Investigation of the Black, Baltic, Kara and Aral Seas

using their sea radiance coefficient spectra obtained by

passive remote sensing

Vera Rostovtseva,

Igor Goncharenko, Dmitrii Khlebnikov, Boris Konovalov

P. P. Shirshov Institute of Oceanology RAS, Moscow, Russia

• Passive remote sensing from board a ship for estimation of the

main water admixtures concentration.

• Sea Radiance Coefficient Spectra which depends on water content

• How to measure the SRC from board a ship

• SRC spectra for Case 1 and Case 2 waters

• Calibration using the characteristics of pure sea water

• SRC spectra and water content in the four different seas

Passive remote sensing of the sea surface

Abstract

Estimation of water content and admixtures distribution in inland seas and coastal regions of oceans by optical

remote sensing from board a ship is of great importance. One of the most informative characteristics is the sea

radiance coefficient spectrum ρ(λ) which we obtained with the special spectrophotometer, named Ro-meter. It was

developed for measuring the three values: upward sea surface radiation, radiance of the adjacent sky area (it is the

area that contributes most to the reflection part of the sea surface radiation) and radiance of the horizontal white

screen (it estimates the total illumination of the sea surface). After subtracting the reflection part from the upward sea

surface radiation and dividing the result by the total illumination of the sea surface we obtained the sea radiance

coefficient spectra.

The measurements were made from board a moving ship in four seas characterized by various water properties: in the

north-eastern part of the Black Sea at the Vulan-river mouth, in the western part of the Aral Sea, in Gdansk Bay of the

Baltic Sea, in Gdansk Gulf of the Baltic Sea and in the Kara Sea including the Ob’ Bay. The spectra were normalized

by the sea radiance coefficients for the four seas at 600nm.

The obtained sea radiance coefficient spectra were compared to the classification of the shelf sea waters developed

for different water types. Comparing the types of the obtained spectra to the modeling results one can conclude that

the Baltic Sea has the high content of dissolved organic matter, the Black Sea has abnormally high scattering, the

Aral Sea water shows significant adsorption by some pigments though it is extremely saline and the Kara Sea differs

greatly from the areas where it is similar to the open ocean waters to the areas of the river mouths with high content

of dissolved organic and suspended matter.

Then the original calibration method based on the spectrum of pure sea water absorption was used to avoid the

impact of different weather conditions on the explored spectra and the absorption spectra of sea water in the chosen

areas of the four seas were calculated. The absorption spectra allowed us to estimate the admixtures concentration

and the efficiency of the suggested method in each case was discussed.

The suggested method of optical remote sensing from board a ship can be useful for sub-satellite measurements to

obtain the coefficients for regional algorithms. It is also necessary for exploring the sea areas, which are too close to

the coastal line or cannot be seen from satellites because of cloudiness.

To obtain Sea Radiance Coefficient from board a ship we have to

measure three characteristics

Sea Radiance Coefficient is a characteristic of the water itself:

intensity of the light backscattered by the water intensity of the incident light

ρ =

As the backscattered light depends on the absorption and

backscattering coefficients of sea water and its

admixtures concentration, the Sea Radiance

Coefficient Spectrum (ρ - spectrum) can reveal the

water content:

0 b

b

k b

a b

ρ =

Passive remote sensing of the sea surface

Vulan - Bsea (upward radiation)

0

1

2

3

4

5

6

7

8

350 450 550 650λ, nm

Vulan-01

Vulan-02

Vulan-03

Vulan-04

Vulan - B white screen

0

20

40

60

80

100

120

140

160

350 450 550 650

λ, nm

Vulan-01

Vulan-02

Vulan-03

Vulan-04

Vulan - Bsky

0

5

10

15

20

25

30

35

40

45

350 450 550 650

λ, nm

Vulan-01

Vulan-02

Vulan-03

Vulan-04

Sea Radiance Coefficient

Three-channel Spectrophotometer for Measurement

of Sea Radiance Coefficient

from board a ship

Spectrophotometer for measurement of sea

radiance coefficient from board a ship

Main parameters of Rometer-A

based on spectrophotometer AvaSpec-102 (AVANTES):

Spectral band – 360 -:- 760 nm

Spectral resolution – 5 nm

Integration time interval – 0.1 -:- 60 s

signal-noise ratio – 1000:1,

Weight of the device – 720 g

Dimensions – 175x110x44 mm

PC-controlled

Sea radiance coefficient for open ocean waters (Case 1)

0

0,02

0,04

0,06

0,08

0 2 4 6 8 10

m

ays

asm

Cp/100

Natural admixtures concentrations in open ocean waters can be estimated using one parameter, for example water type optical index m which is proportional to water vertical extinction coefficient at 500 nm

Dependence of the three main natural admixtures concentrations on the water type

optical index m:

1. "yellow substance" is given in m-1

2. suspended matter concentrations is given in m-1.

3. Phytoplankton pigments concentration is given in mg/m3

0

1

2

3

4

5

6

400 450 500 550 600 650 700

wave length, nm

ρ (

λ),

%

Clear waters

Ср = 0,1 mg/m3

Ср = 0,5 mg/m3

Ср = 1,0 mg/m3

Ср = 2,5 mg/m3

Sea Radiance Coefficient spectra ρ (λ) measured from

Russian r/v in the Atlantic Ocean and Antarctic waters

0

1

2

3

4

5

6

400 450 500 550 600 650 700

wave length, nm

ρ (

λ),

%

Clear waters

Ср = 0,1 mg/m3

Ср = 0,5 mg/m3

Ср = 1,0 mg/m3

Ср = 2,5 mg/m3

Cp < 0.3 [mg/m3]

0

1

2

3

4

5

6

400 500 600 700

Central Atlantic-1

Central Atlantic-2

Central Atlantic-3

0.5 < Cp < 1.0 [mg/m3]

0

1

2

3

4

5

6

400 500 600 700

Canarian upwelling-1

Canarian upwelling-2

Antarctic waters-1

Antarctic waters-2

Modeling

1.0 < Cp < 2.0 [mg/m3]

0

1

2

3

4

5

6

400 500 600 700

Bengelian upwelling

Canarian upwelling-3

Antarctic waters-3

Measurements

Sea radiance coefficient for inland seas and sea coastal

regions (Case 2)

0

1

2

3

4

5

6

400 500 600 700

wave length, nm

ρ (

λ),

%

M (Cp=0,5 ys=0,004

sm=0,014)

M+Y (ys*=0,08)

M+S (sm*=0,04_b*=0,2)

M+YS (ys*=0,08,

sm*=0,04_b*=0,2)

M+YS' (ys*=0,01,

sm*=0,04_b*=0,5)

Modeling

Measurements

0

1

2

3

4

5

6

7

400 500 600

Ionic Sea

Aegen Sea

Baltic Sea

(Kattegat)

Marmora Sea

Black Sea

Pure waters

Calibration of Sea Radiance Coefficient

measured from board a ship

Vulan - Bsea (upward radiation)

0

1

2

3

4

5

6

7

8

350 450 550 650λ, nm

Vulan-01

Vulan-02

Vulan-03

Vulan-04

Vulan - B white screen

0

20

40

60

80

100

120

140

160

350 450 550 650

λ, nm

Vulan-01

Vulan-02

Vulan-03

Vulan-04

Vulan - Bsky

0

5

10

15

20

25

30

35

40

45

350 450 550 650

λ, nm

Vulan-01

Vulan-02

Vulan-03

Vulan-04

0,02sea sky

ws

B BR

B

Cloudy sky

Rough sea

Windy day

ρ(λ)= k R – ΔR

? ?

Vulan - Ro (01-04)

0

0,01

0,02

0,03

0,04

0,05

0,06

0,07

400 500 600 700

Vulan-01 Vulan-02

Vulan-03 Vulan-04

SHORE SHORE

8 1 9 16

7 2 10 15

6 3 11 14

5 4 12 13

Sea-water backscattering

0

0,005

0,01

0,015

0,02

0,025

400 500 600 700

wavelength, nm

bac

ksca

tter

ing

co

effi

cien

t, 1

/m

bw

b

bb

Sea-water absorption

0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

0,4

0,45

0,5

400 500 600 700

wavelength, nm

ab

so

rpti

on

co

eff

icie

nt,

1/m

aw

ays

asm

ap

a

1D

2D

Absorption of pure sea water

Using some peculiarities of pure sea water absorption for

calibration of Sea Radiance Coefficient

Sea-water backscattering

0

0,005

0,01

0,015

0,02

0,025

400 500 600 700

wavelength, nm

bac

ksca

tter

ing

co

effi

cien

t, 1

/m

bw

b

bb

Sea-water absorption

0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

0,4

0,45

0,5

400 500 600 700

wavelength, nm

ab

so

rpti

on

co

eff

icie

nt,

1/m

aw

ays

asm

ap

a

1D

2D2600580

1600700

1

,

D

D

Sea radiance coefficient spectra obtained at the Vulan-river estuary

SHORE SHORE

8 1 9 16

7 2 10 15

6 3 11 14

5 4 12 13

Vulan - Ro (05-08)

0

0,01

0,02

0,03

0,04

0,05

0,06

400 500 600 700

Vulan-05 Vulan-06

Vulan-07 Vulan-08

Vulan - Ro (01-04)

0

0,01

0,02

0,03

0,04

0,05

0,06

0,07

400 500 600 700

Vulan-01 Vulan-02

Vulan-03 Vulan-04

Vulan - Ro (09-12)

0

0,01

0,02

0,03

0,04

0,05

0,06

400 500 600 700

Vulan-09 Vulan-10

Vulan-11 Vulan-12

Vulan - Ro (13-16)

0

0,02

0,04

0,06

0,08

0,1

0,12

400 500 600 700

Vulan-13 Vulan-14

Vulan-15 Vulan-16

Measurement of Sea Radiance Coefficient

from board a ship

Sea radiance coefficient spectra obtained at the Vulan-river estuary

Measurement of Sea Radiance Coefficient

from board a ship

SHORE SHORE

8 1 9 16

7 2 10 15

6 3 11 14

5 4 12 13

Vulan - Ro (05-08)

0

0,01

0,02

0,03

0,04

0,05

0,06

400 500 600 700

Vulan-05 Vulan-06

Vulan-07 Vulan-08

(a+b) b1/b

0

0,1

0,2

0,3

0,4

0,5

0,6

400 500 600 700

V08 V07 V06 V05 aw

Vulan - Ro (01-04)

0

0,01

0,02

0,03

0,04

0,05

0,06

0,07

400 500 600 700

Vulan-01 Vulan-02

Vulan-03 Vulan-04

(a+b) b1/b

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

400 500 600 700

V01 V02 V03 V04 aw

Vulan - Ro (09-12)

0

0,01

0,02

0,03

0,04

0,05

0,06

400 500 600 700

Vulan-09 Vulan-10

Vulan-11 Vulan-12

Vulan - Ro (13-16)

0

0,02

0,04

0,06

0,08

0,1

0,12

400 500 600 700

Vulan-13 Vulan-14

Vulan-15 Vulan-16

(a+b) b1/b

0

0,1

0,2

0,3

0,4

0,5

0,6

400 500 600 700

V09 V10 V11 V12 aw

(a+b) b1/b

0

0,1

0,2

0,3

0,4

0,5

0,6

400 500 600 700

V16 V15 V14 V13 aw

Spectra of chlorophyll-specific

light absorption coefficient of

phytoplankton pigments for

waters of various trophicity

(from O1->E4)

Spectra of specific light

absorption coefficient of

suspended particles -

suspended matter (SM) Gulf of Gdansk and Puck Bay (1-3),

open Baltic (4-6), mid-Atlantic (7-11)

Spectra of absorption coefficients

of Dissolved Organic Matter

(“Yellow Substance”)

Chlorophyll of Phytoplankton Suspended Matter

“Yellow Substance” or DOM Specific absorption ax,ay,as

0

0,05

0,1

400 500 600 700

ay

as

ax

Bogdan Wozniak and Jerzy Dera,

Light Absorption in Sea Water- Springer, 2007

Modeling of the absorption spectra of the main sea

admixtures

0

0,02

0,04

0,06

0,08

0,1

0,12

400 500 600

Wave length, nm

Ab

so

rbti

on

in

dex,

1/m

(a + b) - aw summa_mod

ap_mod ays_mod

asm+b_mod

Cp = 0.7 mg/m3

ay = 0.007 1/m

as = 0.035 1/m

Estimation of water admixtures concentration from ρ(λ) spectra using specific absorption spectra

SHORE SHORE

8 1 9 16

7 2 10 15

6 3 11 14

5 4 12 13

SHORE SHORE

8 1 9 16

7 2 10 15

6 3 11 14

5 4 12 13

Estimation of water admixtures concentration

from ρ(λ) spectra and in water samples

"Yellow substance" absorption at 500 nm, 1/m

0

0,005

0,01

0,015

0,02

0,025

0,03

0,035

0,04

8 7 6 5 4 3 2 1 9 10 11 12 13 14 15 16

Suspended matter absorption, 1/m

0

0,04

0,08

0,12

0,16

8 7 6 5 4 3 2 1 9 10 11 12 13 14 15 16

Coloured columns for estimates (R) from ρ(λ)

Brown columns for estimates (S) in water samples

0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0

Концентрации примесей, измеренных на пробах (нормировано по

максимуму)

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

О

тн

ош

ен

ие

ко

нц

ен

тр

ац

ий

пр

им

есе

й п

о К

СЯ

к ко

нц

ен

тр

ац

иям

в п

ро

ба

х

(н

ор

ми

ро

ван

о п

о м

акс

им

уму)

r = -0,77; r = -0,47; r = -0,45;

Ср

ays(500)asm(500)

D

Estimates-S normalized by their maximal value

Ratio o

f e

stim

ate

s-R

to

estim

ate

s-S

no

rma

lize

d b

y th

eir m

axim

al va

lue

Concentration of Phytoplankton, mg/m3

00,20,40,60,8

1

1,21,41,61,8

2

8 7 6 5 4 3 2 1 9 10 11 12 13 14 15 16

38.48 38.5 38.52 38.54 38.56 38.58

44.3

44.32

44.34

44.36

0.4

0.6

0.8

1

1.2

ArkhipoosipovkaThe Vulan

Phytoplankton concentration, mg/m3

38.48 38.5 38.52 38.54 38.56 38.58

44.3

44.32

44.34

44.36

0.006

0.009

0.012

0.015

0.018

0.021

ArkhipoosipovkaThe Vulan

Concentration of "yellow substance", m-1Phytoplankton concentration, mg/m3 “Yellow Substance” concentration, m -1

38.48 38.5 38.52 38.54 38.56 38.58

44.3

44.32

44.34

44.36

0.03

0.06

0.09

0.12

0.15

ArkhipoosipovkaThe Vulan

Concentration of suspended matter, m-1Suspended Matter concentration, m-1

Estimation of water admixtures distribution

in aquatorium of the Vulan river mouth

Sea radiance coefficient spectra

measured in Gdansk Gulf from board

of “Oceania”

Gdansk - Ro

B

0

0,005

0,01

0,015

0,02

0,025

0,03

0,035

400 500 600 700

25.08.06 10-45

25.08.06 10-45

25.08.06 10-52

25.08.06 10-52

Gdansk - Ro

J

0

0,005

0,01

0,015

0,02

0,025

0,03

0,035

0,04

400 500 600 700

29.08.06 11-44

29.08.06 11-47

Gdansk - Ro

E, F

0

0,005

0,01

0,015

0,02

0,025

0,03

0,035

400 500 600 700

27.08.06 11-18

27.08.06 14-30

Gdansk - Ro

H, I

0

0,005

0,01

0,015

0,02

0,025

0,03

0,035

400 500 600 700

29.08.06 08-22

29.08.06 10-32

Comparison to LIDAR data

Gdansk - Ro

B

0

0,005

0,01

0,015

0,02

0,025

0,03

0,035

400 500 600 700

25.08.06 10-45

25.08.06 10-45

25.08.06 10-52

25.08.06 10-52

Gdansk - Ro

J

0

0,005

0,01

0,015

0,02

0,025

0,03

0,035

0,04

400 500 600 700

29.08.06 11-44

29.08.06 11-47

Gdansk - Ro

E, F

0

0,005

0,01

0,015

0,02

0,025

0,03

0,035

400 500 600 700

27.08.06 11-18

27.08.06 14-30

Gdansk - Ro

H, I

0

0,005

0,01

0,015

0,02

0,025

0,03

0,035

400 500 600 700

29.08.06 08-22

29.08.06 10-32

(axyz+b) (b1/b=1)

0

0,1

0,2

0,3

0,4

0,5

0,6

400 500 600 700

25.08.06 10-45 27.08.06 11-18 29.08.06 08-22

29.08.06 11-44 aw

Cp ays as

25_08 10-45 1,0 0,006 0,17

27_08 11-18 - - 0,17

29_08 08-22 5,0 0,11 0,12

29_08 11-44 4,0 0,05 0,12

Estimates of admixtures concentration

from Sea radiance coefficient spectra

Measurement of Sea Radiance Coefficient

from board a ship in the Aral Sea

0

0,02

0,04

0,06

0,08

0,1

0,12

0,14

0,16

0,18

0,2

400 500 600 700

wave length, nm

ab

so

rbti

on

in

dex,

1/m

(a+b) - aw summa_mod

ap_mod ays_mod

asm+b_mod

Cp = 2.6 mg/m3

ay = 0.012 1/m

as = 0.04 1/m

Aral: Ro(calibrated)/Ro600

0

1

2

3

4

5

6

7

8

9

10

400 500 600 700

14-34 (k*Ro-

delR)/(k*Ro600-delR)

14-44 (k*Ro-

delR)/(k*Ro600-delR)

Aral: Ro

0

0,02

0,04

0,06

0,08

0,1

0,12

0,14

0,16

0,18

0,2

400 500 600 700

14-34

14-44

Measurement of Sea Radiance Coefficient

from board a ship in the Kara Sea

0

0,5

1

1,5

2

2,5

3

400 500 600 700

wave length, nm

ab

so

rpti

on

in

dex,

1/m

(a+b) - aw summa_mod

ays_mod asm+b_mod

ap_mod

The Ob’ Bay Cp = 15,6 mg/m3

ay = 0.5 1/m

as = 0.57 1/m

0

0,2

0,4

0,6

0,8

1

1,2

400 500 600 700

wave length, nm

ab

so

rpti

on

in

dex,

1/m

(a+b) - aw summa_mod

ap_mod ays_mod

asm+b_mod

The Kara Sea Cp = 2,3 mg/m3

ay = 0.1 1/m

as = 0.34 1/m

Ro

0

0,01

0,02

0,03

0,04

0,05

0,06

400 500 600 700

The Kara Sea

The Ob' Bay

Ro(calibrated)/Ro600

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

400 500 600 700

The Kara Sea

The Ob' Bay

1. A method of express analysis of surface water content in the coastal waters from

board a moving ship was developed. It consists of three stages: firstly, passive

remote sensing of the aquatorium from board a moving vehicle with a portative

device, secondly, calculation and calibration of the sea radiance coefficient spectra

using the original methodic and thirdly, estimation of the main natural admixtures

concentrations and visualizing their distribution over the examined area.

2. The calibration takes into account some pure water absorption peculiarities in the

580-700 nm which reveal themselves in the sea radiance coefficient spectra. Using

this calibration one can remove the influence of various weather conditions (cloudy

sky, wind, rough sea) on the sea radiance coefficient spectra.

3. After getting the absorption spectra of the investigated sea-water the procedure of

estimation of main admixtures concentrations by using their specific absorption

spectra are carried out.

Сonclusions

4. The method was tested in the Black Sea region (the Vulan-river mouth), the Baltic

Sea (Gdansk Gulf), the Aral Sea and the Kara Sea and showed its efficiency. It is

not very suitable for open sea regions as the signal in the band for calibration is

low. Here the one-parameter scheme can be used.

Conclusions (continued)

The Kara Sea

Cp: 2,3-:-15 mg/m3

ay: 0.1-:- 0,5 1/m

as: 0.3-:-0.6 1/m

The Aral Sea

Cp = 2.6 mg/m3

ay = 0.012 1/m

as = 0.04 1/m

The Baltic Sea

Cp: 1-:-5 mg/m3

ay: 0.006-:- 0,11 1/m

as: 0.12-:-0.17 1/m

Ro(calibrated) / Ro600

0

1

2

3

4

5

400 500 600 700

The Black Sea

Cp: 0.4-:-1.4 mg/m3

ay: 0.007-:- 0,012 1/m

as: 0.02-:-0.14 1/m

Ro(calibrated)/Ro600

0

1

2

3

4

5

400 500 600 700

Ro(calibrated)/Ro600

0

1

2

3

4

5

400 500 600 700

Ro (calibrated)/Ro600

0

1

2

3

4

5

400 500 600 700

Future plans

1. Development of the device for operating in an automatic regime to get some

series of spectra on move for better mapping the area under investigation.

2. Study of the influence of the surface film on the sea radiance coefficient

spectra and the possibility of its detection by this method

3. Comparison of the results of passive and active remote sensing: can we

judge about admixture distribution in depth?

Thank You for Attention