Variability of chlorophyll-a and some oceanographic parameter in related with monsoon, ENSO and IOD at the Banda Sea.

Abstract

The Banda Sea is a very fertile area because it’s a potential area of fisheriesfield, and is one of the largest fishing areas in Indonesia. The Banda Sea is influenced by external factors such as El Nino Southern Oscilation (ENSO), the cross-currents of Indonesia (Arlindo) and season. Furthermore the Banda Sea can also be called “the heart of “ current flow in the waters of Indonesia, as well as “the capasitor of ”water mass transport to the Indian Ocean and one of the areas that upwelling occurs where the water surface temperature can reach down to 25oC, was caused by the cold water from the bottom layer is elevated to the upper layers. The purpose of this study was to analyze the influence of variability of sea surface height parameter, sea surface temperature and chlorophyll-a; to analyze the influence of ENSO and Indian Ocean Dipole (IOD) has related with the variability of sea surface height (SSH), sea surface temperature (SST) and chlorophyll-a; and to search the internal forcing that causes the variability. The research was carried out in February 2011-June 2012, located in the Banda Sea with position between 3.5-7.5oLS and 124-133oBT. The data used are the sea surface height, sea surface temperature, chlorophyll-a, which are derived from MODIS-Aquamulti-sensor satellite data from 2002 to 2012, and surface wind data obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF). The data were analyzed by using the Ferret software version 6.0 in order to show the view variability of seasonal cycle and it’s annual cycle. Then the wind data, the Nino index 3.4 and Dipole Mode Index (DMI) will be analyzed by using wavelet methods in Matlab 2010 software to show annual cycle in the format of continous wavelet transform (CWT) and cross wavelet transform (XWT). In the variabilityof monthly average sea surface height from 2002 to 2012, there were the maximum value in March (transitional season I) with the value is 0.1498 m. The sea surface height of minimum in August with the value is -0.02 m. The Variability of sea surface temperature is maximum in December (west season) with a value is 30.68oC. The lowest temperature value found in August with avalue was 26.67oC. The value of chlorophyll concentrationat west ranged from 0.125-0.145 mg/m3 and chlorophyll concentration value at transitional season II ranged from 0.125 to 0.146 mg/m3. The chlorophyll concentration values at east season are 0.285 to 0.458 mg/m3 and chlorophyll concentration value at transitional season I range between 0.372-0.134 mg/m3. The highest value of the chlorophyll concentration which occurs on east season in August with a value of 0.458 mg/m3 and the lowest at west season in December with a value of 0.125 mg/m3. Zonal wind circulation patterns in January (west season) with speed 5.32 m/sec is more stronger because occurrence of the southwest monsoon winds are blown strong whereas in July (east season) the wind speed are weaker at -4,987 m/sec. The meridional wind circulation patterns in July (east season) are more powerful with a value 5.252 m/sec, where happened is south eastern wind monsoon while in February (east season) with a value is -1336 m/sec. The distribution of time based on difference of longitude and latitude where at every June to August (west season) from 2002-2012 against high of sea surface temperature and sea surface height was found lower. But in December to January was found high and evenly spread along different position of latitude and longitude. Other wise, the concentration of chlorophyll-a was found low in December to January (west season) and is found high in June to August (east season) and spreads from the east to west on different position of longitudes and latitude but found high on low latitudes position. Wavelet analysis results where energy density spectrum (CWT) of sea surface height has variability of a half annual, annual and annual interagency. A strong variability is the annual variability and annual interagency. Results of the cross-correlation wavelet transformation (XWT) with ENSO and IOD found the existence of a strong annual interagency variability and is antifase. While the relationship with zonal wind and meridional wind has annual variability and were sefase. Wavelet analysis results with energy density spectrum (CWT) of sea surface temperature has a dominant annual variability. While the results of cross-correlation wavelet transformation (XWT) of sea surface temperature has a strong annual variability and were sefase. Cross-correlation with the IOD has a strong annual variability and were antifase, furthermore it’s correlation with zonal wind and meridional wind has annual variability. Wavelet analysis results with energy density spectrum (CWT) of chlorophyll-a has a strong annual variability and were sefase. Cross-correlation with the IOD has a strong annual variability and were antifase and sefase, furthermore it’s correlation with the zonal wind are antifase and meridional wind are sefase and both have a strong annual variability. Sea surface height and sea surface temperature is low during El Nino events and the positive IOD whereas chlorophyll-a high.