SeaWiFS 와 MODIS/Terra 의 엽록소 농도 비교

Abstract

Ocean color data have become an essential component of oceanographic research and monitoring and play an important role in the study of climate change because they can cover vast spatiotemporal variation. Similar ocean color sensors, such as SeaWiFS (since September of 1997) and MODIS (on Terra since March 2000) are in operation to obtain a consistent long-term time series of ocean properties. Using such sensors appropriately, we can improve the understanding of long-term climate changes or other oceanic variations. For such purpose, it is important, first of all, to make sure the data from different sensors are comparable.This study is a comparative analysis of chlorophylls in the JES from SeaWiFS and MODIS/Terra. SeaWiFS and MODIS/Terra data over period from 2000 through 2003 were compared. The chlorophyll concentration from the SeaWiFS was generally higher than that from MODIS during the period. SeaWiFS 8-day mean chlorophyll was about two times higher in spring and fall seasons especially. Also, the SeaWiFS chlorophyll showed an increasing trend from 2000 through 2003, while the MODIS/Terra chlorophyll increased from 2000 through 2002 then decreased in 2003. From comparison of Level-2 data, SeaWiFS chlorophyll was about 5 times higher than MODIS chlorophyll in the Primorye region.There are some possible causes for such discrepancy: differences in the sensor sensitivity, chlorophyll algorithms, and atmospheric correction algorithms. We checked some of these possibilities. We also compared the two data sets in The Okhotsk Sea, Gulf of Maine, and Nino areas in the equatorial Pacific to consider the local effects such as Asian dust and biomass burning. The deviation between the two data sets was highly correlated with chlorophyll concentrations Atmospheric corrections seem the major cause of the discrepancy.