Application of SWOT to the dynamics of Amazon plume and adjacent regions

James carton (University of Maryland, United States)


Semyon Grodsky (University of Maryland, United States); Frank Bryan (NCAR, country United States); Eric Leuliette (NOAA, country United States)

Event: 2015 Ocean Surface Topography Science Team Meeting

Session: Science II: Mesoscale and sub-mesoscale ocean processes: current understanding and preparation for SWOT

Presentation type: Type Oral

The Amazon/Orinoco plume is a shallow, seasonally varying, turbid low salinity layer that spans an area in excess of 10^6 km^2 by late summer - early fall. It has striking features that make it an appealing target for a SWOT mission. It is the World’s largest river-forced freshwater plume, forced by massive discharge from the Amazon and Orinoco River systems, and thus links an active continental hydrologic system to oceanic dynamics. It lies in a region of some of the highest seasonal rainfall rates anywhere in the World Ocean. Its high values of SST and evaporation, and low rates of vertical heat exchange with the cooler water below promote interaction with, and intensification of, fall season hurricanes. And most importantly, the plume lies on top of the vigorous eddy-shedding North Brazil Current system.

This study explores the potential application of mesoscale resolution remote sensing together with numerical modeling to examine plume dynamics; including the roles of surface processes, entrainment, and continental transport; and interactions with the mesoscale/sub-mesoscale ocean dynamics of the western tropical Atlantic. The talk will show preliminary results using remotely sensed winds and rainfall, TERRA/MODIS ocean true color and diffusive attenuation coefficient, surface salinity, and AltiKa sea level as well as analyses of a 0.1x0.1 degree resolution simulation (Fig. 1 shows a snapshot of surface salinity and sea level from the simulation). As an indication of the potential of swath altimetry Altika is interesting because of its 6 km alongtrack sampling, which is clearly able to detect the plume boundaries. Our presentation also highlights features associated with sub-mesoscale mixing and exchange, which are poorly represented in the current model.

Figure 1: 5-day average properties from October, 2000 of the western tropical Atlantic as simulated in a 0.1-deg spatial resolution global general circulation ocean model. The simulation began in 1979 and is forced by daily wind forcing and climatological monthly river discharge. (top) SSS [psu] and (bottom) SSH [cm]. During this season the plume is displaced to the north, while significant amounts of amazon water are carried eastward by the North Equatorial Countercurrent.
Application of SWOT to the dynamics of Amazon plume and adjacent regions

Oral presentation show times:

RoomStart DateEnd Date
Grand Ballroom 2 Wed, Oct 21 2015,15:15 Wed, Oct 21 2015,15:30
James carton
University of Maryland
United States