Assessment of Tsunami Effects on Ocean Color in the Eastern Indian Ocean Using MODIS Satellite

1
Assessment of Tsunami Effects on Ocean Color in
the Eastern Indian Ocean Using MODIS Satellite
2
Clock stopped at 9 am at Bandar Acheh on 26
December 2004
3
(No Transcript)
4
(No Transcript)
5
Before and After Deadly Wave on 26 Dec
20042004?????????
MODIS Aqua 8 days composite chlorophyll a images
18 Dec2004 to 25 Dec2004
Things wash out by tsunami caused increase in
turbidity that falsely interpreted as high chlo
by MODIS Aqua Algorihm
26 Dec2004 to 31 Dec2004
Does the tsunami increase the phytoplankton bloom
at the upwelling area?
1 Jan2005 to 8 Jan2005
6
8 Days Chlo Variation Before and After Tsunami
7
8 Days variation of nLw 5518???nLw551???
Chlo

• Chl-a increased max 10 times
• nLw 551 increased double
• nLw 555 gt 1.0 ? Over-estimation chl-a
• The high chl-a was over-estimated

nLw 551
8
Why Sudden Increase in chlo nLw 551 ?MODIS
250m RGB ??
13 Dec 04
27 Dec 04

• The tsunami destroyed most of the coastal
  vegetation
• More than 1200km coastline, or 80795 ha of land
  was totally destroyed (source EU Joint Research
  Center)

9
nLw 551 Anomaly Rainfall ???
nLw 551
Rainfall
Jan 2005

• In Jan 05, most of the area along Sumatra show
  negative anomalies
• The lost of vegetation caused higher rain runoff
  into the ocean
• In April 05, higher rainfall at the northern
  Sumatra caused the positive nLw 551 anomalies at
  the area.
• Will caused long-term damage to the marine
  environment

Feb 2005
Apr 2005
10
Effects on Upwelling????????????????

• Wind speed related to chlo!
• But, high WS at 31 Dec 04, low chlo
• Lower WS at 8 Jan 05, high chlo

• Daily data show wind speed related to chlo with
  5-7 days time lag

11
Calculation of Suspended Sediments Load by
Tsunami Using nLw 551
12
Anomaly of nLw 551
One month before tsunami
One month after tsunami
nLw 551 anomaly

• Daily Level 3 nLw 551, 4 km resolution
• One month composite ? solved the cloud cover
  problem
• nLw 551 anomaly differences of nLw 551 values
  after and before tsunami
• The positive anomaly is considered as the extra
  sediments loaded into ocean by tsunami.

13
nLw 551 Suspended Sediment
SS (mg/l) 2.3963(nLw 551)

• MASDEC Cruise 5 data in Malacca Straits
• Minimum nLw 551 0.15 , SS 0.3594 mgl-1
• Minimum SS in MS 0.717 mgl-1, ECS 0.25 mgl-1

• Material and Method
• Output the nLw 551 anomaly from Seadas as flat
  file
• Create the header file info. then import into
  ArcGIS
• The boundary selected 30km from the coast at
  northern Sumatra
• Elevation data from Etopo2 (3.704 km resolution)

14
Calculation of suspended sediments load by
assuming the MLD until 90m

• Assumption
• The suspended sediment concentration is equally
  distributed in the water column
• The mix layer depth is until 90m (WOD98)

15
Discussion

• Phuket Andaman Island showed no variation
• Low resolution of 4km GAC
• Uncertainties in SS load calculation
• Shallower Etopo2 data near the coast.
• Maximum nLw 551 of Level 3 SMI images is 1.275.
• SS-nLw 551 algorithm

16
Conclusions

• 2004 Indian Ocean tsunami strongly affecting
  ocean color at western Sumatra
• High nLw 551 and over-estimated chlo caused by
  high sedimentation.
• Sedimentation will be a long-term problem for
  marine ecosystem because the destroyed coastal
  vegetation will not be replace in short time
• We suggest using nLw 551 to monitor the
  sedimentation problem

17
Thank You??????????????
18
Chlo Over-estimation nLw 555
Comparison of SeaWiFS chlo, in-situ chlo and nLw
555
Relationship of nLw 555 suspended sediment
Chlo
nLw 555

• High suspended sediment is the major cause for
  high nLw 555.
• Over-estimation of chlo by OC4v4 algorithm
• Lower nLw 555 at high chlo area in upwelling
  region

SeaWiFS on Jan 2002