1.3.2. thermohaline and optical properties of the drvenik-hvar-pelješac area branka grbec 1...
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1.3.2. Thermohaline and optical properties of the Drvenik-Hvar-Pelješac area
Branka Grbec1(thermohaline), M ira Morović1*(optical), Frano Matić1, Vlado Dadić1, Igor Palandžić2
1-Institute of Oceanography and Fisheries, Split, Croatia2-Hydraulical Institute, Sarajevo, Bosnia and Herzegovina
PR
OF
ILE
A
200
2-20
03
PR
OF
ILE
B
200
2-20
03
PR
OF
ILE
C –
NE
RE
TV
A E
ST
UA
RY
200
2-20
03
July 2006
Strong heating caused sea
temperatures above 26 oC.
Low impact of less saline coastal waters at the surface.
Shallow thermocline, because of the absence of stronger winds.
July
200
6
Strong heating
Low salinity water (salinity < 34) occupied surface layers in the most southward part of the area.
Thermocline depth was fully developed, below 20 m.
Impact of freshwater at the surface lower than in June.
September 2006
Sep
tem
ber
200
6
Conditions during September cruise were stable with more uniform spatial distribution of temperature and salinity with respect to July.
High resolution measurements of downward irradiance and upward radiance at 14 wavelengths from UV to visible light (340; 380; 412; 443; 465; 490; 510; 532; 555; 589; 625; 665; 683; 710); PAR attenuation (400-700nm); fluorescence
Kd=dln(Ed(z))/dz
Ku=dln(Lu(z))/dz
KPar= dln(EPar(z))/dz
Processing:1.Determining cast options2.Selection of better cast for each measurement3.Dark callibration4.Calculations
1. Qualitative and quantitative analysis of spectrum
2. Changes with depth
2. Attenuation coefficients for every wavelength and for PAR
3. Amount of light available for photosynthesis
4. Euphotic zone depth
5. Optical signature of chlorophyll-like pigments
(for comparison of chlorophyll signature from remote sensing)
6. Estimates of concentration of chlorophyll-like pigments
7. Estimation of optical types
8. Estimation of different optical functions
Ed PAR %
dept
h (m
)
1 10 1000
10
20
30
40
50
60
70
80
PAR2
PAR5
PAR7
PAR16
PAR18
PAr21
PAR22
PAR23
Ed PAR %
dept
h (m
)
1 10 1000
10
20
30
40
50
60
70
80
PAR2
PAR7
PAR16
PAR18
PAR21
PAR22
PAR23
PAR irradiance (%) relative to the subsurface in July and September
PAR attenuation coefficient (m-1
)de
pth
(m)
0.0 0.1 0.2 0.3 0.4 0.50
10
20
30
40
50
60
70
80
KPARS2
KPARS5
KPARS7
KPARS8
KPARS9
KPARS11
KPARS13
KPARS16
KPARS17
KPARS18
KPARS20
KPARS21
KPARS22
KPARS23
PAR attenuation coefficient (m -1 )
dept
h (m
)
0.0 0.1 0.2 0.3 0.4 0.50
10
20
30
40
50
60
70
80
KPAR2
KPAR5
KPAR7
KPAR8
KPAR9
KPAR11
KPAR12
KPAR13
KPAR15
KPAR16
KPAR17
KPAR18
KPAR20
KPAR21
KPAR22
KPAR23
PAR attenuation coefficients in July and September
12 July 2006 St5
wavelength (nm)
Kd (
m -
1)
0.0
0.2
0.4
0.6
0.8
1.0
300 350 400 450 500 550 600 650 700 750
depth (m)
2
11
21
31
51
71
12 July 2006 St5
wavelength (nm)
Ku (
m -
1)
0.0
0.2
0.4
0.6
0.8
1.0
300 350 400 450 500 550 600 650 700 750
2
11
21
31
51
71
depth (m)
S20 September
0
0.2
0.4
0.6
0.8
1
1.2
1.4
300 400 500 600 700 800
June S20
0
0.2
0.4
0.6
0.8
1
300 400 500 600 700 800
July September
Figure 10. Estimated concentration of chlorophyll-like pigments in July (left) and September (right).
estimated chlorophyll concentrations (u g m 3)
dept
h (m
)
0.2 2.2 4.2 6.2 8.2 10.20
20
40
60
80
FFCHL S2
FFCHL S5
FFCHL S7
FFCHL S8
FFCHL S9
FFCHL S8
FFCHL S11
FFCHL S16
FFCHL S17
FFCHL S18
FFCHL S20
FFCHL S21
FFCHL S22
FFCHL S23
estimated chlorophyll concentrations (u g m -3)
dept
h (m
)
0.2 2.2 4.2 6.2 8.2 10.20
10
20
30
40
50
60
70
80
FFCHL S2
FFCHL S5
FFCHL S7
FFCHL S8
FFCHL S9
FFCHL S11
FFCHL S12
FFCHL S13
FFCHL S15
FFCHL S16
FFCHL S17
FFCHL S18
FFCHL S20
FFCHL S21
FFCHL S22
FFCHL S23
estimated chlorophyll concentrations (u g m -3)
dept
h (m
)
1 10 1000
10
20
30
40
50
60
70
80
FFCHL S2
FFCHL S5
FFCHL S7
FFCHL S8
FFCHL S9
FFCHL S11
FFCHL S12
FFCHL S13
FFCHL S15
FFCHL S16
FFCHL S17
FFCHL S18
FFCHL S20
FFCHL S21
FFCHL S22
FFCHL S23
Estimates of chlorophyll-like pigments concentrations for July and September 2006
In September, relative to July, the stations close to Klek-Neum Bay, in the surface 10meters, have for the order of magnitude higher estimates of chlorophyll
Chlorophyll from MODIS for July and September AVHRR temperature
According to water characterisation by Matić (2004), the three characteristic sub-regions can be distinguished:
1. Neretva River estuary (St11-St23) - surface layer of permanently low salinity but spatially and temporally changeable under local meteorological conditions;
2. channel waters (St01-St03, St07-St08) – low salinity surface water influenced by the three main rivers: Neretva, Cetina and Jadro; and
3. waters similar to the open sea (St04-St06) without considerable influence from river runoff and vertically well mixed in the cold period of year.
Stations from waters similar to the open sea have different spectrum characteristics from stations of the Neretva river estuary (Klek-Neum area); spectrum max intensity for estuary area is shifted towards longer wavelengths.
Higher attenuation coefficients (for PAR and wavelengths) in September than in July especially in the Klek-Neum area
Higher chlorophyll-like pigments concentrations estimated for September especially at the surface for most stations, than for July, especially in the Klek-Neum area
Optical characteristics are related to thermohaline characterisation
Concluding remarks