El Niño continues the most important coupled ocean-atmosphere phenomenon to cause global climate variability on
seasonal to inter annual time scales. The first independent spatial mode which carried out by EOF analysis of tropical
and north Pacific sea surface temperature (SST) for the period of 1985-2009 in AVHRR dataset is found to be associated
with well-known regional climate phenomena: the El Niño. This paper addresses the need for a reliable El Niño index
that allows for the historical definition of El Niño events in the instrumental record back to 1985-2009 with a new
perspective. For quantitative purposes, possible definitions are explored that match the El Niño identified historically in
1985-2009, and it is suggested that an El Niño can be said to occur if difference of sea surface temperature (SST)
anomalies between the tropical and north Pacific exceeds 0.6 times standard deviation for 5 months or more. An
advantage of such a definition is that it combines the characteristics between tropical and north Pacific. Through seasonal
analysis of SST in El Niño event, we found that the El Niño events are almost beginning in boreal spring or perhaps
boreal summer and peak from November to February. It provides a more complete and flexible description of the El
Niño phenomenon than single area in tropical Pacific.
Mesoscale eddies are widely found in the ocean. They play important roles in heat transport, momentum transport,
ocean circulation and so on. The automatic detection of mesoscale eddies based on satellite remote sensing images is an
important research topic. Some image processing methods have been applied to identify mesoscale eddies such as Canny
operator, Hough transform and so forth, but the accuracy of detection was not very ideal. This paper described a new
algorithm based on watershed segmentation algorithm for automatic detection of mesoscale eddies from sea level
anomaly(SLA) image. Watershed segmentation algorithm has the disadvantage of over-segmentation. It is important to
select appropriate markers. In this study, markers were selected from the reconstructed SLA image, which were used to
modify the gradient image. Then two parameters, radius and amplitude of eddy, were used to filter the segmentation
results. The method was tested on the Northwest Pacific using TOPEX/Poseidon altimeter data. The results are
encouraging, showing that this algorithm is applicable for mesoscale eddies and has a good accuracy. This algorithm has
a good response to weak edges and extracted eddies have complete and continuous boundaries. The eddy boundaries
generally coincide with closed contours of SSH.
The visualization in a single view of abnormal association patterns obtained from mining lengthy marine raster datasets presents a great challenge for traditional visualization techniques. On the basis of the representation model of marine abnormal association patterns, an interactive visualization framework is designed with three complementary components: three-dimensional pie charts, two-dimensional variation maps, and triple-layer mosaics; the details of their implementation steps are given. The combination of the three components allows users to request visualization of the association patterns from global to detailed scales. The three-dimensional pie chart component visualizes the locations where more marine environmental parameters are interrelated and shows the parameters that are involved. The two-dimensional variation map component gives the spatial distribution of interactions between each marine environmental parameter and other parameters. The triple-layer mosaics component displays the detailed association patterns at locations specified by the users. Finally, the effectiveness and the efficiency of the proposed visualization framework are demonstrated using a prototype system with three visualization interfaces based on ArcEngine 10.0, and the abnormal association patterns among marine environmental parameters in the Pacific Ocean are visualized.
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