Post on 02-Aug-2020
2012/5/22 1
Analyzing the impact of climate change on seagrass and coral by using remote sensing techniques
South china sea institute of oceanology
Yang Dingtian
dtyang@scsio.ac.cn; dtdang@tom.com
013710103198
2012/5/22 2
1、questions
Greenhouse effect Sea level change
2012/5/22 3
Coral in Sanya Bay
2012/5/22 4
Coral in Yalong Bay
2012/5/22 5
Coral in little east sea
2012/5/22 6
Coral Reef Bleaching
2012/5/22 7
Temperature and coral calcification
Left coordinate is sea surface temperature; right is calcification rate
8
Remote sensing techniques
jidi
si
z z, limlim
ji
00
ijdi
iz
j
water
u zlimlim,ji
00
dzdzzkzzEzzdE surfsurfdsurfwateru ,2exp,,
2
324
00 8350190 cos.,,
.
ww
),(~
)(b),( ppp
2/32
2
cos21
1
4
1~
HG
2
1
2/12
23
32.4
00
cos21
1
2cos
3
835.0cos,902
2
12exp
),(
,,0
gg
g
g
b
k
zzkQ
zzE
zzEQR p
wsurf
surfd
surfwateruwater
rs
1 RTE model
θ0
ψ1
ψ2
waterEu
(z,λ)
c
o
α0
△Z
Y
z
layer_S
Ed(z,λ)
FOV
Assumption: multi-layer system, each layer of which was described by different optical characteristics. The effect of each water layer on its bottom substrate is determined by flux of multiple scattering and absorption.
1 RTE model
p
O
C
△Ωj
ω
n
Ψ
△zi
φdi
φsi
jidi
si
z z, limlim
ji
00
ijdi
iz
j
water
u zlimlim,ji
00
We assume the layer is divided into innumerable infinitesimals.
And, the jth infinitesimal scattering volume
The spectral volume scattering function
The scattered flux
1 RTE 模型
dzdzzkzzEzzdE surfsurfdsurfwateru ,2exp,,
2
324
00 8350190 cos.,,
.
ww
),(~
)(b),( ppp
2/32
2
cos21
1
4
1~
HG
2
1
2/12
23
32.4
00
cos21
1
2cos
3
835.0cos,902
2
12exp
),(
,,0
gg
g
g
b
k
zzkQ
zzE
zzEQR p
wsurf
surfd
surfwateruwater
rs
Figure (a) Comparison of the in situ measured bottom reflectance with subsurface reflectance;
X-axis shows the reflectance of coral reef measured in Sanya Bay in 2011; Y-axis shows the
subsurface reflectance in situ measured. (b) The experimental reflectance of coral reefs, plotted
with the corresponding values retrieved by the semi-empirical model; X-axis shows the
reflectance of coral reef measured in Sanya Bay in 2011; Y-axis shows the bottom reflectance
calculated with equation (4) following the procedure mentioned in water column correction
algorithm section.
seagrass
Normalized Difference Vegetation Index
RNDVI=(NIR-Red)/(NIR+Red)
NIR-740 nm, Red-660 nm;
GNDVI=(NIR-Green)/(NIR+Green)
Green-550 nm
BNDVI=(NIR-Blue)/(NIR+Blue)
Blue-450 nm
BNDVI,GNDVI和RNDVI increased with LAI
sensitivity of different indexes to LAI is different
LAI
0 1 2 3 4 5 6
VN
DV
I
-1.0
-.8
-.6
-.4
-.2
0.0
.2
R NDVI
B NDVI
G NDVI
R NDVI
G NDVI
B NDVI
r2=0.6705
r2=0.6729
r2=0.7357
coefficient of determination between GNDVI and LAI is relatively larger.
LAI
0 1 2 3 4 5 6
VN
DV
I
-1.0
-.8
-.6
-.4
-.2
0.0
.2
R NDVI
B NDVI
G NDVI
R NDVI
G NDVI
B NDVI
r2=0.6705
r2=0.6729
r2=0.7357
校正模型在海草遥感监测中的应用
summarize
leaving a plateau-like shape between 600 and 650 nm
triple-peaked pattern
2 1
2
st st
rs rs
st
rs
R RPRI
R
The most probable values of the index occupy the range from -0.15 to -0.05 (85.8 %). ). For
comparison, PRI for sand has a value of 0.18, for seagrass is -0.038, and for deep water is -
8.48.
75% of the healthy coral second derivative values at 556 nm were positive which was validated by in situ visual assessment.
2012/5/22 24
Sanya bay
GuangX
i GuangDong
HaiNa
n Sanya
2012/5/22 25
Distribution of coral reef in sanya bay
109.35 109.4 109.45 109.5 109.55
18.15
18.2
18.25
18.3
S01
S03 S04
S05
S07
S08
S09
S11
S12S13S14
S15
S16
S17
S18
S19
S20
S31
站位图例
一般珊瑚礁调查
鱼类调查
浮游生物调查
2012/5/22 26
DISTRIBUTION OF CORAL REEF
b3
East island - sanyabay
West island-sanya bay
1990 2004
2012/5/22 27
Coral cover
1990 1993-941998-99 2001 2002 2002~04 2007
15
20
25
30
35
40
45
cora
l cov
erag
e(%
)
In situ observation year
;但在1998年依然受到很大影响,出现明显的下降.之后一直下降.
National Nature Conservation
was established in 1990
el nino
Coral species
1962-65 1975 1992-93 2006 2010
50
60
70
80
90
100
110
120
Cor
al s
peci
es
In situ observation year
1990年建立自然保护区
the number of coral species
increased
1 Remote sensing technique can be an effective tool to analyze the impact of climate change on seagrass or coral reef.
2 water column corrections are needed to be done before bottom mapping.
3 RTE model can be used to remove the water column effects
4 NDVI can be used to retrieve seagrass informations
5 coral coverage decreased in sanya bay
summary
2012/5/22 30
thank you