Medidas de Productividad Primaria en CaTS Edwin Alfonso1, Angel

Any questions?….
[email protected]
Are internal waves altering the ocean’s carbon cycle?
1
Alfonso ,
1
Capella ,
1
López ,
1
Dieppa
Edwin
Jorge
José M.
and Angel
1Departmento de Ciencias Marinas, Universidad de Puerto Rico, Mayagüez, PR
ABSTRACT
Higher vertical diffusivity values, Kd > 50 x 10-4 m-2 s-1 were measured between SEP-DEC 1997 and MAY-OCT 2000 in oceanic
waters of the Mona Passage. Extremely low values of the Richardson number, Rig < 0.25 and increments in Kd correspond to
increase seiching in the south-west coast of Puerto Rico. The link between both processes are the local generation of internal
waves. The increases in activity are strictly correlated with the lunar cycle and changes in the stratification of the water
column due to the influence of the Orinoco River. During the same period, visits to the stations ADCP1 and InWaPE revealed
increases in biomass and primary productivity in the crest and trough of the internal tide. In ADCP1 productivity increased
between 0.2-0.6 mg C m-3 h-1 and in the near shelf-break station (InWaPE) incremented by 7 mg C m-3 h-1. Because the
internal tide pervades the global ocean this phenomenon could potentially imply that conventional methods may
underestimate primary productivity. Estimates of the carbon fixation by phytoplankton could be underestimated, especially
near the continental margins, island margins and passages between islands.
Please follow the equation:
Breve explicación en español:
El primer recuadro muestra una situación correspondiente a los meses de enero-marzo. Durante esa
época del año la influencia del Rio Orinoco (verde) en nuestras aguas es mínima. El picnoclino está
profundo (línea negra continua), el valor de la frecuencia de BV es bajo y la pendiente del rayo es
alta (>15°) . Por lo tanto la marea interna se genera en pendientes topograficas más elevadas en los
márgenes insulares. La difusividades verticales (color rojo) son altas a lo largo del rayo de enegia
(linea negra punteada) pero las ondas no imparten mucha energia a la plataforma y los seiches
(elevación color gris) son de poca altura. En el segundo recuadro se representan las condiciones
entre septiembre y noviembre. Marcada influencia del R. Orinoco en la estratificación, BV alto y
pendientes del rayo es bastante acostada (<1°). Las marea interna se puede generar con facilidad en
el beril y aumentar la difusividades en profundidades por encima de los 60 m. La energia de las
ondas puede transferirse mejor a las aguas de la plataforma y excitar la actividad de seiches. En
ambos recuadros la condiciones astronómicas son favorables (luna en cuarto creciente)
Astronomical Conditions + Low ray slope + Bathymetry = Energetic internal tide  Enhanced vertical mixing + Seiches+ Increased primary productivity
2
Tidal force index values for year 2000
4
F M A M J
J
A S O N D
Slope along the north-south direction at depths < 200 m
-20
60
-120
-140
-160
55
+
-180
FFT smoothing with a fortnightly window
index
J
F
M
A
M
J
J
2
S
O
N
I. Desecheo
4
D
6
8
Month
10
0.6 -- 0.8
0.4 -- 0.6
0.2 -- 0.4
0 -- 0.2
-0.2 -- 0
-0.4 -- -0.2
-0.6 -- -0.4
-0.8 -- -0.6
Mayaguez
18.0
-200
A
Rincón
I. Mona
12
B
Date (2000)
-68.0
-67.5
-67.0
-66.5
=
22.0
22.5
23.5
23.0
-40
24.0
-100
Critical slope colored
red and blue
degrees
Aguadilla
-60
-80
-100
-120
26.0
65
-80
Pichincho
26.5
26.0
25.5
25.0
24.5
24.0
23.5
23.0
22.5
22.0
21.5
21.0
24.5
+
70
18.5
4.500 -- 5.000
4.000 -- 4.500
3.500 -- 4.000
3.000 -- 3.500
2.500 -- 3.000
2.000 -- 2.500
1.500 -- 2.000
1.000 -- 1.500
0.5000 -- 1.000
0 -- 0.5000
25.5
75
Degrees
25.0
-60
t (kg m )
-20
Depth (m)
80
-3
Latitude
-40
Depth (m)
85
-140
-------------
27.0
26.5
26.0
25.5
25.0
24.5
24.0
23.5
23.0
22.5
22.0
21.5
8

1.0
0.8
Jul 3
Jul 23
Aug 12
Sep 1
Sep 21
8
Oct 11
9 10 11 12 13 14 15 16 17
10
12
14
16
-3
PP mg C m h
1.0
Seiche energy
0.4
0.4
0.2
0.2
0.0
0.0
Difusividad Vertical Turbulenta (Pacanowski y Philander 1981)
-2 -1
m s
0.007 -- 0.008
0.006 -- 0.007
0.005 -- 0.006
0.004 -- 0.005
0.0030 -- 0.004
0.0020 -- 0.0030
1E-3 -- 0.0020
+


-40


-60

-80



-100

-120

-140
-1
2.60 -- 2.80
2.40 -- 2.60
2.20 -- 2.40
2.00 -- 2.20
1.80 -- 2.00
1.60 -- 1.80
1.40 -- 1.60
1.20 -- 1.40
1.00 -- 1.20
0.800 -- 1.00
0.600 -- 0.800
0.400 -- 0.600
0.200 -- 0.400
0 -- 0.200
-20
0.8
0.6
Longitude
Ray slope in station ADCP1 (10/oct/2000)
Jun 13
0.6
-40
-60
-80
-100
-120
-140
-160
Hour (10/oct/2000)
-66.0
May 24
160 180 200 220 240 260 280
-160
7
Sigma-T and
Primary
Productivity
Sigma-t
y Productividad
Primariain ADCP1
Seiche energy in the southwest of PR and vertical diffusivity K at ADCP1
Internal tide at station ADCP1 (10/OCT/2000)
Normalized seiche energy
90
J
Depth (m)
0
50
7
5y6
Ray Slope through the year in CaTS serial station
95

-160
8 10 12 14 16
Hora
160 180 200 220 240 260 280
Yearday 2000
Hour
Slope along the east-west direction at depths < 200 m
-20
Internal tide at station InWaPE (22-septiembre-2000)
0
-120
Mayaguez
18.0
-140
0.5
0.6
0.7
0.8
0.9
1.0
I. Mona
1.1
coastline
Pichincho
slope (degrees)
-68.0
-67.5
-67.0
-66.5
-66.0
Longitude
Orinoco River changes the stratification conditions
-30
-40
-50
-60
-----------
Index
29.50
29.00
28.50
28.00
27.50
27.00
26.50
26.00
25.50
25.00
30.00
29.50
29.00
28.50
28.00
27.50
27.00
26.50
26.00
25.50
Normalized energy
-100
0.6 -- 0.8
0.4 -- 0.6
0.2 -- 0.4
0 -- 0.2
-0.2 -- 0
-0.4 -- -0.2
-0.6 -- -0.4
-0.8 -- -0.6
Pichincho
-20
-70
0.9
0.8
0.7
0.6
0.5
-80
8
9
10
11
12
13
14
15
16
17
Hours
Chlorophyll signal of the Orinoco River (Nov. 4 1998)
Temperatura y Producción primaria durante el dia (22/ago/00)
index
0
Jul 3
Jul 23 Aug 12 Sep 1 Sep 21 Oct 11
1.0
0.8
0.6
0.4
0.2
0.0
seiche
160
180
200
220
240
260
280
Tasa de fotosintesis
-3
mg C m h
-20
29.0
-40
28.0
-50
27.5
-70
mean
26.5
27.0
26.0
-80
8
9
10
11
28.5
13
26.0
26.5
26.026.5
12
-1
12.25 -- 14.00
10.50 -- 12.25
8.750 -- 10.50
7.000 -- 8.750
5.250 -- 7.000
3.500 -- 5.250
1.750 -- 3.500
0 -- 1.750
-30
-60
Vertical eddy diffusivity (Pacanowski y Philander 1981)
0.008
0.006
0.004
0.002
29.0
-10
May 24 Jun 13
1.0
0.8
0.6
0.4
0.2
0.0
-2 -1
mean
Temperature C
Depth (m)
Rincón
Latitude
-80
-10
critical slope colored
red and blue
degrees
Aguadilla
I. Desecheo
Mean Diffusivity (m s )
18.5
-60
Tidal force index, seiche energy and mean vertical diffusivity, d
Profundidad (m)
-40
Depth (m)
14
15
16
17
Hora
160
180
200
220
240
yearday 2000
260
280
Explanation of the equation:
0
PRIMARY PRODUCTION: InWaPE (22/AUG/00)
PHOTOSYNTHETIC RATE
-3
-1
mg C m h
-20
12.00 -- 13.00
11.00 -- 12.00
10.00 -- 11.00
9.000 -- 10.00
8.000 -- 9.000
7.000 -- 8.000
6.000 -- 7.000
5.000 -- 6.000
4.000 -- 5.000
3.000 -- 4.000
2.000 -- 3.000
1.000 -- 2.000
0 -- 1.000
-40
DEPTH (M)
(1) Astronomical conditions combine to increase the tidal forces. (2) Stronger stratification due to the
influence of the Orinoco River allows the baroclinic energy ray slopes to have low values during the period
of optimum astronomical forcing. (3) This condition enables the generation of a large internal tide in
topographic slopes of less than 1° around Puerto Rico. (4) More generation areas increase the internal
wave field at shallower depths. (5) Internal waves increase the shear and enhance the vertical mixing.
(6) Shallow internal waves excite coastal seiches. (7) Primary productivity increases on the crest and
valley of each wave.
-60
-80
-100
-120
MEAN
8 9 10 11 12 13 14 15 16 17
HOUR
Tidal force index for the 18.6-year Moon cycle
84
Is the ocean carbon cycle modulated by the 18.6-year lunar cycle?
The right combination of certain astronomical factors can increment the
energy of the internal tide for some years and decrease it for another set
of years. Internal waves can enhance primary production near topography
and increase the sink of CO2 at the island margins. If stratification
conditions and astronomical forcing coincide this process is enhanced. The
regresion of the lunar nodes (18.6 lunar cycle) can impose a low frequency
modulation in the carbon uptake by phytoplankton.
82
80
Acknowledgements
78
Index
Index of tidal force
3
Profundidad (m)
1
76
74
72
70
68
FFT smoothing with a fortnightly window
66
19 19 19 19 19 19 19 19 19 19 20 20 20 20 20 20 20 20 20
90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08
Date (JAN 1990-DEC 2008)
This work was supported by the NASA/UPR Topical Atmospheric Science Center and by NASA grant No. NAGW3926. We thank NASA EPSCOR and
especially to Dr. Jorge Corredor and Julio Morell for award me the NASA fellowship. Thanks to the Captain and Crew of the R/V Chapman and R/V
Magueyes. I want to acknowledge Carmen Enid Pérez for help me to prepare the drawings. Also to Dr. Fernando Gilbes who provided me with the
L1A level SeaWiFS images and the facilities for the printing of this poster.