Volume
transport of the main equatorial Atlantic Ocean currents are estimated
using temperature profiles from XBT data. The profiles are obtained
from the high density XBT line AX08. These data are combined with
climatological salinity and geostrophy. Levitus salinity (1998) within
the closest 1° x1° square of each XBT observation was used
to estimate an "XBT salinity" by matching the Levitus temperature
to the XBT temperature. This estimate attempts to preserve the T/S
water mass structure as determined by Levitus (1998).
Transport
reveal the major currents within the region (see below) and are consistent
with the slopes of the isotherms. The figure below shows the cumulative
transport starting at zero at 20°N in 100m thick layers. Eastward
flow is negative, westward flow is positive. So for example the NEC
show up as an accumulation of westward flow. Major currents in the
region and their latitudinal extent are highlighted with color coded
arrows and matched up to the appropriate location in the vertical
temperature section.
The
two XBT transects to date confirm what is generally know about the
currents in the region. There is a strong seasonal latitudinal shift
in the NECC. The SEUC remains near 3-5° and the SECC shown large
variability in magnitude as well as location.
Figure
1: The AX08 line is repeated four times a year and results distributed
at an AOML web page (http://www.aoml.noaa.gov).
Figure
1
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