Chlorophyll a concentration (chl a) in the Western Equatorial Atlantic ocean has been
varied in function of great rivers discharge, like the Amazon and Orinoco. Chl a, sea
surface temperature (SST) and winds data from orbital remote sensors has been
allowed a further comprehension of the oceans dynamics, especially in the Amazon
river mouth. This river contributes significantly for primary production in the Equatorial
Atlantic ocean. This work goals the analysis of the seasonal variations and the spatial
structures of chl a in Western Equatorial Atlantic ocean, and their correlations with
TSM, Intertropical Convergence Zone (ITCZ) and Amazon River discharge variability.
Chl a, TSM, winds and discharge river temporal series data were analyzed for the
period from July 2002 to December 2007. Both chl a and SST data were obtained
from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua
satellite. Monthly winds are from microwave scatterometer (SeaWINDS) flown on the
QuikSCAT satellite and discharge river data were acquired on National Agency of
Waters (ANA) database. Monthly average behaviour of chl a and TSM data was
analyzed, as well as the correlations between chl a and TSM, and chl a and the
Amazon River outflow. The data analysis showed that the chl a starts to increase in
July, concomitantly with TSM increase and the North Brazil Current (NBC)
retroflection start to appear. This process always occurs after the larger discharge
period (April-June), with maximum values during boreal summer (July-September). In
this season, the summer bloom indicated by higher chl a and warmer SST are linked
strongly to the ITCZ and NBC retroflection.
|
