Long-term Change of Ocean Productivity: A case study in the Bay of Bengal The 3 rd Asian /12 th Korean-Japan Workshop on Ocean Color Dr.Md.Latifur Rahman Sarker, UTM, Malaysia & RU, Bangladesh & Noor Saadah Sabarudin, UTM, Malaysia
OUTLINE INTRODUCTION STUDY AREA DATA & METHOD RESULT & DISCUSSIONS CONCLUSION
71 % Ocean covers Climate and Weather IMPORTANCE OF OUR OCEAN Ocean productivity support fishery industry
Chlorophyll-a Total suspended matter (TSM) OCEAN PRODUCTIVITY INDICATOR Color dissolve organic matter (CDOM) Sea surface temperature (SST)
OCEAN PRODUCTIVITY Issues Global decreasing trend of ocean productivity Global warming Increasing of temperature Central Indian North Pacific Gyre South Pacific Gyre North Atlantic Gyre South Atlantic Gyre Rate of decline of global ocean productivity: 1% per year Decreasing of Ocean Productivity
Ocean productivity issues at the Bay of Bengal 17 % declination from 1998-2003 (2.8% per year) Increasing trend at some part High populated area High river discharge Ocean productivity trend varied according to the region & other factors Natural disaster
Importance of Ocean Productivity at the Bay of Bengal Bay of Bengal has unique characteristics in terms of: (1) One of the World s 64 largest marine ecosystem, (2) Fisheries production is 6 million tones/year, (3) Bordered mostly by densely populated countries, (4) A number of large rivers flow into this bay, HOWEVER only Few Studies has been conducted Considering Total Areas. THEREFORE the objective is to Monitor Long-term Ocean Productivity at the Bay of Bengal. (5) Stores organic carbon (TOC) at a rate of 1.1 trillion mol/yr, (6) Unique climatic condition: the monsoon current.
STUDY AREA: Bay Of Bengal Why BOB? NE monsoon Unique climatic conditions with seasonal reversing monsoon. Surrounded by High populated Areas i.e. INDIA & BANGLADESH. SW monsoon o Lat. 13 31' 54.2634"N and Lon. 87 32' 22.4982"E Receive large amount of Water discharge from Five Main Rivers. Uncertain Ocean productivity trend due to lack of studies.
DATA & METHOD DATA USED MODIS 12 years data from 2003 to 2014 were used
Determination of Trend of Chl-a concentration MODIS L2 and Chl-a algorithm Pre-processing: Reprojection Analysis: Spatial and temporal variation Mosaic Quantitative variation Change detection analysis Interpolation Chl-a Concentration Spatial and Temporal Variation of Chl-a concentration Data validation
TRANSECTS The arrangement of transects with different interval from the coast 1)50 km 2)100 km 3)150 km 4)200 km 5)250 km Buffer zone 5o km To avoid the effect of COASTAL area
Results: General Trend of Yearly Chl-a Concentration
Results: General Trend of Yearly Chl-a Concentration Percentage % 60 50 40 30 20 10 0 J F M A M J J A S O N D Month 0-0.10 0.10-0.15 0.15-0.20 0.20-0.35 0.35-1 1-6.5
Results: General Trend of Yearly Chl-a Concentration
Results: General Trend of Yearly SST Variation
Results: General Trend of Yearly SST Variation Percentage % 80 70 60 50 40 30 20 10 0 J F M A M J J A S O N D Month 22-26 26-27 27-28 28-29 29-30 30-31 31-35
Results: General Trend of Yearly SST Variation
Results: General Relationship Between Chl-a and SST SST ( C) 30.5 30 R² = 0.65 29.5 29 28.5 28 27.5 27 26.5 0.3 0.35 0.4 0.45 chl-a con. (mg/m³) Inverse relationship between chl-a and SST for one year data
Chl-a Concentration Variation in Winter Season 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Nov Dec Jan Feb
Chl-a Concentration Variation in Summer Season 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Results: Chl-a Concentration Variation Along Transact -1
Results: Chl-a Concentration Variation Along Transact -1
Results: Chl-a Concentration Variation Along Transact -2
Results: Chl-a Concentration Variation Along Transact -3
Results: Chl-a Concentration Variation Along Transact -4
Results: Chl-a Concentration Variation Along Transact -5
Variation of Chl-a from Coastal to Off-shore
Variation of Chl-a Along Transect-1 in Winter
Variation of Chl-a Along Transect-2 in Winter
Variation of Chl-a Along Transect-3 in Winter
Variation of Chl-a Along Transect-4 in Winter
Variation of Chl-a Along Transect-5 in Winter
Variation of Chl-a Along Transects in Summer
DISCUSSION The long term ocean productivity can be monitored using remote sensing technique effectively. There is a variation of chl-a concentration: Seasonal Change, Location of the Ocean, and probably other factors are attributed for this variation. High Chl-a: winter season and coastal areas. Low Chl-a: summer season and off-shore areas Increased of chl-a observed in some parts while decreased of chl-a also observed in some parts. However, no constant rate of change was found from year to year. Overall trend of ocean productivity is almost the same for over the past ten years. There are several parameters such as wind speed, ocean current, salinity, sea surface temperature, climate change and costal environment that need to be investigated in order to understand the total changing patter of Chl-a.
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High chl-a con. during winter 2013-2014 (Dec 2013) chl-a con (mg/m³) NOV 2013 DEC 2013 JAN 2014 FEB 2014 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 Chl-a con. variation along transect 3 Nov-13 Dec-13 Jan-14 Feb-14
Chl-a con. variation along all transects during winter 2013-2014
SST during winter 2013-2014 (Dec 2013) sst ( C) NOV 2013 DEC 2013 JAN 2014 FEB 2014 34 33 32 31 30 29 28 27 26 25 24 sst variation along transect 3 Nov-13 Dec-13 Jan-14 Feb-14
SST variation along all transects during winter 2013-2014
Relationship between chl-a con. and SST during winter 2013-2014 r 2 = 0.274 r 2 = 0.417 r 2 = 0.138 r 2 = 0.135
Ocean current during winter 2013-2014 NOV 2013 DEC 2013 JAN 2014 FEB 2014