standard deviation, 8 , in the lower one.
Tab.
2.
Uśrednione (dla wielodniowych obserwacji w poszczególnych miesiącach
i całego okresu badań) dzienne dozy energii i parametry charakteryzujące
dopływ promieniowania słonecznego do powierzchni morza i jego propa­
gację w strefie eufotycznej fiordu Ezcurrą
Znaczenie symboli w poszczególnych kolummJach takie samo jak w tab. 1,
przy czym odpowiednie wartości mają sens przeciętnych dla wyróżnionych
okresów obserwacji. W każdej kolumnie oprócz średnich (górna liczba)
podano odchylenia standardowe notowanych wartości parametrów (dolna
liczba) — {).
Observation
days
Czas
obserwacji
1
X II
(21, 27—31)
<^p>
<r>
[
< n. >
4
3
-c / m '2 ]
V--0»
1= 11»
5
6
2
3
2463
424
0.56
0.77
0 .1 0
0 .1 0
971
167
68.5
20.9
1= 2!«
X=3C»
<K?>
< * c>
[ m ’l
[m ]
8
9
6.67
3.29
0.743
0.491
0 .0 2 2
2
7
0.248
10
22
I
U O, 1{>—-2i,
27— 31)
1708
761
0.43
0.18
0.84
0.15
706
305
56.9
29.0
7.61
9.67
1.257
1.312
0.231
0.039
24
4
n
(1—28)
1466
429
0.48
0.15
0.82
0 .1 1
590
166
46.6
22.5
6.53
6.49
1.315
2.400
0.231
0.043
24
5
I II
( 1— 1 0 )
1222
0.60
0.25
43.4
21.6
5.31
4.42
0.827
1.019
22
0 .2 2
579
243
0.228
655
0 .0 2 1
2
Total
Łącznie
1632
675
0.49
0.18
0.81
0.15
665
258
51.6
26.5
6.69
5.72
1.160
0.232
23
1.801
0.037
4
0.72
δ
T otal
Ł ą czn ie
III 1-10
II 1-28
δ
δ
δ
I 1-5, 15-27, 29-31
δ
XII 21, 27-31
0.02
0.81
1.59
0.42
0.41
5.56 10.54 16.64 •26.21 36.78 44.38 50.39 53.21 48.51
11.35 12.57 11.93 17.86 21.18 24.26 27.18 24.55
2.81
1.28
45.88 37.16 30.85 22.23 11.35
21.33 16.97 16.33 11.84 7.32
5.16
4.59
2.54
1.25
0.30
0.08
1.13
0.75
0.38
0.13
0.50
0.38
2.80
2.31
3.90
2.52
7.88
2.93
0.10
3.22
2.18
42.57 32.67 25.40 16.25
20.79 18.26 13.20 7.57
1.21
1.48
22.00
1.22
21.CC
3.41
2.4
20.00
1
i
4.98 20.89 37.98 44.66 56.88 54.55 46.55
2.62 17.05 20.21 21.61 21.66 21.45 23.75
j 18.00 19.00
3.19
1.83
17,00
1
8.63
4.57
15.00 16.00
44.07 37.47 30.92 21.06
18.88 15.93 16.69 11.42
13.00 14.00
1
7.52 15.22 25.63 34.92 41.52 43.34 44.88 46.03
2.96 6.80 9.62 11.71 15.17 21.42 21.22 21.93
12.00
8.53
5.49
11.00
46.42 34.98 30.16 23.56 16.15
25.27 17.50 16.42 12.39 9.38
10.00
7.33 13.78 19.44 25.93 33.27 45.41 53.81 57.77 47.11
5.42 9.95 12.25 17.19 18.30 25.88 32.85 33.93 28.17
9.00
1.52
8.00
0.06
'ï.OO
8.57
2.81
6.00
3.45
2.26
5.00
0.06
4.00
58.0 50.78 41.99 32.97 13.08 10.51
11.38 8.35 13.34 9.48 4.79 2.92
3.00
5.46 21.47 30.18 32.95 38.77 55.79 53.65 60.50 75.30 68.29
7.01 15.82 20.18 20.82 24.34 23.09 23.30 21.78 15.09 11.67
*
2.00
Irradiance <ED) lh [mW · cm-2]
Oświetlenie <ED) lh [mW · cm-2]
0.02
0.03
0.10
23.OC
3 Averaged (for observations lasting many days and the whole research period) daily variations of mean 1
k°'ur
solar irradiance of the sea surface, in the whole spectral range, <ED>Ih, in the region of Ezcurra Inlet together with
standard deviations, ô, of the observed irradliance values.
_
3. Przeciętne (dla wielodniowych obserwacji w poszczególnych miesiącach i w całym okresie badan) przebiegi w ciągu
dnia wartości średnich godzinnych oświetleń promieniowaniem
słonecznym w całym zakresie wiamowym, powierz­
chni morza <ED>ih w rejonie fiordu Ezcurra wraz z odchyleniami standardowymi, ô, notowanych
wartości tych
oświetleń.
Observation
days
Czas o bserw a cji
'Tab
Table
-
about
X II
21, 27— 31
Ô
Czas obserwacji
Observation
days
współczynników
Uśrednione (dla
współczynników
layer
II
1— 28
Ô
Ô
I
-5, 15— 27, 29-—31
4
face
of water
body
in Ezcurra
_ _
0.041
0.043
0.050
0.032
Ô
0.232
0.290
0.035
Total
Łącznie
0.207
0.018
0.199
0.048
0.246
----------------------------------------------------------------------0.211
0.065
0.335
0.186
0.634
0.110
0.029
0.071
0.630
0.332
0.015
0.324
0.067
0.029
0.050
0.037
0.042
0.043
0.043
0.210
0.658
0.336
0.203
0.197
0.213
0.226
0.285
0.218
0.130
0.027
0.037
0.031
0.035
0.039
0.046
0.021
Ô
0.635
0.335
0.215
0.195
0.213
0.230
0.277
0.126
0.021
0.041
=425 um
0.023
X=475 nm
0.569
nm
0.317
0.020
L
"
1 =500
0.040
X=525 nrn
0.038
1
Ezcurra.
0.230
X= 550 nin
[m-1]
fiordu
0.198
j
wodnej
<K,ttt»
toni
0.210
= 600 nm
do ok. 30 m
0.248
1 1
1
warstwie
0.292
=675 nm
w powierzchniowej
0.023
1—10
III
Inlet.
wielodniowych obserwacji w poszczególnych miesiącach i dla całego okresu badań) statystyczne widma
osłabiania oświetlenia odgórnego <Kd(X)>, wraiz z odchyleniami standardowymi notowanych wartości tych
30 m thick
4 Averaged (for observations lasting many days in particular months and the whole research period) statistical spectra of
' the downward taadfance attenuation coefficients, <Kd(X)>, together with standard delations of these coefficients in a sur­
--------------------------------------------------------------
1
Tab
Table
lasting
many
days
In
W
particular
months
and
the
s
jfosAU9sqo SB20
sAep
o
rr
(M CO
05 CO
c i w*
CO
CO
N
rH
in
co
Tj< 03
rH O
O
dd
rH CM
to to
dd
0.121
«i< 03
rH
CM O
rH p
p p
d
d
d
in
th
CO rH
C— CO
o p
d d
a> io
o o
do
CM to
CM©
rH p
S p
dd
8
H H-T
m« C
X4
r- 03
O
O .° .
°
d
£
CO CO
C^ 03
in rH
CO p
rH d
o
pp
CO
dd
MJ,
d
op
do
in cd
o o
p p
o o
6.17
2.80
0.480
0.309
d
co o
P
0.0851
0.0470
d
co in
3.05
1.25
1.74
14.08
4.72
1.13
1.13
10.37
4.01
0.822
0.822
18.01
8.61
1.46
1.46
17.86
8.95
1.42
1.34
1.34
1.34
0.0415
0.0554
0.251
0.235
1.20
1.90
23.90
14.13
16.78
6.26
0.0342
0.0336
0'.0186 0.0250 0.0319
0.0196 0.0266 0.0360
0.100
0.218
0.163
1.02
22.33
13.48
18.89
10.67
0.198
0.172
0.154
0.130
1.14
0.75
0.883
0.644
0.117
13.84
7.56
10.79
7.09
0.0261
0.0175
0.167
0.056
0.145
0.049
0.120
0.056
0.198
0.178
1.52
0.93
19.33
10.48
0.158
0.130
1.19
0.70
14.57
7.24
1.46
0.93
18.50
8.32
1.40
0.80
17.71
7.54
1.17
0.60
14.94
5.85
0.0397 0.0323 0.0258
0.05591 0.0420 0.0301
0.235
0.236
1.74
1.20
21.59
13.07
0.938
0.544
12.17
6.28
0.0205
0.0188
0.129
0.090
0.57
0.0130
0.0224
0.596
0.314
8.04
3.96
0.281
0.138
3.79
1.70
0.0410
0.0492
0.0762
0.0940
0.10C
0.071
0.0875
0.0392
1.26
0.66
0.00706
0.01137
0.256
0.251
0.552
0.451
0.778
0.452
3.51
1.00
2.22
9.85
5.14
6.72
3.92
0.0305
0.0117
0.102
0.320
0.00342
0.00186
0.0383
0.0158
0.384
0.098
4.32
1.18
0.00335
0.00577
0.0191
0.0247
0.122
0.136
1.G3
1.05
|
Ezcurra —
godzin n ych
0.00270
0.00130
0.0241
0.0091
0.245
0.072
3.53
1.17
20
0.00433
0.00258
12.57
6.82
0.0189 0.01631 0.0135
0.G09iJ 0.0095 0.0084I 0.0085
0.022C)
0.227
0.057
1.21
0.42
1.11
5.38
rH 03
CO CD
rH rH
p p
d d
1.14
0.54
o
0.0147
0.0178
0.0910
0.0860
ow
pp
od
03
^ t-
^ CO
d d
0.0326
0.0301
CO CO
0.674
0.500
03 Co o
p p
d d
03 CO
in **
0.246
0.191
d
8.09
5.05
0.0218
0.0145
0.0212 0.0198
0.0145 0.0138
0.227
0.110
1.47
0.27
13.56
3.85
rH O
p p
d d
2.69
2.19
0.0139
0.0100 0.0101
0.188
0.100
0.169
0.101
0.180
0.104
1.69
0.33
17.26
5.42
17
20.90
3.45
03 "5t<
O ©
d d
0.0131
0.083
0.111
tH
1.98
0.37
rH
0.702
0.531
o
o
iHC
— 0 3 CM
01
suoftBAuasqo
in
23.90
4.91
17.00
16.00
15.00
rH
0.079
in
2.24
0.69
N " ł1
C— CO
CD C<J
03 CD
CM co’ d d
1.82
0.77
1.18
0.77
1.05
0.69
co
1.63
0.81
15.85
9.82
c24.83
8.74
CO
CM
rH
21.98
9.32
9.29
rH CO
C- CO
Hd
28.24
5.01
Oł
CO
31.04
6.41
12.00
co
co o
c- co
03 CO
d d
03
o
10
o
CO
0 3 CO
96*0
0S*I
N
o
rH
13.81
8.48
o in
11
/
11.00
?C/3
‘
0
10.00
CO
d d
O O
d d
30
u
u
o
a)
9.00
fiordu
średnich
eufotycznej
dow nw ard
values, togeth er
1-hour
03 CO
20
G
CO
7.00
mean
wartości
o
r -ł O
05 rH
30
'-3
W
<D
G
o
JJJ
10
V/
o
22.86
V/
a
o
6.00
badań)
okresie
p
CM
8.98
6.46
£
£
13.00
£
£
s
a
5.00
całym
na różnych głębokościach, z, strefy
tych oświetleń — liczba dolna.
■cm-J]
oświetleń
odgórnych, ( E d ), światłem
widzialnym
w paśmie 400—700 nm
górna liczba, wraz z odchyleniami standardowym i notowanych wartości
w
oi
Inlet — upper
values
in Ezcurra
period)
zone
research
euphotic
whole
<N
tH
15—27,
29—31
observations
a1
00*8
Tab. 5.
(for
irradiance of the 400—700-nm visible light band, (E d ), at various depths, z, of the
with
standard
deviations of these values — lower values.
Przeciętne (dla wielodniowych
obserwacji w poszczególnych
miesiącach
oraz
w
5. Average
O
&
CM
00-61
Table
O
o °
rH t tH CO
d d
CO cCM rH
C M rH
d d
O CM
o o
CO o
p p
o’ d
2 °
p
o
od
I
III
1—10
1
T otal
Ł ączn ie
6
0.00346
30
0.00014 0.0007!9
0.00771 0.0117
0.01060 0.0131
0.0709
0.0763
0.0466
0.0548
0.0228
3.00114 0.0057:2
1
20
0.544
0.484
0.345
0.049
0.181
0.0332
3.0103
(
6.87
4.84
4.36
4.84
2.19
0.648
io
3.134
o (
0.00024 0.00257 0.0121 0.0202 0.0257
0.00028 0.00413 0.0151 0.0209 0.0299
30
0.203
0.181
7 0.0336
0.192 0.0274 0.0311
0.0296 0.0437 0.04310 0.0419
0.106
0.0375 0.0335 0.02713
0.0634 0.0602 0.048:2
0.156
0.144
1.18
0.64
15.15
6.67
0.0388
0.0616
0.192
0.187
1.45
0.82
18.77
8.67
0.213
0.212
1.59
0.99
20.48
10.26
0.223
0.210
0.157
0.156
0.111
0.187
0.162
1.70
1.02
1.60
1.41
0.83
1.18
0.71
0.845
0.591
0.96
21.79
11.22
20. 79
10,.83
10.74
6.68
18.18
8.69
0.0272 0.0272; 0.0219
0.0361 0.0371. 0.0321
0.135
0.144
0.0321
0.0383
0.168
0.164
0.173
0.159
0.204
0.164
1.03
0.76
13.49
7.34
0.202
0.134
0.0305
0.0315
1.30
0.85
17.50
8.33
1.62
0.79
1.38
0.84
19.06
9.54
l.i67
O j 68
22.37
8.60
15.04
7.41
0.0783 0.1°5
0.0718 0.094
0.173
0.133
0.00159 0.0177
0.00147 0.0232
0.56
20
1.34
0.71
1.11
0.146
0.206
0.0137
0.0111
10
0.631
0.472
2.08
3.05
0.176
0.165
23.;32
8.'70
0.0222
0.0436
0.125
0.122
0.964
0.550
12.53
6.47
0.0170
0.0227
0.106
0.102
0.816
0.544
10.62
5.32
0.0234 0.0332 0.0363
0.0402 0.0304 0.0542
18.36
8.71
0.0420
0.0770
0.13367
0.13528
15.53
8.48
0.0272
0.0624
0.0424 0.0398 0.0333
0.0804 0.0807 0.0654
0.208
0.221
o.:L96
o.:L79
0.187
0.175
0.163
0.170
0.117
0.122
8.61
7.36
16
0.131
0.154
15
0.164
0.167
14
0.201
0.218
13
0.208
0.231
12
3.1
10
9
8
0
0.0663
0.0690
1 7
0.00643 0.0102
0.01314 0.0184
1
0.00265
0.00608
5
30
4
0.0316
0.0342
I
0.0122
0.0153
3
20
2
19
0.254
0.111
3.31
1.19
0.00354[
0.00734
0.0143 0.00859
0.0222 0.01620
0.165
0.187
2.10
1.96
0.0211
0.0322
0.374
0.307
4.81
2.88
0.0858 0.0493
0.0712 0.0691
0.677
0.387
8.95
4.63
0.0104 0.00517
0.0120 0.00426
0.0663 0.0328
0.0541 0.0196
0.517
0.295
6.81
3.06
0.00211
0.00412
0.0111
0.0104
18
0.0151 0.00735
0.0295 0.01478
17
0.0796 0.0374
0.0748 0.0373
0.00133i
0.00840
0.0666
0.852
20
0.0 0 0 1
0.0009
0.00913
0.130
21
4. D IS C U S S IO N
The results have been presented separately fer: irradiance conditions
at sea surface, attenuation coefficients of irradiance attenuation in the
water body, and energetic characteristics of ligh t fields in the eaphotic
zone.
4.1. IN F L O W OF S O L A R E N E R G Y TO TH E SEA SU R F A C E
Energetic characteristics o f light fields in the euphotic zone of
a basin depend m ainly cm the absolute en ergy values of solar energy
reaching its surface. Considerable differen tiation and fluctuations of
quantities o f this energy w ere found to be characteristic for the case
analyzed. These re fe rre d both to diurnal irradiation and all-day energy
doses reaching the sea surface on particular days.
Local time
Fig. 1. Exemplary, typical and extremal diurnal variations (averaged for 1-hr
time intervals) of ithe whole spectrum irradiance E p, (left-haind scale) and the visible
W
(400— 700 inm band) light irradiance Ep, (right-hand scale) of the sea surface
Curve numbers for particular days given: 1 — 16th January’78 (day on which the
m aximum daiily dose of energy w as recorded); 2 — &rd M arch’78; 3 — 22nd February’78; 4 — 11th February’78; 5 — 31st January’78 (day on which the minimum
daily dose of energy and maximum cloudiness w ere recorded)
Rys. 1. Przykładowe, typowe i skrajne dzienne przebiegi (uśrednione w jedno­
godzinnych odcinkach czasowych) oświetlenia powierzchni morza promieniowaniem
w całym zakresie widmowym — E p (lewa skala) i światłem widzialnym w paśmiu
W
400— 700 nm — E p (prawa skala)
Poszczególne krzywe dla dni: 1— 16.1.1978 r. (dzień o maksymalnej dziennej doził
energii), 2— 3.III.1978 r., 3— 22.11.1978 r. 4— 11.11.1978 r., 5— 31.1.1978 r. dzień o mini­
malnej dozie energii i maksymalnym średnim stopniu zachmurzenia)
Fig. 1. illustrates the most typical and extrem e diurnal variations
(averaged for 1-hour intervals) of irradiance of the sea surface with the
whole-spectrum radiation, Ep (left-hand scale) and with the visible (400—
w
w
— 700 nm) radiation, Ep (right-hand scale). The Ep values w ere estimated
on the basis o f the E p values assuming ([1. 13. 151 and own data") the con­
tribution of radiant energy over the visible range to total solar energy
reaching the sea surface to amount to 44 per cent on average. As can be
seen, the E p values during the m id-day hours range over w ide limits
of 10— 100 m W · cm '2, the differentiation thus being ten-fold. S till greater
differences w ere noted fo r instantaneous irradiance values, not analysed
in this paper. These w ere due' to the extrem ely high instantaneous Ep
values observed, which on days of medium cloudiness (2— 4 of an 8-grade
scale) and strong dynamic changes in the distribution of clouds showed
substantial fluctuations, their short-term (from a couple to a dozen
or so seconds) values exceeding that of the solar constant (138 m W · cm '2)
considerably. These situations w ere caused by focussing of solar radia­
tion on a selected point of the sea surface ow ing to reflection of the
light from clouds and, to a lesser extent, from the slopes of glaciers sur­
rounding Ezcurra fiord.
The graphs in Fig. 2 (according to Table 2) show averaged (over di­
stinguished periods) diurnal variations of mean hourly irradiance of the
basin surface, ( E p)ih , together w ith standard deviations, recorded in the
Ezcurra In let region. The w ide interval of standard deviations confirms
the strong differentiation of irradiance during particular days which is
characteristic fo r this region. Even so, 'their averaged vaiiiaticmis appear
to be typical fo r this region of the Antarctic, this being supported by
comparison of the results for Ezcurra In let with those [14] for 1964— 1965
obtained at a British actinometric station situated on the Argentina Islands
(cp— 65°15’, X=64°16’ W ), i.e. at a similar latitude. In these two regions,
the irradiance is comparable, w ith the exception of this observed in
March. In the latter case, however, the considerably higher mean irra­
diance values in Ezcurra Inlet, as compared w ith those determined in
the Argentina Islands region, can be interpreted as being due to the pe­
riod of measurements having been too short (10 days). Thus they can be
considered as fortuitous and non-representative for the whole research
period.
------------ >Rys. 2. Przeciętne (dla wielodniowych obserwacji w poszczególnych miesiącach
i w całym okresie badań) zmiany w ciągu dnia średnich godzinnych oświetleń (suW
marycznych) — (E p)m i światłem w paśmie widzialnym 400— 700 nm — <Ep)ih po­
wierzchni morza w rejonie fiordu Ezcurra (krzywe ciągłe), wraz z odchyleniairi
standardowymi notowanych wartości oświetleń (pionowe odcinki ciągle)
Krzywe przerywane obrazują dla porównania podobne uśredniane przebiegi'oświet­
leń wyznaczone na podstawie danych z pracy [14] dla rejonu Wysp Argentyńskich
RUT
Fig. 2. Average (for observations testing for periods 'of several days in particular
months and the whole research period) diurnal variations of mean 1-hour irradianes
(total) — <EP>ih and with visible (400— 700 nm band) light — <Ep«>)ih of the sea sur­
face in the region of Ezcurra Inlet (continuous lines) together with standard de­
viations of the irradiance values (vertical bars)
For comparison, the dashed curves show similar averaged irradiance variations for
the region of the Argentina Islands [14]
Fig. 3. Variations during the research period of: A — solar energy doses over
the whole spectral range, ri»: a) those actually reaching the sea surface (continuous
line), b) falling on the upper layers of the atmosphere above the observation site
(dashed curve 1), c) with would have reached the sea surface in cloudless, standard
atmosphere with the transmittance coefficient p2=0.75 (dashed curve 2); B — absolute
transmission coefficients of diurnal radiant energy through the atmosphere (T ) ; C —
mean diurnal degrees of cloudiness, (n)
Rys. 3. Zmiany w okresie badań: A — dóz energii promieniowania słonecznego
w całym zakresie widm owym nP: a) docierających realnie do powierzchni' morza
(ikrzywa ciągła), b) padających ma górne w arstw y atmosfery nad miejscem obser­
wacji (krzywa, przerywana 1), c) jakie dloctienałyby do powierzdhini akwenu w w a ­
runkach bezchmurnej standardowej laltmosfeiry ze współczynnikiem przezroczystości
p2= 0,75 (krzywią przerywana 2); B — bezwzględnych współczynników transmisji
całodziennych dóz energiili promieniowfania przez atmosferę ( T ) ; C — średnich dzien­
nych stopni zachmurzenia (n)
The in flu x of solar radiation over the w hole research period is illu ­
strated (Fig. 3A, column 2 in Table 1) by actual diurnal doses of radiant
energy, r)P, reaching the sea surface on particular days. For the sake of
comparison, theoretical diurnal variations in solar energy doses reaching
the upper layers of the atmosphere and variations of hypothetical doses
of this energy that would have reached the sea surface in the cloudless
standard atmosphere have also been included (during calculations fo r the
standard atmosphere, a standard transparency coefficient of p2= 0.75 was
assumed, which corresponds to the optical mass of m — 2 [4, 6], The m e­
thod of calculations is described in detail, among others, in [1]).
The systematic decrease in theoretical doses (as w e ll as average
true doses in particular months — cf. column 2, Table 2) in the period
from December and March was due to variations in sun declination. This
is an obvious lim itation of the absolute amount of energy reaching the
sea surface b y astronomical factors. On the othe.r hand, the observed
tim e-independent dispersion of true values of energy doses reaching the
sea surface indicates considerable fluctuations of atmospheric m eteoro­
logical conditions resulting in differentiation of its optical properties on
particular days. This is supported by tim e variations of absolute trans­
mission coefficients of diurnal solar radiation doses through the atmo­
sphere, T, (Figs. 3B amid C according to Table 1, columns 3 and 4) and
mean degrees of cloudiness, n. Tim e variations of these tw o magnitudes
reveal, in addition, a certain negative correlation. As seen in Fig. 4, how ­
ever, the re la tive ly low number and dispersion of data points in the
graph of transmission coefficients, as w e ll as the mean degrees of cloudi­
ness, preclude the description of this relationship by an em pirical equa­
tion.
Fig. 4. Observed relationship betwean albso;lute transmission coefficient of d iu r­
nal solar irradiance doses (T), and mean daily degrees of cloudiness (n)
Rys. 4. Obserwowana zależność bezwzględnych współczynników transmisji ca­
łodziennych dóz energii promieniowania słonecznego — T od średnich dziennych
stopnii zachmurzenia — n
Distributions of relative frequen cy of occurrence of rates cloudi­
ness, n, of transmission, T, and diurnal energy doses reaching the sea
surface, %, (on the probability density scale) during the w h ole research
period, are shown in Fig. 5. Characteristic statistical parameters of these
distributions (mean values and standard deviations) for both the whole
research period and particular observations lasting for periods of several
days, are listed in Table 2 (columns 2— 4). It should be noted that the
results do not show any regularities (o f the cyclic type) in seasonal v a ­
riations of m eteorological conditions of the atmosphere, represented by
the degree of cloudiness, n, and its optical properties described b y the
transmission coefficients, T. R espective mean values of these parameters
for the successive periods distinguished (cf. Table 2) are quite fortuitous.
4 .2 .
I R R A D I A N
Z O N E
O
F
C E
T H
A T T E N
E
U A T I O
N
C O
E F F I C I E N
T S
I N
T H
E
E U P H
O T I C
S E A
Coefficients of diffuse attenuation o f the downward irradiance pro­
vide fundamental optical parameters characterizing the diffusion of ra­
diant energy into the basin. They describe fluctuations, both as regards
spectral and absolute value terms, of the downward irradiance with
Fig. 5 . Distribution o f mean rates o f occurrence o f : A — absolute transmission
coefficients of diurnal energy doses through the atmosphere (T); B — mean daily
degrees c f clcudimess (n); C — diunraal solar energy doses reaching the sea surface
(tip )
Rys. 5 . Rozkłady względnych częstotliwości występowania wartości: A — bez­
względnych współczynników transmisji całodziennych dóz energii promieniowania
słonecznego przez atmosferę (T); B — średnich dziennych stopni zachmurzenia —
(n); C — całodziennych dóz energii promieniowania słonecznego padającego na po­
wierzchnię morza, (nP)
depth, according to the follo w in g relations: monochromatic downward
irradiance (fallin g within the narrow wavelength interval, I -r- X + 5X:
z
r f* , ,
-d
•
-2
1 -
V V
V
E d ( A. ,
■ QYq
-/ K .
(A.,z)dz
2 =0 )
■
;/ U
e
Z: ·
(14)
o
..
dow nw ard'irradianc6 over the visibl'e range (i.e. a w ide w avelength in­
terval: 400— 700 nm):
2
'/
E^z)
-
Ej(z-O)
J
Kd l z l d z
Kw 2
(15)
= E^lz=0 ) e"
w here K d (X) and K d are the mean downward irradiance attenuation coefficien ts in the O — z layer, o f mcinochr-cimatic and visible li"h t, respectively.
A s has been stated, the mean values of the attenuation coefficient
in the surface layer down to a depth of 30 m are discussed rather than
continuous fluctuations of the coefficien t w ith depth (analyses of spatial
variations of monochromatic irradiance attenuation coefficient for several
illustrative w avelengths have been published in this volum e by O lszew­
ski [12])
The spectral nature o f the attenuation of irradiance in the water
body of the basin considered is illustrated by the mean spectrum of
<K d ( I ) ) — fo r the total research period (Fig. 6 based on Table 4) toge­
ther w ith standard deviations of the coefficients. For comparison, a simi­
lar spectrum characteristic fo r various optical types and classes of sea
waters according to J erlov’s optical classification [7] has also been pre­
sented. A s regards optical properties, the sea and oceanic waters w ere
classified b y Jerlov [7] into various types, from the cleanest oceanic
waters (type I), through m oderately transparent oceanic waters o f the
types IA , IB, II and III, to turbid and strongly turbid inshore waters (cla­
sses 1 through 9).
As can be seen, the minimum spectra of the attenuation coefficients
in the spectra of the Ezcurra In let w ater body occurs w ithin the 500—
— 550 nm band (mean 525 nm; green light), which is characteristic for
classes 1 through 5 of the inshore waters.
The absolute values of the coefficients also fa ll w ithin the range cha­
racteristic fo r these clases. The shape of the K d (k) spectrum, however,
d iffers m arkedly from those encountered in other seas. The difference
consists in a considerably sm aller slope o f the curve in the short-wa-
velength range of the visible spectrum in Ezcurra Inlet than in other
basins. This can be explained by the relatively small concentration of
organic matter dissolved in sea w ater which strongly absorbs light within
this portion of the spectrum. Thus, the high concentration of suspended
matter (see the paper by Jonasz in this volume), which attenuates the
light much more non-selectively in respect of the wavelength, m ainly by
scattering, plays a dominating role in light attenuation. This is also sup­
ported by Olszewski’s results [12].
Observations have shown that waters of the basin considered exhibit
strong tim e variations in the absolute values of optical parameters. Both
distinct and rapid fluctuations of the m omentary irradiance attenuaiion
coefficients occurring from hour to hour, which w ere m ostly irregular
i(n m l
Fig. 6 . Spectrum of downward irradiance attenuation coeffients in the surface
layer of the basin: a) statistical means in the layer down to 30 m in Ezcurra
Inlet — continuous curve; the shaded area shows the interval of standard deviations
of the coefficient values; b) in various types of oceanic and sea waters according
to Jerlov’s classification [7] — dashed curve with numbers
Rys. 6 . Wic'mo współczynników osłabiania oświetlenia odgórnego w powierzch­
niowej warstwie akwenu: a) — średnie statystyczne w warstwie do 30 m we fior­
dzie Ezcurra — krzywa ciągła); obszar zaciemniony ilustruje przedział odchyleń
standardowych- notowanych wielkości współczynników; b) w różnych typa-ch wód
oceanicznych i morskich w g klasyfikacji Jerlova [7] — krzywa przerywana z nu­
merami.
and correlated only sligh tly w ith tidal cycles, and day-to-day variations
of the mean diurnal values o f these parameters w ere noted. The latter
are shown in Fig. 7, where mean diurnal variations of attenuation co effi­
cients of the downward irradiance over the visible range (400— 700 nm)
11 — O ceanology N o 15(1933)
Fig. 7. Variations during the research period: A — of the mean (in the surface
layer down to about 30 m) diurnal attenuation coefficient of the downward mo­
nochromatic irradiance K d, 525, for 525 nm light; B of the mean (in the surface
layer down to about 30 m) diurnal attenuation coefficient of the downward irra-
W
diance, K d, for visible light within the 400— 700 nm band
Rys. 7. Zmiany w okresie badań: A — średniego w warstwie powierzchniowej
(do ok. 30 m ) dziennego współczynnika osłabiania monochromatycznego oświetleni?
odgórnego — Kd, 525, dla światła o długości fali 525 nm; B — średniego w warstwie
powierzchniowej (do ok. 30 m) dziennego współczynnika osłabiania oświetlenia od·
W
górnego — K d dla światła widzialnego w paśmie 400— 700 nm
and exem plary monochromatic downward irradiance with the 525-nm
ligh t are presented. The scale of these variations is illustrated b y dis­
tribution of relative rates of occurrence of particular coefficients shown
in Fig. 8 which w ere determ ined for the w hole research period. Charac­
teristic statistical parameters of these coefficients (mean values and stan­
dard deviations) during the w h ole period and for particular tim e inter­
vals are listed in Tables 2 (column 9) and 4.
It is w orth noting that the analyses of the results did not reveal any
regu larity (of the cyclic type) jn tim e variations of mean irradiance at­
tenuation coefficients in the sea, on particular days, as was the case with
optical properties of the atmosphere. A characteristic feature of these
data (cf. Tables 2 and 4) is the substantial constancy of the mean, rather
than diurnal values o f the irradiance attenuation coefficients taken from
observations lasting fo r periods of several days, thus the considerable
day-to-day fluctuations of one-day mean values of optical parameters of
the sea w ater lik ely to be due to short-term (of the order of several days)
local dynamic processes, such as intensified flo w of glaciers, m ixing of
water masses, raising of the bottom material during storms, etc.). On the
other hand, the constancy of the mean values for periods of several days
over the w hole observation period, indicates the possible global stability
of the w ater masses in this basin owing to the restricted exchange of
w ater with the ocean.
•
Fig. 8 . Distribution of the mean rates of occurence of: A — the mean (in th*
surface layer down to about 30 m) diurnal attenuation coefficient of the mnochro·
matic downward irradiance, K d, 525, for 525 nm light; B — the mean (in the s u r fa «
layer down o about 30 m) diurnal attenuation coefficient of the downward irraW
diance, K a, for visible light within the 400— 700 nm band
Rys. 8 . Rozkłady względnych częstotliwości występowania wartości: .4·— śred­
niego w warstwie powierzchniowej (do ok. 30 m) dziennego współczynnika osłabia­
nia monochromatycznego oświetlenia odgórnego — K d, 5?5 dla światła o długości
fali 525 nm; B — średniego w warstwie powierzchniowej (do ók. 30 m) dziennego
»
U)
współczynnika osłabiania
w paśmie 400— 700 nm
oświetlenia
odgórnego — K d dla
światła ' widzialnego
4.3. E N E R G E T IC C H A R A C T E R IS T IC S OF THE IR R A D IA N C E FIELD S A N D
T H E R A N G E OF TH E E U P H O T IC ZO N E IN TH E SEA
A s mentioned in the introduction, energetic characteristics of the irra­
diance fields in the euphotic zone of a basin are determined by the total
effect of attenuation of the solar radiation flu x in the atmosphere and
in the sea. As, in the case considered, the optical conditions in the two
media fluctuated greatly during the period o f research, a strong time-·
-space differentiation of underwater irradiation fields was also observed.
This referred both to the spectral composition of radiant energy pene­
trating into the basin and the absolute values of this energy which
reaches particular depths in the sea.
Fig. 9 gives examples (extrem es in Figs. A and C and interm ediate
in Fig. B) of spectral distributions of the downward irradiance, E d(k), at
various depths observed on various days noon. Ap art from differences in
absolute energy values, the common feature of irradiance distribution
in all these cases is the predomination of the green light, this increasing
w ith depth (w ith a maximum at about 525 nm). This follow s from the
sim ilarity of shapes of the spectra of irradiance attenuation coefficients
Fig. 9. Exemplary spectra of downward irradiance at selected depths in the
basin, observed at midday on 1st Feb.’78 (A ), 5th Feb.’78 (B ) and 27th Jan.’78.
Rys. 9. Przykładowe widm a oświetlenia odgórnego na wybranych głębokościach
w akwenie obserwowane w południe: A — 1.II.1978; B — 5.II.1978; C — 27.1.1978
observed on d ifferen t days during the period of research, which had
a reasonably stable attenuation minimum for X=525 nm. On the other
hand, the differentiation of the absolute values of the downward irra10
diance, both the monochromatic, Ed (I ) and visible, E d (illustrated for the
w h ole day in Fig. 10 w here extrem ely d ifferen t daily isophote values are
shown) was due to fluctuations of irradiance conditions on the sea sur­
face and variations in absolute irradiance attenuation coefficients in the
w ater body.
The graphs in Fig. 11 show averaged diurnal variations of mean
1-hour downward irradiances over the 400— 700-nm range, <£d>m, (for
observations lasting several days in particular months and fo r the whole
GMT
GMT
Fig. 10. Diurnal variations of the isophotes: 1 — 10 mlW · cm-2; 2 — 5 m W ■ cm4 ;
3 — 1 m W · cm-2; 4 — 0.1 m W · cm-2; 5 — O.Ol m W · cm-2; 6 — 0.001 m W · cm-2
observed on days with extremially different (low on 2n|d Feb.’78 and high on 21st
Feb.’78) irradiance levels in the water body
Rys. 10. Dzienne przebiegi izofot: 1 — 10 m W · cm-2, 2 — 5 m W · am-2,
3 — 1 m W · cm-2, 4 — 0.1 m W - cm-2, 5 — 0.01 m W · cm-2, 6 — 0.001 m W · cm-2
obserwotwane w dniach o skrajnie różnych (niskich — 2.11.1978 i wysokich —
21.11.1978) poziomach oświetlenia w toni wodnej
observation period). Standard deviations of these values are listed in T a­
ble 5. A s compared w ith the mean irradiance values, the v e ry high stan­
dard deviation values confirm the observed great differentiation of ener­
getic conditions in the w ater body on particular days, this differentiation
increasing w ith depth. For instance, the standard deviations of irradiance
recorded during the whole period at pre-determ ined hours at a depth
of 0 m (im m ediately b elow the surface) w ere m ostly about tw o times
less than the mean values, whereas at a depth of 30 m they w ere about
1.2— 2 times greater than the mean values.
The in flo w of solar en ergy to the euphotic zone of the basin during
the w hole observation period is illustrated b y all-day energy doses of the
400— 700-nm ligh t which reached differen t depths o f the w ater body on
particular days (Fig. 12 based on Table 1). There are strong, day-to-day,
irregu lar variations of irradiance conditions in the basin, the dispersion
of the ligth energy doses also increasing greatly w ith depth. For instance,
in extrem al cases the ratio of the maximum to minimum diurnal
energy doses amounted to about 9 and more than 800 at depths of 0 and
30 m, respectively. The values of these doses, averaged fo r observations
GMT
Fig. 11. Average (for observations lasting for a period of several days) in par­
ticular months and during the whole research period) variations during the day
of the mean hourly downward irradiance in the 400— 700 nm band — visible light,
to
Ea, recorded at selected depths in the euphotic zone of the sea
Rys. 11. Przeciętne (dla wielodniowych obserwacji w poszczególnych miesiącach
i w całym okresie badań) zmiany w ciągu dnia średnich godzinnych oświetleń od10
górnych światłem widzialnym w paśmie 400— 700 nm — Ea, notowanych na w y ­
branych głębokościach w strefie eufotycznej morza
Fig. 12. Variations of diurnal visible <400— 700 mm band) light energy doses,
W
T)P, reaching selected depths in the sea during the research period
Rys. 12. Zmiany w okresie badań całodziennych dóz energii światła widzialnego
W
w paśmie 400— 700 nm — y|p> docierających na wybrane głębokości w morzu
lasting for several days in particular months and the whole period, toge­
ther with standard deviations are listed in Table 2 (columns 5— 8). As can
be seen, at small depths (0 and 10 m), gradual decrease of the mean diur­
nal energy doses was observed at specific time intervals from December
to March. This was m ostly due to irradiance conditions at the surface
of the basin, in particular to decreasing sun declination during this pe­
riod. On the other hand, at greater depths (20 and 30 m, cf. Table 2,
columns 7 and 8) this astronomical factors was dominated by optical pro­
perties of the w ater body. Hence, at a depth of 20 m, the highest mean
energy was observed in January rather than in December, and at 30 m
the highest mean dose was noted in February.
As mentioned in the introduction, solar radiation penetrating the sea
is the basic source of energy fo r prim ary production of the biomass in
the upper layer of a basin, referred to as the euphotic zone. The extent
of this zone is usually determ ined by the compensating depth of photo­
synthesis in the sea. This depth was shown [2] to be equal to the Ze depth
(eq. 10) reached by l°/o of the radiant energy w ithin the maximum trans­
mission band (in this case it is the 525-nm light). Fig. 13 and 14 show
tim e variations of the mean diurnal Ze values and the distribution of
their relative rates of occurrence during the whole period in Ezcurra
Inlet.
A vera ge daily ranges o f the euphotic zone in the basin considered
fluctuated markedly, as did the previously discussed irradiance attenu­
ation coefficients determ ining the magnitude of ze. On the other hand,
the average values from observations lasting fo r several days w ere
re la tive ly constant (cf. Table 2, column 10). The mean range of
Fig. 13. Variations of mean ranges of the euphotic zone, ze, in the sea on par­
ticular days during the research period
Rys. 13. Zmiany w okresie badań przeciętnych w poszczególnych dniach zasię­
gów strefy eufotycznej — ze, w morzu
z e t "i]
Fig. 14. Distribution o f relative frequency of occurrence of ranges of the eu­
photic zone in the sea
Rys. 14. Rozkład względnych częstotliwości występowania zasięgów strefy eu­
fotycznej w morzu
the euphotic zone in Ezcurra Inlet, determ ined fo r the w hole research
period, was 25 m, which was re la tive ly small as compared w ith its range
in open oceanic waters (about 40 and 140 m in Jerlov’ s [7] I I I and I type
of waters, respectively) and comparable w ith that in the open Baltic
waters.
Finally, when considering the energetic characteristics of ligh t fields
in a basin it is w orth mentioning a practical parameter, the function of
the transmission of solar radiation, P(z). This determines the ratio of ra­
diant en ergy observed at depth z to a sim ilar energy reaching the layer
im m ediately below the surface o f a basin. The knowledge of this func­
tion (in particular, its variations during a particular season or in a sea
region) enables a rough estimate to be made of the doses or irradiance
at various depths of the w ater body on the basis of known, absolute mag­
nitudes of such energy penetrating im m ediately below the w ater surface
or fallin g on the surface of the basin (in the latter case, a knowledge is
also required o f the coefficien t of radiation transmission through the sea
surface which depends, among other things, on the height of the sun,
the .relationship between the irradiance with direct solar flu x to irradiance
w ith the radiation scattered in the atmosphere, the degree of undulation
of the sea surface, etc. P relim in a ry findings of this case, as w e ll as the
results of other papers [1, 5] show, however, that this transmission, w ith
reference to diurnal visible ligh t energy doses at various depths, deter­
mined by us, enabled this function to be determined from the expres­
sion:
P(2 ) -
-------- ^ ---------------w
V z=0)
Table 6. Averaged (for observations lasting many days in particular months and
the whole research period) functions of transmission of whole-day visible
(400— 700 nm) irradiance doses into water body of Ezcurra Inlet toge­
ther wtiith standard deviations of the observed! values of these functions
Tab. 6.
Średnie (dla wielodniowych obserwacji w poszczególnych miesiącach i dila
całego okresu badań) funkcje transmisji w głąb toni wodnej fiordu Ezcur­
ra całodziennych dóz promieniowania słonecznego w zakresie widzialnym
(400— 700 nim) w raz z odchyleniami standardowymi notowanych wairtośoi
tych funkcji
Observation days
Czas obserwacji
iii
0—10 m
1
0— 20 m
!
0—30 m
0.247
0.0685
0.00646
0.000706
0.017
0.0123
0.00271
0.000444
0.248
0.0787
0.0104
0.00172
Ö
0.041
0.0278
0.0076
0.00188
0.244
0.0790
0.0114
0.00242
Ô
0.048
0.0341
0.0130
0.00531
0.240
0.0735
0.00902
0.00137
0.034
0.0185
0.00469
0.00117
0.245
0.0770
0.0102
0.00183
0.041
0.0286
0.0098
0.00369
X II
Ô
r
II
III
Ô
Total
Łącznie
<P(z)>
0—-5
Ô
The P (z) function determ ined in this manner presents the transmis­
sion of the diurnal dose of the 400— 700-nm solar radiation in a layer
lim ited by the 0 and z depths. It can also be taken to be the daily ave­
rage of downward irradiance w ith in this layer. The calculated mean
values of these functions (fo r observations over periods of several days in
particular months and the w hole period) at exem plary depths, together
w ith their standard deviations, are shown in Table 6. Comparison of the
results fo r Ezcurra In let w ith those for the Southern Baltic published in
[1]. shows the transmission functions to be similar in the tw o basins.
5. FINAL REMARKS
The results presented in this paper refer to a specific period and region
of exploration. T h ey should therefore be considered as exem plary for the
summer period and probably typical for small in-shore fiords (w ith lim i­
ted exchange of w ater masses w ith the ocean) situated between latitudes
60— 65° in the zone of direct influence of glaciers.
The analyses w e re presented from the aspect of the physical nature
of the light in flow to a marine ecosystem. It is, however, w orth noting
the possibility of practical utilization of the results, as com plem entary
and au xiliary fo r other branches of oceanography, investigated simul­
taneously during the Second Polish Antarctic Expedition, in v ie w of the
dominating role played by sunlight in several processes occurring in the
sea. A n exam ple of such utilization of the results of optical investigations
in biological research is provided by the analysis of prim ary production
of the ecosystem, as w ell as optical and energetic implications of photo­
synthesis presented by the present authors in another paper in this v o ­
lume.
Bogdan W O Ź N IA K , Ryszard H A P T E R , Barbara M AJ
Polska Akademia Nauk
Zakład Oceanologii w Sopocie
D O PŁYW
E N E R G II S ŁO N E C ZN E J I O Ś W IE T L E N IE S T R E F Y
E U F O T Y C Z N E J W R EJO N IE FIO R D U E Z C U R R A W O K R E SIE
A N T A R K T Y C Z N E G O L A T A 1977/1978
Streszczenie
Przedmiotem badań było naturalne oświetlenie strefy eufotycznej morza w rejonie
fiordu Ezcurra latem 1977/1978 r. Badania eksperymentalne przeprowadzono ze stat­
ku „Antoni Garnuszewski” podczas II Polskiej W ypraw y Antarktycznej. N a podsta­
wie tych badań dokonano analizy — rozłącznie — warunków oświetlenia na po­
wierzchni morza, współczynników osłabiania oświetlenia w toni wodnej i charakte­
rystyk energetycznych pól światła wewnątrz strefy eufotycznej.
W wyniku tych pomiarów i obliczeń określono zarówno czasowe zmienności
wielkości charakteryzujących pola oświetleń w skali dziennej, jak i związane z nimi
odpowiednie całodzienne dozy energii światła dla poszczególnych dni w okresie ba­
dań. Ze względu na dużą objętość uzyskanego materiału niemożliwa jest w tym
artykule kompletna jego prezentacja. Dlatego też ograniczono się tu do przedsta­
wienia jedynie najistotniejszych parametrów, tj. całodziennych dóz energii światła
słonecznego docierającego do powierzchni morza i na wybrane głębokości w strefie
eufotycznej oraz średnich dla poszczególnych dni parametrów optycznych morza
i atmosfery. W yniki te — przedstawione w tab. 1 i na rys. 3, 7, 12, 13 — charakte­
ryzują zmienności pól oświetleń i środowiskowych właściwości optycznych w skali
całego okresu badań. Co zaś się tyczy wspomnianych zmian analizowanych wielkości
w skali jednego dnia, ograniczono się do prezentacji przykładowych, typowych dla
okresu i rejonu badań sytuacji (zo,b. rys. 1, 9, 10) oraz do przedstawienia wyników
odpowiednich statystyk określających dzienne przebiegi parametrów, uśrednione dla
wielodniowych obserwacji i całego okresu badań (tab.
2— 6
i rys.
2 , 6 , 1 1 ).
Jako charakterystyczne dla analizowanego wypadku stwierdzono silne zróżni­
cowanie w czasie i fluktuacje naturalnych pól oświetleń w badanym akwenie.
Spowodowane one były silnymi zmiennościami czasowymi — zarówno chwilowymi,
jak i zachodzącymi z dnia na dzień — warunków optycznych w atmosferze oraz mo­
rzu i dotyczyły zarówno składu spektralnego promieniowania dyfundującego w głąb
morza (z-ob. rys. 9), jiak i bezwzględnych wielkości energia (rys. 11 i 12).
^Spektralny charakter osłabiania oświetlenia w toni wodnej badanego akwenu
ilustruje przedstawione na rys. 6 średnie (dla całego okresu badań) widmo współ­
czynnika osłabiania wraz z przedziałem odchyleń standardowych notowanych w ar­
tości współczynników. Jak widać, minimum osłabiania; w toni wodnej fiordu Ezcurra
przypada na światło widmowe o długości fali ok. 525 nm, co jest cechą charakterys­
tyczną dla wód przybrzeżnych klas od 1 do 5 w g optycznej klasyfikacji Jerlova [7].
Również wartości bezwzględne współczynników mieszczą sdę najczęściej w prze­
dziale charakterystycznym dla tych klas. Jednakże kształty widma Kd(X) w bada­
nym akwenie zasadniczo odbiegają od podobnych spotykanych w innych morzach.
Odstępstwo to polega na znacznie mniejszym, we fiordzie Ezcurra względem innych
akwenów, nachyleniu krzywej w krótkofalowej części widma widzialnego. Sytuacja
ta w analizowanym przypadku może być wyjaśniona stosunkowo małą ilością roz­
puszczonych w wodzie morskiej substancji organicznych, które silnie absorbują
światło w tej części widma. Tak więc przeważający udział w osłabianiu
światła
przez składniki m ają tu występujące w dużych ilościach zawiesiny (zob. w niniej­
szym tomie opracowanie Jonasza), które osłabiają światło znacznie bardziej nieselektywnie względem długości fali, głównie przez proces rozpraszania. Potwierdzają
to również wyniki uzyskane przez Olszewskiego [12].
Przenikające do morza promieniowanie słoneczne jest zasadniczym źródłem
energii podtrzymującym proces produkcji pierwotnej biomasy zachodzący w górnej
warstwie akwenu zwanej strefą eufotyczną. Za zasięg tej strefy przyjmuje się naj­
częściej głębokość kompensującą procesu fotosyntezy w morzu. Jak wykazały ba­
dania [ 2 ], pokrywa się ona dobrze ze zdefiniowaną równaniem 10 głębokością z e ,
do której dociera 1%> energii promieniowania w paśmie o maksymalnej transmisji
(w analizowanym wypadku jest to światło o długości fali ok. 525 nm). N a rys. 13 po­
dane są zmiany w okresie badań, przeciętnych dziennych wartości zasięgu Ze, no­
towanych w e fiordzie Ezcurra. Podobnie jest w wypadku analizowanych wcześniej
i determinujących wielkość ze współczynników osłabiania oświetleń, przeciętne w
poszczególnych dniach zasięgi strefy eufotycznej w badanym akwenie dosyć znacz­
nie fluktuowały, chociaż ich średnie z obserwacji wielodniowych (zob. w kol. 10 tab.
2) okazały się stosunkowo "stabilne. Wyznaczony średni dla całego okresu badań za­
sięg strefy eufotycznej w e fiordzie Ezcurra wynosi 23 m, jest stosunkowo mały w po­
równaniu z zaisdęgaimi tej strefy spotykanymi nia otwartych wodiach oceanicznych,
oid ok. 40 m w tyiplie III wód oceanicznych dio ok. 140 m w typie I [7] i porów nyw al­
ny ze spotykanym w wodach oitwairtego Bałtyku.
Przedstawione w tym artykule wyniki dotyczą wybranego okresu i specyficzne­
go rejonu badań. Przeanalizowaną sytuację należy więc traktować jedynie jako
przykładową dla okresu letniego i prawdopodobnie typową dla niewielkich przy­
brzeżnych akwenów fiordowych (z ograniczoną wymianą mas wodnych z oceanem)
położonych w szerokościach geograficznych 60— 65°, w strefie bezpośredniego wpływu
lodowca.
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Manuscript received in 1979