Detection of Upwelling Using MODIS Image...The North Papua Waters (Satrioajie, W.N. et al.)
DETECTION OF UPWELLING USING MODIS IMAGE AND TRITON BUOY IN THE NORTH PAPUA WATERS Widhya Nugroho Satrioajie1) 1) Technical Implementation Unit for Marine Life Conservation, Indonesian Institute of Sciences Ambon, Moluccas-INDONESIA
Diterima tanggal: 23 Juni 2014; Diterima setelah perbaikan: 15 September 2014; Disetujui terbit tanggal 5 Oktober 2014
ABSTRAK Fenomena upwelling memiliki keterkaitan yang erat dengan distribusi spasial biomassa ikan. Namun, hubungan ini sering diabaikan karena adanya penafsiran keliru, dimana cukup dengan menggunakan data suhu permukaan laut (SPL) untuk menganalisa biomassa ikan laut dalam. Upwelling dapat dideteksi dengan menganalisa profil suhu permukaan dan vertikal laut pada berbagai kedalaman. Salah satu cara adalah penggunakan citra MODIS (Moderate Resolution Imaging Spectroradiometer) dan TRITON buoy (Triangle Trans–Ocean buoy Network) sebagai data in situ. Penelitian ini bertujuan untuk mengobservasi hubungan SPL Citra MODIS dan TRITON buoy serta menganalisa profil suhu vertikal laut TRITON buoy untuk mendeteksi peristiwa upwelling di Perairan Utara Papua. Metode deskriptif digunakan pada penelitian ini, dimana SPL MODIS yang dianalisa pada SeaDas Mapped 5.0 dibandingkan dengan data in situ SPL dari TRITON buoy pada rentang waktu Juli-November 2002 (musim timur 2002); Desember 2006-February 2007 (musim barat 2007) dan Juli-September 2007 (musim barat 2007). Selanjutnya, analisa upwelling dilakukan terhadap data profil suhu vertikal laut dari TRITON buoy pada koordinat stasiun yang telah ditentukan dengan menggunakan ER Mapper 6.4 dan Surfer 3.2. Dari hasil penelitian diketahui antara SPL Citra MODIS dan TRITON buoy mempunyai hubungan kuat masing-masing r=0,5738; 0,5989; 0,5509. Upwelling di Perairan Utara Papua terindikasi terjadi pada Februari 2007 (musim barat 2007), dimana kisaran penurunan suhu permukaan laut mencapai 260C.
Kata kunci: Upwelling, Suhu Permukaan dan Vertikal Laut, Citra MODIS, TRITON buoy. ABSTRACT Upwelling is closely associated with the spatial distribution of fish biomass. However, this phenomenon is often ignored due to misinterpretation that is simply using sea surface temperature (SST) to analyse deep fish biomass. Upwelling can be detected by analysing distribution of sea surface (SST) and vertical temperature at the various depths. One of the methods is the use of MODIS (Moderate Resolution Imaging Spectroradiometer) image and TRITON buoy (Triangle Trans-Ocean buoy Network) as in-situ data. This research aimed to observe the correlation between SST MODIS and TRITON buoy and to analyse sea vertical temperature in order to investigate the upwelling in the North Papua Waters. Descriptive method was used on this study, where SST MODIS that was analysed by SeaDas Mapped 5.0 was compared to the TRITON buoy’s SST data during July 2002 to November 2002 (in east season 2002); December 2006 to February 2007 (in west season 2007) and July 2007-September 2007 (in east season 2007). Then, the analysis of upwelling was carried out towards the TRITON buoy’s vertical temperature on the particular coordinates using ER.Mapper 6.4 and Surfer 3.2. From this research, both of SST MODIS image and TRITON buoy have a strong relationship by r=0.5738; 0.5989; 0.5509 respectively. The upwelling in the North Papua Waters was indicated in February 2007 (west season 2007), when the l degradation level of SST reached up to 260C.
Keywords: Upwelling, Sea Surface-Vertical Temperature, MODIS Image, TRITON buoy.
INTRODUCTION
Upwelling has a relationship with the spatial distribution of fish biomass (Chavez et al., 2003) This Indonesian waters is included to the tropics zone, event can be observed by analysing the sea surface has a unique characteristic due to current of water and vertical temperature profile. Research on upwelling mass from the Pacific Ocean to the India Ocean that is was done by several studies especially in the Western known as the Indonesian through flow (ITF) (Susanto Pacific Ocean such as direct measurement by Gouriou et al., 2006). It is estimated there is a huge amount of & Toole (1993) who used Conductivity–Temperature– diverse schooling fish in that flow areas (Veron, 1995, Depth (CTD) and Acoustic Doppler Current Profiler Dahuri & Dutton, 2000). One of the main factors that (ADCP) data from cruises between 1984 and 1991 (27 influences the abundance of fish is the increase of sections at 165°E and nine at 142°E). This study water mass from the bottom to the surface of ocean resulted 21 sections data that was used to look at the due to the differences of temperature which is called El Niño and the subsequent La Niña during 1986–1987 upwelling (Andrews and Gentien, 1982). There are a (Gouriou & Toole, 1993). The study on Western lot of plankton as food resources for fish on that area, Equatorial Pacific Ocean Circulation Study (WEPOCS) so that it can be assumed to be a good fishing ground analysed various measurements of the upper layer (Cury et al., 2000). and mixed layer thickness (Lukas & Lindstrom, 1991). However, from both studies, there is still a lack Korespondensi Penulis: Jl. Pasir Putih I Ancol Timur, Jakarta Utara 14430. Email:
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J. Segara Vol. 10 No. 2 Desember 2014: 129-136 information about the upwelling process take place, since these studies only used available over a very limited depth range from several observational programs (Johnson et al., 2002).
May 2008. Materials were MODIS Aqua-Terra Satellite data level 2 in Western Pacific area from July 2002 to November 2002 (in east season 2002); December 2006 to February 2007 (in west season 2007) and July 2007-September 2007 (in east season 2007). MODIS image (Moderate Resolution Imaging All data are available at http://oceancolor.gsfc.nasa. Spectroradiometer) is one of the advance remote gov/cgi/browse. Specifically, those data were chosen sensing technologies which measures ocean variables based on the clear-display and reach minimum one near real time by using radiometers wave (Carder et coordinate point of TRITON buoy coverage areas. The al., 2004). One of the methods is the use of sea surface other materials were sea surface (1.5m) and vertical temperature (SST) to approach the upwelling temperature data (up to 750m) from TRITON buoy in estimation (Wentz et al., 2000). However, this method the North Papua Waters within ASCII format. Those has a drawback due to SST from satellite images only data were downloaded from http://www.jamstec.go.jp measures the temperature from radiation object in the (Figure 1 and 2). This research used tools such as earth. So that, it would need the in-situ data for one unit computer, software SeaDas Mapped 5.0, ER. validation (Salomonson et al., 2002). Since regular in- Mapper 6.4 and Surfer 3.2. situ data collection needs a high cost, some researchers attempted a breakthrough by using a buoy-anchored The descriptive research method was used on technologies. TRITON mooring buoys (Triangle Trans- this research, utilizing a visual interpretation of SST Ocean buoy Network) are tools that observe oceanic MODIS image that was analysed by SeaDas Mapped parameters at the various depths in the strategic 5.0 which was compared to the in-situ data of TRITON positions of the Pacific warm pool region by the Japan buoy’s sea surface-vertical temperature in same point Agency for Marine-Earth Science and Technology coordinates stations by using ER.Mapper 6.4 and (JAMSTEC) after late 1999 (Ando et al., 2005, Kashino Surfer 3.2. The analysis was divided into three steps: et al., 2007). i) analysis of SST MODIS; ii) analysis sea surfacevertical temperature of TRITON buoy and iii) detection By using both technologies, this research aimed of upwelling. Analysis of SST MODIS has three steps: to observe the correlation between SST MODIS and image extraction, map projection, and map function TRITON buoy in order to validate the data and to (Kwiatkowska & Fargion, 2002). Analysis of TRITON investigate the upwelling by analysing sea vertical buoy’s sea surface-vertical temperature data was done temperature profile of TRITON buoy in the North Papua by using Excel. On this process, the numeric data was Waters. Moreover, this study is necessary to introduce changed to the tab delimited format (*.text) as data and emphasis the analysis of water temperature input for ER.Mapper 6.4. The numeric data changed profiles at the various depths in order to better to symbolic link format (*.slk) when entered Surfer 3.2 understand upwelling observation using advance analysis. technologies and to improve our skill to analyse it. Data Analysis RESEARCH METHODOLOGY SST MODIS and the TRITON buoy were analysed The research was conducted at Remote Sensing by regression and correlation. The decision of relation Laboratory of Department Fisheries and Marine was following (Walpole, 1988) and (Supranto, 2001), Science Diponegoro University, Semarang in April to when r
