Research Project Results - South Box
The South Box shows similar patterns to the West and North boxes, but the SST seasonal cycle is less variable, and the correlations are less pronounced. The latter observation is primarily due to increased distance from the mainland.
Chl a and SST plot (left): Chl a and SST again have a distinct negative correlation (-0.788). In this region, the winter chl a values are more likely correct, and probably due to winter productivity related to upwelling in the South China Sea and Luzon Strait. The circled point and point indicated by the arrow will be discussed below.
nLw(551) and SST plot (right): In contrast, nLw(551) and SST show essentially no correlation (0.113). There is little influence from sediments in this region, and therefore very low nLw(551) values, similar to those in the East Box. The nLw(551) range from 0.2 to 0.4 milliwatts per square centimeter meter per micron per steradian (mW cm-2 μm-1 sr-1) is likely characteristic of clear open ocean waters.
Chl a, K490, and nLw(551) plot: Chl a and K490 again exhibit a strong positive correlation (0.989), while nLw(551) and K490 have only a weak positive correlation (0.315). These observations are consistent with the relationship between chl a and K490 in open ocean waters, where the primary influence on the optical characteristics of the water is the presence and concentration of phytoplankton. Oceanic regions with these optical conditions are commonly called Case 1 waters.
When each group of midshipmen presented their results to the class, the two points in the chl a and SST time-series plot (above left) were commented on. In the class, it was speculated that this observation of decreased SST (when it would be expected to increase) and slightly elevated chl a was consistent with the influence of tropical storm systems. Tropical storms will cause decreased SST due to mixing of deeper, colder waters to the surface. This process also brings CDOM from deeper waters to the surface, which causes elevated high chl a values because the sensor cannot fully distinguish between absorption due to chlorophyll and absorption due to CDOM.
During the preparation of this Web article, the speculated cause of the observations described above was investigated. It appears that the speculated cause is indeed the likeliest explanation for the decreased SST and elevated chl a in June 2004 in the South Box. In June 2004, the South Box region was affected by the passage of two typhoons, Conson (Frank) and Mindulle (Inge), early and late in the month. The combined effects of these storms influenced the data sufficiently to produce a “signal” observable in the monthly average MODIS-Aqua data which is utilized by Giovanni. These storms have two names, assigned by the Tokyo Typhoon Center and the Phillippine Atmospheric,Geophysical and Astronomical Services Administration.
The tracks of these two storms are shown below (images courtesy of Wikipedia). Conson’s lifetime was June 4-11, 2004. Mindulle’s lifetime was June 23-July 4, 2004. Conson’s track is shown on the left and Mindulle’s on the right.
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USNA Remote Sensing Class Giovanni Research Projects – Summary
The conclusions shown above, with the exception of the influence of typhoons Conson and Mindulle on the South Box data, are the conclusions of the midshipmen in the remote sensing class. This “trial run” research project demonstrates one way that Giovanni can be used for oceanographic and remote sensing education, and also shows how a class can collaborate to create an in-depth analysis of a particular region.
Subsequent to their presentations, the midshipmen were then shown how to utilize Giovanni to answer the questions in the knowledge survey, and their answers reflected the capability of Giovanni to illustrate and visualize various aspects of biological and physical oceanography. The midshipmen also took a survey of their impressions of the use of Giovanni, and suggestions for improvement. Additional groups and classes are being provided with a similar survey, and the results of these surveys will be compiled for publication.
Introduction -- East -- North -- West -- South
Atmos Composition
