Assessing the limitations of NASA's Aquarius Sensor using the Amazon Plume

A Geographic Information System (GIS) methodology was formulated for validating sea surface salinity measurements along coastlines using the Aquarius sensor. The target study area for this research was the Amazon delta freshwater plume due to its large fluvial output. This area, known as the Amazon plume, is a nutrient rich region of low salinity, which extends roughly 200-500km off of Brazil's coastline. While the Aquarius sensor can view this phenomenon from space, it cannot accurately measure sea surface salinity measurements near coastal areas due to terrestrial return interference. The goal of this research was to address the interference two different ways. The first involved analyzing the raw data with in situ data to find a direct correction while the second involved comparing the data to another physical property, such as total suspended sediment. This assessment was made possible by in situ salinity data from the United States Navy. When comparing this data with the Aquarius data, an average percent difference of 0.0137% was found. This allowed for the determination of what areas were contaminated, requiring an in depth statistical analysis in regards to its distance from shore as well as its relationship with suspended sediment. Validation of the Aquarius sensor near coastal regions can be vital in fulfilling the needs of scientists, aquaculture farms, and fisheries in coastal areas.; The image displays both Moderate Resolution Imaging Spectroradiometer (Aqua/MODIS) and Aquarius data for the Amazon delta region. The surface (Aqua/MODIS) image shows an eight day estimate for total suspended sediment (TSS). Values for TSS are displayed as light blue to orange representing low and high sediment concentrations, respectively. The elevated data points, in dark blue, show sea surface salinity (SSS) measurements acquired from NASA's Aquarius sensor, where the height of the points depicts salinity concentration. ; The image displays in situ U.S. Navy data, and Aquarius data for the Amazon delta region. The surface (U.S. Navy) image shows in situ sea surface salinity data with lower salinity values highlighted in pink gradually increasing into blue. The elevated data points, in green, show sea surface salinity (SSS) measurements acquired from NASA's Aquarius sensor. The height of the points correlate with levels of salinity concentration.