The International Workshop on Indian Ocean Research and Ocean Hazard / Tsunami
7June 2006, SCSIO, Guangzhou, China.

( By professor DanLing TANG)
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ABSTRACTS
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(1) Early Warning of Natural Hazards Using Remote Sensing
Ramesh P. Singh (Ph.D)
Email: ramesh@iitk.ac.in
Department of Civil Engineering, Indian Institute of Technology, Kanpur 208 016, India

Significant changes on the land, ocean, atmosphere and ionosphere are being monitored using satellite observations. These parameters are easily mapped using optical and microwave remote sensing satellites through day and night. In the present talk, an overview of various kind of natural hazards occurring around the globe will be presented. Use of multi sensor data will be illustrated which can be used by the scientific community in getting early information about natural hazards.


(2) CLIVAR Observation Strategy for the Indian Ocean
Dongxiao Wang (Ph.D)
Email: dxwang@scsio.ac.cn
LED, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.

It is worthy to notice that significant progresses had been made in outlining observation requirements for the Indian Ocean at the Ocean Observations 1999 meeting in San Raphael, France. Now, under Ocean Observation Panel for Climate's coordination, ARGO, GODAE, GOOS, GLOSS, VOS, SOOP etc. jointly emphasized a basin-wide sustained observations for the Indian Ocean. A brief introduction is provided here.


(3) Changes in Chlorophyll-a and SST in the Indian Ocean during the 2004 south Asian Tsunami 
        period

DanLing TANG (Ph.D), B. Satyanarayana (Ph.D),Chao Hui, Zhang GuangMing, Ramesh P. Singh (Ph.D), Lv Jinhai
Email: lingzistdl@126.com, chaohui@scsio.ac.cn

Satellite remote sensing data has revealed significant observations of Chlorophyll-a (Chl-a) and Sea Surface Temperature (SST) in the Indian Ocean during the south Asian tsunami (December 2004). Chl-a measurements derived from Moderate Resolution Imaging Spectroradiometer (MODIS) for 3 years (2002 to 2005) period and SeaWiFS for 7 years (1998 to 2004) period were examined. Around the epicenter of the earthquake, Chl-a concentration is found to increase prior to the disaster (26 December) and dispersed during the tsunami event, and enhanced again after 10 days, high SST (~30-310C) was observed in and around epicentral region. Meanwhile, large offshore phytoplankton blooms (~300 km2) were observed two to three weeks late after the tsunami. Chl-a concentration in the coastal waters of the south-east Asian countries was found considerably low and diffused with the giant waves after the tsunami. Similar but relatively weak variations of Chl-a and SST are observed during the second earthquake on 28 March 2005. High Chl-a coupled with low SST in the vicinity of the earthquake may indicate the vertical mixing or cold upwelling water with enriched nutrients. The analysis is based on time-series data helps us to assess the tendency of Chl-a influenced by SST, wind, and upwelling water during the earthquake preparation processes.


(4) Applications of SLA from altimeter observation in identifying the path of front in the south
        Indian Ocean

Zhigang He (Ph.D)
Email: zghe@scsio.ac.cn

Hydrographic data, ADCP velocity in one cruise and Sea Level Anomaly derived from altimeter observation in the same period have been used to analyze the path of the Subantarctic Front (SAF) in the Southeast Indian Ocean. SAF, influenced by the out-of-phase double eddies, runs across 48°S three times between 120°-127°E. The surface current within the SAF is strengthened up to 105.4 cms-1 by the geostrophic effect of these eddies. Furthermore eddies may cause the strong current splits into two branches within the SAF.


(5) Estimates and analysis of sea surface evaporation based on space observations

Lili Zeng
Email: lovepp@scsio.ac.cn

The surface-level humidity (Q) values based on total precipitable water (W) from satellite data and the regression proposed by Liu (1986) has been further verified over China Seas. After comparison with ICOADS data, monthly evaporation based on TMI data is applied in the study of the seasonal and interannual variations of the net fresh water flux in the South China Sea.


(6) Chlorophyll anomalies in the equatorial Indian Ocean after the 2004 South Asian tsunami.

Zheng Guangming, DanLing TANG, (Ph.D)
Email: guangmingzheng@126.com, lingzistdl@126.com

Chl-a concentration in the Indian Ocean after the 2004 South Asian tsunami (2004-2005) was examined and compared with that in pre-tsunami years (1997-2004) using SeaWiFS and other remote sensing data. Anomalies of Chl-a appeared 45-d after the tsunami and lasted for 60-d (Feb 10 to Apr 11, 2005) in the western equatorial Indian Ocean. Chl-a concentrations in this open ocean water during this period in 2005 (post-tsunami year, 0.22 ± 0.044 mg m-3) were significantly higher (P<0.001) than those in 1997-2004 (pre-tsunami years, 0.14 ± 0.018 mg m-3). The high Chl-a water seems to be drifted westward from coastal Maldives, probably driven by the winter monsoonal wind, judging from SeaWiFS Chl-a imagery and Quikscat wind field. Water near the west coast of the Maldives experiences annual Chl-a cycles with the peak in January in pre-tsunami years. The peak postponed to February in 2005, after the December 2004 tsunami. Our results could be explained that the tsunami affected the ecosystem of coastal Maldives, resulting in postpone of local winter phytoplankton bloom; offshore advection of this coastal phytoplankton bloom led to Chl-a anomalies in the oceanic water in a broad area.


(7) Changes observed in Land, Ocean and Atmospheric Parameters associated with Sumatra
        Tsunami

Ramesh P. Singh (Ph.D)
Email: ramesh@iitk.ac.in
Department of Civil Engineering, Indian Institute of Technology, Kanpur 208 016, India,

An earthquake of magnitude 9.0 occurred off the coast of Sumatra on 26 December 2004 that triggered disastrous tsunami in Indian Ocean. Detailed analysis of National Centers for Environmental Prediction (NCEP) reanalysis daily mean wind data, surface latent heat flux, sea surface temperature, water vapor etc. have been carried out fromprior and after the mega tsunami. The results show significant changes in various land, ocean and atmospheric parameters which will be presented and discussed in detail.


(8) Spatial and Temporal distribution of the suspended sediments in the East Indian Ocean after
        the 2004 Sumatra Tsunami.

Yan Zhongzheng, DanLing TANG (Ph.D)
Email: nytv@163.com, lingzistdl@126.com

The tremendous Indian ocean tsunami on 26 December 2004 caused more than 283,000 deaths, which giant waves not only wrecked the coastal area in its initial surge, but the ensuing backwash also carried debris and sediments from land and introduced toxins and disease agents to the marine ecosystem. This preliminary study mainly focused on the spatial and temporal changes of the suspended sediments concentration (SSC) in the East Indian Ocean (EIO) after the tsunami. With the evidence of in situ and the remote sensing date, we found that the SSC increased in round of the EIO. In the months of Jan-Mar and Sep-Nov In 2005 and 2006, the SSC were much higher than the same months of the other years, especially in Sep-Nov. The increase of the SSC in Jan-Mar 2005 may be resulted directly from the agitation of the seawater generated by the tsunami waves. Coastal forest may hold the sediments from the erosion of the rainfall. Field survey data show the coastal vegetation is badly destroyed in the tsunami, which may contribute largely to the increase of SSC in Sep-Nov of 2005.


(9) Phytoplankton’s blooms around Indian waters related to tsunami December 26th 2004

M.S. RAVI KUMAR, DanLing TANG (Ph.D)
Email: ravindra97@yahoo.co.in

The Sumatra earthquake and resultant tsunami surge might have caused significant changes in marine environment, not only in the Physiography and tectonics of the region, but also on the marine biodiversity. Understanding and prediction of many interdisciplinary oceanographic processes remain as elusive goals of ocean science. Today the health of large marine ecosystems their diversity, productivity, and resilience is threatened by a global epidemic of coastal algal blooms. This over growth of algalblooms present one of the most scientifically complex and economically significant coastal management issues facing the developed and developing world today. Further more Anthropogenic activities nutrient rich effluents stimulate algal growth and warmer sea surface temperatures shift marine ecosystems towards more toxic species. However, the recent killer tsunami of 2004 has changed the scenario. ‘HAB’ is likely to be considered by India, many of these issues have not been sufficiently studied for Indian waters yet. Incidences of ‘red tide’ are increasing in the Indian seas, particularly along the west coast. Reports on discoloration of waters accompanied by fish mortalities and nauseating stench sickening the people along coastal stretches are quite common. Incidences of paralytic shellfish poisoning are also hitting the newspaper headlines. We summarize here some such instances that occurred along the west coast of India, and illustrate how these tiny microscopic forms suddenly grow into a disproportionate mass to draw global concern.


(10). Interplaying between the Indonesian Throughflow and the water exchange through the
          Luzon Strait

Qinyan Liu (Ph.D)
Email: qyliu66@scsio.ac.cn

The interannual variability of the Indonesian Throughflow and the Luzon Strait transport is out-of-phase, behind which the wind anomaly in the equatorial Pacific plays an important role, and the overshooting processes occurring both in the Luzon Strait and the Indonesian passages caused by the Kuroshio and Mindanao Current are the internal factors related with their interplaying characteristics.



(11) Determination of ocean primary production using support vector machines

Shilin Tang, Chuqun Chen (Ph.D), Haigang Zhan (Ph.D), Tonghui Zhang Email cqchen@scsio.ac.cn
LED, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.

A major task of ocean color observations is to determine the distribution of phytoplankton primary production. At present, the sea surface chlorophyll, temperature, photosynthetically available radiation (PAR) etc can be retrieved from satellite data. We investigated the possibility of using a novel universal approximator-support vector machines (SVMs)-as the nonlinear transfer function between ocean primary production and the information that can be directly retrieved from satellite data. The VGPM (Vertically Generalized Production Model) dataset was used to evaluate the proposed approach. The PPARR2 (Primary Production Algorithm Round Robin 2) dataset was used to further compare the precision between the VGPM model and the SVM model. The result indicated that the SVM model is more precise than the VGPM model. Using this SVM model to calculate the global ocean primary production, the result is 4.6×1016 C yr-1, which is higher than the VGPM result.


(12) The Coastal Wave Climate of Sri Lanka : Measurements and Modeling

Nalin Wikramanayake (Ph.D), Sri lanka
Email: tomwiks@yahoo.com

The coastal wave climate of Sri Lanka has been investigated in increasing detail and sophistication over the last two decades. A major step forward in this progression was the directional wave measurement program off the south-west corner of Sri Lanka and subsequent analysis and modeling of the data. This paper presents the results of several studies aimed at developing composite wave climates at various locations around the coast using all available wave measurements. The principal method was to use the NSW module of MIKE 21 to transform the wave measurements from the location of measurement to the location where the climate is required. A feature of the method was the development of a transformation matrix for a range of wave directions and periods. The actual measured wave time series were then transformed using this matrix. Comparison of measured and transformed time series showed that there were significant differences between the measurements made using Wave-Rider buoys (which had been used between 1983 and 1997) deployed near the shore and the WAVEC deep water buoy used in the directional measurement program. The indication is that the Wave-Rider buoys are not able to measure the higher waves, particularly the sea waves. This under-estimation may be due to the rigidity of the mooring used for the near-shore buoys.
Similar direct comparison between the data from the WAVEC buoy and other directional measurements (made with S4-DW current meters) was not possible due to lack of overlapping measurements. Comparison of wave statistics show that the transformed swell wave climate from the WAVEC buoy is in good agreement with measurements off the west and south coasts. However, comparison with the data measured off the east coast show that there is a set of south-easterly swell waves observed on the east coast that are not observed by the WAVEC buoy. The transformed and measured sea wave statistics are not in such good agreement as the swell waves. The greater inter-annual variability observed in the sea waves is one reason for this disagreement. However, there are also indications the available measurements are insufficient to develop satisfactory wave climates for the north-west, south-east and east coasts at the moment. The paper concludes with an overview of information on wave climates available from regional in-situ measurements, satellite measurements and global ocean forecasts and an outline of how this information can be assimilated in order to improve the coastal wave climate of Sri Lanka.


(13) SEASONAL CHANGES IN A TIDAL INLET LOCATED IN A MONSOON REGIME

Nalin Wikramanayake, Sri lanka
Email: tomwiks@yahoo.com

The Chilaw lagoon and estuary are located on the west coast of Sri Lanka. The lagoon shares the estuary with the Deduru river. The estuary is connected to the sea by three channels. The system is very dynamic due to the large seasonal variations in river discharge and longshore sediment transport and all three inlets become closed during the south-west monsoon. This paper presents the results of field measurements, over a period of one year, of the estuary morphology. The observed changes are explained in terms of the observed forcing by waves and tidal and river flows. The longshore transport is estimated using a mathematical model. These estimates agree reasonably well with the observed changes in the area and volume of the sand spits. The preliminary estimate of the net annual longshore transport is 200,000 m3/s from the south, while the river supplies about 100,000 m3/s to the coast annually. The sediment storage capacity of the dunes to the south could be as much as 80% of the annual sediment budget. The sediment bypasses the inlet by a combination of spit growth and transfer to an offshore bar. The onshore movement of this sand bar is the principal mechanism by which the inlets are closed. The value of the Bruun stability ratio for the lagoon inlet varies with the season and is estimated to take an average value of about 10.