Title: Monitoring of the East China Sea
1Monitoring of the East China Sea Related to the
Three Gorges Dam Operation by MODIS
International EOS/NPP Direct Readout Meeting,
Benevento Italy, 3-6 October 2005
- Ichio Asanuma, JongGeol Park, Yoshizumi Yasuda,
Keitaro Hara - Tokyo University of Information Sciences
- 1200-2, Yato, Wakaba, Chiba, Japan 265-8501
- asanuma_at_rsch.tuis.ac.jp
- MODIS data processing at The Tokyo University of
Information Sciences - The Tokyo University of Information
Sciences is operating the direct receiving
station of MODIS data and archiving oceanographic
data as well as land data. Chlorophyll-a
concentration and sea surface temperature are
data mapped and available in a portable network
graphic (PNG), a binary flat, and a SeaDAS mapped
format. Spatial coverage of mapped region is
exhibited on Fig. 1. A whole region has a
spatial resolution of 2 and 5 km. Other region
is mapped in a spatial resolution of 1 km, except
the region of the East China Sea being 2 km.
Temporal composite include a daily, 5 days, and
30 days composite. User can access and download
from our web site. For a pass of AQUA, which is
missing because of a higher priority to Terra, we
down load from the Data Active Archive Center
(DAAC) of the Goddard Space Flight Center (GSFC)
of NASA. - 2. Distribution of Chlorophyll-a concentration
and sea surface temperature - Fig. 2 shows a sample of chlorophyll-a
concentration and sea surface temperature on the
East China Sea from April to September of 2005
for monthly composite. According to the
chlorophyll-a concentration, the spring bloom of
phytoplankton was observed in April and May on
the continental shelf. In contrast, the
Kuroshio, the western boundary current, kept a
lower productivity. The sea surface temperature
image exhibits the stream line of the Kuroshio in
April, entering to the East China Sea from the
East of Taiwan, running along the continental
shelf and exiting to the Pacific Ocean from the
Tokara straight. Some portion of the Kuroshio
runs to the North as the Tsushima current. But
it is difficult to identify the Kuroshio in the
following month because of high sea surface
temperature and a stratification. -
-
???? Select period
2004 1 2 3 4 5 6 7 8 9 10 11 12
2005 1 2 3 4 5 6 7 8 9 10 11 12
2006 1 2 3 4 5 6 7 8 9 10 11 12
??????a Chl-a ??????a Chl-a ??????a Chl-a ??????a Chl-a ??????a Chl-a ??????a Chl-a ??????a Chl-a ??????a Chl-a ??????a Chl-a ????? SST ????? SST ????? SST ????? SST ????? SST ????? SST ????? SST ????? SST ????? SST
???? Monthly composite ???? Monthly composite ???? Monthly composite 5????5 days composite 5????5 days composite 5????5 days composite ????Daily observation ????Daily observation ????Daily observation ???? Monthly composite ???? Monthly composite ???? Monthly composite 5????5 days composite 5????5 days composite 5????5 days composite ????Daily observation ????Daily observation ????Daily observation
PNG FLAT HDF PNG FLAT HDF PNG FLAT HDF PNG FLAT HDF PNG FLAT HDF PNG FLAT HDF
200509 200509 200509 from241to245 from241to245 from241to245 241 241 241 8?29? 200509 200509 200509 from241to245 from241to245 from241to245 241 241 241
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271 271 271 9?28? 271 271 271
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273 273 273 9?30? 273 273 273
Fig. 1. Ocean products selection at the Tokyo
University of Information Sciences.
http//www.frontier.tuis.ac.jp/modis/research/asan
uma/MODISdataset/ROIselect.htm
Fig. 2. Chlorophyll-a concentration (TOP) and
sea surface temperature (Bottom) from April to
September of 2005.
3. The Changjiang (Yangtze) River and the Three
Gorges Dam Fig. 3 is the mean discharge of
the Changjiang River for each month over all
years from 1978 to 1986. The rain season on the
China main land will exhibits the maximum river
discharge in July. The Three Gorges Dam has
started its operation since July of 2003. The
proposed operating procedure at TGD would keep
the reservoir level at a low pool elevation with
using inflow for power generation, called the
Flood Control Level (FCL), during the flood
season from May through September. After the
flood season, TGD would rise the reservoir level
to the Normal Pool Level (NPL), while the lower
flows with lower sediment concentration will be
impounded. This artificial control of the river
discharge will cause an environmental change
along the Changiang River and on the East China
Sea. A possibility of lower sediment water
because of the dam suspension may cause a higher
light penetration along the water column. The
ammonia-nitrogen from human exhausts and the
nitrate-nitrogen from the Changjiang River has
increased in 10 times in the last 30 years. And
the seasonal change of the river discharge may be
modified. From these combination of changes, the
primary productivity on the East China Sea may
exhibits different response. 4. Depth and time
resolved primary productivity A depth and
time resolved primary productivity was proposed
with chlorophyll-a concentration (C), sea surface
temperature (T), and photosynthetically available
radiation (PAR). The model estimated PAR was
combined for this model for noon (PAR(0,noon))
and each hours (PAR(0,t)). A vertical
distribution of chlorophyll-a concentration
(C(z)) and PAR(z) are estimated by the empirical
equation. A carbon fixation rate (PB) is
estimated as a function of PAR and sea surface
temperature. The equation (1) leads primary
productivity (PPeu mgC.m-2.day-1) for the day.
PPeu? t? zC(z)PBz,PAR(z),T
PAR(0,t)/PAR(0,noon) dz dt ... (1)
Carbon fixation rate PB(z) c 1 exp( - a
PAR(z)/PAR(0) ) exp( - b PAR(z)/PAR(0) ) ..
(2) Associated parameters for the
carbon fixation rate a0.04 ( 0.1 m PAR(0) n )
.. (3)
m -0.0001T 30.0036T 2 -0.0007T0.2557
..(3-1)
n 0.00024T 3-0.0113T 2 0.0868T-0.1042
..(3-2)
b0.3 ( 0.00048T 3 -0.019T 2 0.1T3.1214 )
..(4)
c 17 ..(5) Carbon fixation rate for
each hours PB(z, t) PB (z,noon) PARM(0, t) /
PARM(0, noon)) .. (6), Vertical
distribution of PAR PAR(z) exp (-0.0018 C03
0.022 C02 -0.11 C0 -0.024)Z PAR(0) .. (7)
Vertical distribution of Chlorophyll-a
C(z)1-(0.90.7C0)exp-0.8PAR(z,C0)
exp-0.8PAR(z, C0) C0 ..(8) 5. Primary
productivity from 1997 to 2004 Fig. 4 is a
monthly mean of primary productivity in July,
2004, estimated by SeaWiFS and AVHRR data. A
region indicated by the rectangle area is taken
as the region of interest to calculate statistics
of geophysical parameters. Fig. 5 is the monthly
change of chlorophyll-a concentration of the area
for each month averaged from 1997 to 2004 with
exhibiting a spring bloom in April and a summer
bloom in July. In Fig. 6, primary productivity
similarly exhibits an increase to May and a peak
in July and a very similar change with the change
of river discharge. The primary productivity
model took into account an increase of SST and
PAR from April to May. Then, a reduction of PAR
because of a rain front in June limited primary
productivity. Continuously with the increase of
SST and PAR through July, primary productivity
exhibited a peak in July. At this moment, the
river discharge from the Yangze River might have
a significant contribution to primary
productivity. In August, primary productivity
decreased against an increase of SST because of
reduced PAR and reduced amount of river
discharge. Currently, we are working to
complete dataset of chlorophyll a concentration,
PAR, and sea surface temperature observed by
MODIS on AQUA, because of SeaWiFS data being only
available for the commercial base since Dec. 24,
2004. The GSFC and ocean color science team are
currently working to adjust the MODIS bio-optical
algorithm to keep a consistency between SeaWiFS
and MODIS observation system.
Fig.3 Mean discharge of the Yangtze River for
each month over all years from 1978 to 1986 since
Ning (1998).
Fig.4 Monthly mean of primary productivity in
July, 2004. A red rectangle shows a region to
calcurate statistics.
Fig.5 Monthly mean of chlorophyll-a on the
sampling region from 1997 to 2004.
Fig.6 Monthly mean of primary productivity on the
sampling region from 1997 to 2004.